489 pinion shim depth. Help!

[68Satellite440]

Hey guys, I bought a empty 489 case to rebuild to replace my 741 (2.76).
This is my first ever rebuild of a center section. I bought everything from Cass at Doctor Diff. Sure-grip, 3.55s, the whole kit.
But my problem is I followed a instructional video on YouTube of how to rebuild one. Guy was very helpful and insightful. But there was no mention of how much shim to use under pinion bearing.
My dumb self installed bearing with zero shim, finished assembly. Checked pattern and it was terrible. So I disassembled, and bent the cage on the Koyo pinion bearing in the process. So had to go buy another bearing.

Can someone please give me a starting shim amount? I’ve been told so far .030-35th.

Thanks, -Pat.

 

[steve340]

From memory my one was 28 thousands.

 

[AR67GTX]

Probably around .030” I believe, but you will have to play around with it unless you have a set up gauge. I did a lot of trial set ups on mine so I made a trial set up pinion bearing by honing it out until it would slide on with a little effort. If the one you removed is not too bunged up you might consider using it for that purpose.

 

[RemCharger]

^^^^ nuff said.

 

[1 Wild R/T]

Probably around .030” I believe, but you will have to play around with it unless you have a set up gauge. I did a lot of trial set ups on mine so I made a trial set up pinion bearing by honing it out until it would slide on with a little effort. If the one you removed is not too bunged up you might consider using it for that purpose.

Exactly what I was gonna suggest... And somewhere in the .025-.035 zone...

 

[Cranky]

The best way to set up gears is to have 'trial' bearings.....ones that will slide off and on with relative ease so you can check the pattern with different shims or better yet, have a checking tool. The trial bearings are not the ones that will be permanent however.....

 

[silversedan]

on the 489 case. I always put the shim under the bearing cup in the case, like a dana 60, you don't have to mess with the bearing.

 

[1 Wild R/T]

on the 489 case. I always put the shim under the bearing cup in the case, like a dana 60, you don't have to mess with the bearing.

That's a good option but it can be hard to source the proper shims... Unless you'd like to share your source...

 

[RemCharger]

That's a good option but it can be hard to source the proper shims... Unless you'd like to share your source...

I'm warming up to this idea too.

 

[Cranky]

That's a good option but it can be hard to source the proper shims... Unless you'd like to share your source...

After a few years of doing them, the shim collection can get a bit large....and with the advent of Shineese diffs on the market, you have to check every dang thing to make sure things fit right or it'll bite ya in the arse.

 

[1 Wild R/T]

After a few years of doing them, the shim collection can get a bit large....and with the advent of Shineese diffs on the market, you have to check every dang thing to make sure things fit right or it'll bite ya in the arse.

Oh, I have lots of the standard 8.75 pinion shims but shimming the cup isn't the factory method on an 8.75... & while I haven't checked I doubt the Dana shim fits the 8.75 bore...

 

[Rockland71GTX]

I rebuilt a manual trans for my TC and got bearing shims here:
McMaster-Carr

 

[Cranky]

I rebuilt a manual trans for my TC and got bearing shims here:
McMaster-Carr

I've bought them from lots of places including Dr. Diff and Ratech......Usually I call and ask them if they have the sizes I'm needing. If not, next place.

 

[Krooser]

Try Moser for shims

 

[451Mopar]

Clam shell puller works good for removing the pinion bearing without damage.
I have been thinking of trying to measure out the spacer thickness. I have a new Dr Diff 489 case, 3.55:1 gears and Tru-Track diff I need to put together.
Been thinking of just measuring the distance from the pinion race pocket to bottom of diff race and add 1/2 the diff race OD size to get distance to axle centerline.
Then measure the pinion head thickness plus the entire pinion bearing & race thickness to get the stack-up, then add the specified pinion depth.
Subtract all that from the first measurement (bearing pocket to axle centerline), and with luck should be the shim thickness needed. Might need to account for bearing pre-load too?

 

[Cranky]

Clam shell puller works good for removing the pinion bearing without damage.
I have been thinking of trying to measure out the spacer thickness. I have a new Dr Diff 489 case, 3.55:1 gears and Tru-Track diff I need to put together.
Been thinking of just measuring the distance from the pinion race pocket to bottom of diff race and add 1/2 the diff race OD size to get distance to axle centerline.
Then measure the pinion head thickness plus the entire pinion bearing & race thickness to get the stack-up, then add the specified pinion depth.
Subtract all that from the first measurement (bearing pocket to axle centerline), and with luck should be the shim thickness needed. Might need to account for bearing pre-load too?

Sounds similar to the MD method (mounting distance). The MD is the distance from the front face of the pinion gear head (pinion bearing seat on the gear head) to the to CL of the ring gear. The MD for a Dana 60 is 5.000".....89 case 8 3/4 is 4.344" and the 42 case is 4.350". Measure the thickness of the pinion gear head and subtract it from the MD's and you have your 'desired' pinion distance or PD. I also have the MD's for GM, Ford and AMC rear ends. Having all the numbers from a tech sheet helps get rid of all the measuring hassle. Production tolerances will dictate what the end results are but in most cases (no pun intended) it'll be dang close.

 

[steve340]

I don't worry about all the measuring set-ups.
I just start with a known shim thickness bang it together and do a marking.
Adjust to suit what the marking shows me is needed.

 

[RemCharger]

I don't worry about all the measuring set-ups.
I just start with a known shim thickness bang it together and do a marking.
Adjust to suit what the marking shows me is needed.

 

[Cranky]

I don't worry about all the measuring set-ups.
I just start with a known shim thickness bang it together and do a marking.
Adjust to suit what the marking shows me is needed.

I've had gears that didn't give a good 'marking' but the setup tool said differently.....I actually tested the first few sets before selling or giving them to the customer and they were quiet even though the yellow grease didn't show a good setup.

 

[steve340]

That is interesting info in your post. I have always tried to get the best marking possible and then bang it in the car and see if it is noisy or not.
Most diff gear sets make a slight whine at some point - it is down to what speed it happens at and can you live with it.
I had come to the conclusion it was a total crap shoot.