# Splined flexible coupling



## Inframan (Jan 30, 2011)

Does anyone know if they make splined flexible coupling to meet up with transmission shafts? Everyone that I have seen just has two round holes with key ways on both sides how is the clutch disc center piece substituted on one end?


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## Ziggythewiz (May 16, 2010)

I wouldn't call them flexible, but some are springy.


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## Inframan (Jan 30, 2011)

Cool I thought to do this one time but I was too unsure if it would work so I didn't risk doing it with my motor hub. How did it work for you? and did you have bolts that fit perfectly to the holes of the clutch hub?


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## DJBecker (Nov 3, 2010)

That looks very much like the one I made for our conversion.

Centering is done with a lip on the outside edge so that the old clutch piece has a running fit or a light press fit. With the springs, the inner plate can float a bit so you also need to machine a centering feature for the end of the transmission shaft where the throw-out bearing would have supported it. That gets a running fit. Some insert a brass bushing, but I don't think that's needed.

We used small socket head machine screws in the original rivet holes.

With no clutch and no combustion power pulses I doubt that the springs ever compress.


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## Ziggythewiz (May 16, 2010)

Inframan said:


> Cool I thought to do this one time but I was too unsure if it would work so I didn't risk doing it with my motor hub. How did it work for you? and did you have bolts that fit perfectly to the holes of the clutch hub?


I didn't make it myself, but have been using a similar one for a couple months. There are a few places online that make them.


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## Kerensky (Jul 8, 2011)

Can I request say the top 3 coupler/ adapter sources. Every one I can find seems to be selling the same 2 types. Only difference appears to be price. I would kill to know who actually makes em.Not to mention how hard were they to install/ how reliable has the combo been ?


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## dtbaker (Jan 5, 2008)

Kerensky said:


> Can I request say the top 3 coupler/ adapter sources. Every one I can find seems to be selling the same 2 types. Only difference appears to be price. I would kill to know who actually makes em.Not to mention how hard were they to install/ how reliable has the combo been ?



the guys at CanEV.com are *one* of the major sources for the CLUTCHED design. They have lots of adaptors fit to various common transmissions available 'off the shelf'. Their standard motor hub mounting the clutch/flywheel is typically keyed to match the Kostov, ADC and Netgain motors, but I bet you could get them to do a spline instead.


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## DJBecker (Nov 3, 2010)

Any old guy with a lathe can make the type pictured. The only tricky part is the taper, if you are doing a tapered bushing e.g. QD/SH to connect to the motor shaft.

Someone actually *manufacturing* one would have a broach to cut the splines in the adapter itself. This would avoid having to source and prepare a clutch disk, and make the coupler smaller, lighter and much faster to machine.


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## Zak650 (Sep 20, 2008)

Here's one way,

Take an old clutch plate
Drill out the rivets remove friction material
Round plate of 1/4 steel same or appropriate diameter
round keyed sleave for the motor shaft welded to steel plate
true it up on the lathe
drill for rivet pattern
short spacers between clutch plate and steel plate at the bolts at rivet points
grade 5 nuts and bolts that stick out past the bolts a little
pean over the bolts on the outside of the nuts after assembly
drill hole in the 1/4" plate to clear transmission shaft

viola flexible coupling


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## Kerensky (Jul 8, 2011)

Has anyone used this guys couplers/adapters ?
http://www.evcouplerconnection.com/index_files/Page312.html
How are they ?


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## Weisheimer (May 11, 2009)

Kerensky said:


> ...How are they ?


Kerensky,

I've got no reason to knock them, but they are probably not any better than the one that you already have.

Mark


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## DJBecker (Nov 3, 2010)

Zak650 said:


> Here's one way,
> 
> Take an old clutch plate
> Drill out the rivets remove friction material
> ...


Having a spring center type clutch hub won't make it a flexible coupling.

You'll probably want positive centering features rather than relying on alignment while tightening the bolts to keep it centered.


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## Kerensky (Jul 8, 2011)

Ok so I took what I have to a local machinist. (same guy who fixed the highschoolers welding) he's never done something like this but he wants to remove the spline from my clutch plate and make a new rigid coupler with matching adapter. This is a path which I already considered. Cant find any real arguments against it online. Price is pretty much the same as the available online sources. And ill have a local source for repairs. What do yall think ?


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## Ziggythewiz (May 16, 2010)

The spline seems to be the weakest part of the system, so getting rid of it would seem like a win. I know many people with the bigger motors or direct drive use U or 3 prong connectors to better carry the torque.


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## Kerensky (Jul 8, 2011)

No. He wants to use the spline from the old clutch plate and press that into a rigid coupler with a pilot shaft bearing. Will that work on road ? Will it be durable? Will it be safe ?


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## DJBecker (Nov 3, 2010)

Ziggythewiz said:


> The spline seems to be the weakest part of the system, so getting rid of it would seem like a win. I know many people with the bigger motors or direct drive use U or 3 prong connectors to better carry the torque.


Why suspect the spline of being weak? Most ICEs use a splined input shaft on a manual transmission so that the clutch disk can float. The splines are rarely the weak link.

Splines are difficult to cut without a purpose-built broach. Every clutchless adapter I've seen takes the easier path of using a center section of an old clutch disk and bolting it to the custom-turned motor shaft adapter. That should carry at least as much torque as the original clutch assembly. Probably more since the splines don't see a shock load as they slide when the clutch is dumped, and there are no combustion pulses.


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## PTCruisin (Nov 19, 2009)

Kerensky said:


> Ok so I took what I have to a local machinist. (same guy who fixed the highschoolers welding) he's never done something like this but he wants to remove the spline from my clutch plate and make a new rigid coupler with matching adapter. This is a path which I already considered. Cant find any real arguments against it online. Price is pretty much the same as the available online sources. And ill have a local source for repairs. What do yall think ?



That's exactly what I did. I got a local machinist to fabricate a plate that fits the clutch disc with the spline coupler to the motor shaft coupler (basically a flange). So far so good.

I started out with the whole clutch assembly in the EV but it started to vibrate too much so I got rid of all the mass. I find that I can now shift much faster (clutchless) because the motor spins down faster without all the mass of the flywheel/clutch assembly.


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## Ziggythewiz (May 16, 2010)

DJBecker said:


> Why suspect the spline of being weak? Most ICEs use a splined input shaft on a manual transmission so that the clutch disk can float. The splines are rarely the weak link.


A number of people have suffered spline failures. I would much prefer something like a keyway on both ends.


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## DJBecker (Nov 3, 2010)

Ziggythewiz said:


> A number of people have suffered spline failures. I would much prefer something like a keyway on both ends.


Which people?

There must be additional details.

Doing a search, clutch spline failures happen on motorcycles, but seem really uncommon on cars.


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## EVfun (Mar 14, 2010)

I've heard of a couple cases but they seem to be a RWD transmission with the pilot shaft removed and/or the clutch splines where welded into the coupler. I've been running a VW air cooled Beetle transaxle with a clutchless splined hub for over 10 years. My splined insert was turned from a VW Bus reverse gear (the shaft splines are the same as the Bug clutch splines) so they are very hard.


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## Kerensky (Jul 8, 2011)

EVfun said:


> I've heard of a couple cases but they seem to be a RWD transmission with the pilot shaft removed and/or the clutch splines where welded into the coupler. I've been running a VW air cooled Beetle transaxle with a clutchless splined hub for over 10 years. My splined insert was turned from a VW Bus reverse gear (the shaft splines are the same as the Bug clutch splines) so they are very hard.


Well my coupler didnt fail because of bad alignment. My motor controller did, and my tranny, my adapter plate is scrap. But not my coupler... That was fine. And yea my pilot shaft was removed. 
But yet we digress..... I am keeping the pilot shaft this time. I am doing a clutch less setup again. This guy seriously wants to remove the spline from my old clutch plate. He seems to want to press that and a pilot shaft bearing into a single piece of aliminum to make a 1 piece full rigid coupler. 
Will this do the job safely for the life of the truck ?
This is not a portion of the project I want to revisit.


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## EVfun (Mar 14, 2010)

I'm a bit confused as to why a motor controller would fail from bad alignment. From what I understand your adapter plate is scrap due to poor alignment. That would put the motor off-center and put a lot of stress on the transmission, easily leading to failure.

A coupler like the one in the lower right corner of this page should work fine so long as the pilot shaft is supported inside. You don't actually have to use a pilot bearing but certainly can if its convenient. The splined clutch hub most likely has a centering ring that originally step fit into the clutch disc to locate it accurately in the center. I wouldn't rely on the press fit alone, but the flange could be bolted using the holes that originally held rivets. 

It is very important to have an accurate adapter plate so the motor is well centered. If you are using a key and set screw hub be sure the bore is a good snug fit and the set screws are tight and either locktite or a second set screw is in each location. It should last for years.


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## DJBecker (Nov 3, 2010)

It would be a pilot bearing, not a pilot shaft. Unless you mean that the transmission input shaft was shortened so that there is no longer enough length for a pilot bearing.

You need to be careful shortening a transmission input shaft. The splines are surface hardened and would need to be kept cool with a wet rag while cutting. Similar care needs to be taken if welding a clutch hub to the adapter.

The clutch hub needs a slip or running fit into the adapter , with bolts clamping the surfaces together. This might be what is meant by "pressed in", but it would be a light press fit. The torque is transferred through the clamped surfaces, not by putting the fasteners in shear.

A flat plate and standoffs will have centering and fatigue problems.

For the motor shaft connection we used a taper fitting. A taper fitting has better centering and applies lots of pressure to a large torque transfer surface. I don't see how anyone can be concerned about the strength of splines, and then use a keyway and setscrew connection on the motor side.


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## Kerensky (Jul 8, 2011)

EVfun said:


> I'm a bit confused as to why a motor controller would fail from bad alignment. From what I understand your adapter plate is scrap due to poor alignment. That would put the motor off-center and put a lot of stress on the transmission, easily leading to failure.


I have been lead to believe the added resistance of the poor alignment was a contributory factor in the controller's failure. And yea the plate is at the core of my problems. 




EVfun said:


> A coupler like the one in the lower right corner of this page should work fine so long as the pilot shaft is supported.


That is pretty much what he wants to do. 1 big piece of aluminum with part of the clutch and a pilot shaft support bearing.


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## DJBecker (Nov 3, 2010)

Kerensky said:


> I have been lead to believe the added resistance of the poor alignment was a contributory factor in the controller's failure. And yea the plate is at the core of my problems.
> 
> 
> That is pretty much what he wants to do. 1 big piece of aluminum with part of the clutch and a pilot shaft support bearing.


Poor alignment would have only looked like a slight extra load to the controller. No more than a slight uphill grade. The controller should have protected itself from overheating and overcurrent.

You don't need a pilot bearing to support the end of the transmission shaft, just a snug fit. There isn't any relative motion that would require a bearing or even a bushing. The only reason I can think to put on in is that it may be easier for the machinist to cut a seat for the inexpensive bearing and test fit it immediately than to double-check the measurement for a bored hole.


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