# Any advice on motor mounting methods?



## jaspersk (Jun 26, 2008)

drdonh said:


> 1- cantilevered off the transmission adapter plate (i.e. the electric motor is supported only by its front face, where the transmission is in some way solidly fixed to the vehicle to hold everything up.)


This is not a good option for most folks. The motor is very heavy and the standard transmission mounts are typically rubber mounts. Hanging that much weight off the end will cause the entire transmission to tilt significantly. When you read the instructions on CV joints, they state that it is critical that the transmission alignment be correct.



drdonh said:


> 2- the back face of the motor is braced to the frame, with the other support location being somewhere around the transmission tail shaft


This is sort of what I have. I just mounted the back of the motor to the original ICE mount. The original motor and transmission had 3 mounts. Two on the rear and one in the front middle. I ran angle iron from the back of the electric motor to the rear engine mount so the motor is held up by a combination of the rear bracket and the transmission mounting plate. The way the front transmission mount worked, the front of the plate is actually tied to the front ICE engine mount.



drdonh said:


> 3- straps around the motor mid-section, with a the other support location as above.


I think a strap would work equally as well as mounting something to the back face of the motor. I would put the strap towards the back end of the motor though rather than in the middle. I think a lot of this has to do with how your transmission is mounted. I had two mounts on my transmission which were designed to hold half the weight of the ice engine. So the transmission holds half the electric motor.


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## PatricioIN (Jun 13, 2008)

a lot depends on what you are converting.. fwd/rwd, etc.. most of the "hanging"motors I've seen are on vw bugs. Most of the "strapped"motors are for rear wheel drive vehicles. All others are front wheel drive and will certainly require another mount. I fabricated a relatively simple mount that bolted to the tailshaft end of motor and then bolted onto car's oem passenger side engine mount. Also, many fwd vehicles will have a brace for the passenger side 1/2 shaft that needs to flex along with motor/tranny as they were originally bolted to the ICE. IMO, more support is better. And it should be at least somewhat flexible (as much as the ICE was).


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## rfengineers (Jun 2, 2008)

Don,

I have done two conversions, one front-wheel drive (mostly completed) and one rear-wheel drive (in progress). In both cases I used all of the original transmission and motor mounts. The electric motor was mounted in as much the same method as the original ICE as possible. I did this to preserve the structural integrity of the vehicles.

Joe


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## Jimdear2 (Oct 12, 2008)

rfengineers said:


> Don,
> 
> I have done two conversions, one front-wheel drive (mostly completed) and one rear-wheel drive (in progress). In both cases I used all of the original transmission and motor mounts. The electric motor was mounted in as much the same method as the original ICE as possible. I did this to preserve the structural integrity of the vehicles.
> 
> Joe


My thoughts exactly. It may supprise you but the engineers who designed the car originally are pretty smart fellows with a lot of experiance and background. Some of the other things they take into consideration with ICE mounting are noise suppression, steering and handleing.

Jim


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## Greenflight (Sep 13, 2007)

Yeah, I second the last couple comments. It's best to use something relatively similar to the original mounting scheme. In both my conversions, I was able to adapt the motor to the original engine mounts, rubber damping and all. If you're using just about any motor on the market, for a RWD, this is going to mean circle clamps and a torque rod. For a FWD, you'll only have to make one mount that adapts the end of the motor, and possibly a torque rod if it wasn't attached to the trans already.


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## ZenDaddy (Jul 22, 2008)

Patrick has a very well thought out mount there. He is taking two forces into account:

1: The weight of the motor. Not just the standing weight but the exponential momentum that is created when you bounce over a speed bump at 50 mph. Don't even consider cantilevering the motor off of the tranny. Even if it works at first, over time you are asking for big trouble. Steel and aluminum are just not rigid enough.

Keep in mind that it is not just weight but mass in motion. Up - Down - Lateral - Acceleration - Decelleration. Consider all potential momentum and momentum changes!

2: Torque! There absolutely has to be a mechanical solution to the incredible rotational force that these motors impart to the drive train. If that motor turns even a few degrees there are a miriad of problems that will arise.

The threaded holes in the front of the motor provide a great place to bolt a plate of steel that is either welded or bolted or both to a cross member that is, again, welded or bolted (or both) in at least TWO places to the frame of the vehicle (the existing motor mounts are a good place to start, but consider how the rotational force will affect the mounts as they stand. Rubber is not necessarily a good thing here)

If you use a strap around the motor, make sure it will NEVER allow the motor to rotate. Even after years of vibration and torque.

Don't be thinking about weight when you build your motor mount! Unless you are an engineer with the skills and tools to calculate how thick and what rating the steel/aluminum needs to be to support and anchor your motor.... OVERESTIMATE!!!!!! Grade 8 bolts are a good investment here.

Again, look closely at what Patrick did. The plate in the front, well mounted, and the support mid motor.

Do what he did; Make sure that you have enough thoroughly anchored structure supporting the weight and then make sure that you have the torque provided for.

Good work Patrick!

ZD


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## Zemmo (Sep 13, 2007)

My EV uses the mount plate to the transmission for support and a strap around the center of motor for its support. At the moment my center motor mount strap has been broken. It snapped with the forces of driving. I need to get a new mount made, I put pipe straps onto it for now which is just a band-aid fix at best at the moment but it does keep the car drivable until I get around to getting it fixed. I would say over plan for motor support.


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## piotrsko (Dec 9, 2007)

how about motor plates like the High hp hot rodders use? they bolt to the ICE engine mounts, or frame or other places depending on which one you buy nose middle or back). If they are good for +400 hp, ought to work as a motor mount


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