C2 Rear Axle bearing set-up and other recommendations.

[Richard G.]

	Axle	Bearing ID	Resulting fit
Shaft 1 small end	1.1872	1.1875	-0.0003
Shaft 1 big end	1.3762	1.375	0.0012
Shaft 2 small end	1.1875	1.1875	0
Shaft 2 big end	1.376	1.375	0.001

	Axle	Bearing	resulting fit
1972 small end	1.189	1.1875	0.0015
1972 big end	1.3775	1.375	0.0025

[Gene M.]

Re: C2 Rear Axle bearing set-up and other recommendations.

A press fit of .0005" is plenty. A press of .001" is excessive for function. Keep in mind the bearing races are all locked up to the sleeve and shims solid and nut torqued.

A bearing running fit clearance of .0005 (dry no grease) is good so the wheel alignment is not affected. More than that is seen at the tip of the tire of around .015"- .020" or more play. Not a good thing.

Use a good wheel bearing grease, not gun grease.

[Richard G.]

Re: C2 Rear Axle bearing set-up and other recommendations.

[QUOTE=Gene Manno (8571);794577]A press fit of .0005" is plenty. A press of .001" is excessive for function. Keep in mind the bearing races are all locked up to the sleeve and shims solid and nut torqued.
A bearing running fit clearance of .0005 (dry no grease) is good so the wheel alignment is not affected. More than that is seen at the tip of the tire of around .015"- .020" or more play. Not a good thing. Use a good wheel bearing grease, not gun grease.

Gene
Thanks for the input. GM specifications are as high as .008 loose. This makes sense the specifications are .001 to .008 and the GM supplied shims are in .006 increments. This is why it is sometimes impossible to get the final clearance to the tight end of the specification without shim modifications. When I disassembled the axle one Flange Retaining Nut was loose. This is the same side that had the least remaining bearing race to fit. What I didn't mention is this was this spindles was worn .0005 under-size at the bearing fit. I have chosen to reusing both axles. If this car was going to be used at the track I wouldn't even consider it. I will confirm the nut is torqued correctly and not backed off to get the cotter in. The axial to radial play is not linear. it is dependent on the angle of the tapered race and the distance from the center-line and the bearing clearance. I haven't done the math but it seems you are in the ballpark. Your suggestion has gotten me to wonder what exactly what this number might be and I will check it when I reassemble the car's axles. Much easier to do than the math!
Rick

[Gary R.]

Re: C2 Rear Axle bearing set-up and other recommendations.

Richard you put a lot of time in typing! Good deal.

I have done plenty of 63's and well as every year to 82. The early 63 axles were slightly smaller as the same bearings are used for 63-82's. Your numbers look correct for the axles diameters. 1.376" & 1.188" are where good axles fall. 001 smaller from wear or polishing will result in slip fit and that is not recommended for these drive axles. Plenty of guy on other forums like to slip fit them and swear by it but I never do.

When setting up bearings I made a simple fixture to hold the set up tool in a vertical plane, not horizontal. I do not pay attention to dialing in a specific endplay such as 001-008" instead I parallel grind the shim, spacer, and flange so I know when assembled they are tight and flat. I grind the shim to size for -0- lateral play which results in about 001-0015 endplay but again I am looking to eliminate play. At 003" endplay you can push and pull on an axles see it move. At 003-005" endplay assembled if you press on the rotor you can rock it on the bearings. When I get them dialed in there is no play and they are smooth.

As for the quality of the axles, they were pretty good into the mid 70's then twisted splines and shear threaded ends started showing up in performance and abused cars. The 63 had some issues with the slip fit and the weaker supports without webbing, this was addressed later on. Same for the 63-64 differentials. One of the displays I use at my seminars are from a 63- weak supports, posi case, and pinion gear.

Now for real performance applications, say 500 -900hp, a stock axle isn't going to make it, of course most of the parts south of the crank aren't either. For those applications I use Tom's 31's and those I preload the bearings so again the endplay is not the concern. I just did a set of those today in fact.

[Gene M.]

Re: C2 Rear Axle bearing set-up and other recommendations.

[QUOTE=Richard Geier (7745);794587]

A press fit of .0005" is plenty. A press of .001" is excessive for function. Keep in mind the bearing races are all locked up to the sleeve and shims solid and nut torqued.
A bearing running fit clearance of .0005 (dry no grease) is good so the wheel alignment is not affected. More than that is seen at the tip of the tire of around .015"- .020" or more play. Not a good thing. Use a good wheel bearing grease, not gun grease.

Gene
Thanks for the input. GM specifications are as high as .008 loose. This makes sense the specifications are .001 to .008 and the GM supplied shims are in .006 increments. This is why it is sometimes impossible to get the final clearance to the tight end of the specification without shim modifications. When I disassembled the axle one Flange Retaining Nut was loose. This is the same side that had the least remaining bearing race to fit. What I didn't mention is this was this spindles was worn .0005 under-size at the bearing fit. I have chosen to reusing both axles. If this car was going to be used at the track I wouldn't even consider it. I will confirm the nut is torqued correctly and not backed off to get the cotter in. The axial to radial play is not linear. it is dependent on the angle of the tapered race and the distance from the center-line and the bearing clearance. I haven't done the math but it seems you are in the ballpark. Your suggestion has gotten me to wonder what exactly what this number might be and I will check it when I reassemble the car's axles. Much easier to do than the math!
Rick

Rick,
In the machinist tooling world there are shims available in just about any measurement you desire. Even shims in the tenths of thousands are available. ID and OD to fit the application are almost unlimited also.

[Richard G.]

Re: C2 Rear Axle bearing set-up and other recommendations.

In the machinist tooling world there are shims available in just about any measurement you desire. Even shims in the tenths of thousands are available. ID and OD to fit the application are almost unlimited also.[/QUOTE]

Must be time to look outside the GM box of high priced spacers for equivalents.
Rick

[Gene M.]

Re: C2 Rear Axle bearing set-up and other recommendations.

Must be time to look outside the GM box of high priced spacers for equivalents.
Rick[/QUOTE]


Rick
I forgot to say, make sure you purchase hardened (possibly stainless) shims. Another as Gary does is to get the GM shims surfaced ground to size you require. Most tool and die shops have this service. My best suggestion as I do is to get .0015" to .005" assortment of shims to complement the GM or aftermarket assortment.

[Gary R.]

Re: C2 Rear Axle bearing set-up and other recommendations.

I just setup a set of bearings today for a 68. One side the required shim was .106", the other was .147". One of the spacers was shot and had to be replaced as well. Just about every build I have to grind shims and I have them from .100-.150" in about 003" increments.

[Richard G.]

Re: C2 Rear Axle bearing set-up and other recommendations.

A note to the; I did it myself, forum guys.
I just dissembled a 1964 training arm for rebuilding. On this year, trailing arm, the axle has to come out before one can get the backing plate off. I attempted to use my Axle Knocker to no avail. Got a bigger hammer, the gold standard for getting things apart. Still it didn't budge. Remember this axle is one with drum brakes, so my GM axle press tool will not attach. I have attempted various methods of getting the pusher tool to function on this type of early axle and it just ends in bent parts. So off to the press I went. With the drum brake backing plate in the way, setting this axle setup in a press is a PITA. Any short cuts usually end up bending the brake backing plate. My final set up, in the press, was an ugly conglomeration of what I had on hand. Not pictured for obvious reasons! However, it worked. It required over 25Tons pressure to get the axle out. No amount of beating with a hammer was going to remove this axle. The setup for hammering, the axle out, has the same problems one runs into when pressing it out, getting a perfectly sold base to support the bearing housing. Just isn't that easy with the brake backing plate in the way at every turn. Getting to my point, sometimes one need professional help or tools to finish the job. The factory tools were not of much help in this situation. The captive backing plate complicates the job immensely. I am confident the axles are not of the garden 64 variety and have been replaced. I didn't measure the fits, but I will and report later. If one can get the axles out with the knocker or Kent Moore style tools you are home free, as far as finishing the job at home. Sometimes it takes a press, nothing else is going to work, if you value your used parts anyway.
When you decide to get help, or send the axle off, you are just the victim of high tolerance parts. One sign of a good mechanic is knowing when they just don’t have the tools to do the job correctly or the tooling expense is more than the job justifies.
Just my two cents worth.
Rick in WA State