Need Help w/8.75 Gear Swap

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matsucu06

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First time attempt to swap ring/pinion and rebuild an 8.75 (489 Case) and need some help and insight. Specifically, with setting pinion depth and installing large and small end bearings. Let me explain my situation and list out questions:

Situation:
Ring and pinion are 4:10 Richmond and have a limited number of specialty tools in my garage. Starting point is the bare case, but both large and small pinion bearing races have been replaced.

According to what I've read, if I don't have a pinion depth checking tool, I can use the trial and error method of assembling the unit and checking pinion depth via the gear/teeth pattern method. So, I should start with about .035" shim(s) on the large pinion end, install (Press on) the large pinion bearing, install pinion in case, insert small end pinion bearing, and press on small end bearing via torqueing yoke to spec. Check pinion depth. If incorrect, uninstall add/delete shims, re-install, and recheck. if correct, uninstall, add crush sleeve, re-install, and re-torque to spec.. (Much abbreviated instructions)...

Questions:
1. Does the large end bearing need to be "Pressed on?" If so, can I use a large 3-jaw puller or do I need to take to a machine shop.
2. If I have it pressed on and the pinion depth needs to be changed via adding/taking away shims, will I be able to get the large bearing off and reuse? Bearing to pinion tolerances seem tight...
3. Do I understand it correctly that the small end bearing is pressed on via tightening the yoke nut? Also, same question as large end is pinion depth needs to be changed.

Thanks for anyone's help and sorry for the long winded post!
 
First off, do yourself a favor and buy a crush sleeve eliminator /shim kit.. They are $30.

I'm in the middle of doing my first 8 3/4 as well.

You can use you old bearing as a 'set-up' bearing after honing the inner race for a snug slip fit. That way you can make pinion depth shim changes easily. Once you get the pinion depth to where it leaves you with a good contact pattern, press the new bearing on. What I do is heat the bearing up and put the pinion in the freezer. Get a piece of pipe the same diameter as the inner race of the bearing and plop it on. The warm bearing expands a little and makes it easier for a do-it-yourselfer. It's about a .003 interference fit, so a press is ideal. I would not try to use a 3 jaw puller. You'll mess up the bearing if it grabs on the cage and not the inner race.

And yes, the outer bearing is a snug press fit by drawing it on with the pinion nut and and impact. Dr. Diff told me the torque for a 489 case with fine spline is 280 ft/lbs. So hit it with your impact until you get the right preload. If using shims/spacer, .001 spacer is about 5 in/lbs of preload torque. He said most people don't torque them enough during preassembly and when they assemble them, they torque them to spec and it changes the preload.

Once you've got everything set, take the yoke off and install the seal and locktight the new pinion nut.

Don't forget to lube everything with 80/90 when doing the mockup. It protects the bearings.

Also, don't forget to preload the carrier bearings also. Put white grease on the adjusters and just snug the caps down when doing the pre-assembly. Everytime you assemble and disassemble, things will change because the bearing will seat a little so be patient. It's a trial and error thing. Make Pinion depth changes .003" at a time and start with .036".

This is all info given to me by Cass (Dr. Diff).
 
just to add; only use the Timkin bearings (brand). And I would buy 2 sets for the pinion. One to use as the set up bearings (honed out as previously mentioned) and the other for the actual assembly. WHY: because the tolerance of the timkins are such that they are virtually identical from a measurement perspective. Other bearings do not hold as tight a manufacturing tolerance spec. This will assure thsat the setup will be virtually the same as the assembled setup. you don't really want to have to take the thing apart again so the investment would be a good one. I think the factory also used the timkin bearings but check to make sure. (Plus you could reuse the setup bearings to "setup" other rear chunks. then you could change gear ratiois easy (with the spare setups)
 
Another thing that I have found, is that if you dissasemble a carrier, and remove the big pinion bearing, the shim that is there, will allmost allways be close... Thats what I start with.. If you have the old gears from that case.
 
X2 on the checking bearing. I've done that, it works. BTW, I have an inexpensive pinion depth tool listed in the classifieds...

Gearset should have a marking on it indicating pinion depth measurement. If it's there, start with that and check.

If you don't have the correct bearing puller, you can certainly cut the old bearing off with a cut off wheel. Just be careful not to damage any important machined parts. For final install, you can knock it down with a steel tube that matches the inside diameter of the bearing cage and whack it with a hammer until it's fully seated. Not the best way to go about it but it works.

Do you have a holding fixture? A dial indicator to measure backlash? Inch pound torque wrench to measure pinion turning torque? Big torque wrench to tighten the pinion nut? No small feat to crush the sleeve. How about marking compound to check your pattern? Seal/race drivers?

It's tough to do this properly without the right tools.
 
replicaracer43 said:
Another thing that I have found, is that if you dissasemble a carrier, and remove the big pinion bearing, the shim that is there, will allmost allways be close... Thats what I start with.. If you have the old gears from that case.
Click to expand...
replicaracer43-
Unfortunately, pulled, gutted, and tossed all the gears, bearings, and shims from the cases. Pulled a couple of 489 cases from the local Pick-n-Pull years ago. Being low and open gear sets, didn't think I would need any of this valuable stuff. Wished I've posted this back in the day. Oh well, live and learn...
 
rmchrgr said:
X2 on the checking bearing. I've done that, it works. BTW, I have an inexpensive pinion depth tool listed in the classifieds...

Gearset should have a marking on it indicating pinion depth measurement. If it's there, start with that and check.

If you don't have the correct bearing puller, you can certainly cut the old bearing off with a cut off wheel. Just be careful not to damage any important machined parts. For final install, you can knock it down with a steel tube that matches the inside diameter of the bearing cage and whack it with a hammer until it's fully seated. Not the best way to go about it but it works.

Do you have a holding fixture? A dial indicator to measure backlash? Inch pound torque wrench to measure pinion turning torque? Big torque wrench to tighten the pinion nut? No small feat to crush the sleeve. How about marking compound to check your pattern? Seal/race drivers?

It's tough to do this properly without the right tools.
Click to expand...
rmchrgr-
Yeah, hindsight is 20/20... Will definitely know better for next rebuild. For now, starting from scratch with a bare case and no gears/shims for reference...

Always looking for excuses to buy new tools, but not sure want to invest too much just yet on this project. Made a spanner and yoke holder tool. Have dial indicator, torque wrenches, marking compound, seal/race driver... Good idea about the cut off wheel. I used a Dremel cut off wheel to get the bearing carriers and races of the sure grip housing... Thinking about the crush sleeve eliminator mopowers suggested... Thanks!
 
Some very good information here. I always use the crush sleeve eliminator kit too. Makes the setup easier and if you ever have to take it back apart it doesn't disturb the pinion bearing preload causing you to have to replace the crush sleeve. Only thing I'll add is to use a small amount of sealer on the o.d. of the seal and use a little RTV on the pinion to yoke splines when doing the final assy. and you'll have a leak free unit. In my early days I did a few without sealer and most didn't leak but some had some seepage either from the o.d. of the seal or the pinion splines. I hate leaks, even if their small!!!
 
Looking for any tips or insight...

Creating a pair of set-up bearings the for tapered 489 pinion shaft. What's the best way to do this? Using a honing tool and drill; taking forever... Geez! There's got to be a better way or maybe I'm just impatient.... Okay, I "KNOW" I'm impatient...
 
matsucu06 said:
Looking for any tips or insight...

Creating a pair of set-up bearings the for tapered 489 pinion shaft. What's the best way to do this? Using a honing tool and drill; taking forever... Geez! There's got to be a better way or maybe I'm just impatient.... Okay, I "KNOW" I'm impatient...
Click to expand...

I used a die grinder with a medium burr on it and went gently with it until it slipped on and off with minor resistance.
 
mopowers said:
Why are you creating 2 set-up bearings? You really only need to make the inner one.
Click to expand...

I can't speak for badsport but I made a set because every once in a while I run into a pinion that the front bearing is real tight sliding on and off. I know the front bearing has no impact on pinion depth but it makes it easier to deal with.
 
The die grinder method worked great. Did a rough grind to increase the inner race diameter, then honed to smooth...

Made two "Large" and "Small" pinion end set-up bearings. Needed the small end bearing to come on/off easily to determine shims for solid spacer (Replacing Crush Sleeve/Collar)...
 
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