I just pulled one out of an 86 2.8l camaro, which should be 3.42 gears. Should i change the oil in the differential?? If yes, then what kind of oil should i use?

Also, I rotated the driveshaft 3.25 times in order for the wheel to make a complete circle. Does that mean that the gear could be 3.23's ?? That would suck.

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Mods:Hooker Aerochamber 3" exhaust, gutted kitty,
March 2 piece underdrive pullies, smog pump gone,;these two made a very noticable difference.
14x4 K&N open air element filter-the best mod so far
Eibach springs with KYB's all around.
Appearance: Harwood cowl hood, Z-28 wing, painted black(7/20/00)-original color was light blue
*All these mods were made this year
Stock Options:117,000 miles on motor, 5spd, TBI, 305, T-tops
Run a best of 16.7 @85mph with traction problem. Have to try again sometime.

 

i use mobil 1 in mine. i think it's 75-90, plus i use gm posi additive.

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-=ICON MOTORSPORTS=-
1st & 3rd

 

Hell yeah change the fluid! And also change the rear axleshaft bearings (also mis-named "rear wheel bearings") and seals.

I also use 75w90 (except by Valvoline), along with the GM posi stuff (for my Eaton unit), in my axle.

I also use a gasket for the rear cover instead of RTV; don't know why I do, but I do.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I agree, by all means change the gear lube.

I would highly recommend AMSOIL 75W-90 Series 2000 synthetic. It has the posi additive already in it (assuming your new rear is a posi). The synthetic will reduce friction and wear, and increase your mileage and power put to the ground.

I also prefer the gasket to the RTV. Just seems cleaner, and I haven't had problems with leakage.

The best way to determine the ratio is to pull the cover and look for the teeth numbers on the gears. Do the math to get the ratio. You could also try your "rotate the driveshaft" method again, but count the number of turns it takes to turn the wheel multiple times, like 5, to get a more accurate measure (dividing by 5, of course). You'll get a full turn difference between 3.42's (17+) and 3.23's (16+), instead of trying to determine if it rotated 3.4 turns or 3.25 turns.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.73 unlimited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, TBD heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

No, the unit is not a posi, but would it still help to use the AMSOIL 75W-90 Series 2000 synthetic? And also, how difficult is it to change the axle shaft bearings? Thanks

 

For the time being, my cars have open diffs, and that's what I've been using in them. Yes, it will definately benefit from the synthetic.

 

if the car junkyard you got it from is close by, go back and find the car it came out of and get the rpo codes from the center console(if its still there), if not, then your gonna have to do the math

 

I used five7kid's method, and it came out to be 17+ turns, so i guess i have the 3.42's. And i did put the mobile 75w-90 synthetic in. The diff. is in now and it definitely accelerates faster. No need for first gear anymore when city driving. Thanks for the help.

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Mods:Hooker Aerochamber 3" exhaust, gutted kitty,
March 2 piece underdrive pullies, smog pump gone,
14x4 K&N, 3.42 gears,
Eibach springs with KYB's all around.
Appearance: Harwood cowl hood, Z-28 wing, painted black(7/20/00)-original color was light blue
*All these mods were made this year
Stock Options:120,000 miles on motor, 5spd, TBI, 305, T-tops
Run a best of 16.7 @85mph before gears

 

The ratio should also be stamped on the ring gear, if it's GM. My 3.73's had 41:11 (or something like that) stamped on the ring gear. I counted teeth anyway


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!