Friday, May 1, 2009

Motor Adapter and Coupler

I have the ElectroAuto adapter plate and coupler attached to my Impulse 9 motor and also finished attaching a new pressure plate, clutch disk and flywheel. I installed new pressure plate and flywheel bolts also. Here's a picture of the motor with the spacer, adapter plate, coupler and pressure plate (lightly fitted) attached and chained to the workbench. This is necessary to keep everything solid while tightening the various bolts. Pressure plate bolts were torqued to 55 ft-lbs (74.6 N-m). The blue foam pad is protecting the motor against scratches from the chain. Note the pressure plate lock bar attached to the adapter plate (upper left).



From a lesson I learned on Roger's blog, I trial fitted the ElectroAuto right side motor mount to the back of the motor to be sure it and the adapter plate were oriented correctly. Here is the anti-rotation bar attached to the back of the motor to keep it from twisting while torquing everything.



With this setup, the next step was to set the distance between the pressure plate and the adapter plate. This distance is rather critical so the clutch operates correctly. The instructions say adjust the distance between the pressure plate surface and the adapter plate until it is 1.30" (33.02 mm) then snug all the hex bolts around the coupler which tightens the taper lock and measure again. This time the distance should be 1.28 +/- 0.01 (32.25 +/- 0.25 mm). I was just unlucky and ended up loosening and adjusting the coupler distance about half a dozen times before I was satisfied. To loosen the snugged taper lock coupler you need to back out the hex bolts and tap on the heads. The instructions call for a brass hammer, I didn't have one so I used a moderate sized iron one. It worked OK though I did bend a few of the hex bolts. I could still use them but I think Tim has a much better suggestion of using a puller and buying longer hex bolts.



After I torqued down the pressure plate I applied a little grease to the back of the clutch release plate and installed it with the retaining clip. I cleaned the machined surfaces of the pressure plate and flywheel with some alcohol before installing the clutch disk and flywheel.

I opted to use a new flywheel because the original appeared to be cooked with scorch marks indicating some pretty heavy clutch use. I didn't notice any slippage during the short time I drove the car under ICE power but nevertheless the flywheel would need to be resurfaced or replaced. I chose to replace as this gave the opportunity to upgrade to a lightened flywheel. The stock flywheel weighs around 13 lbs (5.88 kg), my new lighted one is about 8 (3.62 kg). Unlike a 2 or 4 stroke ICE, an electric motor does not require the heavy rotational mass of a flywheel to smooth out its operation. In fact in many EV conversions, they have removed the flywheel, clutch, and pressure plate entirely and couple the motor output shaft directly to the input shaft of the transmission. There are plenty of web posts describing the advantages and disadvantages of going with or without a clutch. My kit is designed for a clutch setup so that is the path I am following. As far as the lightened flywheel, less mass to spin up should mean a little better performance and efficiency. Some folks who have converted cars have removed the old starter teeth around the flywheel again for weight savings and for a possible reduction in drag. I'm actually going to be putting these teeth to use to measure the motor RPM. I'll post more details on that in future posting.

Here is the edge view of the original (right) and the new lighted (left) flywheels. The new one is precision balanced, of course.



The motor with everything attached. The clutch alignment tool is installed and I am ready to torque the 9 flywheel bolts. The flywheel lock is just visible at the top center of the picture.

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