12 bolt setup [Archive] - Chevelle Tech

: 12 bolt setup


Ron454
Jan 3rd, 05, 10:07 PM
Hi folks,

Have chatted a little with Bill (engineguy) about the problems I have had with my 12 bolt. He suggested that the setup was not good. It was my setup, and my first at that.

Here is the problem.

After around 200 passes, the gears 4.10's, began to make niose, and were wearing out. These were Richmond street gears. I had them professionally setup.

After spending countless $$$ over my career having rear ends setup, I decided to finally do the next setup myself.

Bought the gears, read up on what was involved and went about the process.
I don't have a pinion depth setting tool, so I attempted to just get the pattern correct.
Everything I've read says to start with the pinion shim already in the rear. Which I did, and the pattern was wrong. So I began changing the pinion shim in .002" increments all the way from too deep to too shallow. I wanted to see the effects. When I arrived at what looked to me to be the right pattern, I could not get the coast pattern to be correct.
But I went ahead and finished everything up.
I set the back lash at .008 to .010".

I followed Richmonds break in proceedure, and all was well. No noise. Changed the lube (synthetic) and went racing.

Within 5 passes the rear was making noise on decelleration. *****!

Ever since then, the same story. Except it's quiet until it gets hot.

So I called Richmond and explained what was going on. Of course they have no way of knowing what my pattern looked like. But the guy tells me that at 11.0 in a 3500lb car, I'm bending the gear teeth because I've exceeded the limits of the street gears. And I can't run a pro gear, cause I drive the car to the track. He says "we have a lot of gear sets out there making noise, but they live just fine".
Hmmmmm.

I'm now puzzled.
I probably need to change back to a 3.73 ratio with my new engine, and don't want to goof this up again. (I assume I did something wrong)

Suggestions?
Try a different gear company? US Gear maybe? Go back to paying $175 to have this done? (Drives me nuts cause it aint all that hard)

Ron

ratengine
Jan 3rd, 05, 11:29 PM
Ron, I set up 2 12 bolts I know the carrier must be tight going in and to pull out have to pry from housing. Its tuff trial and error to get pattern right. In transmissions ask Big Gear Head
he good and knows what he doing.I sceen him ask for photo of gear pattern and he direct youfrom there.God Luck. Dave

DOUG G
Jan 4th, 05, 9:06 PM
Ron, with BigGearHeads(Fredeie) help and some basic tools (Magnet base dial indicator & clapers) I redid my 10 bolt just as you did,(at home). Broke in rear, drove to track and made 9 passes with only cool down time in staging lanes(less than 45 min. each) and drove home with not one problem. See what Freddie can offer you, he knows his S&%t.

Ron454
Jan 4th, 05, 9:22 PM
I posted this to the Transmissions forum, hopefully he answers.
Thanks!
Ron

ChevelleCLM
Jan 5th, 05, 12:24 AM
Well.
Just cause it whines a little does not mean it is going out.

The gears in my tahoe have whined and have since day 1. When I replaced the GovLoc with an Eaton posi, and set it all back up as the spec it was when it came out.. guess what.. Still whined.

I just set the drive side pattern up right, and leave it alone.