THE quietest ring & pinion - US Gear with "Lightning" treatment, or ?

[stantaur]

Search isn't finding "US Gear" instances, so posting this question. For GM 12 bolt 8.875" car design running between 3.90 and 4.30 gearing, what vendor has proven to be the quietest?

I'm open to ideas, as we're fighting a battle on our 40K mile 1-owner Z/28's 12 bolt which came with 3.73s. Since 2004, we've had 4.10 (40 tooth ring, 10 tooth pinion) gears from Reider thick 4.10s(2004-18), Yukon regular 4.10s (Aug 2018) and Motive thick 4.10s (Sep 2018) in our 12 bolt, including 3 and 4 series carriers, and still have either a loud howl (Reider & Yukon) or light whine (Motive).

Per USG's literature, they do all their manufacturing in Chicago, IL and perform a special treatment that polishes the gearset - currently used in Indy, NASCAR & trophy trucks. So that coating might be worth the extra $100 vs. non-coated.

Next question comes to tooth count. Some theorize that having more teeth meshed at any given time improves strength, and some say it also reduces risk of noise since more teeth are meshed at any given time. That would lead me to conclude that my best option would be US Gear's 3.91:1 ratio with 11 pinion / 43 ring teeth, followed by US Gear's 4.30 ratio with 10 pinion / 43 teeth. At that point, I'm concerned US Gear's 4.11 setup uses 9 pinion teeth and 37 ring teeth (vs. Motive, Yukon, etc. doing 4.10s via 10 pinion / 41 ring teeth).

Goal is to get this thing back to nearly noiseless. Our local highly-reputable shop with 20+ years of experience specializing in diffs, is pulling their hair out after 3 different gearsets being noisy. Our Reider"thick" 4.10 set was meh in 2004 and progressed to the outrageous howl by 2018 that you hear in the bottom link below, shot with camera zip tied to tank (which is about as loud as the interior was FWIW). So we tried Yukons on a proper new 4.10 carrier, thinking that thick gears might be contributing to the noise - but these were no better. We tried Motive thick 4.10s on a 3 series carrier after that - those have been the quietest so far (but nowhere near as silent as the original 3.73s). Kicking myself for changing out the original 3.73s back in '04 but I had no idea how hard it would be to find semi-quiet gears & just wanted 4.10s to optimize my 1/4 mile powerband (high 11s, 121 MPH on drag radials running 6400 RPM thru traps - right at 6500 RPM power peak, 3600 RPM soft launch 1.78 60 ft), autocross, early morning twisty road drives.

Thanks for whatever experiences you can share with various vendors & setups.

Yukon 4.10s:

Motive 4.10s:

Reider 4.10s:

[BBPanel]

More food for thought - https://www.diyford.com/ford-axle-ri...ssembly-guide/ scroll down to the section titled "Gear Ratio Selection and Tooth Combinations". I don't know if there is any merit to these observations but it seems a logical approach. Would be interesting to compile results from users and the different ratios used - might generate data to validate or refute it. But some of the parameters are subjective (define noisey for example) so it would be hard to quantify. Motive Performance Gears are double lapped (just as oem Ford gears were) and that seems to be the reason folks like to find used Ford gears as many say they are quiet. I'm not sure why lightening the ring gear would impact noise levels. I have no idea what REM-finishing does for noise but I guess I'll find out because I just bought a treated 4.22 gear set. Of course, some will say the gears just aren't setup correctly. Some more discussion here recently https://www.pro-touring.com/threads/...isy-3rd-Member

[rennat_2006]

Go with GM gears. 4.10 ratio shouldnt be too difficult to find, youll pay a premium for them but i think itll be your best bet.

Are you sure it isnt carrier bearings or something like that making noise? Too much like for example having a case spreader on the diff and having to pound the carrier in or too little of preload like for example having a case spreader on the diff but not actaully getting any spread on it and setting it up that carrier just drops in will leave you with very little to no preload.

Just something to think about. Ive always ran yukons and have never had any issues.

[stantaur]

Any idea where to find OEM GM gears new or used? The two shops I've worked with so far had no luck.

Automotive Drivetrain checked the trueness of the housing via some bore-alignment checking tools they have. Everything checked out as you'd expect for a 40K mile 12 bolt that never whined with its original 3.73 setup and was never in any accidents, never used slicks and only 8 passes on drag radials leaving the line below 3000 RPM during its lifetime. This thing should be a poster child of quiet, yet it's the exact opposite.

The link below is from two identical action cams, synced to show the camera zip-tied to TKO600 near output shaft at the top of the video frame (and only on left channel of headphones) vs. the lower part of screen being the camera zip-tied to the left axle of the diff, near the pumpkin (and only on the right channel). Welcome your thoughts on this one, as it sounds to us like the diff (right channel) makes most of the howling from the Yukon 4.10s, whereas you can hear a lighter whine of the TKO's gear set starting out from dead stop around 3 minutes into the vid then going away for the most part in upper gears.

Trans vs. Axle Noise Comparison: https://youtu.be/X60lhCYapbg?t=2m55s

[stantaur]

More food for thought - https://www.diyford.com/ford-axle-ri...ssembly-guide/ scroll down to the section titled "Gear Ratio Selection and Tooth Combinations". I don't know if there is any merit to these observations but it seems a logical approach. Would be interesting to compile results from users and the different ratios used - might generate data to validate or refute it. But some of the parameters are subjective (define noisey for example) so it would be hard to quantify. Motive Performance Gears are double lapped (just as oem Ford gears were) and that seems to be the reason folks like to find used Ford gears as many say they are quiet. I'm not sure why lightening the ring gear would impact noise levels. I have no idea what REM-finishing does for noise but I guess I'll find out because I just bought a treated 4.22 gear set. Of course, some will say the gears just aren't setup correctly. Some more discussion here recently https://www.pro-touring.com/threads/...isy-3rd-Member

Thank you for this tooth count idea, Bob. It's interesting to see a google search for 4.10 noise vs. 4.11 noise. More incidences of 4.10 noise outright, but that's not comparing percentages of total 4.10 installations which might outnumber 4.11 installs and perhaps the percentage would be the same between the two. Still, I'm wondering whether US Gear 4.11s with 9 pinion / 37 ring gear teeth vs. either their 4.30 (10p/43r) or 3.91 (11p/43r) would be quieter.

[rennat_2006]

I appologize, i wasnt able to find anything higher than 3.73 in genuine GM gears. Ive done alot of gear swaps in the 4x4 world and havent had any problems finding up to like 4.56 or higher in genuine dana or gm in those applications.

[alocker]

I would give the US gear a shot. Not only do they sell them direct, they also private label for Strange and Bob's differentials. The 2 sets I installed in a 12 bolt were quiet but did get a bit louder after punishing them with a lot of HP in a heavy car. I think they will work in your car and I'm interested to see if the treatment helps. I almost got the treatment but decided not to.

[CarlC]

The Camaro has 3.73:1 US Gears with the special treatment installed about a year ago. They are quite good, much better than the early 80's vintage Richmond gears that were in the car.

The exhaust is pretty quiet during cruise where most gear noise is noted. During cruise it's silent. Can it be heard? Yes, but I've never been in a car with a quiet exhaust where there wasn't some notable gear noise especially on decel.

[stantaur]

Would have edited my top post for the TLDR crowd, but don't see a way to here. Long/short, the ISF treated US Gear 4.11s made it here this week and we got them installed by Automotive Drivetrain in Tualatin, OR. Result: nearly zero whine on coast and virtually silent on cruise and accel. Big improvement over the prior Reiders (2004-18), American, Sierra and two sets of Yukons.

Here's the comparison on same stretch of road. https://youtu.be/prZZKanJz1g if you want to listen in or download a copy. US Gear ISF on the left channel audio and top screen, Yukon on the right channel audio and bottom screen. Same car, same camera / mic & location, approximately the same speeds.

Worth me mentioning people hear different things from a given sound, as demonstrated in this summer's "Laurel vs. Yanny" comparison linked here: https://youtu.be/SbjnIK6VEjc?t=9 I hear Laurel, my wife hears Yanny. Not sure which one you guys hear.

Since I hear Laurel, the sound in the right channel of my clip is like nails on a chalkboard to me and I can hear it from 30 to 75 MPH (the vid's between 50-60 MPH). The right / Yukon channel I can hear the whine & howl on acceleration, cruise and decel, with some "whip-whip-whip" noise on decel.



By comparison, I can barely hear some lesser-amplitude whine at 50-55 MPH cruise on the US Gears, and I can detect some similar whine on decel, but there's nearly no whine at all on accel and during level cruise. So the US Gear ISFs have a narrower band of whine which is lower amplitude and it's outside my "average" speed where I spend the majority of my time in that car (which averages 34 MPH around town & country / twisty road drives).