# Clutch Forces too much for Motor bearings?



## adamj12b (May 4, 2009)

Hello,

Im trying to figure out if I should design my adaptor plate to include a a thrust bearing for concentrating the forces of the clutch into the frame of the motor instead of putting it all on the bearings. I understand that this would always be a good idea and help the motor bearings last longer, but its tough to find thrust bearings that can handle the high RPM's that the Warp11HV can do. 

One plan of mine was to use a 1-1/8" ID Needle Thrust bearing directly on the motor shaft. This would be pressed up against the motor housing when the clutch is pushed in. 

Before anybody asks why im using a clutch, We want to, and its free. If its really not needed, we may take it out but with all the hills around us, and wanting to be able to quick change gears, its kinda needed.

My real concern is premature bearing failure in the needle thrust bearing. I cannot find a sealed unit that is pre greased and good for above 4200 RPM.

My other idea would be to upgrade the bearings in the motor to something that can handle the high thrust loads, or supplement it on the outside with something. But this is my second problem, Bearing thickness. I cannot have an overly thick bearing. I have 0.250" of room for the bearing before my 2012 taper-lock bushing loses full contact with the motor shaft. 

Does anybody have any suggestions? 

-Adam


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## DavidDymaxion (Dec 1, 2008)

My car has a pressure plate that has triple the clamping pressure of stock. It did in the original clutch cable, but motor bearings seem fine so far (crosses fingers). I haven't driven very far yet, so I'd guess that's of the order of 1000 clutch actuations.

Don't forget you shift less often in an EV, too.


adamj12b said:


> Hello,
> 
> Im trying to figure out if I should design my adaptor plate to include a a thrust bearing for concentrating the forces of the clutch into the frame of the motor instead of putting it all on the bearings. I understand that this would always be a good idea and help the motor bearings last longer, but its tough to find thrust bearings that can handle the high RPM's that the Warp11HV can do.
> 
> ...


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## Yabert (Feb 7, 2010)

Please don't waste your time about this.....

The radial ball bearing you can find on the on Warp motor (forklift style) can take 50% of her radial load capacity in the axial direction.... so they can take 3500-4000 lbs in axial load!

So it don't care of the few hundred lbs than can generate the pressure plate for few sec. each time you shift a speed.


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## Coley (Jul 26, 2007)

My suggestion would be to use another throwout bearing ahead of the flywheel. They make some fairly short ones. Adapters for one would be simple.

As for how long a throwout bearing will run, remember that early 60s Ramblers used a cultch setup that used the throwout bearing to make the clutch ENGAGE and it was applied all the time the car was moving!!

Just the opposite of a regular clutch.


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## adamj12b (May 4, 2009)

Well I got the motor last night and noticed a few things. 

1st: This motor is HUGE!
2. The rear bearing is preloaded with a spring washer. This could be a problem because the clutch will compress the spring before dis-engaging the clutch. 

I like the idea of using another throwout bearing to take the load. Im looking into taking the bearing out of its extended housing and machining it into the end of the motor housing. This will all me a slightly larger space to put it. 

I will post some pics of the spring washer this afternoon and also the bearing info. I can see the bearing number without taking the motor apart.

-Adam


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## Yabert (Feb 7, 2010)

adamj12b said:


> The rear bearing is preloaded with a spring washer.


Yeah this is there to take the elongation of the shaft cause by the steel growing up in temperature. It probably move less than 1/16".



> This could be a problem because the clutch will compress the spring before dis-engaging the clutch


Are you sure? The front bearing isn't fix like in some other motor? (probably between the front cap and a snap ring). In this case, the front bearing will take all the load if your coupling is seat on.












Anyway, I don't said it's a bad idea, but it's useless because those bearings can take the load.... especially for few sec each few minutes. 
About the 50% load capacity for axial load, It was not me who say that, it's SKF...... So find you bearing number, find their capacity and multiply by 1/2.


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## coulombKid (Jan 10, 2009)

Yabert said:


> Yeah this is there to take the elongation of the shaft cause by the steel growing up in temperature. It probably move less than 1/16".
> 
> 
> 
> ...


I've seen one motor ad where there was an optional bearing available designed to handle large over-hung loads imposed by belts or chains. It was a roller bearing. A roller bearing would have no thrust capability but spherical roller bearings would give the best of both worlds. Higher over-hung load capability AND higher thrust capability. Finding one to fit the existing end housing bores is the biggest challenge. I wouldn't want to do it without consulting the motor OEM (Netgain, Kostov etc).


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## mizlplix (May 1, 2011)

Dont worry about the bearing. Just be concerned about the way it is secured on the shaft.

If the front bearing(the one opposite the drive end) is set against a step on the shaft, that is perfect. Your only other concern is the motor end cap it presses against. 

A regular cheap cooler motor has paper thrust washers. They wear out eventually and old motors usually have an end float of .040" - .125".

I dont think a purpose built EV motor is built this cheaply. But if there is a concern, determine the washer material. Plastic or paper is a no-go. You might have some inconel washers made to replace them. 

Either way, the bearings are good-to-go as-is.

Miz


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## EVfun (Mar 14, 2010)

adamj12b said:


> 2. The rear bearing is preloaded with a spring washer. This could be a problem because the clutch will compress the spring before dis-engaging the clutch.


One end of the motor shaft is supported with a bearing that is preloaded with a spring. The bearing on the other end of the motor shaft is fixed. This allows for some tolerance in the manufacturing and thermal expansion of the shaft when the motor gets hot.


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