# Warp 9 Motor Thrust Force



## shoup (Feb 10, 2009)

Does anyone know how much thrust the Warp 9 motor shaft is designed for? I am designing the motor x transmission adapters for converting my BMW 325i and I'm not sure if I need to use a thrust bearing or not. I would am keeping the clutch because i want to be able to shift while the motor is spinning (I would like to auto-x the car). My initial thinking is I don't want to put any additional load on the motor than necessary so a thrust bearing would be required.

Most of the conversions I have seen do not have a thrust bearing and seem to work ok, but I want my design to be robust. Has anyone else used a thrust bearing to take load off the motor shaft?


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## DIYguy (Sep 18, 2008)

shoup said:


> Does anyone know how much thrust the Warp 9 motor shaft is designed for? I am designing the motor x transmission adapters for converting my BMW 325i and I'm not sure if I need to use a thrust bearing or not. I would am keeping the clutch because i want to be able to shift while the motor is spinning (I would like to auto-x the car). My initial thinking is I don't want to put any additional load on the motor than necessary so a thrust bearing would be required.
> 
> Most of the conversions I have seen do not have a thrust bearing and seem to work ok, but I want my design to be robust. Has anyone else used a thrust bearing to take load off the motor shaft?


From where do you anticipate thrust on a motor shaft? If you align it properly, there should be pretty much ...none. Most motors have a radial ball bearing on each end of the armature shaft. The drive end tends to be heavier. There should be no problem that I can forsee...


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## Jimdear2 (Oct 12, 2008)

shoup said:


> Does anyone know how much thrust the Warp 9 motor shaft is designed for? I am designing the motor x transmission adapters for converting my BMW 325i and I'm not sure if I need to use a thrust bearing or not. I would am keeping the clutch because i want to be able to shift while the motor is spinning (I would like to auto-x the car). My initial thinking is I don't want to put any additional load on the motor than necessary so a thrust bearing would be required.
> 
> Most of the conversions I have seen do not have a thrust bearing and seem to work ok, but I want my design to be robust. Has anyone else used a thrust bearing to take load off the motor shaft?


When you depress the clutch there is quite a bit of thrust being applied to the shaft. There is a lot of spring pressure to be overcome. A clutch rebuilder or even the OEM may be able to give you the force specification.

I would contact the motor builder and see if the ball bearings used in your motor can withstand the side loads that will be generated when the clutch is depressed. You just may be OK because they have been building these motors for EVs for a long time and should have considered this before now.

If those installed are not up to the task you may be able to find a bearing that will. Check with bearing catalogs.

If all else fails you may be able to support the motor shaft at the tailshaft with a fixture and bearing.


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## DIYguy (Sep 18, 2008)

The majority of the forces are rotational torque, not side thrust. Whether there is a clutch, a torque converter or any other form of inline drive... there is not a great deal of thrust to deal with. Depressing a clutch simply overcomes the spring pressure exerted on the clutch disc, this is all still inline. Just how I sees it through my foggy eyes.


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## shoup (Feb 10, 2009)

I am talking about axial thrust. Disengaging the clutch requires between 400 and 500 lb force. This force is applied to the clutch fingers by the throw out bearing and is transferred to the flywheel. The flywheel is attached to the motor shaft. If the motor was not designed to take this kind of load then the bearings will fail. 



Jimdear2 said:


> If all else fails you may be able to support the motor shaft at the tailshaft with a fixture and bearing.



Thanks for the recommendation. I was considering putting a thrust bearing between my motor coupler and the motor case, but I'm not sure how solid the motor case is since I haven't ordered it yet (probably a Warp 9).


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## Jimdear2 (Oct 12, 2008)

shoup said:


> I am talking about axial thrust. Disengaging the clutch requires between 400 and 500 lb force. This force is applied to the clutch fingers by the throw out bearing and is transferred to the flywheel. The flywheel is attached to the motor shaft. If the motor was not designed to take this kind of load then the bearings will fail.
> 
> 
> 
> ...


Since you haven't ordered yet check with the motor builder. They do make bearings that will take both radial and axial loads at the same time. a few dollars additional at the build for this type bearing may make your life much easier.


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## DIYguy (Sep 18, 2008)

Sorry, I missed your point. I thought you were talking about side thrust. Its a good point to consider. I went clutchless, so I never thought about this...


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## JRP3 (Mar 7, 2008)

I've never heard of anyone doing a conversion with a clutch having problems with motor bearings.


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## Jimdear2 (Oct 12, 2008)

JRP3 said:


> I've never heard of anyone doing a conversion with a clutch having problems with motor bearings.


Thats why I keep suggesting he contact the motor builder. They may have already designed in the necessary support.

But I never hurts to be sure.


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## m38mike (Dec 27, 2008)

I can't talk to the Warp9, but I have a Warp11 and I'm putting the clutch back in it. I've talked with Netgain several times about installing the flywheel and clutch and they have assured me that the bearings and races they use in the Warp series motors can handle the axial loads created when the throwout bearing presses against the pressure plate arms to release the clutch. 

I agree that you should give Netgain a call and talk with them directly. I found them very easy to talk with, and they often have good ideas and advice that may help with your installation. I know they've helped me a bunch.


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## shoup (Feb 10, 2009)

I've requested the information from Netgain and will post it when I get it.


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## Coley (Jul 26, 2007)

Possibly using Timpken style roller bearings, such as the front wheel bearings, could be done. The only problem would be sealing them as well as ball bearings.


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## shoup (Feb 10, 2009)

I talked with Netgain and they have only had only had 1 failure with the motor shaft being pushed out since they started making EV motors. The only thing holding the motor shaft in the axial direction is a snap ring on the Warp 9. Many have used this motor with a clutch and it has worked fine. I am still concerned about the force applied by the clutch. I am going to try to work in a thrust bearing between the motor and the flywheel to prevent this loading.


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## lazzer408 (May 18, 2008)

Great question. I'll throw in my $.02 from my experience.

The bearing on the output shaft can handle the force of clutch throwout (thrust) without a problem. What you want to do is put a spacer between your flywheel adaptor and the bearing so the thrust force is on the bearing's inner race not the motor's shaft. If the spacer isn't used then the thrust is on the shaft and will want to push the shaft out of the front bearing and the rear bearing will have to take the force. That's usually a much smaller bearing in an aluminum housing.

Second thing to note is how the front bearing is held into the front end housing. One motor I had only used a thin metal plate held on with 4 little screws just to hold the bearing in place. I bent the plate with the thrust force and had to make a new one out of thicker 1/4" steel and drill/tap the housing to accept larger bolts.

EDIT - Pic attached. Note spacer. (not to scale)


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## shoup (Feb 10, 2009)

lazzer408, thanks for the information. I will check out my motor when I get it to see how the bearing is held. Your layout with the spacer looks much better than loading the shaft with all the load from the clutch force, but I'm still not sure how much axial load that bearing is designed to take. I got the bearing p/n from Netgain, but have not had a chance to check the specs.


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## rebirthauto (Nov 3, 2008)

Shoup,
Although this might be a conflict of interest, I do nevertheless think that you have a valid concern. We build adapters with a floating coupling that rides on both axial and thrust bearings. We have just completed a BMW 2002 setup. I'm not too sure if it's the same layout, but we can always build you an adapter suited for your application (if you send us your tranny). Thanks.

Sebastien
[email protected]


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## lazzer408 (May 18, 2008)

Looking at rebirthauto's pics it looks like the warp's bearing is probably held in with a snap-ring from the inside of the shaft side housing. fwiw

EDIT - I realised I'm looking at the brush side shaft. I have no idea what's on the output shaft's housing. Anyone got pics?


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## JRP3 (Mar 7, 2008)

Here's a drawing of the DE from Netgain
http://www.go-ev.com/images/003_20_00-08311_WarP_11_DE_Eng_Drawing.jpg
Here's a PDF with a picture of a disassembled motor
http://www.go-ev.com/images/002_09_WarP_11_Sales_Sheet.pdf
You can always browse through Jim's photos to see how different motors are put together
http://hitorqueelectric.com/gallery...2_GALLERYSID=a072e23b422b886001ca7edf72f3fdbf
I still can't see it as a valid concern since no one has ever reported a problem to my knowledge, and I'm sure we'd be seeing many failures if it were.


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## Carroll_1 (Dec 18, 2007)

Call me crazy, but a properly fit taper lock (or set screw style) adapter will transfer all of the lateral force from a clutch pressure plate directly to the motor output shaft. We supply a spacer ring with our couplers that fits between the output shaft inner bearing race and the coupler, to properly locate the coupler in the correct position on the output shaft. At first I believed that this spacer helped transfer force to the inner bearing race, but after studying it a bit, I now realize that it only serves as a locating device. If the taper lock adapter is actually loose enough to transfer force through the spacer to that bearing race, game over, and really bad things are about to happen.


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## lazzer408 (May 18, 2008)

Carroll_1 said:


> Call me crazy, but a properly fit taper lock (or set screw style) adapter will transfer all of the lateral force from a clutch pressure plate directly to the motor output shaft. We supply a spacer ring with our couplers that fits between the output shaft inner bearing race and the coupler, to properly locate the coupler in the correct position on the output shaft. At first I believed that this spacer helped transfer force to the inner bearing race, but after studying it a bit, I now realize that it only serves as a locating device. If the taper lock adapter is actually loose enough to transfer force through the spacer to that bearing race, game over, and really bad things are about to happen.


If the adaptor is loose yes, bad things will happen. If the force is only on the motor shaft bad things can also happen. The force MUST be transfered to the bearing and not allowed to push on the shaft. I'll stand by that fact.

It looks as if the Warp has nothing to retain the DE bearing in the housing. If it's been working this way it's not by design but by luck. It's not that hard to visualise the force applied to the shaft and what direction the shaft wants to move. Start asking yourself what prevents any movement?


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## Jimdear2 (Oct 12, 2008)

Does the armature shaft have a step in it on the brush end? It's hard to tell from the picture I've seen but it looks like the Brush End bearing has a smaller ID If it does and that step bears against the inner race and the BE bearing is iin a pocket like the drive end, then the path of force would be as follows
Clutch throw out to
Pressure plate to
Flywheel to
Coupler to
Armature shaft to
BE bearing to
BE cover to
Motor case to
Motor mounts.
Most modern ball bearings sets have a pretty good tolerance for axial loads and there are ball bearings designed to take axial loads in one direction. 

If the motor is designed as described above, to pass axial loads through the armature shaft into the BE cover and the proper BE bearing is used I think your proplem is NO problem.

Hope this helps


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## JRP3 (Mar 7, 2008)

Notice the pockets in each end of this Warp Impulse motor. As Jimdear says the force on the shaft can't push the shaft out since the CE bearing is held by the end plate.









Notice the step on the shaft that prevents the shaft from sliding through the bearing


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## lazzer408 (May 18, 2008)

Jimdear2 said:


> Does the armature shaft have a step in it on the brush end? It's hard to tell from the picture I've seen but it looks like the Brush End bearing has a smaller ID If it does and that step bears against the inner race and the BE bearing is iin a pocket like the drive end, then the path of force would be as follows
> Clutch throw out to
> Pressure plate to
> Flywheel to
> ...


Yup you got it. The BE bearing is a pee-wee compaired to the other one. A spacer is all that's needed to put the load on the larger bearing.


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## JRP3 (Mar 7, 2008)

lazzer408 said:


> Yup you got it. The BE bearing is a pee-wee compaired to the other one. A spacer is all that's needed to put the load on the larger bearing.


Yes it's smaller, but that doesn't mean it's too small to take the load. We'd need to find the actual spec on that bearing, then figure out the actual load to determine if it's not up to the task. Since we've never seen a failure....well you know my thoughts


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## Jimdear2 (Oct 12, 2008)

lazzer408 said:


> Yup you got it. The BE bearing is a pee-wee compaired to the other one. A spacer is all that's needed to put the load on the larger bearing.


lazzer408,

Again I can't tell from the picture but the netgain drawing jrp3 has supplied clearly shows that there is no retainer for the drive end bearing.

Without some form of retainer to hold the bearing into its pocket, placeing a spacer between the coupler and the bearing inner race will have no effect except to try to push the bearing out of its pocket. The load path is still to the BE bearing.

If you want the load carried by the DE bearing you should have a new DE cap made with a LOT more beef, that cover in the picture does not have enough metal to take a lot of load. 

Using the existing DE cover, the best would be to have the load shared by the DE and BE bearings. you will need to make some form of retainer to hold the bearing into its pocket (maybe cut a snap ring groove), then it will also require that you shim the armature shaft with a slight pre load to compensate for expansion of length when the motor warms up. If you do not do this then all of the load goes through that thin area in the front cover which may break it.

A simple solution to the whole question is look up the axial load specs of the BE bearing. If it exceeds the loads that will be placed on it then the problem is no problem.


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## major (Apr 4, 2008)

JRP3 said:


> Yes it's smaller, but that doesn't mean it's too small to take the load.


Hey JRP and all,

Here is how the bearing system in most traction motors works. First, some motor lingo. The Drive End Head (DEH). The casting at the business end of the motor, where the output shaft is. The Comm End Head (CEH). The casting at the opposite end of the motor where the commutator and brushes are located. It may or may not have an external shaft extension.

Not all motors will be as I describe, but I think most of the traction motors used by you guys will be.

First, look at the DEH. lazzer put up a decent diagram.

 

If the image doesn't show here, see post #14. The DE bearing is press fit onto the shaft, which means there is a precision interference between the ID of the inner race of the bearing and the OD of the journal on the shaft, like to the tenths of a thousandth of an inch. It is pressed up to a shoulder on the shaft. The outer race of the DE bearing is a mean loose fit in the DEH housing, meaning a few tenths of a thousandth of an inch clearance between the OD of the outer race and the ID of the housing bore. Then a snap ring, usually beveled to provide pressure against the outer race to keep it from spinning, is used to positively locate the DE bearing.

Down at the CEH, it is done differently. The CE bearing is again pressed onto the shaft up to a locating shoulder. And again, the bore in the CEH is machined to provide a mean loose fit. No snap ring or other means are employed to positively locate the outer race of the CE bearing axially. It is purposely allowed to float axially. This allows for build tolerances and thermal expansion of the shaft. A spring washer is installed between the outer race of the CE bearing and the back of the bore. This can be a wave washer or belleville type. It provides pressure on the outer race of the CE bearing to keep it from spinning in the housing bore. But must not be relied on for axial location of the armature shaft.

The armature shaft is positively located by the DE bearing. The press fit of the DE bearing on the shaft is sufficient to prevent the shaft movement towards the motor center for moderate axial thrust loads. If there are excessive axial loads, or repeated impact loading axially, then a spacer arrangement as shown in the diagram is required.

The CE bearing should never have any axial loading in this type of design. There are other designs for motors where the situation is reversed and the CE bearing is designed to take axial loads, but I doubt you guys would see many of those.

Regards,

major


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## Jimdear2 (Oct 12, 2008)

major said:


> Hey JRP and all,
> 
> Here is how the bearing system in most traction motors works. First, some motor lingo. The Drive End Head (DEH). The casting at the business end of the motor, where the output shaft is. The Comm End Head (CEH). The casting at the opposite end of the motor where the commutator and brushes are located. It may or may not have an external shaft extension.
> 
> ...


Major,

Thanks for clearing that up. What confused me was in none of the drawings or photos could I see the presence of a snap ring groove or any type of bearing retainer at the drive end. That ment that the load had to be taken at the brush end. 

Now that you confrim that most traction motors will have the DE bering retained by a snap ring and the bearing is press fit to the armature shaft we now know the axial load path is through the DE head.

Now all that needs to be done is give the people who question the ability of the bearing to handle the axial loads assurance that since it has been doing it it probably can continue doing it.

If all assurances about and the history of this motor fails to build their confidence they should contact a bearing manufacturer with the bearing number used by the motor buder and ask for the specifications.


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## JRP3 (Mar 7, 2008)

lazzer408 said:


> The force MUST be transfered to the bearing and not allowed to push on the shaft. I'll stand by that fact.
> 
> It looks as if the Warp has nothing to retain the DE bearing in the housing. If it's been working this way it's not by design but by luck. It's not that hard to visualise the force applied to the shaft and what direction the shaft wants to move. Start asking yourself what prevents any movement?


So from Major's explanation it's the press fit of the bearing on the shaft that prevents movement. If the force required to press the bearing onto the shaft is greater than the force applied when the clutch is pushed in then the shaft can't move and the thrust is applied to the bearing through the press fit.


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## major (Apr 4, 2008)

Jimdear2 said:


> What confused me was in none of the drawings or photos could I see the presence of a snap ring groove or any type of bearing retainer at the drive end.


Hey Jim,

Look closely at the photo in post #22 from JRP3. The DEH (on the right). You can (or at least I can) just barely make out that snap ring groove.

major


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## lazzer408 (May 18, 2008)

Jimdear2 said:


> Now all that needs to be done is give the people who question the ability of the bearing to handle the axial loads assurance that since it has been doing it it probably can continue doing it.
> 
> If all assurances about and the history of this motor fails to build their confidence they should contact a bearing manufacturer with the bearing number used by the motor buder and ask for the specifications.


That was my first response to the OP was the bearing CAN handle it. Those bearings are rated in the 1000s of pounds. Like ~8000lbs. There's no doubt that the bearing can handle a fraction of that from clutch throwout which may be under ~1000lbs.

It was my suggestion he...

1: Verify DE bearing is securely retained (as shown in my picture)
2: Use a spacer to assure the forces are applied to the bearing not the shaft.

I've clearly addressed both issues but you guys just keep at it.


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## lazzer408 (May 18, 2008)

JRP3 said:


> So from Major's explanation it's the press fit of the bearing on the shaft that prevents movement. If the force required to press the bearing onto the shaft is greater than the force applied when the clutch is pushed in then the shaft can't move and the thrust is applied to the bearing through the press fit.


Correct. "IF"

GM once used a press fit hub on one of their cars. Might have been an Eldorodo. They weren't known to come loose but....some did.

So... leave out a $.50 spacer and take the risk? Or do it right? I guess it's the OP choice.


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## major (Apr 4, 2008)

JRP3 said:


> If the force required to press the bearing onto the shaft


Hey JRP,

For a quality ground shaft journal (to the spec diameter), it takes several tons to press the bearing in place. This is at room temperature. Of course, as things heat up, things change. That is why I use words like "moderate" axial loading. And there is always the case where the shaft and bearing are at the size tolerance limit (heaven forbid the shaft would be 0.0003 inch undersize). So, in a nutshell, when you're designing a coupler for an axial load application, I would use that spacer sleeve and put the axial load right on the DE bearing inner race. What do you have to lose? 

Regards,

major


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## Jimdear2 (Oct 12, 2008)

major said:


> Hey JRP,
> 
> For a quality ground shaft journal (to the spec diameter), it takes several tons to press the bearing in place. This is at room temperature. Of course, as things heat up, things change. That is why I use words like "moderate" axial loading. And there is always the case where the shaft and bearing are at the size tolerance limit (heaven forbid the shaft would be 0.0003 inch undersize). So, in a nutshell, when you're designing a coupler for an axial load application, I would use that spacer sleeve and put the axial load right on the DE bearing inner race. What do you have to lose?
> 
> ...


I think we can all agree; 

The motor has been working as is with an axial load applied and will probably continue working that way.

It won't hurt to put in a spacer between the coupler and the DE housing bearing.

Major knows his motors (Major Help me with my fan problem if you can see my thread under this subject page)

My old eyes can't see snap ring grooves in fuzzy pictures (What do you mean clean my galsses)


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## JRP3 (Mar 7, 2008)

OK, to keep stirring the pot  let's use the spacer as has been suggested. If there is enough force to push the shaft through the bearing so that the spacer transfers the load to the bearing, isn't the weak link ultimately the snap ring behind the DE bearing? Whether it's the press fit on the shaft -> bearing, or spacer -> bearing, it's always bearing-> snap ring -> motor housing. My guess, quite possibly wrong, is that the snap ring would give before a proper press fit fails. Anyone know the pressure value a snap ring in a groove can take? I'm going clutchless by the way, so none of this matters to me really, but I just like to know stuff


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## shoup (Feb 10, 2009)

When I am designing something I don't like to assume since it has worked in the past it must be ok. All of the discussion has been great and the information is much appreciated. 

The bearing used on the DEH is a 6207 2RS, but I'm not sure about the manufacturer. I have not been able to find an exact spec, but based on several sources the 6200 series bearings are "deep groove bearings" designed for taking moderate axial loads at lower rpm along with the typical radial loads. The axial loading applied by the clutch throw out bearing is around 400lbs, which is moderate considering the axial loads these bearings can take are in the 5000lb range. 

The bearing used on the CEH is a 6305 2RS, which is even larger than the one on the DEH. This is a quote from brancekrachy.com: "6300 Series ball bearings are similar to the 6200 Series, but heavier components allow for greater radial thrust and load capacity for a given bore size."

Based on this it seems it would be better to transfer the load to the CEH because then you don't need to rely on a snap ring to hold the bearing in. You have the entire CEH holding the bearing. 

Tranferring the load to the DEH bearing inner race may be perfectly fine, but I don't have the snap ring or groove dimensions to calculate the shear stresses on the parts. 

Nothing wrong with a little pot stirring.


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## lazzer408 (May 18, 2008)

JRP3 said:


> ...isn't the weak link ultimately the snap ring behind the DE bearing?


In his Warp, yes. His motor uses a snap-ring to retain the bearing in the housing. The motor I'm using (Hyster/GE) has a cast iron housing with the snap-ring on the front of the housing. Force on the bearing would go right to the housing. 



shoup said:


> When I am designing something I don't like to assume since it has worked in the past it must be ok..


Good thinking.



shoup said:


> The axial loading applied by the clutch throw out bearing is around 400lbs,


Is it really that low? I was under the impression it was greater. Probably would be if a "stage 3" pressure plate was used. It's so nice not having to slip an EV's clutch. The clutch stays nice and cool.


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## major (Apr 4, 2008)

JRP3 said:


> isn't the weak link ultimately the snap ring behind the DE bearing?


Hey JRP,

When the snap ring is done properly (design wise and quality manufactured), it is plenty strong enough. Take apart a few old ones and you'll find out. How much force do you have to exert with the puller to get that DEH assembly off the armature shaft? It ain't easy. I've seen castings break and bearings come apart. Never seen a snap ring give up.

I suppose you can find that force value from the design guide for that particular snap ring. If you don't believe me, look it up.

Regards,

major


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