James J

I road race a C-4 Corvette and have considerable experience ruining wheel bearings front and rear. I recently purchased new roller bearing rear hubs from WBI (Wheel Bearing Inc.) for about $135.00. They made it through 3 race weekends (two 15 minute practice sessions, 2, 15 miunte qualifing sessions, 2 - 20 minute heat race and 2, 30 minute main races). The car has 560 rwhp and turns corners at 1.3G.

The rear hubs became sloppy so I removed the axle nuts which were loose (orginally torqued to 165 ft #'s and perhaps should be 200) I discovered lubricant leaking from the hubs. I then dissassebled the bearings. The bearing assembly is held in the hub housing by a big snap ring. To my surprise, the roller bearings and races were not damaged. The retaining ring that prevents the bearing assembly from moving laterally on the hub was indented by the inner bearing race and the thin washers on the stub axles were damaged as well. I assume that's and why the nuts were loose.

I found a replacement bearing assembly (NTN p.n ET-CR1-0846LLCS1). The bearing assembly was in a box marked BCA - Federal Mogul Bearings p.n. 513058) for $40. I'm attempting to press the outer race from the hub housing. If that race can be removed and I'm sure it can, I'll rebuild these hubs for $40 each and a little work. And, the bearing may last longer if the retainer ring is harder. I think compression of the retainer ring allowed the bearing to move and damaged the seal. Once the lubricant is gone, game over. Or it might be brake heat damaging the seals. Whatever the problem is, if I can rebuild the hubs for $40 bucks, its a step in the right direction.

Does anyone wish to point out what I'm missing??

Charleston2012

Unless u have the drawings for the bearings, these can't be rebuilt due to tolerances when pressed together. Others have tried. Good luck

James J

Thanks, some good luck may be in order.

The replacement bearing noted in the post is identical to the unit that came in the hub. How can it not work?

The only question I have at this point is how the retainer ring loads the bearing assembly laterally. If I'm right and that ring is too soft to restrain the bearing assembly laterally in a racing environment, then perhaps a harder retainer will help the bearings live longer. However I also understand that the bearing design is marginal since the bearings are so close together.

I have read many posts on this topic in the forum. I've also taken a number of these bearings apart both front and rear. I'd buy Camaro hubs from the junk yard, run them a day or two then toss them because they became loose. I dissassembled several of those I removed because I was curious what they looked like inside, and found no bearing damage. But they had play so I replaced them. I ran a number of them until they were really loose and the ball bearings were destoyed.

I wonder if the bearing retainer which is pressed on the hub axle and not held by a nut like the rear, is sliding on the shaft due to the high lateral loads (12" sticky slicks) allowing too much point load on the ball bearings and poof, they are toast.

I'll keep working on it and will update when I know more.

Sidney004

Same failure that I have found on every bearing that has gone bad with my raced 94. Good luck, I will be watching this thread closely.

Aardwolf

A couple threads from the past with tech and pix:

http://forums.corvetteforum.com/c4-t...ontinuted.html

http://forums.corvetteforum.com/c4-t...-research.html

http://forums.corvetteforum.com/c4-t...er-prices.html

James J

I successfully removed the outer bearing race from the hub housing today. I had to heat up the housing before it would press out.

Now all I have to do is install the new bearing assembly. The bearing is in the fridge cooling. When it's cold, I'll heat the housing to about 130 and HOPEFULLY slide the new bearing assembly into place.

Then it's head to the track and monitor the axle nut torque and see if the bearing retainer ring compresses.

I think this is progress. Stay tuned for what happens at the track - July 25th.

JrRifleCoach

Please be careful.

We don't want your nuts flying off!! (old joke around here)

Awaiting your results.....

USAsOnlyWay

Would it be prudent to maybe try this on one hub before throwing both on for a test run?

I hope it works!

94vettelover2

Maybe you can make some money rebuilding "old" bearings & selling as updated/rebuilt with better partsThats the Business man in me thinking

ddahlgren

Why wouldn't you use angle contact rollers with preload? It seems like the axial load carrying ability would be much greater.
Dave

James J

Not sure I understand your question Dave, but the replacement NTN / BCA bearing assembly has tapered roller bearings back to back, identical to the bearings that came in the hub from WBI.

The assembly pre-load is determined by the axle nut torque. What I have observed is the retaining ring sandwiched between the inner bearing race and the axle shoulder was indented on the bearing side by the inner bearing race load, and the thin washer between the retainer and the axle shoulder was damage by spinning. I've concluded that retainer ring indentation reduced the assemblies tension, which damaged the seals.

I'm not aware of anyone on the forum that road races, and has bothered to check the axle nut tension during a race, but my guess is that the retaining ring is too soft to tolerate the high lateral loads from racing, and if that retainer is harder, perhaps the bearings will last longer. Make sense?

I'll post some photos when my son returns my camera!

James

The Bus

Contact this guy. He worked or was crew chief for Tommy Morrision racing C4's in races. He has let over stock front and rear bearings that were custom packed with grease. I bought a few sets and never had a bearing failure except for from a wreck. A couple have been on three years. Run in ST2 in NASA.
Here is the guy's e Mail address rjkinnindy@aol.com

The Bus

Sorry I had one too many N's.
Correct E Mail address rjkinindy@aol.com

Crepitus

ddahlgren

At first it sounded like they were plain roller bearings. What you describe is the same bearing setup used on the feed screwws on my cnc. you set the preload with the thickness of the center shim. SKF and others industrial catalogs should have the setup instructions. I am not sure of the purpose of the soft washer though.
Dave

James J

Dave,

Go to this post and look at the first photo - it shows the soft washer next to the hub shaft and flange piece.

<http://forums.corvetteforum.com/c4-tech-performance/1841697-rear-wheel-bearing-research-continuted.html>

James

ddahlgren

That should be a hardened steel washer if you expect it to live. You could probably have some made out of 4340 prehardened steel and have them surface ground flat. I am assuming the champher on the ID matches a fillet on the spindle. The whole assembly to be honest looks pretty light duty for a race car. Take a look at the Winters Racing catalog and you will see what I mean. The OD of the bearing could be substancially larger and could have been made longer in the front by putting the inner bearing inboard of the spindle.
Dave

James J

Thanks for the lead.

I've contacted Ralph. He has bearings for sale and I'll buy a few if my experiment doesn't lengthen rear wheel bearing life and make it cheaper to fix when they fail.

James J

I ran the car last weekend with the new bearings. I machined the stock retainers flat and installed new hardened washers before the race. I ran two twenty minute practice sessions on the east track at Miller Motorsports Park. I checked the axle nut torque between runs and they lost about 5 pounds of torque during the first session. ( Used 190 ft pounds initally) I took the car home and inspected the rear wheel bearing assemblies. The bearings themselves appear to be fine, but as I suspected, the bearing retainers were starting to fail again. They had compressed a few thousands where the retainer contacts the inner bearing race. The new hardened washers were starting to fail as well.

I purchased new 6820 steel to machine new retainers from and will have them hardened. The stock retainers rockwell tested at 20 HRC. I'm going to shoot for 40 HRC with the new retainers and eliminate the hardened washers and see how that works. Next test is August 5th - stay tuned.

Charleston2012

Have you thought of checking bearing temperatures? I bet if we ran wheel bearing coolers, like we do for brakes, things will last longer.