Rear Wheel Bearings

[erictharg]

The past two sets of aftermarket rear bearings I've bought have had a lot more axial play than I would expect. More in fact than the original bearings I took out. I've done half a season, including Spa, on them and they seem fine otherwise. I realise they all expand as they get hotter, and some of that clearance disappears, but it still offends to feel the play (rocking) in the hubs when the halfshafts are out. The second set I bought today for stock (from Unipart - claim to meet OE spec) are UK made NSK bearings and marked C3 clearance, which is a special wide clearance spec.
As usual, I don't feel the need to change them for anything more exotic as long as they perform. Anyone found anything that feels better? Maybe tried a stock C1 clearance bearing, that appears to be off the shelf from local stockists from SKF (6207 size)?

[Westfield 129]

If you take your bearing measurement (or the whole bearing) to a bearing house, you can find a bearing that has a couple of more balls, less lateral play, and is much stronger. I don't have a part number for these as yet.

Or... You can switch to the double bearing hubs, which are expensive, and require a bit of work to install, such as cutting the brake backing plates, for starters. There are also occasional complaints about oil leaks, as the inner bearing seal rides on a part of the axle that may not offer a smooth enough surface for oil retention. However, they do have two bearings on the axle housing, and are quite stout. No wobble at all. They may be worth the money.

Another thing to look at is the hub itself. Mine are worn, and the bearing is not held as tightly as it should be. The axle has a little wear as well, and the fit of the bearing on the axle housing is not quite as tight as I would like it to be. Wobble can start with a bearing loose in the hub, or loose on the axle housing. Your play may not be within the bearing, but rather the support for that bearing. I would select bearings that fit snugly on the axle housing and best stabilize the floating hub. This fit is important, as it directly effects the axle.

The standard single ball bearings and the hub wobble. Stability is offered by the axle drive plate, but this is problematic. If the thin stock drive plate is subjected to the side loading and wobblies, it may eventually fail, or the axle might snap.

If this looks like a case for the stronger race axles with the bolt on, machined drive plate, you are correct.

I have failed both axles on my car, using a 120 HP engine, and a TranX LSD. One failed the drive plate. The axle just spun out of it. The other, snapped at the usual spot, at the head of the splines at the differential. Both were due to torque, but the drive plate failure was also due to bearing play, in a new set of factory spec bearings with the bronze races. These axles didn't fail at the track. They failed when I was off to the corner store for a milk, bread and eggs. Pulling away, slowly from a stop light.

I am building a new car with the double bearings and racing wire wheel axles. We will see how that works. Meanwhile, I am continuing my search for a set of the heavier duty rear axle bearings.

[erictharg]

Thanks for the feedback. I'm inclined to keep with the stock arrangement as long as it lasts. I'm a pretty easy driver on my drivetrain, even when racing (necessitated by years of having to fix my own stuff), and Peter May uses stock bearings on his racer but replaces them every season. So, I think I'll go on down to my bearing stockist and see what they can do for a better quality item.
I also found my orignal hubs have "stretched" so the bearing is a loose fit in them. I've got a used pair of spares that I'll try. Otherwise they're not too difficult to turn up from billet...
I'm also going to try the "growlerising" of the stock shafts once I've crack tested them and my spares. I have a tame contact who can shot peen them to the right spec.

[Westfield 129]

It really doesn't matter what you do to the shafts. The material is just not up to the job of transmitting 40% more torque, especially if it is through an LSD. Before I changed over, I damaged quite a few shafts, spinning off the drive plate (treating the axles wont help this common failure), and twisting them in half (thinning the already weak material probably wont be of much help).

You don't have to turn new hubs. You can weld and re machine them. Remember that the fit of the bearing on the axle housing is important to the life of the bearings and axles. If they fit loose on the axle housing, tightening them at the hub over the outer race wont be much help.

Your best bet is to install better axles, with bolt on, billet drive plates. This will help stabilize the axle outer end. I know that there is a heavy duty bearing that will improve bearing life.

Interesting that Peter May uses single bearings, when he sells very expensive double bearing hubs. I just bought a set of race axles with wire wheel hubs from him. They are mounted to double bearing hubs.

I have tried this week to get a part number on the improved bearings, but everyone is in Monterey for the hysterics this weekend.