My gears have always made a little noise but today it got about 1000 times worse.
Whenever I let off of the gas the rearend (I guess it's the rearend) makes an extremely loud noise like something is about ready to break.

Please help, I'm not really even sure where to start with this.
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i just drained all of the fluid out of the rearend and it's a dark grey color...haven't seen any metal shavings yet so I'm hoping I just forgot to add the posi additive or it needs the fluid changed badly!!!
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I put in new synthetic fluid and posi additive and it's still making the noise when I let off the gas.
For some reason I'm thinking it might not be the rearend but the driveshaft because there is a tiny leak where the driveshaft bolts to the rearend.

Somebody help, this is so disappointing


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1990 GTA
-355 carb'd, nicely reworked '64 vette heads, 2500 stall, 4.10's, other small things.
-Alston SFC's, Eibach Pro-kit, Koni's all around
-100+ nitrous shot
-Cruising in style with leather and nice stereo.

 

If the oil is dark grey, it's full of metal particles. Just stick a magnet in it and the 'sludge' will stick to it. You probably also had a pile of stuff stuck to the magnet in the cover. Did you check the backlash when you drained the oil? Disconnect the driveshaft at the rear and check to see if there's play (back and forth and sideways) in the yoke. You may gave a pinion bearing that's shot.

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1985 Yellow IROC-Z 5.0 HO, T-5 3.73 Torsen, 4 wheel disks
PFCM pads, GTA wheels, Koni yellows, B&M Ripper, Dynomax

 

How do I check for backlash and what will that tell me?

 

PJ, one other thing to check since you say you have a small leak at the pinion seal is the nut on the yoke. I have seen these come loose and only make a noticable noise on deceleration. Just a thought.

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1984 Z28 350
Never argue with an idiot, they'll just bring you down to their level and beat you with experience
My Web Page

 

PJ,
Definetly check the pinion nut. I had a Chevelle that I broke the yoke on, after I changed it, I tightened the nut as much as possible(I was 15), when I would let off the gas, the rearend would whine like hell. After I tightened it, noise was gone. No ill effects.

Hope this helps,


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Joshua Johnston
1991 Z-28
Flowmaster
K&N
305 / 5spd. (Temporary)

 

Yep, sounds like loose or bad pinion bearings. If the seal is leaking, its probably because the pinion got wobbly from loose bearings. I dunno why, but these rears have this problem alot. Best luck I've had is setting the pinion preload somewhat high (28 in./lbs.) and then breaking them in real easily. By the time they take a set, preload is usually down to about 15 in./lbs. Smaller gears are less forgiving to improper setup than larger ones.

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-Jason M. 1991 Camaro Z28

 

Not to sound like an idiot? but what is "Preload" mean?
I am working on a rear end right now.. 3.73 and got some questions about it anyway.

1. I have had two other rearends opened up before and pulled the differential out of a 3.42 setup, but after pulling off the cover of this one I just opened, the differential was totally different, no opening in the middle to get c-clips off the axle, the whole thing is totally sealed? does this mean it's POSI? its jammed up so I can't play with it to find out right now cuz the bearings I belive are shot on the pinion shaft.
I need to get this thing out and can I change these bearings or does someone else have to change these to get them on the right way ro whatever...

 

Jason, do you remember what you torqued the nut to in order to get the right preload?

I've heard in the range of 150 ft/lbs but I don't have an inch-pounds wrench to check the preload, so I'm hoping someone can just tell me the amount of torque I need to put on the nut.

The sound was being caused by a really loose pinion nut and I did tighten it, but I still need to tighten it more since I had no idea it was supposed to be that tight.