'68 Rear Wheel Bearings

[Joel K.]

I'm reading a couple of old magazine articles on changing rear wheel bearing assemblies, that make it sound like a fairly easy do-it-yourself job. I'm working on a '68 convertible with 54,000 miles, have the spindles out of their carriers and the bearings look like new, despite the grease having turned into wax. Several other sources recommend sending the spindle assemblies out for rebuilding. Would appreciate thoughts, suggestions, experiences with this job. Thanks!!

[Dick W.]

Re: '68 Rear Wheel Bearings

Unless you are very mechanically inclined and have the necessary tools to complete the job, I would recommend that you send them out for rebuilding. Setting up the bearings and reassembling the parts require specialized tools.

[Gary Schisler]

Re: '68 Rear Wheel Bearings

I have watched professionals do this very same job. I couldn't disagree with your statement more that this is an easy DIY job. Special tools, special attention to detail, and the right techniques. I have done EVERYTHING on my car but the trailing arms. I consider myself an accomplished DIY kind of guy but I don't do rear bearings.

Gary

[Joe L.]

Re: '68 Rear Wheel Bearings

Gary-----

I would agree with the others that your best bet is to have this professionally done.

And, I would not even consider re-using the bearings no matter how they look. You want to use new Timken bearings and most of the better sources for the rebuilding will use them, anyway.

By the way, the reason that your grease has turned to "wax" is that grease is a combination of an oil + a soap. After a long time, most of the oil "gets away" and what you're left with is mostly soap.

[Mike M.]

Re: '68 Rear Wheel Bearings

if you have a dial indicator and the midyear shop manual(don't know if the 68 shop manual covers this proceedure but suspect it does--nevertheless, the midyear shop manual definitly does provide coverage), it's not an overly complicated proceedure. however, your level of mechanical experieince is unknown to me. read the book and if you feel comfortable , go for it. the shims , as far as i know, are still available from GM. let us know how ya do and good luck. mike

[Tom S.]

Re: '68 Rear Wheel Bearings

I vote for sending them out unless you have all the tools. And it is not worth buying the tools if you are only going to do the one job.Plus the exprience factor, getting them loaded correctly is very important. Improper bearing adjustment is the #1 factor in bearing failure. Tom

[Jim T.]

Re: '68 Rear Wheel Bearings

I have only done the rear bearings on my original owner 68 and 70. If you removed the spindle yourself, you had accomplished the hardest part of the job of servicing the rear wheel bearings. Did you measure the end play before you removed the spindle? When I did the job on my 68, the bearings and end play were within spec and it had more miles on them than your 68. This was 20 years ago when I cleaned the bearings, hand packed them, and reinstalled the assembly with new seals. Still have no problems with that repack. My spindles still have the factory assembled rivetted discs, no runout problems, no pumping of air into the brake calipers. If you need your discs rivetted to your spindles, check out Bairs for their service, they will do it all and provide shipping boxes for a reasonable price.

[Chuck R.]

Re: '68 Rear Wheel Bearings

As I consider myself an accomplished mechanical "improvisor" , here's what I came up with for necessary shade tree mechanic tools.

Spindle knocker or a minimum ten ton press.

Knockers are certainly more affordable than the press, but they either work with one or two good blows or you can sometimes beat on them till your exhausted with no progress. Plus it's pretty violent work and you'll need a large ball peen hammer (at least two pound), heavy leather gloves and safety glasses.

Even with the press, I had to weld up a jig to hold the assembly plumb while I pressed the spindle out. Gloves and safety glasses should be used here too.

With my twenty ton press, I even had to let one assembly set with a strain on it for a while and then it let go with a pretty loud BANG!

The spindle setup tool I made from a pitted up spindle I had laying around. I ran the spindle at slow speed in my drill press and reduced the diameter of the outter bearing shoulder until I achieved a snug slip fit so that I could remove the outter bearing without pressing.

Then it was off to the media cabinet to blast the support, caliper bracket, half shaft flange and the EXPOSED surfaces of the spindle etc.

A dial indicator and foot pound torque wrench are also a must.

I also purchased new shim kits along with the bearings.

I echo Joe's sentiment regarding used bearings. If you have them out, replace them, no matter how "nice" they appear.

I've worked on vehicles for as long as I could hold a wrench, and if I hadn't had these tools, I'd have sent mine out for rebuild without even thinking twice about it.

Oh and a word to the wise, when you mount the assemblies back into the trailing arms, make sure that you have the proper support on the proper side. I had a fifty fifty chance and lost when I went to install the outter strut/shock bolts and found out I had them backwards. The adjectives were flying that night Joel!

Hope this helps,

Chuck

[Dick W.]

Re: '68 Rear Wheel Bearings

I am just finishing up a "bubba'd" set of rear bearings. On the left side they had turned the spindle down so the bearings would slide on, the right side they had gouged the seal surface with a torch while apparently cutting the bearing cone off. This is the second set of "bubba'd" bearings that I have done in the past 6 months.

Send yours out to a professional. Bair's, Vette Brakes, etc

[Warren L.]

Re: '68 Rear Wheel Bearings

Whats the formula for tolerance lost due to interferance fit tapered roller bearings when pressed onto a spindle?

How do you measure bearing end play correctly?

Warren

[Dick W.]

Re: '68 Rear Wheel Bearings

There is not formula for tolerance lost. The bearing end play is determined by use of a dummy spindle. You install the bearing races in the hub, install the bearing cones with spacer on the dummy spindle. You assemble the dummy spindle just like you would with the regular spindle, apply the proper torque, then measure the end clearance. Once that you have gotten the proper spacers determined, pack the bearings, install the bearing and seals (not forgetting that the spacers must go in at this time) and then use the installation tool to install the spindle. A lot simpler than it sounds if you have the dummy spindle. With good luck you can do both rear bearings in less than six hours.

[Warren L.]

Re: '68 Rear Wheel Bearings

Dummy spindles are wrong.

There is a formula for tolerance lose due to interferance bearings and there is more to it than articles written on it. Just ask Art at Van Steel who smiled when asked about tolerance loss due to interferance fit.

Ask Mike Hanson he understood that. Call up Timken and ask for an engineer and ask them how tapered bearings behave and if there is loss due to interferance fit and they will tell you yes, so will my dial indicator it backed up what the engineer said. Ask them about bearing tolerance during manufacture. Why would it be when I asked the mechanic that did mine about loss he whipped out the formula from his mind he didnt go somewhere and look it up. It exists yet you say no. He had never done a corvette spindle in his life.

It's not simpler than I think, there is more to it than I have ever read in any GM manual or article or read here.

You said you measure the end clearance so how do you do that?

Warren

[Gary R.]

Re: '68 Rear Wheel Bearings

I've rebuilt a lot of these and one step I do is to parallel grind the spacer and shims when setting them up. You will need access to a good surface grinder to do this,but I wouldn't do it any other way. The spacers can be off as much as .005" and this will make a difference going from the setup tool to the spindle. I use only Timken bearings as I had other brands fail in setup. I set them to .0015-.002" max and use Mobil 1 red grease with them. You want to have the rotor runout set at the same time so you avoid any brake issues. I dial them in to .000-.002". I tap the flange for 3/8-24 and bolt the rotors on. Do not turn the rotors. If anything use a 100 grit D/A on them or replace them.
It is criticle that there is no movement in the indicator mount when checking, just hand pressure will throw off the reading.

[Dick W.]

Re: '68 Rear Wheel Bearings

Dummy spindles wrong?? GM included these in over 3,000 dealer essential service tool kits that went to the dealers. The majority of the bearing rebuilds are done using these. I too set the clearance, using a dummy spindle, to .0015-.0020 measured with a dial indicator with .0001 graduations. I have never had one vary more than .0005 from what the dummy
spindle measured to what they measured when the spindle was installed.
We just finished doing a '71 today and the variation was less than .0005 on either side. I would find it hard to come up with a formula that would take in consideration the tolerances on the spindles.

[Warren L.]

Re: '68 Rear Wheel Bearings

Dummy tools do not allow for expansion due to interferance fit.

There is a formula and my loss was more than the calculation. In fact I believe .003 on one spindle. I can't open the file cause it got corrupt and I had to remove it cause it was stopping windows from booting up so I am going from memory.

Both spindles on the the tool and on the actual spindle with the actual bearings incurred losses that came from the interferance fit. If I could open the file I wouid print out the formula for you. We calculated but it is too hard for me to measure with my tools they are just not accurate enough.

Ask an engineer who understands the bearings and how they react when tapered roller bearings are installed interferance fit. The Timken Engineers who explained this to me had never seen a Corvette spindle but the know their bearings and how they are designed and work.

I know you said it is simple, You said you make .001 on your dial indicator, how do you measure your bearings? What are you doing to get that number?

Warren