# Coupler Suggestions??



## green caveman (Oct 2, 2009)

Slow progress on the Sidekick conversion - but any progress is better than no progress.

Thanks to much help from the forum (especially Todd!!) we have the measurements and a prototype adapter plate.

Before we can machine the final adapter plate, we need to make the coupler since that will determine the required thickness for the adapter.

Anyone have any suggestions as to how to link the pieces in the photograph together?

The PTO clutch disk (did I mention thanks Todd??) fits the motor. That hub then needs to be attached to the flywheel. The flywheel is, of course, convex and the center hub of the PTO disk is only just larger than the center ridge of the flywheel. 

One thought is to machine the PTO disk center hub down so that it fits inside the center depression on the flywheel. Since there would then not be enough material to run bolts through, attaching it would be a problem - welding is the only idea we can think of, but (not being a welding expert) I'm not sure how easy it would be to weld to the flywheel and then balance the flywheel.

Another choice is a donut spacer of some sort, then attach through the spring steel of the PTO disk and into tapped holes in the flywheel. Centering would seem to be a challenge in this case.

Any thoughts, suggests, etc. would be appreciated.

[Just noticed that the image sizes are different. The PTO disk is about the same total diameter as the flywheel (9" or so), the flywheel is just a little larger. The motor is just a little larger diameter again].


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## Woodsmith (Jun 5, 2008)

Are you determined to keep the flywheel and clutch?

With the pto and the original clutch centre you can mate the motor to the trans directly without the flywheel and clutch.

My immediate concern with using the pto centre on the motor shaft to support the flywheel is that it would not be a tight fit and would allow the flywheel to move and wobble. Even if you drilled and put in set screws I don't think it would give a tight enough fixing and also it would then not be as well centred.

I would recommend using a rigid attachment like a taper lock bush to clamp around the motor shaft. The flywheel could then be bolted to that either with its own set of bolts or with bolts that also do the clamping.

Others may well have their own take on this though.


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## Duncan (Dec 8, 2008)

Hi Caveman,

I'm with Woody on this you don't want to mount a flywheel on a splined coupling I visualise it wobbling all over the place!
Not to mention the axial loads from the clutch release mechanism

If you do keep the flywheel machine off all of the surplus metal you can - especially from the outside

A better bet would be to get your two clutch plates and work out how to bolt them together to get a clutchless transmission
Most EV types only use two of the gears and treat it a a City and a Highway gear


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## green caveman (Oct 2, 2009)

Woody,

I think that the flywheel and clutch are here to stay.

Good thought on supporting the weight. 

I'm not sure I buy into the spline theory though, after all, the connection to the tranny is a spline. The flywheel is heavier, but the spline is a pretty tight fit and the extra space can be filled, even if with something like silicone. Unlike the transmission it doesn't need enough play to move.


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## EVfun (Mar 14, 2010)

green caveman said:


> I'm not sure I buy into the spline theory though, after all, the connection to the tranny is a spline. The flywheel is heavier, but the spline is a pretty tight fit and the extra space can be filled, even if with something like silicone. Unlike the transmission it doesn't need enough play to move.


The flywheel on the stock ICE is supported by the crankshaft and so by the engine bearings. The transmission input shaft is supported by the pilot bushing which has been located in the flywheel or crankshaft so it to is rigidly supported by the crankshaft bearings. The clutch disc is clamped between the flywheel and pressure plate (attached to the flywheel) to drive the splines. The splines transmit torque but locate nothing.


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## Woodsmith (Jun 5, 2008)

green caveman said:


> Woody,
> 
> I think that the flywheel and clutch are here to stay.
> 
> ...


If you can slide it on it is slack and free floating. In engineering terms a pretty tight fit would require pressing on. A tight fit would require the outer to be heated and shunk on.

There is a reason why the original flywheel was mounted with 6-8 bolts onto a flange that locates inside a lip on the back of the flywheel and possibly in the hole in the centre.

There is a lot of mass, even when lightened, to have on anything but a rigid connection. If you go over a bump the mass of a static flywheel will move on the spline. If it is also spinning then you will have dynamic and centripital forces all acting whenever the vehicle moves, bumps, jolts, etc.
The spline fitting would only really be useful if it was a very tight shrink fit onto the shaft. In reality there is too much spinning mass for this to be useful as there would be no way of ensuring it is spinning true given the diameter of the flywheel. Fine with a gear wheel but the large diameter exaggerates any discrepancy.
Even with a taper lock there is a need to check with a dial gauge, while the bolts are being tightened, that it is staying true and aligned.

The primary shaft of your transmission also need to locate in the bush that would have been in the end of the crank shaft. That will need to be replicated on the coupler in the centre of the flywheel. Again, even the slightest movement and the clutch could clamp the driven plate off centre leading to greatly increased vibration.

Look at the arrangement from the motor though to the transmission.

Rigidly located motor shaft on two bearings.
Coupler and flywheel free floating.
Clutch plate free floating.
Transmission shaft supported on one bearing on inner end and free floating at the clutch end.

There is a lot of free floating spinning mass that will suffer misalignment whenever the clutch pedal is depressed and released.


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## toddshotrods (Feb 10, 2009)

Thanks green, I am just contributing what I learn to help others, like the crew on this board has helped me. Give credit to the whole, not the one, because the forum makes all this possible.

Unfortunately, I have to agree with the consensus here. Having that same motor and PTO combination, I know for sure it is a slip-fit connection that is only good for transmitting torque. I suspect that whatever these motors plugged into on the Hyster forklifts had a shaft or hub that was also supported by bearings because the shaft also seems to be cut and treated for a slip-fit connection. I say that because the PTO hub fits and rides on it like it was meant to be there - just like a clutch disc would on a transmission input shaft, or a driveshaft yoke on the output shaft. Those shafts often have some type of hard-chrome like surface, and my motor shaft appears to have this as well. If you mount a flywheel to that, you're going to have one heckuva wobble!  If you're able to drive it, I would guess that it would eventually break the motor shaft. Sorry. 

What you really need is to find a sealed roller bearing with a large enough internal diameter to fit over an adapter made to mate the PTO hub to the flywheel. A quick search on McMaster turned up plenty of bearings with a large enough center hole, but not rated for the motor speeds you'll turn. I didn't do an exhaustive search though. The bearing would fit over the adapter, and into a race or register in the adapter plate. That means the adapter plate would be carrying all the radial loading of the flywheel.

The problem is a bearing that size is going to be expensive. A thin bronze sleeve bearing would be ideal for size and cost, but lubrication becomes an issue.

The other caveat is your machinist has to be spot on with the coordinates and machining. Any misalignment is going to put a bind on the motor and/or transmission shafts. Eventually something is going to give if there's a bind. Best case is just a trashed bearing.


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## green caveman (Oct 2, 2009)

Three (four?) dissenting voices - I think I'm detecting a pattern - I'm glad I asked.

How much bearing would people think would be required for support? I'm thinking that there is (maybe) enough spare material on the PTO disk to machine it parallel over, say a 3/4". Attach the PTO hub to the flywheel and then use a flange bearing over the PTO hub attached to the adapter plate. (Some possible spacing problems here).

Still doesn't seem like much support to me, but I'm (obviously) not a good judge.


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## toddshotrods (Feb 10, 2009)

green caveman said:


> ...I'm thinking that there is (maybe) enough spare material on the PTO disk to machine it parallel over, say a 3/4". Attach the PTO hub to the flywheel and then use a flange bearing over the PTO hub attached to the adapter plate. (Some possible spacing problems here).
> 
> Still doesn't seem like much support to me, but I'm (obviously) not a good judge.


That might be a workable idea. I would want more than 3/4" though. Ideally, you want to push the bearing as close to the flywheel as possible, to avoid having the weight of the flywheel hanging on the end of the machined hub, and placing side loading on the bearing. You should be able to find a bearing that would require minimal machining of the hub. He'll also need to turn a (slight press-fit) spindle for machining the PTO. It can be made of a slightly softer material to avoid damaging the splines. Again, the machine work needs to be very precise.

You also need to think about keep the flywheel in place, longitudinally, on the shaft. Since the motor shaft is drilled and tapped, you may be able to use a small bolt with a thrust bearing inside the PTO-to-flywheel adapter. So you would press the bearing into the adapter plate, install it on the motor, bolt the PTO and fywheel together with the adapter, install the trust washer, slip it on the shaft seating the machined PTO hub in the bearing, lock it together with a small bolt, install clutch and transmission...

There is also the possibility of shaving that center ring off the motor's DE head to get the whole assembly seated closer to the motor. That would require less thickness in the adapter plate, or fewer components to build it.

Doable, but there are a lot of components to get right. Not saying anything bad about your machinist but, as some of us have learned, it's easy for them to underestimate an automotive powertrain system and not get it quite right. You have to be like a fruit fly buzzing around their head incessantly screaming about precision. If they get annoyed with that mandate, or seem opposed to considering it from every possible angle, or are in a rush to get it done, you might consider testing them on something less critical first.


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## green caveman (Oct 2, 2009)

toddshotrods said:


> I would want more than 3/4" though. Ideally, you want to push the bearing as close to the flywheel as possible, to avoid having the weight of the flywheel hanging on the end of the machined hub, and placing side loading on the bearing.


3/4 is all you get on that PTO hub. I was imagining the PTO hub attached directly to the flywheel, so the bearing would be pretty close.

It may not work because we still need 1.7" or (1.706?) from the front of the transmission to the flywheel clutch plate (magic number).

It might be easier just to machine a short shaft that bolts to the flywheel and uses the existing bolt holes in the PTO hub. With the bearing on that shaft we can make it any reasonable length.

Maybe something like the attached sketch? 



toddshotrods said:


> You also need to think about keep the flywheel in place, longitudinally, on the shaft. Since the motor shaft is drilled and tapped, you may be able to use a small bolt with a thrust bearing inside the PTO-to-flywheel adapter. So you would press the bearing into the adapter plate, install it on the motor, bolt the PTO and fywheel together with the adapter, install the trust washer, slip it on the shaft seating the machined PTO hub in the bearing, lock it together with a small bolt, install clutch and transmission...


More argument in favor of a shaft. It'd be hard to do this with just the PTO hub.



toddshotrods said:


> There is also the possibility of shaving that center ring off the motor's DE head to get the whole assembly seated closer to the motor. That would require less thickness in the adapter plate, or fewer components to build it.


Interesting thought. I'm still not *absolutely* certain that the motor is going to clear the front diff. 



toddshotrods said:


> Doable, but there are a lot of components to get right. Not saying anything bad about your machinist but, as some of us have learned, it's easy for them to underestimate an automotive powertrain system and not get it quite right. You have to be like a fruit fly buzzing around their head incessantly screaming about precision. If they get annoyed with that mandate, or seem opposed to considering it from every possible angle, or are in a rush to get it done, you might consider testing them on something less critical first.


Judging is a little out of my league, but he seems pretty detailed. The trick seems to be getting the SolidWorks models right (which you can tell is out of my league just by looking at the sketch!).


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## Woodsmith (Jun 5, 2008)

toddshotrods said:


> Doable, but there are a lot of components to get right. Not saying anything bad about your machinist but, *as some of us have learned*, it's easy for them to underestimate an automotive powertrain system and not get it quite right. You have to be like a fruit fly buzzing around their head incessantly screaming about precision. If they get annoyed with that mandate, or seem opposed to considering it from every possible angle, or are in a rush to get it done, you might *consider testing them on something less critical first*.


I machinist offered a favour in machining the coupler for my 12" motor. The favour has left the motor unusable as the shaft is no longer concentric to the armature and the coupler and bearing support are not concentric nor square to the axis of the armature. As the armature is without a bearing and relys on the coupler to provide a bearing surface the motor is now U/S unless I spend around £400+ on reshafting it.

Try to design around using a proper bearing rather then say one of these.








They allow for misalignment and so it would be much more difficult to ensure that it is properly aligned 

You can make up a similar shaped bearing cap to support a single or double row bearing that rides on the outside of the PTO centre. It can be bolted to the front of the DE cap and then the flywheel bolted to the modified PTO centre.

Here was my 12".
This is the DE. The shaft in not supported and the bearing is larger then original in the DE cap.









This is the end of the crank shaft machined and bored out to fit the shaft.









This is the crank end being pressed onto the shaft and though the bearing.









This is how it looks when pressed most of the way home.









When all the way home it should look like this with the flywheel and clutch on the trans. In this shot the rest of the motor and armature were removed to figure out why it wasn't concentric.


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## Woodsmith (Jun 5, 2008)

Here are some alternative shots of the DE cap with the bearing carrier in place.


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## Woodsmith (Jun 5, 2008)

There is a flange around the shaft on the outside of the DE cap.









Can that be used as part of the bearing support for the bigger bearing?
It could maybe take half the thickness of the big bearing and then a cap can be made that supports the outer half of the bearing and locates on the outside of that flange.

It will mean machining the DE but I figured you have to machine it anyway.


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## Woodsmith (Jun 5, 2008)

Here are some photos of my 11" motor.

The shaft at the DE has no bearing surface.









The bearing is on a spur gear that I removed from the forklift axle.

















When the spur gear is fully on the shaft it protrudes this much from the frame. One bearing will be fitted in the new DE cap to take the inner end of the bearing.









Mine will be used for a chain drive and so once the DE is made I can then make a second component to support a bearing on the outer end of the spur gear. The spur gear will be machined down to take a chain sprocket.









So although different application I have the same problem of a floating splined 'tube' that need to be controlled.
I will most likely use two bearings, one on each side of the sprocket but I will try shrinking the spline tube, when the gear teeth are machined off, and then using a bolt to pull the tube tight onto the motor shaft. I can consider risking this as there is much less risk with dynamic misalignment (as there is no flywheel weight), only increased chain and spline wear. It will do to test and set up initially.


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## green caveman (Oct 2, 2009)

Woodsmith said:


> I machinist offered a favour in machining the coupler for my 12" motor. The favour has left the motor unusable as the shaft is no longer concentric to the armature and the coupler and bearing support are not concentric nor square to the axis of the armature. As the armature is without a bearing and relys on the coupler to provide a bearing surface the motor is now U/S unless I spend around £400+ on reshafting it.


Call me chicken, but that's why I'm trying to avoid machining either the motor or the flywheel. One of the reasons I was happy to find the spline. The PTO plate is easy enough to replace (the flywheel's not that bad but I'd like to avoid problems there).



Woodsmith said:


> Try to design around using a proper bearing rather then say one of these.
> 
> 
> 
> ...


Depending on the distance, and I haven't measured them recently enough to be sure, one of these was looking as though it would be an ideal fit with the design I sketched. It would allow about a 1" bearing surface and still keep the 1.7xx" spacing. 



Woodsmith said:


> There is a flange around the shaft on the outside of the DE cap.
> 
> Can that be used as part of the bearing support for the bigger bearing?
> It could maybe take half the thickness of the big bearing and then a cap can be made that supports the outer half of the bearing and locates on the outside of that flange.
> ...


If I was just going to use the PTO hub then this might work, but I think that has problems with spacing, bearing surface, etc. If I go with the sketched design the bearing is some distance from the motor.

Could be an option to use another bearing here and add some more support.


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## toddshotrods (Feb 10, 2009)

green caveman said:


> ...It might be easier just to machine a short shaft that bolts to the flywheel and uses the existing bolt holes in the PTO hub. With the bearing on that shaft we can make it any reasonable length.
> 
> Maybe something like the attached sketch?...


That could work, but I thought you were already tight on space for the motor. That adds a matter of inches! 

The beauty of it is it pretty much releases the motor shaft from any misalignment stresses. The PTO hub can wiggle a little, and if you use silicone it shouldn't keep up too much racket. I would probably do some testing without the silicone to make sure there weren't any gross misalignment noises.

If you can figure out a way to make that work, and to build a longer adapter, I don't see why it wouldn't work. Double bearings would be good.



Woodsmith said:


> I machinist offered a favour in machining the coupler for my 12" motor. The favour has left the motor unusable as the shaft is no longer concentric to the armature and the coupler and bearing support are not concentric nor square to the axis of the armature. As the armature is without a bearing and relys on the coupler to provide a bearing surface the motor is now U/S unless I spend around £400+ on reshafting it....


I didn't want to name names, but was hoping you would chime in to confirm...


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## Woodsmith (Jun 5, 2008)

Caveman, can you post a side view of the pto centre?
Maybe put a ruler next to it for scale.


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## green caveman (Oct 2, 2009)

toddshotrods said:


> That could work, but I thought you were already tight on space for the motor. That adds a matter of inches!


I just remeasured the thickness of the flywheel - ~1.5", so there is more of a space constraint than I remembered.

This means that Woody's idea of just using the flange on the DE of the motor as a bearing holder and machining down the PTO may work and be fairly simple (1.7 is the target distance). That leaves the problem of attaching the PTO hub to the flywheel. If it's going to be a direct connect, it would be hard to bolt, but I didn't get much of an uptake on the idea of welding it, but I suspect that even if that's possible balancing it afterwards would be a challenge.

With another shaft, since that would increase the distance, it would just take some really creative machining of the adapter plate to get all the pieces spaced correctly. Something like a bearing mounted into the back of the plate and the motor mounted on the front. I have a 2" block of aluminum for the adapter plate so it may not be impossible, but I suspect that even with that it would take some spacers on the motor side to get enough length.

We'll either clear the front diff or we won't, the extra shaft doesn't matter. If it clears it, there's space under the hood for the motor. Of course, we can't be certain that it's going to clear it until everything is back together. We still have to figure out the location of the transmission, the only suggestion I've seen for that is to make sure that the driveshaft is straight.


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## green caveman (Oct 2, 2009)

Woodsmith said:


> Caveman, can you post a side view of the pto centre?
> Maybe put a ruler next to it for scale.


Here's the image.


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## Woodsmith (Jun 5, 2008)

Thanks.

I am assuming that the other side of the disc has a small centre hole and some more of the splined part pokes through?

Both ends could be machined parallel and a thick flange made up to bolt between the PTO flange and the flywheel recess. Bolts could then be used to couple everything together.

Except that the bolt heads or nuts would protrude out where you have the ruler now.

So make a steel flange to fit the flywheel and then weld it to the PTO centre both around the rim of the flange and through the holes to plug weld. The steel flange can be made a shrink fit onto the PTO centre so that it is tight and square before welding.
After welding it can be machined true by pressing a shaft through the centre and turning. Alternatively the shaft can be a three part unit. Two cones on a smaller shaft. The shaft can be threaded like a bolt and a nut used to tightern the cones together to locate and centralise the PTO spline. A DTI gauge will confirm it is true.
After turning true the other end of the PTO, where your ruler is, can then have a bearing put on it.

Once the PTO centre is true it can be slipped onto the motor shaft and pressed into the new bearing that you have fitted with a new bearing retainer cap.
A cap screw and shaped plug can be wound into the threaded hole in the end of the shaft to keep the PTO centre pulled in tight.
The welded on part that fits the flywheel will also have a hole in the end that suits a bush for the transmission primary shaft.
The flywheel can then be bolted on to threaded holes with thread lock.


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## toddshotrods (Feb 10, 2009)

green caveman said:


> ...This means that Woody's idea of just using the flange on the DE of the motor as a bearing holder and machining down the PTO may work and be fairly simple...


I would be really anal about making sure that whatever you're attaching the bearing to is concentric with the motor shaft. That flange on the DE fit into something on the Hyster, but I've never really checked to see if it was indeed concentric with the shaft. Now that we've brought the subject up, you should also check the pattern you got from me with the motor shaft - since you have a mock-up cut, that's just a matter of using a dial indicator and/or a caliper to see how it plays out. I would be interested to see the results of that. When I did the pattern concentricity was considered, but wasn't critical because I'm running direct drive and my rear mount has nothing to do with the driveshaft. It just secures the motor in the chassis.




green caveman said:


> ...With another shaft, since that would increase the distance, it would just take some really creative machining of the adapter plate to get all the pieces spaced correctly. Something like a bearing mounted into the back of the plate and the motor mounted on the front. I have a 2" block of aluminum for the adapter plate so it may not be impossible, but I suspect that even with that it would take some spacers on the motor side to get enough length.
> 
> We'll either clear the front diff or we won't, the extra shaft doesn't matter. If it clears it, there's space under the hood for the motor. Of course, we can't be certain that it's going to clear it until everything is back together. We still have to figure out the location of the transmission, the only suggestion I've seen for that is to make sure that the driveshaft is straight.


Not sure I'm following all this. How about some more sketches to show how it all mounts in the vehicle before I start assuming things? An overhead view and side view of what you're planning would be nice.



green caveman said:


> Here's the image.


I see, I forgot how shallow these PTO hubs are. I was also too lazy to go outside and look at mine, or at least look at the pictures! 




green caveman said:


> ...I didn't get much of an uptake on the idea of welding it, but I suspect that even if that's possible balancing it afterwards would be a challenge...


It opens the whole can of metallury worms. What materials are they made of, what type of filler rod would be used to join them, what would be the long-term effect of having that much heat concentrated on the center of the flywheel (which is submitted to various stresses in use)?

Just too many variables, that could be eliminated with a proper bolt-up solution...


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## Duncan (Dec 8, 2008)

Hi Guys

I have looked at the suggestions and I think all of them will fail - fast
The problem is the mass and inertia of that flywheel - it is not needed for an EV and that much mass will give huge problems with whirl and ballance

Have a look at the flywheel - there will be holes for clutch pressure plate - everything outboard of those is not just useless but a pain

Can you find a piece of plate about 6mm thick big enough for the clutch pressure plate?

Machine a hole in the middle for the gearbox input shaft bearing
Drill and tapp holes for the clutch pressure plate

Throw the flywheel over a hedge

This should drop the rotating mass enough for one of the other ideas to work


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## green caveman (Oct 2, 2009)

toddshotrods said:


> .. flange on the DE fit into something on the Hyster, but I've never really checked to see if it was indeed concentric with the shaft


I don't think that the flange on the motor does us any good. The shaft sticks out an inch from there - the length of the shaft on the PTO hub.



toddshotrods said:


> Not sure I'm following all this. How about some more sketches to show how it all mounts in the vehicle before I start assuming things? An overhead view and side view of what you're planning would be nice.


Like anything I draw will help! Forget the motor mount, that's a problem (or not) for another day.

How about the attached sketch. It's a little confused. The idea is to build the aluminum coupler in the middle, the part that's hatched. This centers into the indent in the flywheel and the indent in the back of the PTO hub (see picture). The PTO hub and the flywheel both bolt to this. It should be as thin as possible (how thin is that?)

If the PTO hub is machined parallel, then there should be about 3/4 left for a bearing. The bearing could be pushed into the adapter plate. I *think* that a 2" aluminum block/sheet will work - that is, I think that the distance from the front of the motor to the clutch face of the flywheel can be kept to less than 3.7"

The coupler is constrained concentric circles, which I'm assuming are fairly easy to build/align, although I'm not sure about the back of the PTO disk.


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## Woodsmith (Jun 5, 2008)

Duncan said:


> Hi Guys
> 
> I have looked at the suggestions and I think all of them will fail - fast
> The problem is the mass and inertia of that flywheel - it is not needed for an EV and that much mass will give huge problems with whirl and ballance
> ...


The flywheel is the problem, coupled with a floating spline.

The flywheel could be machined down to remove a lot of weight or it could be remade as a plate. Both have their machining and balance issues that absorb cash.

Having now seen the back of the PTO disc I am back to thinking a good old taper lock bush bolted to the flywheel will be the better. 
Short, tight, all bolts on one side, no additional bearings or retainers, easy to fit, simple to make.

Better still, forget the clutch and flywheel and just have a solid coupler.


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## green caveman (Oct 2, 2009)

Duncan said:


> Hi Guys
> 
> I have looked at the suggestions and I think all of them will fail - fast
> The problem is the mass and inertia of that flywheel - it is not needed for an EV and that much mass will give huge problems with whirl and ballance
> ...


There's a discussion of clutches and flywheel here:

http://www.diyelectriccar.com/forums/showthread.php?t=41564

Whether to keep it, and whether the flywheel causes range problems is discussed. 

I agree that decreasing the mass of the flywheel would decrease any possible vibration problems, but, as others have pointed out, since it's rotating pretty fast it's a non-trivial engineering project to remove/replace.


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## green caveman (Oct 2, 2009)

Woodsmith said:


> Better still, forget the clutch and flywheel and just have a solid coupler.


You'd have to argue that with the rest of the crew, they're (at least one in particular is) pretty adamant about keeping the clutch.


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## green caveman (Oct 2, 2009)

This isn't the first design with a clutch. What did others do, just hard attach the flywheel to the motor shaft and rely on the bearings in the motor to hold it in place?


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## green caveman (Oct 2, 2009)

Woodsmith said:


> Having now seen the back of the PTO disc I am back to thinking a good old taper lock bush bolted to the flywheel will be the better.
> Short, tight, all bolts on one side, no additional bearings or retainers, easy to fit, simple to make.


OK, if I understand your idea correctly, you're proposing a taper lock bush into the inside (?) back of the PTO hub said bush would then be drilled/tapped and bolted to the center of the flywheel?

Or, was the proposal to go round the outside of the PTO hub.

I think I like the idea, but am concerned that the weight of the flywheel is hanging on the bush.


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## toddshotrods (Feb 10, 2009)

green caveman said:


> This isn't the first design with a clutch. What did others do, just hard attach the flywheel to the motor shaft and rely on the bearings in the motor to hold it in place?


The issue is because your motor has splines. If it had a simple shaft with a keyway, you would put a taper lock on the shaft and simply bolt the flywheel to it. Removing as much weight as possible from the flywheel is a concern then, because it's hanging on the motor's DE bearing. You could also disassemble the motor and have the splines turned off of the shaft and go with a conventional setup. If your machinist's lathe is big enough he should be able to do that easily. The caveat is remember what happened to Woody's motor shaft! If it's not turned true, it's possibly ruined. 

Without touching the motor, you have to come up with a supported adapter system that makes use of the splined PTO hub. As far as the weight of the flywheel, it can be turned down until it's as light as possible. Why reinvent the wheel? I still like the idea of turning the PTO hub to accept a bearing, and a steel adapter to mate it to the flywheel most. You don't want aluminum there.


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## toddshotrods (Feb 10, 2009)

How about a pic of the other side of the flywheel? Just at a glance, there is a LOT of weight to be removed. The ring gear, and that whole lip on the front side can be totally shaved off. Machine it down to just outside the pressure plate mounting holes, and possibly shave a little more of the thickness, and it will be fit and trim.

Just for the record, I would run a solid, clutchless, adapter. I just kept my concentration on your stated goals, instead of what I would do.


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## green caveman (Oct 2, 2009)

toddshotrods said:


> How about a pic of the other side of the flywheel? Just at a glance, there is a LOT of weight to be removed.


If we're going to start in on the flywheel, then the simplest solution to the coupler problem would be to machine the "back" side flat and bolt the PTO hub directly to it. Then just machine down the PTO hub and stick it in a bearing.

There are two problems that I see with that. Centering the PTO hub on the flywheel and convincing the guy we're working with the machine through 1/2" of cast iron. 

The second problem could probably be solved by convincing somebody else to take of the first 3/8", say a place that faces flywheels for a living. Heck, if they could convince me that the faces would be parallel they could take off the whole 1/2" or whatever.

The first problem would seem to be the more difficult. Something like creating a shaft though the flywheel and the PTO hub to get them aligned. However, I'm not sure that the flywheel is thick enough to provide a guide, so it would have to be some sort of disk attached to a shaft. Better ideas?? 

Might be possible to align them before facing the flywheel using the depression in the center of the flywheel and the back of the PTO hub. Drill/tap the holes and then cut down the flywheel.

There's still a 2" block of polyethylene somewhere around that should be sufficiently dimensionally stable to use to make that shaft. Certainly easy to machine!


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## dtbaker (Jan 5, 2008)

ok, I am jumping into this late.... and I know ya'll Los Alamos guys are bright, but it looks like you're sweating over a problem that doesn't exist.

why NOT stick with the 'standard' solution for people retaining a clutch and put the stock clutch/flywheel on a keyed hub to the motor, with thickness set to the same 'magic distance' working with stock tranny?

going to great lengths to remove ounces of rotating weight, close to center, seems like a BIG risk and significant expense for minimal gain unless you are drag racing.....


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## green caveman (Oct 2, 2009)

dtbaker said:


> ok, I am jumping into this late.... and I know ya'll Los Alamos guys are bright, but it looks like you're sweating over a problem that doesn't exist.
> 
> why NOT stick with the 'standard' solution for people retaining a clutch and put the stock clutch/flywheel on a keyed hub to the motor, with thickness set to the same 'magic distance' working with stock tranny?
> 
> going to great lengths to remove ounces of rotating weight, close to center, seems like a BIG risk and significant expense for minimal gain unless you are drag racing.....


Maybe. Given Woody's experience there's some reluctance to machining down the motor shaft. You still need to attach "something" to the motor shaft and the flywheel, and that's still undefined. Whatever that is still need to be machined and centered on the flywheel.

The only problem you really eliminate is the idea of a bearing because you're using the bearings in the motor to support the weight of the flywheel. You add the problem of machining the motor shaft, which the spline eliminates.


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## Guest (Feb 15, 2011)

Even in drag racing you'd more than likely be able to remove more from other places. Also if your taking weight off the flywheel you don't want to take it off the inside but you want to take it from the outside. Reduces rotational weight and if you have more weight closer to the center you spin up faster. Same as riding a merry go round and you jump to the center changing the rotational mass from out on the edge to close to the center you spin up faster. Same thing. Keep your mass in the center if you must. But ounces of weight make little difference unless your trying to squeak an extra 100 thousandths of a second off your 1/4 mile run time. I'd say you'd be better off trying to put more power to the system than trying to remove ounces of weight. For the street it is absolutely not needed. Don't waste your time. 

Pete


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## dtbaker (Jan 5, 2008)

green caveman said:


> Maybe. Given Woody's experience there's some reluctance to machining down the motor shaft. You still need to attach "something" to the motor shaft and the flywheel, and that's still undefined. Whatever that is still need to be machined and centered on the flywheel.
> 
> The only problem you really eliminate is the idea of a bearing because you're using the bearings in the motor to support the weight of the flywheel. You add the problem of machining the motor shaft, which the spline eliminates.


I am totally not following the argument I guess. machining down a shaft designed to handle torque seems like a REALLY bad idea. saving ounces on a hub experimenting with materials not designed for several hundred foot-pounds of torque also seems like a bad idea.

why introduce a bearing in the middle? there are no 'support' issues of consequence that the motor shaft bearings and tranny shaft bearings have not been designed to handle... why mess with tiny tweaks in time tested transmissions? There are reasons that the plate clutch (rather than a fixed coupler) has been developed over years made out of steel (rather than lightweight plastics or other alloys) to handle the alignment, torque, balance, and rotational stress issues ....


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## Duncan (Dec 8, 2008)

Hi Guys

This may be something that has been tried, 
why not use a split coupling onto the outside of the splines?

A good split coupling transfers all of the torque by friction, the key is only for insurance

So if you don't want to machine your shaft get a split taper coupling - make a special key that engages in the key-way on one side and in between two splines on the other

Modify the end of the coupling for the flywheel (lightening would help a lot) then attach the coupling with a healthy dose of the correct Loctite and a good high torque

The coupling will clamp onto the outsides of the splines this will reduce the clamping area but increase the clamping pressure

Then check the flywheel for runout

You don't use the other clutch plate at all in this method


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## Jimdear2 (Oct 12, 2008)

This is basically what we did for the 13 inch GE motor we are using for the pulling tractor. A good taper lock bushing and a sprocket that can be machined into an adapter to mount the flywheel.

A couple of notes on the process.

If you do this, use caution to get repeatability when you mount the taper lock. You might need to mount it several times to get it true.

Use the best bearing you can find on the DE end of the motor.

Have the flywheel lightened as much as possible. Most flywheels are registered so they will install in the same relationship and location. Make sure what you have made up is the same. Balance it as an assembly if possible

Check the existing spline diameter for run out, If it is ok and the spline is of a common size consider just grinding in a keyway and choosing a taper lock.

If there is enough wear in the spline that it is no longer concentric you will need to rework it.

The spline is probably glass hard so you might look into having it ground. Carbide works but it takes forever.

Same with cutting a keyway.

Work with the existing shaft centering holes with good live centers in the holes on each end of the shaft. This is what I think happened to Woodies 12 inch. The machinest cut off the shaft before drilling the centering hole deeper.

Good luck



Duncan said:


> Hi Guys
> 
> This may be something that has been tried,
> why not use a split coupling onto the outside of the splines?
> ...


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## Woodsmith (Jun 5, 2008)

From what I gather on this thread the machining of the flywheel mass is an aside.

The main issue is trying to use the PTO spline as it fits the spline on the motor shaft.
This method results in a free floating coupling that would then allow any imbalance in the flywheel to cause a vibration and also would allow misalignment whenever the clutch is depressed. The flywheel would also float back and forth on the shaft.

The need is to find an effective way to use the PTO hub to mount the flywheel rigidly to the motor shaft and still remain true OR mount the PTO hub onto a bearing that keeps it true but floating on the shaft.

Using a taperlock bush would be good but due to the fineness of the splines there would be very little contact area for friction only and so a key would be needed or the splines removing.

Removing the splines would/should not weaken the shaft as it is only as strong as the root diameter of the splines anyway but it is a risk that the job could be done badly. Use a motor shop rather then a general machine shop?

The motor bearings, if replaced for good ones would be more then enough to support the dynamic mass of the flywheel IF it was rigidly coupled. The only reason for another bearing is to stablise the floating PTO spline so the flywheel doesn't cause the PTO spline to whip and vibrate.

Caveman, Do not machine away the location at the back of the flywheel, you will need it to centre the flywheel onto whatever you use. If it is flat then you are only relying on the bolts to keep it centred.

I don't think it is a good idea to machine cast iron too thin. Not sure if it is a risk but something bothers me about that.


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## toddshotrods (Feb 10, 2009)

First, to address the issue of machining the flywheel, it wasn't for racing or theoretical power gains. The point was to reduce the amount of weight adding side or radial loading on the bearing.




green caveman said:


> If we're going to start in on the flywheel, then the simplest solution to the coupler problem would be to machine the "back" side flat and bolt the PTO hub directly to it. Then just machine down the PTO hub and stick it in a bearing.
> 
> There are two problems that I see with that. Centering the PTO hub on the flywheel and convincing the guy we're working with the machine through 1/2" of cast iron.
> 
> ...


No polyethylene! That's not suitable for anything here, other than a mock-up adapter plate.

You're making simple machine work sound more difficult than it is. Machining some material off that flywheel, and keeping everything concentric, should be child's play to a decent machinist. Even cutting a new register in the center for the PTO hub is just a matter of precision. This is what the PTO side of my driveshaft adapter looks like. The same thing could be machined into your flywheel (if it doesn't interfere with the existing mounting face and holes). No shaft is needed because this is machined perfectly for the hub to press into.











Jimdear2 said:


> This is basically what we did for the 13 inch GE motor we are using for the pulling tractor. A good taper lock bushing and a sprocket that can be machined into an adapter to mount the flywheel.
> 
> A couple of notes on the process.
> 
> ...


I'm not crazy about the idea of a taper lock on a splined shaft, but Jim is proof positive that it can work. With the torque and stress his pulling tractor is subjected to, it has to be a good connection. I'm just, admittedly, too anal about engineering and machine work. If you choose that route, heed his advice about checking the shaft for wear.

Also, notice he still recommends removing the excess weight from the flywheel?


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## green caveman (Oct 2, 2009)

OK, I think we have two topics running:

1) Lightening the flywheel for:
a) Performance, which we don't really care about
b) To reduce the mass that has to be support and controlled. This seems reasonable. I'd add that my real motivation to do this would be to make mounting something to the flywheel easier because the back face could be made flat and parallel to the front face. Clearly there's too much material on the flywheel so even conservative machining would help here.

2) Attaching to the motor shaft:
a) Something around the outside.
b) The spline hub.

I'd have to check, but I recall that the motor shaft has some wear, but I don't know if enough to make it out of round. I don't like the idea that the bush could be put in such that it's out of round because I have no feel for how difficult it would be to make this connection concentric, or concentric enough. Probably I just don't understand the issue well enough and it's not a real concern. You're also adding the flywheel weight to the DE bearings, but in a practical sense that doesn't seem to have caused others problems.

The spline hub resolves the issue of eccentricity in the connection, but adds the problem of requiring an additional bearing support. It moves the problem of ensuring that everything is concentric to the fabrication rather then the assembly phase. I think that's a good thing.

The risk here is that the only easy solution to providing a bearing is to use the turned PTO hub which gives only about 3/4" for a bearing and it's not clear that's enough to support the flywheel assembly.


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## green caveman (Oct 2, 2009)

If we keep the splined hub and thin down the flywheel, then would anyone expect something like the attached to have a problem?

Just bolt the PTO disk to the flywheel and support the assembly with a 3/4" bearing over the PTO disk.

The problem just comes down to centering the PTO disk on the flywheel.


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## toddshotrods (Feb 10, 2009)

green caveman said:


> If we keep the splined hub and thin down the flywheel, then would anyone expect something like the attached to have a problem?
> 
> Just bolt the PTO disk to the flywheel and support the assembly with a 3/4" bearing over the PTO disk.
> 
> The problem just comes down to centering the PTO disk on the flywheel.


That's probably the way I would go. If you can lighten the flywheel significantly it doesn't appear that there would be that much stress on the PTO. It looks like you have the later design PTO hub, and they seem to be made of some pretty tough steel.

As for mounting the PTO hub to the flywheel, if you're going to have that area machined down just machine it to accept the hub. Done correctly, the hub will press into the flywheel. That lip on the back side of it is what centers it (just like it did on the disc). A recess needs to be cut in the flywheel to accept that. Unless the two bolt patterns are conflicting, then you might need an adapter.

It's hard to say for sure, without exact measurements or patterns.

Another option you can consider, if you like parts matching, is to try and find an aluminum flywheel that uses the same size clutch disc, or same spline pattern in the disc. Shave the starter ring and machine it to accept the PTO hub, and you'd have a featherweight setup that places minimal stress on the support bearing.


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## Woodsmith (Jun 5, 2008)

green caveman said:


> If we keep the splined hub and thin down the flywheel, then would anyone expect something like the attached to have a problem?
> 
> Just bolt the PTO disk to the flywheel and support the assembly with a 3/4" bearing over the PTO disk.
> 
> The problem just comes down to centering the PTO disk on the flywheel.


This would be the simpler solution but I would still advise against removing the rebate at the back of the flywheel as this is the key that centres the flywheel. If it were flat then you would have the huge (relatively) clearance holes to allow the flywheel to slop about.

Just this to think about.


> The spline hub resolves the issue of eccentricity in the connection,


The spline is a floating fit, you may think it is tight but if it was tight you would say it didn't fit. It will not give you a concentric fit to the shaft. This is what the additional bearing and carrier will achieve if it is made right.

The taper lock bush is tight, very tight, and can be made concentric by correct fitting. The fitting process is important and instructions can be found from manufacturers.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> This would be the simpler solution but I would still advise against removing the rebate at the back of the flywheel as this is the key that centres the flywheel. If it were flat then you would have the huge (relatively) clearance holes to allow the flywheel to slop about...


That's why I keep suggesting machining the flywheel to accept the PTO hub - or - making a new adapter. Based on the old rebate, as you call it Woody, the new one would be cut to accept the PTO hub. Whether it's on a lathe or in a mill, any machine work done to the flywheel should be based off that rebate. On a lathe you would chuck the flywheel, and true it with a dial gauge reading the lip of that rebate. On a mill you put the dial gauge on the spindle and find x-y origin, according to the lip of that rebate. Either way, you have the exact center's coordinates and all machine work is done from that point. Cutting a new recess, register, or rebate, to accept the PTO would then be easy as pie. If the machinist can't do this simple operation they need to brush up on the basics, or the machines are off.








This is how any machined part goes through multiple setups in machining. It's extremely accurate when done properly.


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## green caveman (Oct 2, 2009)

toddshotrods said:


> That's probably the way I would go. If you can lighten the flywheel significantly it doesn't appear that there would be that much stress on the PTO.
> [...]
> That lip on the back side of it is what centers it (just like it did on the disc). A recess needs to be cut in the flywheel to accept that. Unless the two bolt patterns are conflicting, then you might need an adapter.


That should work.

I don't think that there's a conflict once the lip (rebate) has been removed from the flywheel.



toddshotrods said:


> Another option you can consider, if you like parts matching, is to try and find an aluminum flywheel that uses the same size clutch disc, or same spline pattern in the disc. Shave the starter ring and machine it to accept the PTO hub, and you'd have a featherweight setup that places minimal stress on the support bearing.


That would be cool. They make them for the Sidekick. Mod'ing Sidekicks is a pretty popular occupation so there are bunch of after-market parts - suspension parts will definitely get some attention once the batteries are added.

The only problem with that option is that an aluminum flywheel is about $350 - most of the original cost of the donor car. Maybe we'll end up trashing the current one and that will provide an excuse for a new one.


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## green caveman (Oct 2, 2009)

I took a look at the motor, and the outside of the splines still seem to have remnants of the black surface treatment, which suggests to me that they haven't worn all that much and so the shaft may be fairly round. (We may get to check that with the machinist this weekend). 

If that's the case, I'm starting to like Jim & Duncan's suggestion of just putting a split taper busing on the outside of the splines. It does seem simpler than adding another bearing.

My thought would be to get a flanged bushing and machine down the flange to fit inside the rebate on the flywheel and use the old flywheel mounting holes into the bushing.

If I may ask another question out of ignorance, since the flange is split, won't that go out of round when the bushing is tightened? Or is it such a small amount that it can safely be ignored?


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## Woodsmith (Jun 5, 2008)

One route would be to get a cheap sprocket with a taperlock bush that fits the motor shaft diameter.
If the sprocket is big enough then the teeth can be machined off to fit the flywheel.









Or you can make your own taper in the coupler.


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## green caveman (Oct 2, 2009)

Woodsmith said:


> One route would be to get a cheap sprocket with a taperlock bush that fits the motor shaft diameter.
> If the sprocket is big enough then the teeth can be machined off to fit the flywheel.


I had in mind something more like this and then just use the flange to attach to the flywheel. I'm guessing from the fact that you suggested a two-part coupler, that there's a problem with that idea.


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## Woodsmith (Jun 5, 2008)

green caveman said:


> I had in mind something more like this and then just use the flange to attach to the flywheel. I'm guessing from the fact that you suggested a two-part coupler, that there's a problem with that idea.


That sort of coupler is intended to fit over a shaft but inside the larger taper bore of a pulley or other member.
Like this.









The pulley and taper would be tightened onto the shaft and then the flywheel is bolted to the pulley. The pulley would be machined to fit the flywheel recess to keep it centred and true.

Have a look at this thread:
http://www.diyelectriccar.com/forums/showthread.php/2001-vw-jetta-homemade-coupler-and-38895.html


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## Duncan (Dec 8, 2008)

Hi Green

*If I may ask another question out of ignorance, since the flange is split, won't that go out of round when the bushing is tightened? Or is it such a small amount that it can safely be ignored?*

The idea is that as it closes the thickness all round remains the same so it stays concentric

The coupling you show has a keyway - this prevents the taper from closing evenly 
the solution is, as that coupling has - two slots! symmetrically around the key

I would still be machining as much as possible off the flywheel - especially the outside


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## green caveman (Oct 2, 2009)

Duncan said:


> Hi Green
> 
> *If I may ask another question out of ignorance, since the flange is split, won't that go out of round when the bushing is tightened? Or is it such a small amount that it can safely be ignored?*
> 
> ...


These products are new to me and probably won't make much sense unless/until I actually see and handle one. I'm going to go over these with the guy who's doing the machining. Haven't caught up with him yet.



Duncan said:


> I would still be machining as much as possible off the flywheel - especially the outside


One benefit of just re-using the existing mounting holes/rebate is that I can take the whole assembly to a flywheel balancing place or similar and take off material on the backside of the flywheel until I stop being willing to pay for it (or it's thin enough). If we're not mounting to the modified flywheel, then there's no precision required on that machining job. So long as the flywheel gets thinner and not too thin (and is still balanced!) then the result is fine. If it's a balancing shop, hopefully at the end of it the flywheel will be balanced.


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