Rear diff rebuild
 

Anyone out there know about the 283 stock rearend gear ratios? I have built up a 1958 corvette 283 semi-performance. The truck has a existing 3:54 posi dana 44 in it. The diff is growling and I picked up a 12 bolt diff from a 79 blazer with 3:08 gearing, rebuilt it and wondering if that is going to be too high gearing for the application.:ito:

Re: Rear diff rebuild
 

What transmission?

Re: Rear diff rebuild
 

The 283's don't produce good low end torque, so the 3.08's may be too high. Of course this depends on the tire size as well as the trans as Shaky said.

Re: Rear diff rebuild
 

sm-420

Re: Rear diff rebuild
 

With the 3:54's I'm shifting into 4th gear around 35 miles an hour. With the standard trans SM-420 find myself chasing gears all the time.:metal:

Re: Rear diff rebuild
 

I think you're gonna need all the gear you can find to make up those big rpm drops on the SM420.

Re: Rear diff rebuild
 

Are you saying the 3:08 gears are going to be to high for the existing set-up?
:smoke:

Re: Rear diff rebuild
 

In reality, 3.54 to 3.08 isn't that big of a change. However, The SM420 has a big drop between gears. So, you will have to wind out 2nd a little more and then when you hit 3rd, you'll be further down on rpm. So, you'll have to wait longer for the engine to "recover" and get back up to where it makes decent power.

It all depends on whether this matters to you or not.

Ultimately, I plan on either a Ranger or Gearvendors overdrive to make my SM420 into an 8-speed.

Re: Rear diff rebuild
 

The main thing is I'm chasing gears right now with the 3:54's but I believe this was:smoke: a stock set up with the original trans and full set-up from factory with the stock 283. My concern is will I be lugging with in town driving with the 3:08's. The 3:54 is a dana 44 posi, the 3:08 is a gm 12 bolt no posi. I have rebuilt the 12 bolt diff bearing shims etc. Before bolting this in I just want to be sure.