gm 7.5 rearend for g / str

[kiwi belly tank]

You missed one, the highest ratio is a 2.136.
  Sid.

[wheels777]

GM 7.5" fact corrections:
Ratios mass-produced:
2.294:1, 2.412:1, 2.5625:1, 2.733:1, 2.929:1, 3.077:1, 3.231:1, 3.417:1, 3.727:1, aftermarket 3.909:1, 4.10:1, 4.30:1, 4.556:1
There were a few aftermarket 3.546:1 sets. Happy hunting for those.
 HP capacity: around 500, fully built. Forget a 900-horse anything unless there's NO traction. In which case why have 900 horses?
With stock 28-spline axles, or aftermarket 26-spline axles, the weak link is typically the R&P, even with a girdle, though I've failed the differential cross pin, behind a 170-horse 305 with an automatic transmission. May have been a defective pin.
 '85-up were 7.625" ring gear, possibly excepting S-10 / Astro, which easily fits all 7.5" cases. 28-spline shafts appeared in Camaro / Firebird, even V6/auto, in mid '89 or mid '90, I forget which. Probably '90.
 S-10 starts narrowest overall, '93-'02 'maro / 'bird is widest. All '82-'02 'maro / 'bird versions used a torque arm, all Malibu / Monte / Cutlass / Regal / Grand Prix used a triangulated 4-link, all others were leaf springs.

I have (2) Monza rears, one 2.29:1 and one 3.08.  Can I swap those gears into my 3.42:1 1987 Camaro rear?  I've read where the S-10 gears can be swapped into the Monza rear if you machine the pinion.  Reading the above quoted post makes me think the Camaro rear used the smaller parts until 89, and the "machined" S-10 gears were 85 and up.  Also, the 500 HP noted above, is that a general rule, or 'asphalt' limit, and the 900 HP a 'salt' limit, or ?  My engine makes 690. 

[SPARKY]

I run a AA/GL with this rear with 2.14 ratio, The pinion is HUGE and a pretty good 565 BBC about 9.5 on the hp--with no problems

BUT:  I run no torque converter, and a PG/GV set up---My guess would be that one can run 2X that much hp ---so long as one stays away from SHOCK LOADS  ymmv

[Sumner]

...... Can I swap those gears into my 3.42:1 1987 Camaro rear?

Your Camaro should be the 7.5 or the 7.625 and the gears will work with one problem if that is what you have.  They need a 2 series carrier and with the 3.42 you have the 3 series carrier.  So the housing would be ok, but you need to get the 2 series open carrier or torsen (recommended) if you go to those gears.  You can find them on e-bay if you keep looking.  If you go with the torsen center you will also go from 26 spline to 28 spline axles but the 28 spline are as large as you can go.  The torsen...

http://www.torsen.com/products/T-2.htm

.... also comes in a 2 and 3 series so get the correct one.  The flange where the ring gear fits is thinner on the 2 series to get the correct spacing for the larger pinion.  You can go from a 2 series to a 3 series gear set by buying a spacer to go on the carrier but not the other way.  Torsens came in some Camaro's from about '99 to 2002 or in that neighborhood (the info is out there).

Here is a link to a place that has a 1350 yoke for the 7.5 rear-end...

http://www.dennysdriveshaft.com/p1056_1350_series_pinion_yoke_for_7.5_inch_10_bolt_with_27_splines.html

... they are hard to find.  Good luck,

Sum

[overdue]

The Motor Vehicle Manufacturing Association files don't show the 2.14:1 for anything, ever, so that's why I specified mass-produced. I may stand corrected. But if so, that would have to be a 47:22 ring and pinion, which is a huge jump from 2.29:1 and 2.41:1 both using a 17-tooth pinion. 37:17 would be 2.17647:1 which seems more plausible. Otherwise the teeth would be microscopic, but you'd likely always have at least part of at least 2 pinion teeth pushing on the ring gear.
 500 HP is the practical upper limit for street, beyond 500 it's a ticking time bomb, guaranteed to fail sooner or sooner. Even if you buy every upgrade and avoid both drag radials and shock loads. On salt it may not matter, I have no experience yet.
 I'm not sure the Torsen that was factory optional in 4th-generation Z28s, Formulas and Trans Ams was used with the 2.73:1 gears standard with an automatic. Those used Auburns, which I have many good experiences with. The optional gear for automatics was 3.23:1, and 6-speed manuals got 3.42:1 only, except '93. I'm sure '93 was Auburn-only, but there was a deep-geared T56 for 2.73:1, and another T56 for 3.23:1. I'm sure the Torsen required the optional ratio for automatics. I know for fact my '95 Z28 auto was 2.73:1 Auburn, right from GM. The Auburn was so driveable in dry, wet, snow, dirt, and gravel, that I'd expect it to be excellent on salt. Even with more than 100,000 miles on one, twin black stripes were easy, even on dry pavement. Auburns do wear out, and are difficult to freshen.
 I've heard that the Monza was different from all other 7.5s. Non-Monza 7.5" gears fit 7.625" housings, obviously, and generally the reverse is true with no clearancing. ANY 7.625" R&P WILL fail before you need a 1350 yoke.
 From my own experiences and from all I've read on LS1Tech.com, I would run a girdle, but I would not run much preload. Richmond gears are the strongest, but also the loudest.
 Nobody ever discusses lubes versus backlash versus torque capacity, let alone stress-relieving by vibration, or cryo-treating, but I had a 3.73:1 7.5" survive 470-ish HP on drag radials, 3600# race weight and automatic transmission, running 80W90 non-synthetic and no girdle.

[Sumner]

The Motor Vehicle Manufacturing Association files don't show the 2.14:1 for anything, ever, so that's why I specified mass-produced. I may stand corrected. But if so, that would have to be a 47:22 ring and pinion, which is a huge jump from 2.29:1 and 2.41:1 both using a 17-tooth pinion. 37:17 would be 2.17647:1 which seems more plausible. Otherwise the teeth would be microscopic, but you'd likely always have at least part of at least 2 pinion teeth pushing on the ring gear.....

You know a lot more about GM rearends than I do, but the 2.14's are pretty easy to find along with the 2.28/2.29's.  I bought the last set these guys had, but it was a new gear set  (look at top of page)....

http://www.tomsdifferentials.com/2011catalog/Pages35-37.pdf

Used sets come up on ebay fairly often.  We have a used set we got from John on here and Sparky has a few sets himself.

On the torsen they were in some of the '98-02 Camaro's/Firebirds and in the 2 series and 3 series (we need the 2 series)....

I have a Torsen differential that starts with the numbers 9032 or 9022.  Which differential is it?  Top of the Page

Those numbers are Torsen part numbers associated with the production 7.6" GM F-Car series (Camaro, Firebird) vehicles.  The 9030, 9031 and 9032 numbers refer to the low numeric series or Series 2 axles (2.73, 2.93, and 3.08 rear axle ratios) whereas the 9020, 9021, and 9022 numbers reference the high numeric or Series 3 axles (3.23, 3.42, 3.73, and 4.11 rear axle ratios).

http://www.torsen.com/general/general_faq.htm#Is%20it%20true%20that%20the%20Torsen%20unit%20in%20the%20production%20Camaro%20needs%20the%20GM%20modifier%20added

I bought one off of ebay and Buddy gave us another one in a Camaro rearend.  There is a 2 series listed now...

http://www.ebay.com/itm/98-02-Camaro-7-5-2-73-Differential-Ring-Pinion-POSI-10-bolt-28-spline-Torsen-2/121298075478?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222008%26algo%3DSIC.MOTORS%26ao%3D1%26asc%3D21399%26meid%3D5853243939430586486%26pid%3D100011%26prg%3D9407%26rk%3D1%26rkt%3D10%26sd%3D310845086559

I agree that 500 might be the upper limit on the street but I know of at least one 900+ HP car that has run the 2.14's and a torsen without breaking them.  Remember that the salt only has about 1/2 the traction as pavement and these cars don't make hundreds of runs,

Sumner

[overdue]

Okay, I'll stop disputing what I don't have personal knowledge of. Sorry.