Re: 12 Bolt vs 10 Bolt Rear
 

Vehicle weight is a big deal. Moser may offer a bolt-in 12 bolt. I would check with them.

Re: 12 Bolt vs 10 Bolt Rear
 

Dan
Isn't that a 7.5 inch 10 bolt in the Impalas. ? I had to run Pro Gears in my 68 Impala, broke street gears, but then again a 4000 l b BBC stick car at that point. Running same 4:88's in my 65 automativ car.

Will Lamprecht
65 Impala 396/325

Re: 12 Bolt vs 10 Bolt Rear
 

Camaro’s and Firebirds got that rear.
B-body’s got the 8.5 inch rear.
None of us in the Impala club are having problems.
Unless they are using a Stick.

Chipper brought up that the 8.5 rear uses the same bearings as a 12 Bolt.
That makes it stout.
Wonder if a 12 bolt ring and gear and Spool will fit in a 8.5 Pumpkin?

Re: 12 Bolt vs 10 Bolt Rear
 

Still trying to figure out the best gear ratio.
Using 4.56s with a 4L60E trans.
Not using the locking converter now.
Looking at 5.38’s and locking it up in high gear.
I can program that in the PCM...

Hope to get close to the K/SA index with current cam.

Re: 12 Bolt vs 10 Bolt Rear
 

Not correct.
The Impala SS may have all come with the 8.5.


Pinion bearings and flange are different, for one thing.
8.5 and 12 bolt take different side shims.

Re: 12 Bolt vs 10 Bolt Rear
 

The 91-96 B-boys are the Caprices, Impalas, Roadmaster and Caddy’s.
All were 10 bolt 8.5 rear

Camaro/FB all came with smaller 7.2 rear.
They can surprisingly survive with a good bit of power too..!

About a $1k less to beef up a 10 bolt than installing a prepared 12 bolt unit.
They make them to fit our B-body.
Interesting being the same suspension configurations as the early Chevelles, GTO, Cutlass, GTX.

D

Re: 12 Bolt vs 10 Bolt Rear
 

Generally the B bodies with the Baby LT-1 or 305 have the smaller rear. The LT-1's generally have the 8.5 (Impala and Caprice).

Re: 12 Bolt vs 10 Bolt Rear
 

The later F-Bodies got a beefed up 7.5 rearend , with a bigger 7 5/8" ring gear .

Re: 12 Bolt vs 10 Bolt Rear
 

With the money you save from staying with the 10 bolt you can probably afford a golf cart and a tow strap. Eventually, you will need it.

Re: 12 Bolt vs 10 Bolt Rear
 

Shhhh..Don't tell Dan. He's spent too much time on the SS forum, and not under those cars.
Whatever you do , don't tell him the early Chevelles did not have the same suspension. Although it looks similar, it is not a metric configuration.
Also , I have never seen a bolt in 12 bolt for those cars. Maybe those SS guys can help him. Apparently we are not qualified here.