Rear Wheel Bearings Question - Again!!

[Ray C.]

Is there an average or common range of shim thickness for rear wheel bearings? There was a single shim on the left wheel side of .136 and I believe this to be the original set up, casting date number of May 1965. The right side has a date stamp on the casting of May 1962 and must have been a replacement (from a 1963). The right side came apart easy and has two shims with a combined value of .207. After torquing to one hundred ft. lbs. and using a dial indicator there is a run out of .035. I plan on having a machine shop mill the shims to the correct thickness or untill the run out is .002 to .005.

Thanks for any help!!

Ray #36314

[Wayne W.]

Re: Rear Wheel Bearings Question - Again!!

I dont know exactly what you are asking for here. Yes there is a more common setup. If you set up a bunch of them a pattern come out, but this may have no bearing in your case. You can purchase different shims from GM or other suppliers to get your setup right. Just purchase a kit from a corvette supply house or figure which one you need and order that one from the dealer. I would suggest you get a few near that measurement too make sure you have it covered.

[Craig S.]

Re: Rear Wheel Bearings Question - Again!!

Ray - as Wayne comments, the shims are available from various suppliers, one that offers shims every thou or two is Tom at International Axle. FYI, the 63 stub axle came apart easy as GM changed to press fit after the 63, I believe in 64 due to problems with bearing failures. They wanted the press as a safety measure. Most shops convert the 63 assemblies to the 64 up spindles, I seem to recall GM even had a service bulletin on this. I would personally change to the press fit version. Good luck!...Craig

[Duke W.]

Re: Rear Wheel Bearings Question - Again!!

The press fit went into production on Dec. 3, '62 and carried through to '82 without substantial changes, and a service bulletin was issued on the changes for both production and the field fix for the earier slip fit design that experienced problems - basically install the new press fit design parts. One of the changes associated with the new press fit design was elimination of the 30K mile repack specified in the '63 shop manual. The new design has no specified service interval.

Early '63s have the slip fit, but they caused problems, and after a couple of interim changes, which were basically bandaids, the final design went into production as stated above.

I doubt if any of the early designs survived this long at this point in time. In any event, the '65 would have the press fit. The design changes affected the spindle, spindle drive flange, and washer, which is .210" thick for the final design. There were no changes to the carrier.

Modifying the press fit for a slip fit is probably okay on a race car that will see frequent teardowns and spindle pack servicing, but for a street application the press fit is the way to go. If it's assembled to the proper end play with a high quality synthetic grease, it should be troublefree for a LOOOOONG time.

Duke

[Craig S.]

Re: Rear Wheel Bearings Question - Again!!

Duke - when I took the trailing arm rebuild class in Bloomington this year, one of the guys in the class had a 63, one of each type. He bought some new parts from Tom at International Axle the next day when the swap meet opened, so I guess a few hung in there! Thx for the detailed and accurate transition information, I just knew it was somewhere around 63-64...Craig

[Gene M.]

Re: Rear Wheel Bearings Question - Again!!

Ray, If I remrember correctly there is an offset difference in the drum brake spindle and the disk brake spindle. Also the actual castings look a little different. How are you measuring runout if you don't have the proper end cleanance? The .035" slop you mentioned is way to much to even run the bearing true to check runout of the spindle let alone the rotor.

[Ray C.]

Re: Rear Wheel Bearings Question - Again!!

I first would like to thank all that have help in the restoration of my 65. The information I was seeking in refference to shim thickness: The left wheel which I believed had never been removed had a single shim of .136. The right wheel which had replaced wheel bearings and spindle bearing housing (casting date of may 62) had shims of .097 and .110 = .207. or a difference of .071 between the left and right wheel. Where I goofed, I did not check the free play or run out prior to disassembly of the rear bearing unit. What would be maximum or minimum amount of shims that could be used? (.001 to.300 or more)I may be wrong, but I believe Duke answered this with his post of newer designed set up of .210, this would be the norm or 0 point. Gene, after the installation of new bearings,races and tourqing to 100 ft. lbs. I calculated the .035 of free play by the use of a dial indicator that was secured to the assembly. I used the .035 as a refference point and have had a machine shop remove .028. I will retorque to 100ft. lbs. and then check for free play again. I will then make finial adjustments and try to acheive the .001 to .004(.008 max)free play.

Again, I would like to thank all!!
Ray

[Craig S.]

Re: Rear Wheel Bearings Question - Again!!

Ray - are you pressing the assembly together each time, or using the setup tool with a slip fit? It is far easier with this tool...without risking bearing damage. Since the shims come in 0.001 increments, it is easy to tune in the thickness. I would think a machine shop would be an expensive way to go to reduce the thickness of a shim, probably with a surface grinder with magnetic base....I have a metal lathe and to chuck the shims accurately can be done but is just not worth the hassle. I am sure your approch will work, but I am just questioning the efficiency of calculating and cutting, recutting, etc. You may want to give Tom at International Axle a call for your shims vs cut your old ones...good luck on your project, Craig

[Duke W.]

Re: Rear Wheel Bearings Question - Again!!

The .210" thickness I quoted for the washer has no affect on the clearance. This is the washer under the spindle nut. The thickness was probably increased because of the increase in nut torque to 100 lb-ft, from 50 for the original design. I mentioned it because it was one of the three parts that changed with the implementation of the press fit design.

If your measurements indicated .035" end play with a combined shim thickness of .207, and you shoot for the middle of the range - .004" - then the required shim would be .207 - .031 = .176".

According to my 9-77 P&A catalog available shims range from .097 to .145 in six thou increments.

The axial length of the inner bearing races, which is one dimension that determines shim thickness is a tight spec, which should be within a thou or two of nominal. Often, new bearings are installed with no need to change the shim or just one size change. The other two parts that affect shim selection are the spacer and spindle shoulder. (The outer bearing inner race rests against the spindle shoulder.) All these parts should be carefully inspected for wear, especially galling.

The fact that your spindle end play cannot be brought into tolerance with an available shim indicates that there is something wrong, and I would not recommend you assemble the bearing pack until you have identified the problem and corrected it.

As a pure intuitive guess, I would bet that the spacer is the bad actor. It may be worn and require replacement to get the required shim thickness into the available range of a single shim.

Duke

[Duke W.]

Correction!

I recommend you NOT assemble the pack until the problem has been isolated and corrected.

Duke

[Craig S.]

Re: Correction!

Duke - I think you are right on the money. I got sold on Tom's shims at international axle as he offers them up at 0.001 increments, in a huge kit for about $90. It let's you tune it the setting exactly, versus just get within the specified ranage...just one of those blueprinting things....Craig

[Gene M.]

Re: Rear Wheel Bearings Question - Again!!

Ray a shim kit is the way to go. The original shims are some what hardened and will require surface grinding also some what expensive, plus you loose the surface hardness. Are your spindles of the same offset?.....'63 drum vs '65 disk?