We are changing the rear wheel bearing in the trailing arm of our 71 corvette .. before we removed the old bearings or began to remove anything we checked the end play and found it to be around 010" .. a little high but since we were changing bushing, parking brakes etc .. we thought we would just go ahead and change the wheel bearings ... the bearing are the exact same brand etc ... all we did was pressed out the old and in with the new .. as we were tightening down the spindle nut (drawing in the inner bearing) we thought to spin the wheel hub ... It was tighter then we expected so we checked the bearing play (thinking It was not all the way seated (??).. at least we can still draw more with the nut) .. well now we have NO end play ..... how could we have gone from 010" to zero making no changes to the shims ???
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Re: C3 71 wheel bearing issue
Don't know what the tolerance is for the bearing height, but the new ones are likely higher, or wider, depending on your point of view.
You're going to have to replace the shim with at least the next thinner. When installing new bearings it would be a good idea to mike both the new and old bearings and calculate the change in shim thickness, if any.
Duke -
Re: C3 71 wheel bearing issue
Absolutely you could. When GM put it together originally it had no end play. The bearings wore to allow the .010 in clearance that you originally measured. Ideally you should have it shimmed for zero clearance (you are sure that you now have the races completly seated?). I know of many folks that prefer to set the rear wheek bearings up with light interference (1-2 inch pounds). That allows them to wear in to zero clearance (not unlike rear pinion bearings that are spec'd for several inch pounds of rotational interferenece).Comment
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Re: C3 71 wheel bearing issue
Actually, I have found bearings to be very close in tolerences. Most of the time new bearings will have essentially the same clearence as the old ones. Believe it or not, one particular thickness shim is most often used, if you put enough of them together you will find this to be true. Bearings are not really designed to wear in. They should remain fairly constant for life. The bearings that I see bad, are bad for a reason, not from normal wear. The factory did not shim for 0 clearence, they used the same spec. as they published. I have actually seen factory assembled units that were not completely seated and guess what, it really doesnt make any difference because the clearence is the same no matter what. If you are too tight, you need a thicker shim. Now all that said, what you probably have is a pinched rubber seal on the inside bearing. Most replacemant seals are not made correctly and cause this problem. Let the sniping begin.Comment
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Re: C3 71 wheel bearing issue
I should clarify the comment that it doesnt make any difference whether the races or shafts are completely seated or not. The way the factory put these things together was a little different than we usually do them in the field. They used a fixture that presed these things together as a unit. If the races were not fully seated and the shim thickness was set for that position then assembling them that way would still exibit correct endplay. Also if the shaft is not driven into the setup completely the shim and spacer hold the bearing clearence anyway. I am not saying that this is good and the way you want to do it, but I have seen several from the factory that way.Comment
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Re: C3 71 wheel bearing issue
Wayne is right in that the GM spec is actually not zero. However they set their bearing end play spec looser than needed to allow for greater assembly tolerances. Setting at or close to zero requires more time (I have always used a surface grinder - a high precision machine capable of accurately removing 0.001 inch of material from a shim at a time)to ensure a precise result. I don't think anyone is sniping or disagreeing here, as there is no single answer. I personally prefer to keep the end play on the tighter side to minamize end play and reduce the ability for the rotor movement which can lead to air in the caliper on lip seal brake calipers.
BillComment
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Re: C3 71 wheel bearing issue
The specified clearance is one to seven or eight thou, and I would consider the minimum to be preferable.
DukeComment
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Re: C3 71 wheel bearing issue-reply
the unit is currently at the machine shop .. what I have learned is that it is NOT possible to assume that even if you use the exact same bearing manufacturer and part number, same exact shims that came from the orginal factory assembly you will get a totally different bearing fit .. so back to the machine shop .. they are going add shims to get me back to 001 to 005 end play .....
more to come as the asssembly goes on .. Thanks to all that have provided insight to this issueComment
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Re: C3 71 wheel bearing issue-reply-update
since this is a learning and sharing tech area .. I thought I would pass this along .. the machine shop had to add 0.042" worth of ADDITIONAL shims above what the factory had installed way back in 71 .. the end play is now about 0.004" ... remember I am replacing Timken bearings with Timken bearings .. same exact part numbers but what a differnt fit !! the task of installing the trailing arm starts this weekend ... more up dates to come .. recall all this started with the rear wanting to pass the frontComment
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Re: C3 71 wheel bearing issue-reply-update
That is an amazing difference....I can't believe the bearing variation was that much but must have been! I have checked all of my original inner/outer races and used a calipers to measure the overall assembled thickness and seen only very slight differances of a few thousanths maximum, and that was comparing NDH original GM bearings to new replacement Timken....hmmm..interesting is all I can say!....CraigComment
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Re: C3 71 wheel bearing issue-reply-update
you need to remember I was under the same impression .. recall I thought if the bearings had end play of 0.010" to start I should have no more then that just by changing out the bearings and with luck a little less .......I have been looking at this and trying to understand it from day one ... recall the end play was a little high .. but there was a large movement when trying to twist the wheel by push in with my left hand (placed at 9 o clock) and pulling with the other (at 3 oclock) I wish I had a solid answer but it appears that it was produced at the factory that way .... I am 100% sure I am the first person to get inside of that wheel ... the final truth will be when the "rubber hits the road again"Comment
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Re: C3 71 wheel bearing issue-reply-update
Very interesting!!!Comment
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