[track73]

I’m familiar with installing ring and pinions but not very good at troubleshooting them. I have a howling noise at 40 to 60 mph and not much at 70. This is only driving and not coasting. I don’t know if it’s worn gears, wrong pinion depth or too much backlash. So I don’t know weather to buy new gears or readjust what’s there. I can get the whole kit for a little over 2 bills. I suppose I could crawl under the car and do a contact sweep. But I’m old crippled and unmotivated. Any ideas?

[Schurkey]

What ratio, how many miles on the gears, when did the howl start, when was the lube last changed, and have you verified the U-joints, wheel bearings, pinion bearings, and side bearings?

Does it matter if you accelerate or hold speed?

[track73]

I was a used gear. And have no idea how many miles were on it. It is a 2.73. I installed it about 10 years ago. The gear lube is new. Actually I changed it twice. I’ve driven it less than 250 miles. I put the whole axle in last year. And since the COVID deal I haven’t driven the Trans Am much.

[TB1]

Originally Posted by track73

I’m familiar with installing ring and pinions but not very good at troubleshooting them. I have a howling noise at 40 to 60 mph and not much at 70. This is only driving and not coasting. I don’t know if it’s worn gears, wrong pinion depth or too much backlash. So I don’t know weather to buy new gears or readjust what’s there. I can get the whole kit for a little over 2 bills. I suppose I could crawl under the car and do a contact sweep. But I’m old crippled and unmotivated. Any ideas?

I have spent most of the summer dealing with just this as you describe, I had a guy assemble an 8.5" for my 65 LeMans, I supplied all brand new Yukon parts. I just got it back today from another shop and it's now perfect, Cost me a set of gears and labour to assemble again but finally happy. The new shop said they were set up wrong from the start pinion depth was off and it had no preload. The contact pattern was terrible and the gears basically started to destroy themselves.
I figured it was a pinion bearing issue as it was only noticeable in 4th gear at pretty low RPM but i'm sure it never really went away the exhaust just took over. Good luck I learned a expensive lesson and should have followed my gut from the start would have enjoyed my car this summer as the first guy was having more than a bad day when he assembled this rear for me.........

[Schurkey]

Used gears are notoriously difficult to set up in a different housing.

Is the pinion depth correct?
What was the backlash on those used gears in the original housing?
What is the backlash on those gears in the housing they're in now?
Is it the same?

[track73]

When I initially set it up the backlash was within spec. Now it seems to have increased when I "rock" the drive shaft by hand. I put in 90-140 GL5 and it seems to quiet down before the lube heats up.

[Schurkey]

"In spec" doesn't really matter.

The gears need to be set up the SAME as they were in the previous axle. Same pinion depth, same backlash. That's why you don't take them OUT of the old housing before checking and recording the existing measurements, so you can duplicate 'em in the new housing.

[geeteeohguy]

Originally Posted by Schurkey

"In spec" doesn't really matter.

The gears need to be set up the SAME as they were in the previous axle. Same pinion depth, same backlash. That's why you don't take them OUT of the old housing before checking and recording the existing measurements, so you can duplicate 'em in the new housing.

This. ^^^^. Howl at cruise is generally worn gears. Howling on accel only is too tight pinion to ring and howl on decel is a pinion to ring that is too loose. I had Larry Woltzen at California DIfferential change out my 3.55 gears for used 3.36 gears in 1990, and that rear end is still quiet as a church mouse 30 years later. The gears need to be set up to run exactly like they ran in their old rear housing to keep the pattern the same and the noise down.