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Coolball 06-06-2011 08:08 AM

Gear pattern check
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Hi all I am working towards setting up a rear end for the first time. Wondering if I can get some feedback and corrections from everybody on how my pattern looks so far. It's a GM 10 bolt and I switched the ring and pinion to a 3.42 set of gears and used the same shims to start.

I know the current backlash is too much so I will need to tighten that up.

HalfOunce 06-06-2011 10:47 AM

One should ALWAYS start with pinion depth. there should be a number engraved on the face of the pinion.

Coolball 06-06-2011 11:23 AM

Thanks for the reply. the numbers say 12:41 7 5/8''

Now to me that's not the pinion depth markings. So I need to measure from the center of the ring gear to the top of the pinion for depth and compare it to?

These are OEM gears I pulled from a rear end a guy gave me for free just to haul off.

I don't have a 200ft lb torque wrench at the moment to crush the new sleeve

HalfOunce 06-06-2011 12:46 PM

There should be some that are stamped for the gear ratio but the pinion depth should be engraved ie hand written with an engraver. Most reputable companies do this. other wise you will have one heck of a time trying to guess what they had it set as to lap the gears at the factory. Anyway... It looks to me like the pinion needs a shim to set it back closer to the ring gear. hope ya have a set up bearing for the pinion or its gonna get old pressing the bearing off and on.

Coolball 06-06-2011 01:04 PM

That's okay I seem to have one heck of a time's on a weekly basis most times!

Since it's a used set I can try my best to match up the old wear pattern. I originally added a pinion shim and it made the gears bind, but it was a thick one so I'll start off with the thinnest. I'd be working towards more of a center pattern then?

About the set up bearing yes I read about that along the way and made both of the old pinion bearings interference fit where I can pop em' off by hand. Thanks for looking out.

HalfOunce 06-06-2011 01:17 PM

a used set you are at the mercy of the original pattern. anything off from the original pattern and it will make noise.

Coolball 06-06-2011 01:26 PM

Ahh, I see. Thanks. I should be pretty close then using the old shims, barring differences in the housings.

prostreet6t9 06-06-2011 02:42 PM

Leave the crush sleeve and seal out during set up and set the correct prelaod. The number on the pinion will do you no good unless your using a depth gauge. If your backlash is too much now,it should bring that coast side down a little when you get the correct backlash. As it sits now it will make noise on Decel.

gearman50 06-09-2011 10:52 AM

start with about .028 behind pinion,about.008to.0012 that should get you close then move in about .002 increments.good luck!

Coolball 06-09-2011 12:40 PM

Thank you for the advice gearman, I am moving back to this project sometime in the next few days and will have more questions I'll be sure to post back.

prostreet6t9 06-10-2011 09:47 AM

Get your backlash correct and check pattern before you do any depth changes.

Coolball 06-10-2011 10:43 AM

What should my backlash be for this type set? I have already tried a small shim on the pinion and brought the ring gear in a little and now I'm too tight at .001 which wouldn't give the gears any expansion room when they heat up.

I'm going to dive back into this tonight.

lmsport 06-10-2011 01:16 PM


prostreet6t9 06-10-2011 01:41 PM

I thought your backlash was "Loose" with that pattern. Backlash should be 8 to 10. Always keep your backlash consistent during the set up.

gearman50 06-10-2011 02:13 PM

coolball sounds like prostreet is giving you good feedback,ill step out for now. have a nice day

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