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Discussion Starter · #1 · (Edited)
I installed my precision brand 4.10 gears and my own solid spacer/reluctor. I have installed several gearsets without issue before. I have had these gears for 3 years sitting around, just never got the chance to install them. Now I fought these gears to get a pattern. The drive is almost perfect just a touch shallow. Coast is a touch deep but near the toe. This is the best pattern I could get after MANY trials. The pattern Is within acceptable range on drive and coast with coast being the worst of the two. Glad I allways use setup bearings! Backlash was .009-.011. The gears made noise on coast and drive when just on the gas,coast is a little less. So I took it back apart and checked everything again(all right). I did lower by backlash to .007-.009. A touch tight I know. pinion shim is .048 preload is 16ish without a seal and I have good preload on the carrier. The whine is a little less and perhaps liveable. Im NOT happy with it though. Any ideas In case I decide to go it again to get it quieter? I would have and may still go with AAM gears but they werent available when I got the package deal.
 

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From what ive herd...
once they whine from being set wrong there always going to whine,no matter how much you toy with them afterwords.
 

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Discussion Starter · #3 ·
I have allways heard that too! however in the days of searching pattern and gear info many people have corrected their whine to some extent or alltogether after driving on them. I figured I had nothing to lose taking itapart a 2nd time. I also got it quieter just changing backlash. I know Im not getting rid of the whine completely just wanted some more opinions. The pinion shim is large for normal I know. I started at.035 which was way to shallow. went up .005 then .005 and from there .001-.002 to 50(to deep) setteled on .048. I actually passed .048 a few times to double check since the shim was so thick. perhaps some gears DO inherently whine just from being odd ones out? I dont know really.
 

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Once the gears go through the first heat cycle you most likely will not be able to get rid of the noise. I messed up my first ring and pinion install took everything apart and got the pattern and backlash perfect but the noise did not go away. I just did a 4.56 gear change using AAM gears and they are quit.

Do you know what the shim thickness was on the original pinion? .048 seems seems pretty big. The GM 8.5 is usually around .036. Not sure what your gear manufactor recommends for back lash but the factory specs are .005-.009.

When getting a pattern did you put a load on the carrier? I had a hard time getting a good pattern by spinning the carrier. Then I tried what the factory service manual recommends and got a very clean pattern.. Put the axels and brakes in. Set parking brake to the point where it takes approx. 50lbs torque to spin the pinion.

Also did you tighten the carrier to spec, 55lbs, before checking pattern and backlash?

Hope this helps

Looks like you are running a custom clutch pedal set up. I did the same. would you mind pm ing the details
 

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Discussion Starter · #5 ·
Well I havnt changed the pattern much if at all. Only the backlash not the pinion depth. The carrier was loaded and the pattern was decent to read(just crappy).
The shim thickness I allready explained how and why I ended up there. Im confident thats very close(.047 was better coast but but worse drive)I know its weird but not unheard of. Everything was tightened to spec on every pattern check(15 minimum), backlash too.
I dont know what the factory shim was. I will pressthe bearing off tomorrow and check.
I dont know what the precision specs are as I dont have the instructions and precisions sight has no contact info to get some from them. I knew I should have got the AAM"s. what kind of company wont support you with a simple phone #! I doubt the BL is as low as .005 for this cut gear. The AAM gears get tighter BL from what Iv read.
The only reason I have not touched the pinion depth is I dont know if deeper or more shallow is better and I dont want to road test every change.
 
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