----- Original Message ----- From: [EMAIL PROTECTED] > Spin just the hub up to 7000 > RPM, everything is smooth, no vibration. This proves your motor/coupler setup is OK. > I attached the flywheel and pressure plate > (which were professionally balanced) and the whole system > gets a scary vibration, > I put the runout gauge on the flywheel, and measured almost > 40/1000's runout on the flywheel. Runout or wobble? Sounds like whoever cut your flywheel didn't have it centered on the lathe chuck. > I have not been able to have the balance shop do the > hub/flywheel/pressure plate together, becuase his balancing arbor won't > fit inside the splined portion of the hub Don't worry about that, just get them to balance the flywheel and pressure plate together. That should be enough. You've proven the hub is balanced and centered already. > Some possible thoughts: > 1. The Siemens motor has a shaft almost 4" long, Shouldn't matter. > 2. The balancer isn't balancing, Most likely. > or the machinist that resurfaces the flywheel isn't verifying that the > front and rear faces are perfectly parallel. That shouldn't matter either, technically. If it was spun-balanced the thicker side would need material taken off to balance it, that's all. > Is 40/1000's acceptable for a flywheel face? No. I would shoot for <10mil > Should I shop around for a balancer with a smaller arbor on his machine? Just find a shop that will do a decent balance job. I went to a shop that did flywheels for race cars, and they knew exactly what to do. > Or make an adapter that would convert from the spline to something an > arbor could grab? If your coupler is good, and your flywheel is straight and balanced, you won't need to go through all this. Sounds like whoever cut your flywheel horked it up. Been there, done that, I had to get a 2nd flywheel from the boneyard to replace the one a well-known EV parts supplier butchered. You can try a trick that Otmar told me about, it worked well enough to get me on the road until I got my problem straightened out. This takes a bit of fiddling but keep at it. Number your pressure plate bolt holes, then one at a time put a washer under the head of each bolt and spin it up. Note which bolts makes the vibration better or worse. There will be a definite difference. Next put two washers under the bolts that reduced the vibration and note the effect. Keep adding, subtracting and moving washers around until the vibration is nil or close to it. I found that sometimes you need to "share" washers between two bolts to get absolute minimum. It doesn't take many iterations to find nearly perfect balance. I put many miles on this setup until I got a good hub/flywheel combo. Mark Brueggemann Albuquerque, NM S-10 EV
