sixpackrt

I am not really that savvy on gm rear ends but I have an 87' formula that has a 10 bolt with a doggy 2.73 rear end. The car has only 75,000 original miles and the limited slip is in perfect shape. I was wondering if I could put a set of 3.42-3.73 gears in. I know some rear ends are only able to house gears as deep as 3.08 so you can see where I am coming from. I don't want to do any complete rear end swapping or anything like that so If I could have my mechanic buddy put like a 3.53 ring/pinion into my existing rear end and use my original limited slip I would be just tickled pink. Any advice is definitely appreciated! Thanks, Bret

vic_V8

3.42 and 3.73 is as close as you can get with a gm. You can buy a 2 series gear in a 3.XX summit has them (Motive Gear) they will have a * next to them, ** for 3 series.

sixpackrt

I guess I just wanted to know if i could put anything lower (3.43-3.73) in my factory 10 bolt housing/carrier than my original 2.73 or if I had to change to a different rear end all together. I was wondering because I have a freind with a 72 cutlass and he actually had a 12 bolt that could only have up to a 3.08 otherwise he had to swith to a different typoe of 12 bolt.

novatuc

3.08 and lower are 2 series, higher than 3.08 are 3 series. With stock gears the pinion is smaller as the ratio gets higher so GM actually has 3 different carriers that place the ring gear differently based on pinion size. You can get aftermarket gears for a 2 series carrier that have a thicker ring gear to make up for the smaller pinion if you want to go higher than 3.08 but keep your stock 2 series carrier.

84z28350

So, to once angain answer your question...

YES you can put a 3.23-4.11+ gear on your stock 2 series carrier. But you HAVE to make sure you buy a set of gears that are made to fit the 2 series carrier or buy the spacer plate.

Sonix

iTrader: (1)

Yes, that's the secret other option
So yea, either thick gears, or any ol' normal 3.42 or whatever size you want, and the spacer. Price out and see what's cheaper, because it's exactly the same in the end.
Oh, and don't get the gears made for racing (richmond?) . Apparently they suck on the street and wear out very fast.

sixpackrt

Thanks guys for all the input, I had no Idea about any 2 or series kind of carriers. Thanks once again, Bret

84z28350

You wouldnt have been the first person to buy a set of gears and find out that their are different carriers only after you have the car tore apart!