08
Sep

Motor with the custom adaptor

Written by admin. Posted in AC Traction Motor

The motor has been returned with the custom adaptor mounted. This critical detail was handled by a power coupling specialist in California. Thank you Leo, excellent job.

Here is the first check of the resulting fit:


With exact alignment, the transmission shaft slides into the pilot bearing and bottoms out leaving 5/8 inch between motor face and bell housing. This means that when the 3/4 inch plate is installed between the two, it will leave 1/8 inch gap between the ends of the shafts.  Perfect.

All the torque is transferred through this interference fit on the short 1 inch length stub.

(For reference, the original shaft can be seen at the top photo on this page)

The pilot bearing is visible here, pressed into the adaptor

This flywheel from the original BMW engine mounts directly to this adaptor. The fit is precise, as needed to prevent vibration when spinning up to 10,000 RPM.

The clutch assembly mounts on the face of the flywheel. We will be machining an aluminum equivalent to reduce the weight, i.e. side load on the motor which has a spec limit of 10kg (22 lbs) of side loading for the sake of bearing life. After all, the bearings are the only wear items in this motor.

This flywheel has built-in vibration reduction that will certainly not be needed when driven from a smooth electric motor. The flywheel’s only function now is to hold the clutch for the occasional shifting at highway speeds. Since the clutch will not be used when accelerating from a stop, there is no wear issue using plain 6061 Aluminum for the flywheel face.

To ensure the motor and transmission shafts are in precise concentric alignment, we will be inserting alignment pins in the corners of this motor face, just like the bell housing is aligned to the block on the original gas engine. These will be the hollow type alignment pins that the mounting bolts pass through. These 4 mounting holes happen to be the exact size of the mounting holes with alignment pins/bolts on the transmission so the same ones will be used.

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