63 rear wheel bearings

[Ray C.]

When did the assembly procedure change on the rear wheel bearing for the C-2? The 65 bearings had to be pressed off and on and I believe that the 63 bearings were just a slip fit. Could someone please educate me on the differences of the rear wheel bearings?

Thanks for any help!
Ray #36314

[Mike M.]

Re: 63 rear wheel bearings

slip fit to press fit spindle bearing change occured in about dec of 62. either will work. i prefer slip fit and modify all my post 63 midyears to slip fit by turning the spindles. makes for easier disassembly to re-lubricate every 25 k miles. mike

[Duke W.]

Re: 63 rear wheel bearings

I don't have first hand knowledge, but the early slip fit design must have caused problems early on. Otherwise they would not have changed the design.

The good news is that with the press fit design, the 30K mile service interval was eliminated! Since drum brakes have a higher thermal resistance path to the hub, if you overhaul the pack and use a high quality synthetic wheel bearing grease, current owners will likely never have to do any more work on them in our lifetimes.

Duke

[Michael H.]

Re: 63 rear wheel bearings

Duke,

There were actually two revisions for this bearing in early 63, both of which increased the press fit of the bearing on the spindle. The entire original design system was off the design paper and into production when someone in engineering had a horrible vision. What if one of the spindle flanges cracked and eventually came apart at speed? (likely in drag racing) It suddenly occured to him that the flange alone was responsible for keeping the rear wheels from departing the vehicle. Soon after (very soon) the press fit was introduced. About a month later, the specs were changed again to increase the press fit.

This wouldn't be nearly as serious a problem on 65 and later with disc brakes as the rotor in the caliper would prevent the assy from coming out but the press fit bearing was still used as a precaution.

Other than the safety factor in the event of a broken flange, I know of no reason why the bearings would have to be press fit. Their exactly the same as a front wheel bearing on any pass car and these have been slip fit for decades without any problem.

[Duke W.]

Re: 63 rear wheel bearings

The entire design and production configuration history is detailed in a TSB that I have and detailed in previous posts some time ago. There were actually IIRC two interim designs implemented on the line in November before the final design went into production on Dec. 1.

Do you know for a fact that the design change was motivated purely by this "horrible vision" or was it really motivated by a high failure rate? I don't see this "horrible vision". On both the floating and press fit designs the axle nut is torqued and cotter pinned to the axle, so the likelyhood of the axle nut departing allowing the axle to float out is nil if it's properly assembled. On the front end the nut is only held on by the cotter key, but the nut does not see hub torque because it is a dead axle not a live axle like the rear, which does see both brake and drive torque. They are different design architectures - dead and live axle.

If the stub axle breaks or the hub breaks off the axle the wheel will depart the vehicle with either design - just like all GM live axles used on cars.

I'm not aware that GM issued a recall (rare to non-existant in those days). They probably just repaired failures as they occured under warranty.

Duke

[Michael H.]

Re: 63 rear wheel bearings

There may have actually been more than two design changes. I know there were at least two, both of which had to do with bearing press fit and wheel/tire assy retention. I don't remember for sure if it was the spindle OD that increased in size or the bearing ID that decreased. (most likely spindle OD) If the flange disintragated, which is not at all uncommon, there would be nothing left to retain the spindle assy. The nut would be retaining nothing and the entire assy could leave the vehicle. With a press fit bearing, at least the bearing would retain the assy. If I remember correctly, the flange was redesigned about that time also. I think the flange went through a few design changes over the next year to elimiate breakage. There may have been, as you mentioned, several different rasons why the bearing clearance/press fit was changed but I know for sure that wheel/assy loss was one and I'd have to guess it was probably the most important one. I suppose the nut and cotter pin were a factor also as they could have had the same result on wheel assy loss. Either way, it wouldn't have been a pretty picture. Can you imagine Dr. Thompson or Doug Hooper loosing a complete wheel/tire assy at one of the first road racing events for the new 63 Corvette? Bet there wasn't a lot of time that passed between the initial ECR release and the actual change in production.

[Wayne W.]

Re: 63 rear wheel bearings

We have had long discussions on the merrits of slip fitting rear bearings. Personally I would never drive a vehicle that I knew had slip fit. Here are the reasons why. Both of these vehicles lost their wheels and axles and they are C3s and had disk brakes. So this is not just a drum brake issue.

http://www.members.aol.com/wombvette/AxleFail

There is another reason not to slip fit. The bearing race surfaces are not intended to run loose and wear occurs where they slip. This wear makes it impossible to hold the bearing tolerances to specification and you get considerable play in the axle. Here is a picture of that occurance.

http://www.members.aol.com/wombvette/AxleFail3

[Dick W.]

Re: 63 rear wheel bearings

Just my two cents worth. I have seen two spindles that all that was holding the nuts on were the cotter keys. Apparently someone in a prior repair had overtightend the nut and stripped the threads. Scary thought on a slip fit.

[Michael H.]

Picture really is worth 1000 words.....

Thanks Wayne. I guess that pic says it all.

[Michael H.]

Re: 63 rear wheel bearings

Dick,

I think I know the mechanic that did that. He worked on my x girlfriends car a few months ago. Same outstanding quality.

[Dick W.]

Re: 63 rear wheel bearings

Livin' proof that Bubba is alive and well.