confused about differential preload

confused about differential preload

Joined: September 3rd, 2005, 10:45 pm

May 9th, 2008, 10:57 pm #1

woo hoo, I finally understand how synchros work after a lot of studying, and reading, and now have the gear clusters all reassembled and a gasket kit on the way. I decided to strip the whole case down, and deep clean, and paint it, upon doing so I discovered a crack in the case, right next to where the axle stubs bolt to the axles, crack was all the way through. I had another 5 speed, and took it apart, to use the other case half, funny thing is it ALSO had a dent in the same place, looks like the axle may have come loose at one time and the CV joint slammed it
Anyways, my question is how to set preload for the differential, or if I even should, the races do have some very light pitting and I'm thinking of replacing the bearings, I see from the manual how they say to do it, but isn't the race gonna be tight. I'm guessing that I need to reassemble the case halves with the new races/bearings in place, and the race retainer removed, and bolting the case halves together will push the race out, then use the old shim to measure the difference, and get a new shim,is this correct?
BTW, I found another way to remove the axle stubs without a slide hammer, just use long 13 mm bolts to push the shaft out against some wood wedges
Thanks in advance for any advice, Kevin Cozzo
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Damonfg
Damonfg

May 9th, 2008, 11:12 pm #2

replace the diff bearings.

Assemble with no shims, measure the gap - say .010". If you need .005 preload, add the gap plus the preload (.010 + .005) and shim by that amount.
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lezesig
lezesig

May 9th, 2008, 11:42 pm #3

woo hoo, I finally understand how synchros work after a lot of studying, and reading, and now have the gear clusters all reassembled and a gasket kit on the way. I decided to strip the whole case down, and deep clean, and paint it, upon doing so I discovered a crack in the case, right next to where the axle stubs bolt to the axles, crack was all the way through. I had another 5 speed, and took it apart, to use the other case half, funny thing is it ALSO had a dent in the same place, looks like the axle may have come loose at one time and the CV joint slammed it
Anyways, my question is how to set preload for the differential, or if I even should, the races do have some very light pitting and I'm thinking of replacing the bearings, I see from the manual how they say to do it, but isn't the race gonna be tight. I'm guessing that I need to reassemble the case halves with the new races/bearings in place, and the race retainer removed, and bolting the case halves together will push the race out, then use the old shim to measure the difference, and get a new shim,is this correct?
BTW, I found another way to remove the axle stubs without a slide hammer, just use long 13 mm bolts to push the shaft out against some wood wedges
Thanks in advance for any advice, Kevin Cozzo
Kevin,
By the book worked beautiful for me. I obtained a whole stack of different thickness shims and ended up using the very same thickness upon reassembly. Two new TIMKEN type bearings installed.

As you have probably found....the measuring/determining task is really pretty easy. The jump to the next size available shim will seem WAY OUT of tolerance.


lezesig '79 X 1/9

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Andrew Patterson
Andrew Patterson

May 9th, 2008, 11:46 pm #4

woo hoo, I finally understand how synchros work after a lot of studying, and reading, and now have the gear clusters all reassembled and a gasket kit on the way. I decided to strip the whole case down, and deep clean, and paint it, upon doing so I discovered a crack in the case, right next to where the axle stubs bolt to the axles, crack was all the way through. I had another 5 speed, and took it apart, to use the other case half, funny thing is it ALSO had a dent in the same place, looks like the axle may have come loose at one time and the CV joint slammed it
Anyways, my question is how to set preload for the differential, or if I even should, the races do have some very light pitting and I'm thinking of replacing the bearings, I see from the manual how they say to do it, but isn't the race gonna be tight. I'm guessing that I need to reassemble the case halves with the new races/bearings in place, and the race retainer removed, and bolting the case halves together will push the race out, then use the old shim to measure the difference, and get a new shim,is this correct?
BTW, I found another way to remove the axle stubs without a slide hammer, just use long 13 mm bolts to push the shaft out against some wood wedges
Thanks in advance for any advice, Kevin Cozzo
Thought I had read that somewhere; the reason being that they are bored together as one unit. So another half may not match up as exactly as it should.
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kevin cozzo
kevin cozzo

May 10th, 2008, 12:15 am #5

still got the other side if I need it
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Joined: September 3rd, 2005, 10:45 pm

May 10th, 2008, 2:24 am #6

Kevin,
By the book worked beautiful for me. I obtained a whole stack of different thickness shims and ended up using the very same thickness upon reassembly. Two new TIMKEN type bearings installed.

As you have probably found....the measuring/determining task is really pretty easy. The jump to the next size available shim will seem WAY OUT of tolerance.


lezesig '79 X 1/9
I spotted Bernice's description in "best of" Now I'm concerned about the mix and match on the case halves, and Isn't the reverse shaft a different dia, from 79 to 86, don't know if my guts will fit, guess I better go test fit some parts
Kevin
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Andrew Patterson
Andrew Patterson

May 10th, 2008, 3:03 am #7

still got the other side if I need it
A search turned this up:
http://www.network54.com/Forum/12159/message/1144284698
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Joined: September 3rd, 2005, 10:45 pm

May 10th, 2008, 5:02 am #8

the extra trans parts are off a 79, the one I'm trying to save is from an 86. The reverse shaft on the 79 is smaller in diameter than the one in the 86, long story short, the reverse shaft and gear have to stay with it's own case, and reverse on the 79 is trashed. I was thinking about taking the whole mess down to my machine shop, and having them cut down the diameter on the end of the shaft that would fit into the 79 case halve ugh, what to do, Kevin Cozzo
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DougESmith
DougESmith

May 10th, 2008, 12:19 pm #9

It shimmed out just like Lezesigs, the same LOL
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Damonfg
Damonfg

May 10th, 2008, 12:44 pm #10

the extra trans parts are off a 79, the one I'm trying to save is from an 86. The reverse shaft on the 79 is smaller in diameter than the one in the 86, long story short, the reverse shaft and gear have to stay with it's own case, and reverse on the 79 is trashed. I was thinking about taking the whole mess down to my machine shop, and having them cut down the diameter on the end of the shaft that would fit into the 79 case halve ugh, what to do, Kevin Cozzo
Don't cut down the reverse shaft, instead bolt the mismatched case together and have the 1979 half measured for alignment, and rebored if necessary.
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