Tuesday, May 4, 2010

Motor Pull

Funny, you usually see an entry in and EV blog called "Motor Pull" as one of the first entries. Certainly not one after the proud builder has put only 901 miles on the completed car!

OK, enough grousing. Here's the, once again, empty engine bay.

My dad was kind enough to come over and help me get the motor out of the engine bay. It was quick work. I had everything disconnected by 10:30 and we had the motor out 1/2 hour later.

The first order of business was to start testing. We pulled the transmission off of the adaptor plate to expose the clutch and flywheel. I secured the motor and we spun it up. Sure enough, there was the wobble. It took a while for the 12 volt battery to spin it fast enough to see the wobble, but it got us there.

Next, we took off the pressure plate. So only the fly wheel was mounted to the hub. We spun it up again and... wobble. OK, so now we can check off the pressure plate and clutch disk as the cause. Next we removed the flywheel, leaving only the motor and the hub.

We put the battery on it again and watched carefully. There was still a bit of wobble, but it was substantially less. Perhaps 85 to 90% of the wobble was gone with the flywheel off. So, here's the culprit:

I was kind of surprised to see that there was some wobble with the flywheel off. I did what George from Netgain suggested. I spun it up and looked straight down in the hub. There was no sign of movement at all. I held a piece of aluminum right next to the side of the hub as it spun to see if it rubbed periodically or consistently. There is no variation in the spin at all. Perhaps the slight wobble that we see is from a slight imbalance in the motor. All I know is that it is very minor and there is absolutely no play in the shaft or bearings, so I'm not going to worry about it.

Next I need to get that flywheel down to a shop that can balance it.


Anonymous said...

Get the flywheel balanced while on your motor. It will then also correct/fix the very slight imbalance of the motor as well.

Tim Catellier said...

Boy, I'd love to do that, but I'm not sure how that would be accomplished. I'll have to ask the machinists if they've ever heard of a method for doing this.