# Rigid motor mounting?



## jddcircuit (Mar 18, 2010)

For simplicity sake, I want to hard mount my motor and gearbox package rigid to the frame of the car as opposed to using any of the rubber motor mounts that were there for the original engine and tranny.

Does anyone have experience with not using rubber motor mounts in their conversion?

I am unsure about the amount of vibration or stresses.

Thanks
Jeff


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## Woodsmith (Jun 5, 2008)

What car and set up is it?

I've maintained that it should always be rubber mounted as the frame/chassis of the car will flex. But if the frame/chassis is very stiff and both the motor and transmission are rigidly mounted then maybe you might get away with it if the mounts are fairly close to each other.

For a front engine rear drive car where the mounts are at the front of the engine and the tailshaft of the trans I would say not to rigid mount as the frame will flex over that distance.

Easier to just rubber mount IMO, cheaper too if you are re using the existing mounts removed from the ICE.


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## EVfun (Mar 14, 2010)

My Buggy is that way, solid transaxle mounts and a rigid clutchless coupler between the motor and transaxle too.


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## dtbaker (Jan 5, 2008)

use the existing mounts if at all possible. you won't have much vibration with electric motor, but rigid mounts combined with flex and torque are bound to break something before its time...


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## fb_bf (Jul 6, 2011)

Because electric vehicles are inherently quiet, I'd definitely go with rubber mounts. I know I could tell my rear u-jount had just a little play because when I backed off the acceleration I could feel some vibration. I also could feel that my flywheel wasn't completely balanced. I would feel some vibration above 3,000 RPM. When I rebuilt the transmission I cut down my flywheel to reduce inertia and reduced stored energy in it. When I put it back on I hand balanced the clutch assembly with extra washers under the screw heads. I just spun it up wit a 12 volt battery when it was resting on the floor. I could easily tell when I had it better balanced. My point is that an electric vehicle should be smoother than a ICE version, and it would be a shame to hard mount everything, and then feel vibration at various RPMs.


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