Gather around kids, today I'm going to tell you a story about the live rear axle. Clearly, everything was working too well, because I started taking the 7 apart again :lol: The reason was that rear hubs developed some play last summer, so I wanted to investigate the issue.
First some background. The axle is from Morris Ital, modified by Caterham, fitted with Quaife LSD and uprated halfshafts, and as it turns out, different hub design. This became apparent when I got leftover assembly (halfshafts + bearings + hubs) from a friend, and discovered that they look pretty different:
Top is the original design, with tapered, keyed hub fit, bottom is what I have, with a straight splined hub fit. Obviously the hubs are different too, so my original idea to just replace the hubs wont work here.
Furthermore, the bearings on the donor halfshafts are welded in place, while my shaft has a lip that positions the bearing:
Further investigation showed that welding the bearing in place was a pretty common practice to stop if from "walking". Caterham did it too. The bearing is simply pressed on a slightly tapered shaft, as is the hub, so there will be a gap between them eventually, which leads to bearing breaking loose and end-float on the axle.
It's remarkably difficult to find photos or schematics, for some reason, but if I understand things correctly, the bearing outer race is sandwiched between the axle case and the drumbrake rear plate. The inner race is simply pressed on the axle, taper stops it from going in, and ideally the hub stops it from coming out. Some people put shims in front of the bearing, so that the hub is definitely in contact with the inner race when tightened, others tack-weld the bearing to the shaft which also solves the issue. Unfortunately this process weakens the shaft, so eventually you may end up with....
So for now I decided against using this halfshaft/hub, and will try to fix mine instead. At least I can change bearings on mine
Since my hubs have a spline fit, I can really tighten the bearing against a lip on the halfshaft. Unfortunately I seem to have a bit of (radial) play of the hub-halfshaft meshing. That, coupled with a right-handed thread on both halfshafts, leads to the left side often getting loose.
In addition, there's an oil seal riding over the hub, which stops dirt from coming into the bearing, and it appears to have grinded the hub quite significantly!
Original hub on the top, mine on the bottom. Both hubs are more or less like that, but the left one is worse. I guess the issue is that the oil seal is essentially dry. There is no oil behind it, it's just a dust shield. Anyway, it doesn't seal at all now. And the bearings look pretty dirty too, and a bit noisy, so I've replaced them. Not sure what to do with the hub seal. I'm considering turning the diameter down to make it parallel, and using an undersized seal. Ideally, I'd need new hubs, but I can't find who makes them! I asked Quaife, and they said their kit uses original hubs, so I guess my halfshafts and hubs are not from Quaife after all, but some other source :?