want to know if anyone can recommend a good pinion depth tool kit. I can track down all the original GM pieces. But that's rather expensive. I'm running the factory 7.5 10 bolt. Thanks

 

Don't bother. I had a T&D pinion depth tool for a while and I used it a few times and got rid of it. There are better ways of setting the pinion depth. Reading the contact pattern should always be the final word, with or without a pinion depth tool. The only thing that a pinion depth tool might be useful for is if you are installing a used gear and you have the pinion depth number for that gear. Many gears don't even have the pinion depth marked on them.

 

Every single 10-bolt I've ever built had a .035" pinion shim in it.

I just put the same thing back in and have never had any trouble. New or used gears.

The ONE exception to this is, the Richmond single-purpose drag race gears. Those... you pretty much have to do by pattern. But since you DON'T want to run those if the car EVER hits the street, EVEN ONCE, it's just as easy to avoid them altogether in the first place.

 

if I cant find what I need I'll just grind down the pinion gears that's in it now so the bearing will slide on and off easy. that way I wont have to press it on and off every time I check it and have to adjust. just figured I would try and find the tools and only do it once.

 

That's not real bright... if that works PERFECT, you'll end up discovering that you need the shim that's already there. (since the factory did ... whatever ... and put that shim on that gear in that housing, which if your method then also is right, will produce the EXACT SAME results)

OTOH whatever gear you put in it, might be different from that gear (esp if you get the Richmonds) in which case messing with the pinion you have now tells you nothing about the one you're putting in.

Makes AWHOLEHELLUVALOT more sense to buy an extra pinion bearing cone and hone that out with a brake cyl hone so it slides on and off your NEW gear.

Then all you have to do is figure out when you've got it right.

Which I'd put better than 90% odds that if your new gears are a good-quality set from a reputable mfr other than the Richmond drag-race ones, you'll go through all that trouble and time, and in the end, find you need a .035" anyway.

Or buy abuncha tools, and find the same thing.

It really helps to get a good mental grip on what you're actually doing when setting up gears. Which is, you're shimming the HOUSING not the gear, even though you put the shim on the gear... the HOUSING is the part with all the tolerance in it. IOW, imagine that you could have yourself a perfectly set-up set of gears just floating around out in space there somewhere, and you have a totally random housing, and you're trying to pick the right shims to fit the HOUSING to the GEARS. Kinda like, you don't trim your shoulders to fit a new suit, do you?; you adjust the suit to fit your shoulders. Gears and housings are the same way.

Gears are REALLY precise. Housings are CRUDE. But GM got the pinion bearing bore pretty close to right on 10-bolts newer than about the mid-70s; there's just not much variation in them at all, unlike some other (esp OLDER) rear ends. Musta started using a machine for the pinion bearing bore that indexed its depth off of the carrier bearing bore... the same as the tool you're asking about does. The carrier bearings, not so much; but that's EEEEEEEZZZZY. Put the pinion head bearing in with a .035" shim, use a crush sleeve eliminator to set the pinion bearing preload right without the seal in there, take the yoke back off one last time and put the seal in and final-assemble, set the backlash by way of carrier shims, add about .005" to each shim pack to create some preload in the carrier bearings, put it all together, you're done.

 

LOL That's rough. I mean there are some really sensitive people around here, man. You have to be careful, you might hurt Sofa's feelings so bad... Why you don't know WHAT he might do.

 

On the topic at hand. I had occasion to need to measure pinion depth on my 9 bolt to install a new carrier and Yukon 3.70 gears. The gears were marked for depth. At least in the case of my 9 bolt the pinion shim did not turn out the same. After a lot of consideration I bought one of these:

http://www.ebay.com/itm/232361114227

It's very nicely made and reasonably priced. I tried using a Chinese one but the components were very poorly manufactured and nothing was square - I didn't trust it. I think it was Proform brand. Total junk.

My pattern was as close as it could be with Yukon (Chinese) gears. And they whine a bit when "floating" at cruise. I've been in there a few times since and they look great. From what I've read the whining is pretty typical of these poorly manufactured aftermarket gear sets. Too bad you can't easily buy quality parts for the 9 bolt. Stuff has to come from Australia and gear sets are hard to get unless you want used.

GD

 

I think you would be better off with the honed out bearing. If you don't have a press then that makes the job more difficult. Reading the pattern really is the best way to do this. A pinion depth tool will get you close, but most of the time it's going to be off a little and you will have to go back and make at least one more adjustment to get the pattern right.

 

Honing out the pinion bearing cone is a good idea. I did that wth the old bearing on my 9 bolt gear setup. Makes shimming the pinion much easier. Thats pretty much accepted practice from what I understand.

I'm not sure what grinding down the old pinion would do for you. Unless you do it on a lathe with a tool post grinder it would be very hard to insure it was even and concentric. A brake cylinder hone would do a quick job of the bearing con though.

GD

 

I didn't have a hone when I built the 8.8 in my Mustang. I'm pretty sure I polished the bearing to a reasonable slip fit with sandpaper by hand. I know it wasn't difficult because I don't remember that part sucking. The part that sucked was mocking up every shim combination under the sun, and generating gear patterns, in an attempt to make an acceptable pattern using the stamped pinion depth and math... In the end, I reused the original factory shim, because it gave me the best pattern. It's quiet as can be, even before the Flowmaster drone kicks in at interstate speeds.

 

Mine only has the high pitched whine under light throttle and can only be heard on really smooth (new or almost new) pavement. Gear pattern was excellent - just the way the gears were made unfortunately. Many others have had similar results and even Chevy had a bunch of the 5th gen Camaro's with gear whine. Customers got told by the service departments that if they tried to fix it, they might actually make it worse so just live with it.

GD

 

FWIW, I own and manage a shop, and not one customer has asked about "ASE" anything since I started offering my services in 2009. I have 5 bays and 3 techs plus myself. None of us have any such foolishness. I do have an intern about to get his "ASE Certification" and just about every job he does I have to redo or school him on how to do properly.

ASE teaches nothing about older cars, and nothing about performance modification, tuning, racing, or a host of other niche subjects that this board deals with on the regular. They teach some basics but their "graduates" are poorly prepared for the real life operation of a shop IMO.

GD

 

Downsouthboy, have you moved forward on this project? Do you have the new set of gears that you are wanting to install? I'm assuming that you are changing the gear ratio or you wouldn't be bothering with a gear change. What ratio do you have now and what are you going to install? Are you also going to be changing the differential too? The more information that we have the better we will be able to help. There may be some things that you have overlooked that we might be able to catch before you get too far into the job.