Rear end gearing

[WisconsinCutlass]

Right now my 1987 cutlass has a 7.5" rear with 2.14 gears. It does have position though. The car is a dog. Im looking to change the rear to some better gears so I can at least spin the tires. I've never done any work inside a rear end before and don't really know how posi works compared to the open rear end. I found a 7.625. Rear with 3:73 gears in it but its an open rear end. I want to know if I can take the 3:73 gears from the 7.625 and put them in the 7.5" that I have. Or vise Vera swap the posi into the 7.625

 

[pontiacgp]

With the 2.14 gears you have a 2 series carrier and the 3.73 gears take a 3 series carrier so you can't replace your gears for the 3.73 gears using the carrier for the 2.14. For the 7.625 carrier which is open you can't turn that into a posi. You'll need to get a posi carrier for the 3.73 gears. Rear gears are no that hard to do but if you don't plan on changing the gears too often then it's probably not worth it to go get the tools you'll need and to learn how to do them. If you'd rather stay clean you can probably find a guy to do the rear end for about $100 if you supply all the parts.

 

[jacobdavis1979]

Agreed with pontiacgp.
I know how it feels to have such a high gear like that. My bu has got like a 2.28 or 2.58 or somthin i dont remember but yea it was a dog untill i put 400 horses under the hood. Im gonna have a buddy do mine since i dont have experience. Im providing the stuff and he said he would do it for $50. Id ask around. Unless your swappin the whole rear

 

[WisconsinCutlass]

That dissapoints me that that stuff wont swap. If I want to change the gears in the 7.5 that's in my car now I would have to get just a ring and pinion gear right? This would be what I need correct? http://m.summitracing.com/parts/sum-741012

 

[pontiacgp]

Check to see what's available close to home. If there are oval race tracks near you check their classified sections. Personally I wouldn't put much money into a 7.5 since the money you spend on that could be spent on getting another rear end like an 8.5 or an 8.2. I bought my 8.2 which is good up to 500 hp for $600 and that came with an Eaton posi and the 3.08 gears I like

 

[WisconsinCutlass]

I can't find any 8.5 rear ends by me. The only one I've found they were asking $1500. That's way more than I want to spend.

 

[pontiacgp]

ouch, that's gouging, they must think they are selling gas. With the 7.625 rear you have some of them came with 28 spline axles. If that has the 28 spline you can get a detroit locker or something similar and that will be just about as strong as an 8.5

 

[FE3X CLONE]

I had a 7.5" rear built back in '97-'98 and it cost right around $1,000 with all new parts (except axles), cleaning the housing and assembly. There was probably $500-$600 in parts. Richmond 3.73 gears and Auburn limited slip diff plus all of the misc. seals, bearings, etc.

Your cheapest and easiest route would be to find another 7.5" that already has the limited slip and 3.73 gears and swap it in. Easier said than done I know.

 

[King_V]

Andrew,

That's what you've got behind the 455? And it'll take that much abuse? Dang! I'm impressed!

 

[jacobdavis1979]

That must be a pretty well built rear lol. Ive never had a 7.5 handle that kind of power mine always get chewed up when i go with anything lower geared than 3.23