Rear wheel bearings for C2s?

[Darryl D.]

[Gerard F.]

Re: Rear wheel bearings for C2s?

Darryl,

If you are over 50 K miles (and the 5 year guarantee) you should get them checked. If you hear a clicking noise while just cruising along, check the play in the rear wheel bearings, by rocking the rear wheels top and bottom.

There is an article in the Summer 2009 Restorer called a Top Flight Adventure where I lost a wheel bearing on my 67 coming home from a Chapter meet. Lucky I didn't wreck the car. Send me a private message with your email address if you want a copy of the story.

Here's a photo of the 67 sitting alongside the road with the wheel bearing failed:



I understand that this has happened to lots of driven C2's

[Bruce B.]

Re: Rear wheel bearings for C2s?

In my 65 coupe I started to hear a slight noise in the rear wheel as failure started. I put my car up on the lift and it was easy the hear and feel the bearing begining to fail.
I bought a rebuilt wheel bearing assembly from Bairs , installed it and went on a 2600 mile Power Tour the next day, the bearing assembly continues to work flawlessly over the last 4 years.

[Richard G.]

Re: Rear wheel bearings for C2s?

If I had the car's bearing history and knew both sides had been rebuilt by a competent person with a modern grease, I wouldn't be concerned about the bearings for 100K.
No history? I would do them both. The cost way less money than an accident or fender. I have observed many back yard jobs on these axles and it ain't pretty. One of my pet peeves is sanding down the axle fits so it can be assembled easier. GM figured out in early 63 this didn't work. The job requires a major expense in tools. Unless I planned on doing more than two I would recommend sending them out. Don't forget to check the U-joints as they are a integral part of the suspension unlike modern cars.

[Duke W.]

Re: Rear wheel bearings for C2s?

Sudden rear wheel bearing failure can occur on any C2/3, but it seems to be more prevalent on disk brake models. I believe this is because the disk brake rotor geometry provides a shorter/lower resistance heat transfer path to the bearings, so they run hotter. With drum brakes most of the heat is on the outside of the drum and the heat transfer path is through the web to the spindle flange, which is a longer/higher resistance path.

When bearings start to spall, clearance will increase, so whenever the rear wheels are off the ground, grab the top and bottom of the tire and wiggle to check for excess clearance. Do it on the front wheels, too.

Also, rotate the wheels and check for roughness.

Duke

[Richard G.]

Re: Rear wheel bearings for C2s?

It is a fact that bearings will last longer with some preloading set into the bearing. I know it makes little sense. I believe it may be because all the rollers are in contact at any one given moment. I have always wondered why the wheel bearing set up specifications were not for a bearing preloaded? Ease of setup? Possibly a discussion for later.

The greases of the day are junk by today's standards. GM was known for keeping costs down and it is my belief the greases they used were of a lower grade even back in the day. I have resorted to disassembling even NOS wing window gearboxes because the grease looks more like pine pitch than a lubricant. Proper set up with a clean modern grease should give one decades of service.

[Gene M.]

Re: Rear wheel bearings for C2s?

It is a fact that bearings will last longer with some preloading set into the bearing. I know it makes little sense. I believe it may be because all the rollers are in contact at any one given moment. I have always wondered why the wheel bearing set up specifications were not for a bearing preloaded? Ease of setup? Possibly a discussion for later.

The greases of the day are junk by today's standards. GM was known for keeping costs down and it is my belief the greases they used were of a lower grade even back in the day. I have resorted to disassembling even NOS wing window gearboxes because the grease looks more like pine pitch than a lubricant. Proper set up with a clean modern grease should give one decades of service.

What you say is so true. The taper roller bearings are best when run at zero clearance. Treat them same as front wheel bearings for set up and lubrication. Understand if setup as the spec’s call for with clearance that it will affect the alignment and premature wear. Richard gives good advice in eliminating clearance even though it takes more effort to get the shims to achieve goal.

[Duke W.]

Re: Rear wheel bearings for C2s?

It is a fact that bearings will last longer with some preloading set into the bearing.

Can you explain in detail?

Consider that wheels bearing loading is different than, say, axle drive pinion and differential case side bearings. The former has a "point load" while the latter are used to keep the parts in precise alignment and the preload places a uniform load on all the rollers.

Some misconstrue the instructions in service manuals to preload front wheel bearings to about 12 lb-ft in order to seat them, and then back off the the spindle nut to obtain the recommended clearance range, and I prefer the minimum, say one to two thou.

Failure to follow these instructions by leaving the front wheel bearings preloaded and not backing off the spindle nut to the specified clearance range usually results in rapid failure.

Duke

[Gary R.]

Re: Rear wheel bearings for C2s?

With stock 17 spline axles I set them up without any lateral play, no concern about trying to make an endplay number because I found play in plenty at 002"setups. Once the lateral play is removed there is still about 0015" endplay. With 31 spline axles I set them up for 5 in/lb preload and that works great.

[Darryl D.]

Re: Rear wheel bearings for C2s?

Thanks for the info guys.

[Mark E.]

Re: Rear wheel bearings for C2s?

Sudden rear wheel bearing failure can occur on any C2/3, but it seems to be more prevalent on disk brake models. I believe this is because the disk brake rotor geometry provides a shorter/lower resistance heat transfer path to the bearings, so they run hotter. With drum brakes most of the heat is on the outside of the drum and the heat transfer path is through the web to the spindle flange, which is a longer/higher resistance path.Duke

Interesting point. I never considered heat from the brakes affecting bearing life, but it makes sense.

I can see brake heat as a significant issue while road racing because of the regular, heavy braking at each corner. But is there really any significant brake head load on the street?

Duke, I know you have a racing background, so maybe you're speaking from that perspective?

[Richard G.]

Re: Rear wheel bearings for C2s?

Duke;
Failure to follow these instructions by leaving the front wheel bearings preloaded and not backing off the spindle nut to the specified clearance range usually results in rapid failure.
No I can't explain it.
May have something to do with the sliding fits on the spindles verses an interference fit. Or heat building from over greasing. The "bearings last longer preloaded" is the result of specific testing done by the bearings manufactures and may not be true in every instance. May have been related to oil bath only but I would have to dig out the books again to be sure. In general terms it is very true. Add dirt, incorrect lubrication, incorrect set up and all bets are off. The studies were controlled studies that attempted to eliminate these variables. Best to stay within factory recommendations. Possibly my bearing engineering comment was ill placed for this discussion?

Interesting GM's clearance settings allowed up to .008 axial play. The available factory shims allowed one to meet this specification as they come in .006 increments. This allows one to hit the factory specified clearances but reducing it to .001 or .002 sometimes difficult. I use a surface grinder to reduce one of the thicker shims to the required thickness. Most don't have this luxury. I find differences in the center spacer's width. Swapping them side to side or having an extra around usually helps get this spec a little closer to the .002 which I prefer. This is especially important with a disc brake car.

[Duke W.]

Re: Rear wheel bearings for C2s?

Fresh out of the U. of Washington in 1968 with a BSME, my first job was at Pontiac Production Engineering, and my first task was to investigate a high front wheel bearing failure rate, which was mostly in the northeast. I had taken a Bearings and Lubrication course, so I felt I had a grip on the situation, and a couple of complete knuckle/drum assemblies were on the way for me to do a failure analysis.

The first thing I did was go to the responsible design engineer to review his design. Roller bearings come in numerous standard sizes, so you basically look in a bearing catalog and use speed, design life, and load to select the bearings. The design life criteria was 50K miles at 50 MPH at gross weight, and when I asked the design engineer why those criteria were chosen his answer to the FNG was: "That's the warranty". This was my introduction to automotive design.

It's not actually as bad as it sounds because the bearing you pick from the load and life is for a very low failure rate at design life, but I don't remember the specific value.

When I disassembled the complete knuckle assemblies that came in from the field I found lots of grit in the hubs and the "felt" seals were wet and disintegrating. A review of the plant procedures revealed that the plant had been soaking the seals in oil prior to installation, but discontinued the procedure at some point. Then I contacted my counterpart at Chevrolet Engineering and ascertained that Chevrolet has long been using a neoprene seal.

I then prepared an ECR to replace the felt seals with the neoprene type along with what was essentially an emergency change request to begin soaking the felt seals in oil until the new parts were available.

So two weeks on the job and four weeks out of college I'm up in front of the CCB with Chief Engineer and all the engineering department bosses making my pitch. Fortunately they weren't too hard on the rookie. There were a couple of easy questions, and then a unanimous vote to approve both requests.

Duke

[Joe R.]

Re: Rear wheel bearings for C2s?

You might want to keep this pic in mind if you are waiting for 50 thousand miles to lubricate your original rear bearings.

A friends 66 did this job but he was backing up in his driveway cause he had noticed a little noise somewhere in the rear of his Corvette.

Found it!

JR

[Richard G.]

Re: Rear wheel bearings for C2s?

Warranty was denied because of the addition of fender flairs and wider tires!
My idea of a joke... But if you are selling Automobiles likely not a good one.

Possibly Joe could confirm my assumptions?
I have seen them with the twist in them but none broken like this.
Road hard and put away wet...
Like most Corvette in the day.

No degree but spent many days chasing down reliability issues. Usually a good idea to ask the janitor, as they will tell you stuff no one else will as typically they don't have any skin in the game. Another great idea is to read the manual! VBG.