View Single Post
Old 12-01-2009, 09:56 PM   #8
GMCMG
Registered User
 
GMCMG's Avatar
 
Join Date: Nov 2009
Location: Center, MO
Posts: 121
Re: Can I fit 8.875 12-bolt car ring/pinion in truck rear end?

Cableguy0 / Philatruck,
I really don't have anything in it right now. This is a build, and I'm starting from scratch. The 6-lug 10-bolt that's under my frame is a 3.54, and I think the 5-lug 12-bolt in the donor truck is a 3.73 (haven't opened it yet). I've got a 2.73 ring/pinion that will fit the 10-bolt, but it doesn't do me much good since I'll be swapping out to the 12-bolt. I was hoping to pick up a set of car gears to go to 2.56 or 2.41, but I think you guys have talked some sense into me. I'm dropping a 6.2 diesel in the truck, and using a 5-speed OD tranny with a .73 final ratio. I was hoping that with the torque the diesel can put out, that I could run low rpms, but I may be shooting too low. After reading your responses, I ran some calculations based on larger tires and 2.73 gears (something a little more rational), and I think I'll be able to pull close to 65 or 70 at 1600-1700 rpms, which is really probably all the lower I should plan on running the engine. I think (?) I can get truck 2.73 gears for the 12-bolt, so I may start there. I'm doing a frame-off, so I really wanted to get everything right the first time, as I won't be able to try it out until it's pretty well done, and this is my first project. Thanks for the input!!! I have had a lot of help in a short time from members here on my various questions.
__________________
GMCMG
1964 GMC 1/2 ton LWB project
- 1982 GMC 6.2 diesel engine/suspension donor
- 1966 Chevy 3/4 ton frame/doors/fenders donor
- tons of parts - cause you can't build a truck without 4 of everything!

2001 3/4HD Duramax Diesel extended cab lwb4x4
1984 Chevy C30 6.2 diesel lift truck (project)
1962 GMC w/5 lugs, 350/350 auto (was for parts, but couldn't bring myself to do it!)

glascock.m@hotmail.com
GMCMG is offline   Reply With Quote