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Re: [oletrucks] pinion shims

To: Old Trucks List <oletrucks@autox.team.net>
Subject: Re: [oletrucks] pinion shims
From: J Forbes <jforb@mindspring.com>
Date: Tue, 13 Apr 2004 21:22:18 -0700
> Date: Tue, 13 Apr 2004 20:21:43 -0700 (PDT)
> From: Jim Nordwall <jimnordwall@yahoo.com>
> Subject: [oletrucks] pinion shims
> 
> When I put the 350 in my truck, I also installed the
> rear axle from a 1974 Firebird. At the time I was not
> to concerned with the ratio since I had 205R14 tires.
> Now that I am switching to 275R60 tires, I am
> replacing the 2.56:1 gears with a 3.08:1 limited slip
> carrier. This equates to 2400RPM at 65MPH. If I don't
> like that, I also have 3.77 ring and pinion. (2880RPM
> @ 65MPH). Without a 700r, that is too much gear for
> highway driving.

3.08 should be just right, in my opinion.

> When I installed the new carrier with the 3.08 ring
> and pinion, I applied the white gear paint from
> Richmond gear. Then I spun the gears a couple of times
> to check the gear pattern. The pattern does not really
> show up in a way that I can understand. Since I was
> not happy the results, I cleaned all of the gear teeth
> and tried it again. This time, I mounted wheels and
> held them so that I really put some pressure on the
> ring and pinion. The results weren't any better. What
> am I missing? There must be a way to do this.

I usually just apply hand pressure to the pinion yoke and 
turn the ring gear by hand.  Do you have a *lot* of marking 
compound on the teeth?  You need to put it on thick, perhaps 
.010" or more, to really see anything.  Make sure you can't 
see thru the compound after you brush it on, it needs to be 
fully opaque.  Then when you turn the gears, it will become 
"see through" where the teeth are making contact.

You just need to paint a couple evenly spaced groups of 2 or 
3 teeth on the ring gear, and only turn it once, less than 
one complete revolution, both directions, making contact on 
coast side of the teeth one time, and drive the other time.

Also, if the setup is way out to lunch, the mesh will be off 
to the side of the teeth and you won't see a recognizable 
pattern.

-- 
Jim

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