Would changing rear ratio from 3.42 be bad?

[Tom Tom Turbo]

I have one of the non-posi TRs and a friend of mine has a 3.73 posi rear with a fresh rebuild from a late 80's S-10. He is offering it to me for $300 complete drum to drum. I figure this way I get the S-10 brake parts too....more boost @ the line!!! My dad discourages it because he says that if the TRs were made to run with 3.73s that GM would have put those in it. Is anyone running 3.73s or anything other than 3.42? Do you think it would hurt/help my car? My other option is a new Eaton posi, but then I'd have to swap gears and all the other crap too.

 

[Roc87]

My GN has 3.73's from the previous owner "Wanting to reduce turbo lag " (Why didn't he get a stall? Who knows!) I personally don't think it helps, and in fact I believe it actually hurts the car. My Iroc has 4.10s which is WAY TOO MUCH, and I will switch to a 3.23 or 3.42 as soon as I get enough $ to.

Not only would the gears probably hurt your car, but you don't really want to put in a 7.5" 10 bolt when the GN has the stronger rear do you? Just my .02

 

[GNVAIR]

First off. The 84-87 Turbo Buicks have an 8.5 10 bolt which is highly desirable compared to the more common 7.5 10 bolt which almost every other g body came with.
Your Buick has a 4 link coil sprung rear. The s 10 has a leaf sprung rear. The S10 has a 7.5 10 bolt. Basically, the swap wont work and I dont think you would want it to work since
you would definitely be down grading. I would stick with the 3.42's in your original 8.5 and just have an Eaton posi unit installed. You dont have to replace the ring and pinion when you install a new carrier. Just make sure to check the back lash and the pattern BEFORE you take it apart. That way you can set it up as close to it was before.
Hth/

 

[Intimidator]

Just add the posi

Stick with your rear end and just add the posi. Stronger and the 3.42's are good for mid to high 10 sec. et's
Our engines make lots of torque, 3.42's take advantage of that.
Also gives better gas milage.
The S10 brake cylinders you want are from a non power brake S10, is that what he is selling? I doubt, I don't see many of the non power brake trucks.
I say use your rear end and just add the posi.

 

[BM Computer Src]

The previous owner put 3.73's in my TTA. I only have 26" tall slicks, so I have to shift into 4th gear at the track.

I would stay with the 3.42's.

The S-10 Brake cyl's are cheap enough anyway.