The pinion depth does primarily control the contact pattern from the face to the root of the tooth. You do need some preload on the pinion get a decent pattern I usually leave the crush sleeve out when doing the mock-up assembly. When checking the pattern the backlash needs to be close to the minimum and tightening the backlash will move the pattern towards the toe.

 

Well tonight was another few hours of shimming painting pulling reshimming. The ratech pinion tool proved to be useless when doing this underneith the car on the ground. I cant hold it and get a caliper in there straight and pull the caliper out to read it without bumping on **** under the car. So now its start at stock shim and pull the carrier and expierament.
Move pinion in......reset lash...run pattern...pull apart repeat over and ****ing over.
Ive about had it. Im thinking if I cant get it by tomorrow, next step is to pull the housing and take it to someone to set up the gears install the carrier and pinion then Ill just take it home and put the axles in and put the housing back in. Ive put automatic trannys in in less time than I have into this disaster.

 

If it comes to it and Im kinda thinking I should.
What do you think Id have to pay to have the carrier and pinion setup and installed? If i pull and bring the housing to someone.....Ill install the axles and cover and finish it here when I get it back.
Bearings are pressed on the carrier and ring gear is torqued on. Id bring the housing "loaded carrier" and pinion. Along with crush collar and all bearings and shims. Pinion races would need to be pulled and the new installed(if I end up paying might as well do it right). Could bring the clearanced test bearings if needed.
Im going into day 3(tomorrow) very unconfident that even if I get what i think is a pattern its gonna whine and or break down the road.

 

Rear end novice here. But I have done two 10 bolts. Experts please correct anything wrong that I have said here.

Once you have the housing out of the car and sitting across jack stands, the entire process becomes so much easier. I can't imagine trying to do it first time in the car, as many times as you may have to assemble and disassemble things. Guys setting up rear ends for a living may have their own rules for what they expect for parts. This is because they are expected to give you a rear that doesn't howl and they know what has worked for them in the past. I no longer think there is big magic to doing rear ends - but like engines, screw-ups could be expensive and painful. I think you can do the job yourself - just be sure of what you are doing and most of all BE PATIENT. Hopefully this is not your daily driver.

Replace those pinion bearing races. Make a test bearing out of another of the same exact bearing that you intend to use in the end - any differences can change your pattern when you put press the final bearing on. Start with the original thickness of pinion shims installed behind your pinion, using the test bearing. Pinion doesn't need to be torqued down completely - tight enough is tight enough.

Install your carrier with new bearings and races, with appropriate shims to end up in the middle of your backlash range. Test pattern. If OK, go with that. If not, do the min and max of your backlash range and evaluate. If one of them is OK, go with that. If not you will need to change a pinion shim and see what that does to the pattern (and so forth). You can use charts to give you an idea what needs changed (pinion depth or backlash and which way), but you still have to use a systematic plan. Pinion depth gets set first. Original shims is a good place to start. Once you have your pattern good, then press a new bearing on the pinion.

First time on a 10 bolt, I used shims instead of a crush collar on the other side of the pinion as well - found it much easier than a crush sleeve to get things just right for pinion preload (once contact pattern is good), but it is a little extra work to trial and error the shims that you need. Plus you don't have to crank down on the pinion nut to such high torque to crush things, requiring special tools (even in the end).

Once you have pinion preload set, check the pattern again with the new bearing - if OK then proceed.

Finally you will need to add 0.004" each side in carrier bearing shims to preload the bearings (0.003" each side if used bearings). This can be a bit tricky. Never try to pound them in with a hammer along side other shims. I found it easiest to get a helper (wife, she's a good sport) to support the carrier itself and be sure to put thick shims as outer shims on both of the shim packs. Then start shims and races into place, equally on both sides, at the same time (angled shims). Carrier will stick and not go in - but after a couple of hits with a 3# plastic dead blow hammer from Harbor Freight, it pops in for me. One more check of pattern and you are done.

 

What you said about exact bearing scares me a bit. I used the original GM bearing as a test bearing, the new one came in a Standard Gear install set.

 

Patience is the key in this job, it's not complicated and it's not hard to understand what's going on it just takes a willingness to do multiple mock-ups. If you want to avoid dealing with the crush sleeve under the car I recommend the ratech 11003 smart sleeve which takes much less torque to crush and as much easier to manage with just a big breaker bar.

 

After a nights sleep and getting away from it I went in with a plan.
First I cleaned all the compound off and ran a fresh pattern.
Too Shallow.
Then I intentionaly went large.
Too Deep
Then I knew I need between the two points. I tried a couple middle ground shims.
While setting lash each time.
I FINALLY ended up with an acceptable pattern. Set the final lash .010(well like 10.5) and rechecked and Im happy.
This is all with test bearings.
Now I got everything clean and set for tomorrow.
Pinion bearing pressed on, seal in.
Was gonna do the crush collar and finish it tonight.....then I realized I left my 1/4-3/8 adapter in my box at home for my in/lb torque wrench to do preload.....so I stopped for the night. But happy.
Im glad I didnt try just pressing the bearing on with the stock pinion shim like a few told me, stock was 35 i ended up with 46 for a shim.
I have a better understanding now and if I do another one Im pretty sure Ill just pull the housing and set it on jack stands, thats TOO MUCH lifting laying on concrete.

 

So if the bearings need to be the same exact bearings both the ones in final assembly and test. I used the original bearings to setup my pattern. The ones in the kit are from standard gear and according to there site they are KOYO.
And to further complicate things I am using the old races.
Now I got thinking(bad idea to reuse old races aside, its a done deal) are the KOYOs gonna ride on the races the same as the stock bearings?
Being as there is no two ways about it original races are staying, should I go buy the exact same bearings as the originals to use? To both insure I dont have to play shimming games no more and the matting surface between rollers and race? Are the GM ones Timkens?
Im doing this project in someones garage and I kinda need to get it done and out.

 

I bought two new pinion bearings the same brand (Koyo) and used one as the test bearing. Whether or not this was truly necessary, I can't really say. But I always have thought it was the best case scenario for having nothing change when the second bearing was pressed onto the pinion. Someone else with more experience might be able to answer this question better than I. I always assumed there could be some tiny differences in manufacturing dimensions, more so from maker to maker - or from wear. What I don't know is how much difference it takes to actually make a change in the contact pattern.

Good luck and best wishes!

 

Thanks guys thats kinda a sigh of relief. I hope everything goes well as Im getting anxiety.

 

Well............
All nervous that I was gonna have an issue. I went to the car tightened just the slack outta the pinion and ran another pattern with the final bearing etc.....
Yea the pattern was ever so slightly different with the KOYO bearing......it actually got BETTER befor was as close to perfect as I could get with the .003 shims I had...it musta been like .001 in the right direction.
I rechecked my lash and had to make one small shim adjustment got a final wide .009.
Finished her up...oiled her up and drove my first 15mi breakin run. On the way back at 40mph I pushed in the clutch and shut the car off and coasted....DEAD SILENCE!!!!!!...no whine.
I get anxiety and stay up over thinking stuff sometimes.

Thanks for the advice and putting up with my anxious ranting LOL

 

Congrats!! You did it!!

 

For future reference, ALL bearing have a classification of tolerances and the press fit will change sizing some as well.
A tighter tolerance is always better but in the end, it's just a starting reference point and you'll end up giving it what it wants anyway.

 

I've sold pallets of Koyo bearings, and pallets of Timken bearings. I'd be happy with either.

Congrats!

 

Old bearings are worn by the nature of how they operate. The m802048 set up bearing I have been using for 25 years is a used bearing that is worn about 0.002, I just account for it when I'm selecting the pinion shim. I've done many thousands of differential builds and have never seen a meaningful difference between coil and timken bearings, they will work even if you interchange the cups and the cones.

 

Cool Thanks guys. Ive put a number of motors and trannys in. Heads, cams, assembled shortblocks(not in many years). But a differential was not only a new expieriance for me but an intricate one requiring exact precision. And that got me all nerved up. I mean I knew how to pull the axles and disassemble/reassemble a rear end, but not set up an actual gear mesh.
But in the end now I know how to do it, I know what mistakes I made allong the way and what to do next time. Really if I had just walked away the first night and thought it over I coulda pulled the diff allot less times than I did. Stick the stock shim in, pattern it, see what ya got,,then make a big jump the other way, then ya know its somewere in between.

 

... a differential was not only a new expieriance for me but an intricate one requiring exact precision. And that got me all nerved up. I mean I knew how to pull the axles and disassemble/reassemble a rear end, but not set up an actual gear mesh.

That was exactly my situation as well. Avoided setting up rear ends all my life until I finally did mine! And same thing for me with automatic transmissions!