i just got a new set of gears.i have heard that pinion depth is relavent to the housing so the old pinion shims shoul give me the correct depth correct????also on precision gears what is the # painted on the pinioin gear mean???i thought is was pinion depth but i just wanted to be sure
thanks

The original pinion shim is a good place to start, but usually not the correct shim. It should be within .005 of the right thickness. Don't think that this is close enough and just throw it together, .002 can make a big difference in how a gear runs. Backlash and bearing preload are also very important. When everything is right you will get a good contact pattern on the ring gear teeth. Did you get a good installation kit with the gears? You will need one. You also need a dial indicator with a magnetic base, press, bearing separater and some other tools. Don't worry about the pinion depth numbers, the contact pattern will tell you if you have the pinion depth right.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

how do i weasure for the correct depth with the depth gauge???is there any way to know the correct shim before pressing on the bearing????

No. Setting up a ring & pinion takes a LOT of trial and error. You must put everything together and check the contact pattern and then take it apart and make your shim adjustments. The put it back together and try again. You must be willing to spend a lot of time trying different shims untill you get it right. If you know how to read the contact pattern you can get it on the second or third try. You must be patient or you better get someone else to do it right.

Don't mess with the pinion depth gauge. I have found these to be inaccurate. They will get you close, but reading the contact pattern is the only way to get it right.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

[This message has been edited by big gear head (edited 07-22-2002).]

I just got done putting a new gear and posi in my car. We calculated the shim thickness that gave us the correct centre distance of the pinion (measured from the face of the pinion to the centre line of the axle). Once that was in and the proper preload on the pinion was applied, we set the backlash on the gear to 0.008" and the gear mesh was perfect. We assembled it once...

I figure richmond puts the C.D. on the pinion and the B.L. on the gear for a reason. Following it gave us a perfect install.

Some people might not have the luck that the last guy had and will need to try mutliple shims in order to get it right. My suggestion is this: When you are buying bearings, buy two of the larger pinion bearings-one for final assy. and one for trial assy. When you get home, take one of the two larger pinion bearings and hone out the inside of the bearing so that it will slide on and off the pinion without the use of a press. That way, you can try multiple shims until you find the one that you need. Once you have identified the proper shim/pinion depth, you can then press on the other large pinion bearing that you have for final assy. I keep a honed out bearing in my tool chest just for this purpose. Very important though that your honed out bearing, and your final bearing are from the same manufacturer. I have seen some variance in pinion depth based solely on the bearing used. Not talking HUGE amounts here, but as BGH states above, .002" can make quite a difference. Remember, this is an area that you SHOULD not compromise on. If you get "close" but not perfect and decide that it is good enought. You will get to do that job over again real soon at GREAT expense. Contact pattern is KEY to gear/bearing/axle longevity! If you are off, and the gears start to shred each other, chances are they will destroy every other bearing/seal/axle/all else in the rear end.

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1969 Camaro SS 350-383ci., T-56, 12 bolt, Eaton posi, 3.73 gears, 4 wheel disc, Deluxe black houndstooth interior, rear window defogger, tilt steering, console w/AutoMeter gauge package, center mntd. clock, Tach.

Over the weekend, I bought new bearings and seals to replace in my 4.10 Posi, but after readin g this and several other threads, I think I will leave to the pros. I was quoted 350 to replace bearings and seals, not too bad saying the bearings and seal I bought were 100 bucks!

Question though, By visually inspecting the gears, or any other means, can I determine the overall welness of my posi unit? I don't want to take it to the shop and have them call me up and say I need a new posi unit when I really don't.

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Kevin

68 Camaro SS - 383, Edlebrock Performer RPM, Trick Flow 23 degree heads, edlebrock 750cfm carb, dynomax headers, Tremec TKO, 4.10 Posi

I hope you bought Timken bearings and not anything made in China. If you did get bearings made in China, take them back now and get some Timken bearings. The China bearings will NOT loast long! $350 is about $100 too much for the labor. If you have an original GM posi then it can be rebuilt if it is worn. You don't need a new one, unless you have a Auburn. The clutches and other parts can be replaced, except Auburn, which is trash when it wears out.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

The $350 was parts plus labor. Now that I got the rear end out of the car, I pulled the axles and the pass. side is worn and pitted. How can I tell if it is an Auburn or not? If it helps, My ring gear part number is 3988517. I can also post a pick of the setup. Thanks

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Kevin

68 Camaro SS - 383, Edlebrock Performer RPM, Trick Flow 23 degree heads, edlebrock 750cfm carb, dynomax headers, Tremec TKO, 4.10 Posi

The Auburn usually has 5 preload springs and the Eaton has 4 springs. The Eaton has a solid casting and the Auburn has a cap screwed into the end of the case. The Eaton casting numbers are ED-32088 for the 2 series, EDB-30140 for the 3 series and EDB-30174 for the 4 The numbers are next to the bearing on the end opposite of the ring gear. Post a picture and I can tell you what you have.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

Hope Its not too big, but here goes:

http://home.houston.rr.com/camarorestor/diff.jpg

I got a quote for doing a rebuild for about $950.00 including axles. I have one axle that is definately worn and pitted, and might as well do both if I am going to have it rebuilt.
Here's a breakdown:

Rebuild Posi $100 parts and labor
2 axles 150ea 300
New gears 169
new bearings
& seals 200
Labor for all 175

Total $944

Are the prices reasonable? Thanks for all your help


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Kevin

68 Camaro SS - 383, Edlebrock Performer RPM, Trick Flow 23 degree heads, edlebrock 750cfm carb, dynomax headers, Tremec TKO, 4.10 Posi

[This message has been edited by kdorsett (edited 07-24-2002).]

Kevin,
I assumed that you had a 12 bolt, but that is a 8.5 10 bolt. That is the GM posi and it can be rebuilt. The prices for the bearings and seals is too high, should be about $117, and the price for the axles is a little high, should be about $258. The rest is about right.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

Thanks for all your help BGH!! Also thanks to tazacm for this thread http://www.camaros.net/forum/biggrin.gif

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Kevin

68 Camaro SS - 383, Edlebrock Performer RPM, Trick Flow 23 degree heads, edlebrock 750cfm carb, dynomax headers, Tremec TKO, 4.10 Posi