I completed a 305 to bored SBC 350 swap last year and want to tackle the rear end next. I was thinking about swaping drum to disc but have decided I want to go ahead and get posi and some nice gears first.

Where do I start? Is buying new from summit/jegs worth the money or should I try and find a junker for a used rear end?

'87 Trans Am, Chevy 350 to 700R4. (430 hp now) Building for a future 500-600 hp (street car, rarely track)

I apologize for the stupid questions ahead of time. I am new to this part of the car and need some help please. I do plan to do a transmission swap someday. Would this impact what I chose for differential...?

Thanks a bunch

 

If you are planning a 600 HP engine then you need to save your money for an aftermarket rear end. The 7.5 10 bolt that came in these cars is one of the weakest rear ends that GM made. You are going to need a 12 bolt or 9 inch for that amount of power. Plan on spending around $2300 to $2600, depending on how you want it built.

Now if you are just dreaming of 600 HP and you will really never have more than about 350 HP then you can make your 7.5 hold up pretty well. I recommend a set of 28 spline axles to replace your 26 spline axles, a Eaton Post or Duragrip, a good set of quality gears and a good installation kit. Don't get any of that junk Summit or Jeg's brand stuff.

 

I agree...

Problem is, you may have a 9-bolt, in which case, you're basically stuck; or, you have a 26-spline 10-bolt with drum brakes, which is about the worst candidate for an upgrade.

Given that you'll be spending $1200 or so just on parts, doesn't make sense to do all this to ANYTHING BUT the finest of cores. Find yourself a 89-92 disc brake rear to do it to, so that you get the good rear brakes with the PBR aluminum calipers; NOT your existing 26-spline drum core, and NOT a 82-88 core with the crappy cast-iron disc brakes.

Here's a parts list.

Posi carrier http://www.summitracing.com/parts/ETN-19599-010/
Axles http://www.summitracing.com/parts/SAG-EV10-4/
Kit http://www.summitracing.com/parts/RAT-308TK/
Crush sleeve eliminator http://www.summitracing.com/parts/RAT-4111/
Cover http://www.taperformance.com/proddet...prod=TA%5F1809 w/ TA-1815 stud kit
Gears http://www.summitracing.com/parts/SAG-G75373/
LCARBs http://www.spohn.net/shop/1982-1992-...tion-Brackets/

Have the axle tubes welded all the way around, where they fit into the pumpkin, USING A JIG TO MAKE SURE THEY ARE STRAIGHT, and have the plug welds filled in so they don't leak. Have the LCARBs welded on at the same time, again using a jig to ensure straightness.

I don't think there's much else you can possibly do to one of these rears.

 

Thanks guys.
I'll keep reading and learning.
I tend to make my dreams realities and that much power is definitely in mind. It's nice to have helpful tips like this though since every link of the car impacts another.

I'm definitely going to explore both options above. For aftermarket rear ends, where is a good place to look for products and how much fab. is *generally* required for these to fit into third gens?

 

Moser makes a good 12 bolt and a 9 inch that bolt in. The only problem that I know of with the 9 inch is that they tend to hit the bottom of the floor in some cars. These rear ends are made to fit, so fab work is usually not required. You can get the 9 inch as a housing and axle package and add your own center chunk. Sometimes this will save you some money. The 12 bolt starts at about $2220 plus shipping and the 9 inch housing and axle package starts at around $980 plus shipping. The 12 bolt is shipped assembled and come by truck. The 9 inch comes in pieces and can be shipped by UPS.

 

I'd skip both the 9 inch and the 12 bolt and get a dana 60 from strange.