Motor mounts for some cars and not for others?

[lenapralos]

I would like to convert a Geo Metro pretty soon here and was wondering if that vehicles actually needs a motor mount.  I saw a converted VW bug at the Green my Ride show and saw it needed no motor mount whatsoever simply because the orignal engine bolted right into the tranny (which is firmly secured to the chasis) and had no sort of mount.  I was wondering if some one would say which cars needed motor mounts for conversion and which ones didn't because for some one who does not have a machine shop in their garage this makes a big difference....Thoughts?

John

[leitmotif]

IF you are bolting the motor direct to the driven load then your "load" ie gearbox (industry) or transaxle / rear axle serves as a motor mount.  You will still need some kind of coupling to allow for varying shaft lentgths (heating cooling).  In this case if MOTOR is approx same (or less) weight as was the ENGINE then I would not do MOTOR mounts.  If MOTOR is heavier than the ENGINE then do motor mounts.   

IF you are bolting motor direct to transmission or to old bell housing in theory you would not need a motor mount.  The transmission may have all the mounts you need.  HOWEVER it is common in rear wheel drive to have front ENGINE mounts AND with the transmission or bell housing having mounts that serve for rear ENGINE mounts.  In this case I would have a set of MOTOR mounts.

You do not need a machine shop to fab these in many cases.  You will need some structural shape angle or square tube and may need some welding done.  IF you are real careful with measurements and layout work you can take the jigged and clamped brackets to a weld shop and have them welded at much less cost.

Dan Bentler

[Paul]

Generally, if the stock vehicle had an engine mount then the EV conversion should have a motor mount. The old VW Beetle didn't have an engine mount.

The Geo Metro appears to rely on the stock engine mount to locate the motor and transaxle. I only see 2 transaxle mounts on the vehicle so the engine mount would be required. At least 3 mounting points are required to secure the motor and transaxle.

HTH,
Paul

[madderscience]

as far as I know air-cooled VW's are particularly easy for EV conversion from a mechanical perspective because 1)  the adapter plates are comparatively easy to come by and 2) the air-cooled engine was supported entirely by the transaxle, so the electric motor ends up the same way.

In most cars however the motor/transmission assembly is supported by 3 or 4 motor mounts, and some of these will attach to the tranny and some to the engine.  Assuming you aren't repositioning things (like I had to) the transmission mounts will not need to be modified, but you will need to come up with something to attach the electric motor to the mounts that supported the engine.  As has already been said, this generally isn't brain surgery to do, but it does need to be sturdy.

[ev-supply]

You always need some sort of mount to keep the motor/transmission secure.  One of the few exceptions would be the aircooled Volkswagens and their deviations. 

Whether or not to have any sort of rubber isolation is a matter of preference.  It works either way.  You can bolt the motor clamp directly to the frame, or to the frame via modified stock motor mounts.  This is another of the many debates of the EV world, right up there with clutch vs. clutchless, and direct drive vs. transmission.  There is no right answer. 

What you do need to have is some form of anti-rotation in addition to the clamp, such as a bolt through the lifting eye threads, or a plate bolted to the front face of the motor.  You don't want it to spin in it's clamp, or it will get misaligned and stay that way.