Differential problems? (T56)
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 92
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From: Columbus, OH
Differential problems? (T56) I've owned my T56 Trans Am for about 3 months now, and it has ~71,500 miles on the clock. Yesterday it started to make a wheeeeeee (hum) type sound when I accelerated slowly, or when I was slowing down. A friend of mine told me it must be a differential problem and could be as little as it needing a fluid change (highly doubt the previous owners changed it). What do you all think? I appreciate the help, so thanks!
TECH Regular
Joined: Aug 2010
Posts: 462
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From: houston, texas
i didnt hear the noise in your first post, can you make it again?
j/k. most likely it is the rearend, but if you just bought the car it is a
good idea to change all of the fluids/ filters and check the brakes and
all that good stuff.
j/k. most likely it is the rearend, but if you just bought the car it is a
good idea to change all of the fluids/ filters and check the brakes and
all that good stuff.
TECH Enthusiast
Joined: Apr 2010
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Yea, just start with the fluids. Mine makes a descently loud noise too just because it's getting older. Sounds more like a "Wheeeeeaaaa", unlike your "Wheeeeee", so...
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 92
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From: Columbus, OH
Haha "Wheeeaaaaa" seems to sound a little better. I took the fluid adding bolt off the diff and it appears to have sufficient fluid, so it seems that isn't the problem. If that's not it, what are the usual problems on mid-mileage cars like mine? Worn gear or something? Haha and all of the other fluids/filters have been changed, hadn't gotten around to checking in on the diff until today.
TECH Regular
Joined: Aug 2010
Posts: 462
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From: houston, texas
what did the fluid look like? probably wouldnt hurt picking up some RTV, fresh fluid, and LSD additive. could be axle bearings, differential, or pinion bearings. if the fluid level has been kept up; i doubt the bearings are bad.
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Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 92
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From: Columbus, OH
Would it make sense to change the fluid and just try that before bringing it to a shop (IPS Motorsports) to be looked at?
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Verdad Gallardo TECH Enthusiast
Joined: Apr 2010
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Well its worth a shot considering that it could save you some good money. If it's original fluid than it's definitely time to change it out 
But either way, it's normal for these rear diffs to whine. Mine whines like a little baby.
But either way, it's normal for these rear diffs to whine. Mine whines like a little baby. 
Registered User
Joined: Dec 2011
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Trouble shooting Brendo have you isolated the conditions that cause the noise? I.E in gear, out of gear, clutch in, clutch engaged. turning, straight line, etc. In my experience, unless you have been stressing the diff (burn outs, etc), and fluid is present (as you have verified) a differential will last a very long time without issue.
Have you changed anything in the drive train lately? Tires? Some trouble shooting thoughts:
1) if you can modulate the noise by accelerating and decelerating with the thottle, just take up the slack in the gears, IN any gear, 1,2,3,4, you can eliniminate the trans mission,
2) if the sound does not change when your turning or going straight you can probably eliminate the internal workings of the differential
3) if as you have indicated, it is speed related, and no other factors above effect the noise, then you may be looking and a pinion bearing, driveshaft universal ( most likely), or even ring and pinion issue.
Good luck
Have you changed anything in the drive train lately? Tires? Some trouble shooting thoughts:
1) if you can modulate the noise by accelerating and decelerating with the thottle, just take up the slack in the gears, IN any gear, 1,2,3,4, you can eliniminate the trans mission,
2) if the sound does not change when your turning or going straight you can probably eliminate the internal workings of the differential
3) if as you have indicated, it is speed related, and no other factors above effect the noise, then you may be looking and a pinion bearing, driveshaft universal ( most likely), or even ring and pinion issue.
Good luck
