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Three new differential gear sets, two mechanics shops, 5 set ups and I still have noise.


FBBO Gold Member
FBBO Gold Member
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7:51 PM
Jan 28, 2012
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I hoped that dumping the Richmonds, getting a set of US Gears - gears, and using a regular drive line shop would finally be the end of my differential noise but it hasn't happened. The noise is different every time a set of gears is changed or the pattern is adjusted, but it still howls. With the US Gear set it only howls from 40 to 50 on light cruise throttle. Doesn't howl on acceleration or coast or outside that speed range. It's such a narrow speed range I would almost say the heck with it - but it's really loud. Can't say much about the pattern as the yellow paste was pretty dried up and not too clear when I picked it up. I bought him a kit to replace the collapsible shim collar and he found a slightly damaged cage on the rear pinion bearing that he replaced. I did check backlash and several areas and it was .007" as he said.

I wonder if it could be a bearing but everytime the gear set is changed or pattern adjusted, the noise is different. I would think if it was a bearing somewhere the noise would stay somewhat constant. I have the axle end play set at .014". U-joints are new. Original axle bearings are in place but I greased them up good.

I guess I'll go over and take him for a ride and see if he has any thoughts.

Any comments on what a light steady cruise howl means concerning pattern or backlash?
I've come to the conclusion that it's the way these sets are manufactured. We have a new Chevy Colorado at work and the rear is very noisy. Other stores in the company are experiencing the same thing with their new Colorados.

I installed a set of Nitros from Dr Diff in my '62 and I had a perfect pattern and they run quite. Installed a set of Motive Gears in my 03 Dakota and could not get a decent pattern no matter what I did. It's one of the easiest rears to set up and I could only do so much trying to get a good pattern. They have a high pitch singing between 45 and 50. It's been getting quieter the more I drive it and I'm not too concerned anymore.

There's other threads on here and all over the www on this very topic. It has to be how these manufacturers are cutting in these sets if they are even cutting them in at all. I researched which ones that are known to be noisy and certain brands do stand out. I don't remember which ones anymore but it doesn't take much to find out. I always refer any of my questions and problems to Cass (Dr. Diff) and he always seems to have all the right answers.
Have you considered that the pinion bore to axle shaft centerline is not machined in the proper location? Pinion C/L out of perpendicular in one plane, Pinion shaft C/L to high or low?
Same axle housing? Have it placed on an alignment jig and checked. Mine had a bent tube. You can measure flange to flange across the front then across the rear to see if there's a difference. Mine was off 5/8". I shipped it to Dr Diff and Cass straighted it and returned it. The nouse was gone.
Don't rule out the wheel bearings...
Tiny bit of condensation and some rust on a roller...
Need a buddy in the trunk to listen lol
Many times this noise description indicates your preload is set incorrectly.
It’s the same housing and center section that the original 3.23 open was in and I never noticed any sound out of it. Installed an Auburn Suregrip in it. I found where I checked the carrier for runout in 2016 and it was flat. Backlash doesn’t change around the ring gear. No typical wheel bearing noise such as howling in corners. The noise always changes with a change of gears or changing the gear set up. I bought the gears so they probably are going to be hesitant to take much responsibility but I’ll take the owner for a ride and see if he has any ideas.
741, 3.23 suregrip. My gears were noisy. I reset everything and changed the clutches. No change. Finally decided to remove the front and rear bearings...reinstalled...the noise was gone.
Are you speaking of the pinion bearings?
A whine at a specific speed is almost always gear setup. I set up a ton of gears, hundreds, although they are not for Mopars. I use a factory tool to set pinion depth, and then use a dial indicator to check side preload and backlash. I NEVER use Motive or Richmond gears as I have had issues with them wearing and making noise even tho they were quiet upon install. Took it apart to inspect and the gears had worn and changed backlash. Replaced with OEM and no issue. I have also had good luck with off brand gears but now it's just not worth the risk to me.
So, short story long, OP, I believe your gear install, specifically the pinion depth is a little off. Jmho.
I wonder who cuts these gears nowadays. I worked at Gleason Works in Rochester, NY in 1974, and back then every automotive rear axle gearset in the world was cut on a Gleason gearcutter. They pretty much pioneered cutting ring and pinion gears.
I would almost say the heck with it
Sometimes you get the bear,sometimes it gets you.There is a thing called harmonics that occurs within anything mechanical at a certain RPM.
Just a thought.
I had a friend, since passed, who owned a rearend shop. He told me that if initial setup isn't right, and gears howl, they will ALWAYS howl from then on, no matter what is done to setup. Only solution is new gears.
Since that time, it seems that lots of gears are cut offshore, and will make noise, no matter how good the tech is or how good the setup. Seems like best bet for quiet gears is oem gears from dealer parts dept. Probably not the cheapest way to go......
There is a business out there that advertises quiet gear setup. Turns out, he does ONLY nine inch Ford.
Well, I took the shop owner for a ride and he said it was definitely gear noise. It does make a bit of noise on coast down too - just not as loud as the Richmond’s. He and his mechanic said they were factory lapped gears and set up real easily - both are standing by that the position the pattern looked as good as you can get. They replaced one pinion bearing and I asked if maybe the other was bad. They said all the other bearings were fine. They mentioned all the same things about gear harmonics, sad state of aftermarket gears, etc. He said they are seeing it in new vehicles too and 40 to 50 seems to be a common speed for noise. He checked on the gears he normally uses (Revolution) but they stopped carrying 8-3/4 gears several years ago. He said a used, OEM gear set might be my best bet. I wish now I had kept the old 3.23 set.

He said they would be glad to take another look at the pattern if I wanted to pull it again just to double check it. He said they might be able to play with the pattern a little to get it better but it’s just trial and error and might get worse and might take several attempts with no promise of success. I told him that after pulling and replacing it 4 times already I might as well do it again and we can just look at it and we can then decide then whether to mess with it. He seemed willing to help.

After that he recommended some noise insulation under the seat and at the trunk divider. He didn’t mention louder pipes though.:rolleyes:
Just wanted to chime in, my brand new Strange S60 with spool and 4.56 gears has a whine on decel that sounds like an ambulance coming up behind me. Kinda reminds me of my moms Rambler wagon when I was a kid.
Can’t hear it with open headers though.