Saturday, November 3, 2007

Step 13: Attaching the Hub and Flywheel

Description: Attaching the hub, bushing and flywheel to the electric engine.

Tools Needed: Allen ratchets, torque wrench, red loctite.

Estimated Time: 2-3 Hours (Once you have the parts).

Caveats: Could not do it as presented in EA manual, so I'll discuss what I had to do.

Purpose of this step: The flywheel attaches to the engine and will interface with the clutch as it did with the gas engine. The Serrated edge was only for the starter, so that is no longer necessary (Some people have had it lathed off to decrease overall flywheel weight and make the engine more efficient. I didn't bother).

As noted, the motor key was a bit too long, so I needed to hacksaw it down so it would be flush on the end of the motor shaft and not hanging over. This was imprecise on my part, but I don't think it needed to be perfect.
The motor key sits in the groove and I need to put the hub and bushing on over the motor key.

First, here is the hub. This baby is one of the reasons that ElectroAutomotive has a bit of a monopoly on the electric car conversion set up. You need a specially designed hub to mimic the old interface between the engine and transmission. It is different for every car and EA has a "library" full of different designs for different cars that Mike designs with a CAD and a digital camera.

This "bushing" fits inside the hub and then both fit around the engine shaft, then the flywheel attaches to that. Note the groove in the hub where the motor key fits.

The next part required me to stray from the EA instructions. They tell you to put the hub and bushing on just tight enough to allow it to slide on the motor shaft and temporarily place on the flywheel so you can set the proper length, then pull the flywheel back off and tighten the hub/bushing fully on the shaft, before putting the flywheel back on. At least in my case, this couldn't be done. The hub fits too snug in the flywheel and if I try to slide out the flywheel, the semiattached hub/bushing come right out with it (WD40 was no help). I thought this was going to be too much of an obstacle, but I believe I found a way around it. I figured out how far into the the hub the flywheel goes, then I added that distance (in my case it was .230 inches) to the 1.790" recommended. I tightened the hub/bushing loosely onto the shaft so that it could still slide and held the flywheel just flush with the hub (not inserted). Then I slid the the hub until the total distance was 1.790 + .230 = 2.020".
At that point, I tightened the hub/bushing all the way (this is an allen wrench procedure on five provided little bolts) so it wouldn't move on the shaft. For the record, tightening the hub pulls it back in from 1.790" to 1.769" according to EA. Then it's time to add the flywheel. But before that, I took the time for a little prayer to the flywheel gods.
As far as I can determine (and I'm willing to be corrected on this), it is good enough.
Of course, make sure when you put the flywheel on that the bolt holes line up with the ones on the hub. In order to get the flywheel all the way in, I had to screw all the flywheel bolts in tight, so I needed to use the flywheel lock. Again, this is different from the instructions, because I couldn't just slide the flywheel all the way in (also, don't forget the little washer plate that fits in the flywheel before you put on the bolts. Once I determined that the measurements were adequate (by my standards), I pulled each bolt out, one at a time, put red loctite on them and screwed them back in, then pulled the next bolt, etc.. The EA manual recommends tightenting the bolts to 80 foot pounds. I can't say that I was exact on that. I screwed them in about as tight as I could without rolling the engine off the crate. I think this is about as precise as an amateur like myself will be able to do this, so I hope it's good enough. Next up is the Clutch.

I posted a picture of my dog Whitman here in the past and my other dog, Finny got a little jealous, so here's Finny enjoying some girl talk:

Finny is a Westhighland White Terrier (Westie). We got him when we were living in Seattle (much to the dismay of his brother). Finny is the quintessential terrier, in that he is a pain in the ass. I love the little guy, though.

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