Originally Posted by Keith Seymore (Post 6611696)

Backlash and shim recommendations are just a starting point; *the set up then needs to be tuned to get the correct contact pattern.

If it is truely a defective gear set and if it doesn't respond to repeated trials then the only recourse is to replace with another ring and pinion set.

He did start with the indicated pinion depth and then fine tuned the pattern several times.

K

Originally Posted by Half-Inch Stud (Post 6611699)

Good to know if it has a constant drone (as if pinion depth is not where the gears were rung-in) or a cyclic drone (like as if not seated flush with diff Carrier flange.


If itsa cyclic then look into a proepr seating or a better posi carrier.

Originally Posted by steve25 (Post 6611877)

Did all 4 new bearings go in on the gear swap?
Some new off shore *bearings are crap.

Originally Posted by mgarblik (Post 6611798)

Did the shop doing the work have any comments about what the pattern check looked like when they were done setting it up? *Very hard to comment without seeing the results of that check. *I would like to see both a drive side and coast side check results. *In general, the lower the numerical gear ratio, the easier it is to get a nice pattern and quiet operation. * In my experience, GM ratios steeper than 3.73:1 are a little more difficult to make really quiet as the number of teeth on the pinion gear decrease. *A 3.08:1 ratio, in theory should be fairly easy to set up. *Of course, it's always possible the gear set is defective.

Originally Posted by SRGN (Post 6611701)

Since it was quiet before the gears, it's unlikely that the carrier has an issue. I've had a couple of carriers with excessive runout cause an issue with noise, I just spend the extra money on Eaton units for my vehicles these days. If you can post a picture of the pattern, it will be a lot easier to diagnose.

Originally Posted by DanC (Post 6611996)

Noise was another reason I changed the gears to begin with, but the main reason was to drop the rpms at cruise. The 3.42 was pretty noisy all the time that I only discovered after quieting the exhaust by getting rid of the Flowmasters. *So perhaps it could be the Yukon carrier? If it has excessive runout, would that not show up on the micrometer or pattern paint?

Originally Posted by HWYSTR455 (Post 6612012)

My Moser 12 bolt is noisy as heck, and I'm on my 2nd US Gear 3.42 ring & pinion in 5k miles. I did carrier bearings at that time too.

Maybe I should look at me axle bearings?

I called Moser (they did the rear initially) and they told me some gears are just noisier than others, not sure if that's true or not, but I'm going to install another set of them.

I have all new carrier bearings this time too, but was considering a different brand R&P.

I actually have a new True Track carrier too.

What should I look for on the axle bearings?



.

Originally Posted by Keith Seymore (Post 6612073)

Bearings would be a low growl or drone or rumble.

Ring/pinion gear mesh is a high frequency pure tone (a howl or whine).

K

Originally Posted by mgarblik (Post 6612004)

Thanks for answering all those questions. You mentioned the rear end was noisy with the other ring and pinion set as well. This leads me to the axle bearings. What are their condition? Axle bearings can transfer tremendous noise through the tubes at speed.

Originally Posted by steve25 (Post 6612033)

So did the OPs noisy gears that got taken out show ware, and in particular show ware that would have lead to failure?

Originally Posted by Keith Seymore (Post 6612073)

Bearings would be a low growl or drone or rumble.

Ring/pinion gear mesh is a high frequency pure tone (a howl or whine).

K

Originally Posted by HWYSTR455 (Post 6612110)

Then mine is def a R&P singing.

I have the hybrid ends on the Moser housing, using a Ford big bearing (double row).

I bought it as a complete assembly minus brakes, broke it in as instructed, and it sang from day one. Yes, used correct fluid. They use US Gear exclusively. They don't list bearing brands on their' website, but I will look at the kit they provided and check the bearings.


.

Originally Posted by DanC (Post 6613234)

The pattern and condition of the 3.42 R&P look fine and I tried to attached two pics 180 out of both but was unsuccessful.

Originally Posted by DanC (Post 6611680)

I recently had my R&P changed out from 3.42 to 3.08 using a new "USA Standard Gear" set.

The setup starts to make an audible whine around 1800 rpm and goes away ~2150 rpm, more pronounced under accel/load, and horrendous and loudest at ~2000 rpm.

The installer states that the backlash and shimming is correct and trying different settings just changes the rpm range of the noise. He is also upset that he cannot get the setup to be quite like it should be and he has done "dozens" of the 8.5 GM setups and never had an issue until now.

Now I don't know if "it's just me" , but it seems like the whine is getting louder but staying in the same rpm range.



Any ideas here on why and what, if anything, can be done about this?

Thanks, DanC


1978 Firebird Espirt original 10 Bolt housing "PJ" (2.43 open)
Yukon Dura Grip YDGGM8.5-3-28-1 carrier
USA Standard Gear ZG GM8.5-308