Tranny is going out! Severe whine above 45 mph!

[Roastem]

Guys, I think this is the tranny. Over the Christmas holidays I worked on my Z a little. I changed the rear end fluid, and I replaced a leaking pinion seal. I had to remove the rear cover and remove the pinion yoke to do this. I counted the threads on the pinion to make sure I didn't crush the pinion crush sleeve any more. The gears looked fine (good wear pattern), and everything was quiet as a church for 2-3 days. Then, after some spirited driving I noticed a whining noise coming from the transmission tunnel. I thought I might have blown a seal and didn't have any fluid in it from the ear piercing whine coming from the tranny area. I put the car on four jackstands and listened, but the sound actually seemed to come from the driveshaft. I unbolted the aluminum driveshaft and both U-joints seemed to be working fine, and I turned the rear over a few times to see if it was stiff or some teeth might have broken off. The backlash seemed proper and the rear spun freely. Can I rule out the Driveshaft and Rear, and blame the tranny?

[BIG D's SS]

That is wierd. I would say it is the rear.

[Ric]

If it's a steady whine with the same pitch no matter what gear you're in, then I'd still suspect the rear end. If the whine changes pitch or goes away in certain gears, then it's something in the trans. Either way, it needs immediate attention.

[Roastem]

Yeah Big D, I talked to a customer service guy at a place who sells reman upgraded t-56's, and he said it sounded like I had a bad bearing in the rear end. He said that bad bearings will resonate through the driveshaft, and that was why the noise was coming from the driveshaft. Do you think it will be worthwhile to take the differential assembly apart and take a look at the bearings?

[Roastem]

The whine is low before about 40 mph, then it becomes kinda ear piercing.

[Roastem]

GM said that the t-56 was 4100 bucks!!! WTF???

[BIG D's SS]

That is the way my rear was and it was a bad bearing.

[Roastem]

Thanks Big D, I am gonna take it apart this afternoon and have a look. If I replace the bearings, do you think I might need to get a new crush sleeve, and new shims? Or, do you think I can reuse the same settings?

[warpwr]

How many miles on the rear?

IMO you caused the bearing to fail by opening up the rear and putting it back together.

I would change the bearing and chrush sleeve and maybe the seal again. You also may need different / more or less shims. They don't wear out but are to give you the correct spacing.

[Roastem]

I bought the car on Thanksgiving this year, and it had about 88000 miles on it. With all the track type upgrades, I still think somone used to race the car at the track. The rear always had a roar to it since purchase, and I thought it was from the install, but I checked the wear pattern and it looked good, plus after fixing the seal leak, and filling it up with fluid and the friction modifier, it got more quiet than before. Until it went kaput after a pretty damn hard launch against a set of heated 295/35's. Then it went from audible to painful. Not just to the ears, but to the pocket too!

[BIG D's SS]

I would replace all the bearings and seals in it an the crush sleeve. The shims should be good since your not replacing the ring and pinion. Make sure you tq the pinion nut to the proper tq or it will come loose. Saw that happen on a 95 Dakota that I had that I let a guy rebuild the rear. He said it was because I went to the drag strip. THis guy raced for a living and he blamed it on the drag strip.

[Roastem]

Hey Big D. Question. Strange gave me a price on one of their 12-bolt axle sets of 2700 shipped. That axle will take anything I throw at it. Do you think it would be worth it? Or, should I just fix my 7.5 every time it breaks? I plan to put about 425 to the wheels, and take it to the track on occasion.

[Corvettestripes]

ttt

[keliente]

Rear end...noise travels, hence why you think it is the transmission. It is not a strange scenario by any means.

When you put the rear end back together you probably changed the pinion depth without knowing it. Sounds like you didn't check the bearing preload, just went by sight.

It is probably just the pinion bearings. You could get away with just replacing the front & rear pinion bearing, crush sleeve, and changing the fluid.

No sense really in putting excess money into the 10 bolt, just fix what breaks. When it breaks every week, start looking towards a 9 inch or 12 bolt.

www.keliente.com/gears.htm

[Roastem]

Not the tranny, gears are messed up. Couple teeth missing. Fixing it now, but I won't pour more money into that rear (only enough to keep it working properly under normal conditions), and I won't be doing a lot of clutch drops and hard shifts until I can get a 12 bolt. (well, maybe a little, hehe)