US-Gear 12-bolt pro gear issues ???

[Kevin Panzino]

Looking for some feedback from others on US gear 12 bolt pro gear sets. I honestly am completely lost right now on why this set is to damm loud on shutdown, and why the coast pattern looks so terrible when the drive pattern is good and all the other parameters are dead nuts.
Its, not only loud, but I can actually feel the pulsation of vibrations in my seat as the car coasts to a stop.

And with axles out, car on lift, driveshaft disconnected, just spinning spool with my hand it sounds horrendous....

I have pinion depth dead nuts, backlash at .008" and drive paste pattern looking good.

But, coast pattern is almost non existent. A thin line that is way, way too far down into the root to make any sense.

There is literally nothing else I could change to alter this situation..

Perhaps my housing warped/tweaked ???

Looking for some feedback, or maybe if anyone else has had similar issues with US gear Pro sets???

I'm about to put my old Richmond 5.57 back in with prob 200+ passes on em...

Kp

[Adger Smith]

Have you tried it at any other settings on BL ?

[Jeff Stout]

Curious on what shim you have on pinion.
My very first rear end I did when I was 18. New gear and bearings and I learned how to get the pattern needed. I fought this the whole weekend and couldn't get it right. I was so frustrated thinking it was me missing something. Called Monday and they sent another set out. Sent mine back and found out the gear was boxed before it was finish. It was the coast side that wouldn't come in. That first time gear change had me learn that new may not be right.

[Mark Ugrich]

I agree with Jeff. If you can get a decent load side pattern but the coast is deep in the gear, it would make sense the gear was manufactured wrong.

[Gary Evans]

Originally Posted by Mark Ugrich

I agree with Jeff. If you can get a decent load side pattern but the coast is deep in the gear, it would make sense the gear was manufactured wrong.

I would agree that the ring gear was not manufactured correctly. Wouldn?t be afraid to put the Richmond gears back in. I just changed the gears in my A/SA Camaro after 29 years and over 2300 passes

[Kevin Panzino]

Thanks for the replies gents. I have tried .008 backlash and also tried .010?. To me the .008 sounds worse.
I am at .032? pinion shim and are spot on the 2.854? checking distance.
I?m really thinking I got a bad set.

Kp

[Greg Reimer 7376]

Seemed to me back in the days when 12 bolts were the newest things,a .030"-.032" pinion shim was correct about 90%of the time.It was far more common to be able to reuse the original pinion shim than not.It didn't matter too often if the gears were 2.73's or 5.86's. With a drag race ratio or anything in the 4.56-6.14 ratios, there would be variation in whatever carrier bearing shim you needed far more often than the pinion bearing shim.It was also common to take out an open carrier and install a correct series positraction carrier reusing the gear set without having to start from scratch to determine the proper shim thicknesses. The vendor that GM used to supply the gears must have been very accurate as to quality control.When everything that rotates gets replaced as in a new rear axle assembly being built, it usually is pretty consistent as well. The 8.50" 10 bolt that came out in 1973 to replace the 12 bolt was fairly close as well. Sounds to me that what you describe was a problem with the new gears.

[Kevin Panzino]

Again, thank you all very much for the replies. Going through my records over the years, I have had from .023 to .032 pinion shim, and in the beginning I didn't even measure pinion depth, I just started with a .020 and focused on pattern and went from there. So I tend to think my .032" is not likely in left field. I do believe I got myself crossed up though with the cheap Proform tool that had my depth off by .008" compared to a ground flat bar, and a depth mic which is what I just did this time to look into it further, (albeit using the cap face as Centerline, which I still have to look into and understand.)

But I have good preload on pinion and carrier, I have a good looking drive paste pattern, and .008" backlash. So the axles are going back in and its all get buttoned up to run the Dutch.
I do think I will be ordering a Richmond set to put in over the winter however. It will be very interesting to see how that set is with essentially the same setup values.

I must admit, I am still somewhat wondering if my housing has had some warpage/movement over the years, because I will say I always have had a loud coastdown after clicking it into clean neutral. Its just that with this set, it is crazy loud, and I really got concerned when I could feel individual vibration pulses as it coasted to a stop, and as I gravity rolled down the staging lanes at the grove last week..

Thanks again to everyone. This forum is a blessing. Googling this kind of detail gets you pages of some guy on a Chevelle or Camaro street forum talking about how great so and so company is that he bought his entire rear-end from...


Kp

[Bob Gullett]

I run the same gear in mine with no issues. 5:57 US pro gear. I have found in most cases that a .035-.037 pinion shim is right on the money. .008-.011 BL. Pattern is right on the money both sides. But that doesn't mean you got a bad set. A few years ago we had set of Richmond pro gears in my wifes car. Set them up with a perfect pattern. 20 runs they sheared all the teeth off. Only conclusion we came up with is that they weren't heat treated properly or were a set of street gears marked as a pro gear set.

[Glenn Briglio]

Originally Posted by Kevin Panzino

Again, thank you all very much for the replies. Going through my records over the years, I have had from .023 to .032 pinion shim, and in the beginning I didn't even measure pinion depth, I just started with a .020 and focused on pattern and went from there. So I tend to think my .032" is not likely in left field. I do believe I got myself crossed up though with the cheap Proform tool that had my depth off by .008" compared to a ground flat bar, and a depth mic which is what I just did this time to look into it further, (albeit using the cap face as Centerline, which I still have to look into and understand.)

But I have good preload on pinion and carrier, I have a good looking drive paste pattern, and .008" backlash. So the axles are going back in and its all get buttoned up to run the Dutch.
I do think I will be ordering a Richmond set to put in over the winter however. It will be very interesting to see how that set is with essentially the same setup values.

I must admit, I am still somewhat wondering if my housing has had some warpage/movement over the years, because I will say I always have had a loud coastdown after clicking it into clean neutral. Its just that with this set, it is crazy loud, and I really got concerned when I could feel individual vibration pulses as it coasted to a stop, and as I gravity rolled down the staging lanes at the grove last week..

Thanks again to everyone. This forum is a blessing. Googling this kind of detail gets you pages of some guy on a Chevelle or Camaro street forum talking about how great so and so company is that he bought his entire rear-end from...


Kp

Pattern and backlash is the only thing that is necessary. I haven?t used a pinion depth device in thirty years and haven?t had any breakage or noises.