8 3/4 gear setup

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I took a small flap wheel to the inside of that pinion bearing and now it barely slides on with no play. Great way to mock it up. My jig measures a .020 shim needed from the number on the end. Ill start with that.
 
oldkimmer said:
I can tell u that maybe 1/3 of the diffs I do has the caps cut in the Center of the circle. I have been doing diffs for 40 years. The proper tools are by far the best and the fastest to use. The old school way was to install the pinion with the factory shim and see what kind of a pattern u got. Then u guessed what shim u would need. When I first started doing diffs I could not beg, borrow or steal the arbour set up. Kim
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Could you post a picture of one of the 2/3s that are not cut in the middle?
 
I'll be needing to do this soon once I get my 4.30 gears for my 489. Did my 3.55 489 case with crush sleeve eliminator and it whines so I obviously didn't get it set up right. Perfect excuse though to upgrade to 4.30 gears while I fix my previous mistake.
 
68Dart500 said:
I'll be needing to do this soon once I get my 4.30 gears for my 489. Did my 3.55 489 case with crush sleeve eliminator and it whines so I obviously didn't get it set up right. Perfect excuse though to upgrade to 4.30 gears while I fix my previous mistake.
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How did you mess that up? Curious....did you get a good depth pattern? Did the lash change when you tightened everything up ?
 
pishta said:
How did you mess that up? Curious....did you get a good depth pattern? Did the lash change when you tightened everything up ?
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Everything was within spec after tightening. I thought I had a good pattern according to the grease markings. It was a used gear set so maybe it was doomed before i even started
 
I picked 1 random center section out of my collection, and did some measuring, to see if I was "full of crap" as one member stated. The carrier bearing bore measures at 3.268, so the dead center of that circle would be 1.634. Measuring the housing on the pinion side, from the machined flat surface measures 1.627, and the bearing cap measured from the machined flat measures 1.641. So clearly, the caps are NOT cut dead center of the bearing bore. THAT is why the factory, and every gear manufacturer recommends checking with the proper tool that measures from the CENTER of the bearing. Not some old pushrod. And why listening to poorly thought out shortcuts on the internet isnt always a good idea.

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And every housing varies, some are closer than others. And if you check the bearing bore with a dial bore gauge, you will find some are not as round as you think either!
 
replicaracer43 said:
I picked 1 random center section out of my collection, and did some measuring, to see if I was "full of crap" as one member stated. The carrier bearing bore measures at 3.268, so the dead center of that circle would be 1.634. Measuring the housing on the pinion side, from the machined flat surface measures 1.627, and the bearing cap measured from the machined flat measures 1.641. So clearly, the caps are NOT cut dead center of the bearing bore. THAT is why the factory, and every gear manufacturer recommends checking with the proper tool that measures from the CENTER of the bearing. Not some old pushrod. And why listening to poorly thought out shortcuts on the internet isnt always a good idea.

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You get the .007 out of tolerance award. lmao
There's a reason I have you on ignore.
 
replicaracer43 said:
And every housing varies, some are closer than others. And if you check the bearing bore with a dial bore gauge, you will find some are not as round as you think either!
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replicaracer43 said:
I picked 1 random center section out of my collection, and did some measuring, to see if I was "full of crap" as one member stated. The carrier bearing bore measures at 3.268, so the dead center of that circle would be 1.634. Measuring the housing on the pinion side, from the machined flat surface measures 1.627, and the bearing cap measured from the machined flat measures 1.641. So clearly, the caps are NOT cut dead center of the bearing bore. THAT is why the factory, and every gear manufacturer recommends checking with the proper tool that measures from the CENTER of the bearing. Not some old pushrod. And why listening to poorly thought out shortcuts on the internet isnt always a good idea.

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U r correct. I’ve had some that I needed a .060 thicker shim to get the pinion where I needed/wanted it. Used gears r tricky to get right. Kim
 
Jadaharabi said:
You get the .007 out of tolerance award. lmao
There's a reason I have you on ignore.
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I dont care if you have me on ignore, I'm pointing out with FACTS that your wrong. And your half *** shortcut method could cause someone to screwup there gear set.
 
Does not matter how or what you use to get there. In the end it is the pattern and backlash that counts.
 
@Jadaharabi I too have measured carrier bearing bores and found them not to be cut exactly in the middle. I have one on the stand right now and will try to get a picture of taking measurements in the next couple days
 
Tried to set up a 489 pumpkin today.
New 3.23 oem gears. With a
030 shim behind the inner bearing the depth is 2.78 and the back of the pinion gear rubs the suregrip .
Using all new bearings and a crush sleeve Eliminator.
It's like the suregrip housing is to big around.
 
Jadaharabi said:
Tried to set up a 489 pumpkin today.
New 3.23 oem gears. With a
030 shim behind the inner bearing the depth is 2.78 and the back of the pinion gear rubs the suregrip .
Using all new bearings and a crush sleeve Eliminator.
It's like the suregrip housing is to big around.
Click to expand...
Using a cone or clutch SG?
 
Jadaharabi said:
Cone.
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I have never encountered that with a 489/3.23/cone. And I have done more than a few. You sure the race is all the way in the case? .030 shim is within the normal range. Did the eliminator set the the preload correct? How much shim did it take with the eliminator?
 
Inner race looks to be seated no shims behind it.
With .015 have 30 inch pounds and with .020 have 10 inch pounds. Will try .018 tomorrow.
 
U will heed to take at least .020 out of the pinion for it not to hit the unit. When ur getting on ur car the crown gear wants/try’s to pull the pinion into it. There was a discussion awhile ago about the case and the caps not being cut perfectly in the center. Yours will be 1 of them. U need another case. Kim
 
Great thread. I have set up a few 8 3/4 and have found that if you have the shim from the old gear set that was previously installed in the pumkin you are working on, it usually is very very close to what you need. Next time i'm going to hone a new bearing, maybe get one of those set up tools. The pushrod across the caps may get you close but i wouldnt trust that method very much.
 
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