Differential Whine only at 67-70mph speed range?

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outrun

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My differential makes a loud whine only at 67-70mph. Throttling or braking out of that range promptly eliminates the noise.

The unit has been babied with conservative lubricant change intervals with Redline 75W90.

Some online sources say this indicative of ring and pinion wear ... although this is not singularly the end of the world. Is a ring and pinion overhaul the only solution to eliminate the noise? Could it be something else? Could something "heavy" like Redline Shockproof do the trick and silence this? A quality reman Jasper unit (2300$) would be over-kill and a ring-pinion overhaul would be some 6-7 hours of labor I have read.

Application GM 7.5inch 10-bolt rear, Auburn Limited Slip, 3.42, 188,000miles.
 
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some shimming of the ring and setting the correct pinion depth can usually make a rear end pretty quite. Just have to have a tech who knows what he or she is doing.
 
I had rear diff develop whine in Subaru when I switched from OEM dino to Redline 75W90 at 40000 miles.

I would switch from 75W90 to good quality dino SAE 90 or even 110 (as you are in Texas).
 
Once you have a ring&pinion get noisy, no amount of reshimming or changing backlash will fix it. That being said, pinion bearings whine as well, but the amount of whine is very load dependant.

Something has to happen to cause a gear whine. The number one cause is the rear pinion bearing, followed by a pinion yoke nut backing off over time. Ck for any lateral free play in the pinion. If possible measure backlash, then pull the carrier out and inspect carrier bearings, pinion integrity, and ck for "glitter" in the lube.

Something else to consider, you can get noises transmitted from the axle to the body through any number of components, example- bad bushing, a park brake cable out of position, a torque arm bent etc.
 
If you are going to try a new lube, look at the gear wear pattern on the ring gear and see if it is way off. Online pics or a manual will help.
Bearings, esp the pinion, should be checked . Whine is from the teeth, but a loose bearing can make then noisy, because of misalignment.
I hope the fresh lube fixes it enough to make you happy.
 
Originally Posted By: outrun
My differential makes a loud whine only at 67-70mph. Throttling or braking out of that range promptly eliminates the noise.

The unit has been babied with conservative lubricant change intervals with Redline 75W90.

Some online sources say this indicative of ring and pinion wear ... although this is not singularly the end of the world. Is a ring and pinion overhaul the only solution to eliminate the noise? Could it be something else? Could something "heavy" like Redline Shockproof do the trick and silence this? A quality reman Jasper unit (2300$) would be over-kill and a ring-pinion overhaul would be some 6-7 hours of labor I have read.

Does your car spec 80W or 75W? I`ve heard about people having diff whine when going to a 75W if their car specs an 80W.

Application GM 7.5inch 10-bolt rear, Auburn Limited Slip, 3.42, 188,000miles.


Does your car spec 80W or 75W? I`ve heard about people having diff whine when going to a 75W if their car specs an 80W.
 
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I have helped these in other cars with a heavier lube. Try some 75w-140.

If you are sure its gears then you can shim it, it will at least alter the sound provided bearings are tight.

Sooner or later you'll need some parts.
 
My Toyota 4Runner has a harmonic since new at 60-70mph. Not very loud. Put amsoil 80w90 in it. Still a tone. Dealer and others say its normal.
 
Originally Posted By: aquariuscsm
Does your car spec 80W or 75W? I`ve heard about people having diff whine when going to a 75W if their car specs an 80W.


That happened to me with my wifes Lexus RX330...went back to 80w90 and it stopped immediately.
 
Problems with multiviscosity gear oils that they shear down just like engine oils. Even synthetic ones. Another balancing act between fuel efficiency and wear protection.

I believe that except for cold climate, straight SAE90 should be used. This is actually specified in rear diff in my 2006 Rav4 in the service manual (above 32F), but incorrectly listed as 80W90 in the user manual (dumbed down version).
 
Had a 98 GMC Z71 that had a similar problem. The longer I drove it, the worse it got, and the range in speed it occoured at got bigger and bigger. Lucked out in the end though only wound up replacing the pinion bearings, but I did end up wearing the ring a pinion a bit goofy so it still whined (not near as bad) after it was fixed. Moral of the story, get it looked at before something else gets wrecked.
 
Originally Posted By: friendly_jacek
Problems with multiviscosity gear oils that they shear down just like engine oils. Even synthetic ones. Another balancing act between fuel efficiency and wear protection.

I believe that except for cold climate, straight SAE90 should be used. This is actually specified in rear diff in my 2006 Rav4 in the service manual (above 32F), but incorrectly listed as 80W90 in the user manual (dumbed down version).


My 4 Runner is speced for 90w or 80w90. Good luck finding a straight 90w.
 
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