howl from the rear: gears, axles or diff?
01-13-2008, 12:11 AM
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howl from the rear: gears, axles or diff? Short version: can a rear-end howl be caused by the axles or differential, or is it necessarily the gearset? if it can be the diff or axles, are there any adjustments that can be done, or must they be replaced to banish the banshee in my rear end?
Since when I got my 2001 TA I was getting vibration from the back during braking- the shop said the axles and diff were messed up, so I had them put in Moser axles and an Auburn diff. In addition, GM 3.73's.
The 3.73's, axles and diff went in all at once.
When I picked it up, the rear howled like a banshee from 20mph up. As I drove it over the next several hundred miles the sound gradually went away from most speeds and got a little quieter. Problem is, from 50-70 or so, depending on how hard i'm on the gas (light-moderate), the banshee is still howling, and it's damn annoying.
I was nice and gentle with everything during the break-in period, except, unfortunately, at once point, when I was still under 100 miles on it, forgot and downshifted and punched it.
I figured my lapse (which was at the same speeds the howl continues at) is what is causing the sound, and from reading the posts here it seems that gearsets tend to cause this sort of problem especially when abused during break-in. The shop guy also believed the problem was the gearset. So I had them replace the gearset, again with GM 3.73's.
Unlike the first time I got the car back, there was no howl at all speeds that gradually went away. It acted just like nothing had been done to it, soundwise. No change.
So my questions are:
Does the existing gearset simply need to be shimmed differently?
or
Does the differential or the axles need to be adjusted in some way, or replaced?
any insight would be greatly appreciated. Thank you.
-sectari
Since when I got my 2001 TA I was getting vibration from the back during braking- the shop said the axles and diff were messed up, so I had them put in Moser axles and an Auburn diff. In addition, GM 3.73's.
The 3.73's, axles and diff went in all at once.
When I picked it up, the rear howled like a banshee from 20mph up. As I drove it over the next several hundred miles the sound gradually went away from most speeds and got a little quieter. Problem is, from 50-70 or so, depending on how hard i'm on the gas (light-moderate), the banshee is still howling, and it's damn annoying.
I was nice and gentle with everything during the break-in period, except, unfortunately, at once point, when I was still under 100 miles on it, forgot and downshifted and punched it.
I figured my lapse (which was at the same speeds the howl continues at) is what is causing the sound, and from reading the posts here it seems that gearsets tend to cause this sort of problem especially when abused during break-in. The shop guy also believed the problem was the gearset. So I had them replace the gearset, again with GM 3.73's.
Unlike the first time I got the car back, there was no howl at all speeds that gradually went away. It acted just like nothing had been done to it, soundwise. No change.
So my questions are:
Does the existing gearset simply need to be shimmed differently?
or
Does the differential or the axles need to be adjusted in some way, or replaced?
any insight would be greatly appreciated. Thank you.
-sectari
01-13-2008, 01:03 PM
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Thanks, guys.
these are the settings the shop guy said it's at:
2.301, spec 2.303 & backlash @ .006, spec is 6 - 10.
I'll have him try something different (what, I don't know, don't know much about the rear end (yet, at least...).
-sectari
these are the settings the shop guy said it's at:
2.301, spec 2.303 & backlash @ .006, spec is 6 - 10.
I'll have him try something different (what, I don't know, don't know much about the rear end (yet, at least...).
-sectari
01-13-2008, 10:52 PM
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Jeff
01-15-2008, 10:27 PM
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the invoice says gm7.5-373 on it- I had them buy it, not me, so I didn't see them (well, now I can see them since I got the parts, but they're still in the trunk and I haven't looked at them yet 
)
Took the car back to the shop yesterday, and the senior guy took it over and put in a set of US Gears, since he said that's what he's familiar with and knows how to make them pretty quiet (this was at no cost to me).
2.297 pnion depth & 7-8 thou backlash. forgot to ask about the shim depth.
Put 66 miles on it today in two stages. Sure, it's louder than stock, but just in a not-so-bad gears-turning-sound sort of way- the godawful high-pitched tone/whine is nearly all gone. I'll cross my fingers through the rest of the break-in period, but I think my problem might be solved!
P.S. STang4Lunch, my understanding is that 4.10's are inherently a bit louder that 3.73's and they do cut down on top speed, but I don't know how much.
In my case the sound would go away above about 72mph rather than just getting worse and worse (just what I needed- an INCENTIVE to speed
) (Well, officer, I was being chased by a banshee, and I had to outrun her..)
-sectari
)Took the car back to the shop yesterday, and the senior guy took it over and put in a set of US Gears, since he said that's what he's familiar with and knows how to make them pretty quiet (this was at no cost to me).
2.297 pnion depth & 7-8 thou backlash. forgot to ask about the shim depth.
Put 66 miles on it today in two stages. Sure, it's louder than stock, but just in a not-so-bad gears-turning-sound sort of way- the godawful high-pitched tone/whine is nearly all gone. I'll cross my fingers through the rest of the break-in period, but I think my problem might be solved!
P.S. STang4Lunch, my understanding is that 4.10's are inherently a bit louder that 3.73's and they do cut down on top speed, but I don't know how much.
In my case the sound would go away above about 72mph rather than just getting worse and worse (just what I needed- an INCENTIVE to speed
) (Well, officer, I was being chased by a banshee, and I had to outrun her..)-sectari
