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Topic: Rear end repair - Advice & opinion needed

in Forum: C3 Driveline Components


Rear end repair - Advice & opinion needed

Posted: 4/1/06 2:38pm Message 1 of 10
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Kendall Park, NJ - USA
Joined: 3/9/2005
Posts: 789
Vette(s): 1981 - 59 Beige over Cinnebar leather. Edlebrock top end, 2200 stall w/shift kit, 3:55s, Mufflex maniback exhaust, nice stereo, 16 in AREs w/BFGs

I just brought my 81 in for its springtime maintainence.  I had a slight whine out of the rear last year.  My guys told me not to worry about it until its gets worse.  Anyway, its worse and they told me to worry about it.  I have to get it looked at and repaired.  My friends at the performance center wont touch it.  They think it needs bearings all around. 

A little bit about the car.  It has 64k on the clock, the car is meticualasly maintained.  Has some minor tweeks - Edlebrock intake, hiflow exhaust, B&M shift kit and a 2000 stall converter.

Heres my questions

What is the typical problem with something like this?

As long as they are going to be in there, is there anything else that should be done as long as its going to be repaired?

Any idea on cost?

Heres my big question(s) - does any one know the stock rear ratio for an 81 automatic?  I heard everything from 2:73 to 3:08.  I'd like to have the car jump alittle better off the line but I dont want to sacrifice my hiway driving which I do alot of.  I dont race the car.  So, should I change the gears? if yes what ratios do you recommend.... 

And once again how bad will all this brealk the bank?

ANy one know anyone in NJ that does this work?

 

THANKS!!  Kevin..

     

 

 




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Rear end repair - Advice & opinion needed

Posted: 4/1/06 3:01pm Message 2 of 10
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

2.73 or 3.08 depends on the transmission installed.  Could be either one.  One was for standard, the other for automatic.

If you are happy with the system the way it is, there is no need to change gears.  If you go to a higher ratio, the top end and fuel mileage will drop, and acelleration will go up.  It's a trade off, and depends on what you want the car to do.  Based on your statement my guess would be you want to keep the original gears.

As far as the cost goes, it depends on what is actually creating the noise.  You have a HUGE range you are looking at.  If you do need to get inside the rear diff, changing ratios could increase your cost quite a bit.

If cost is not an option and you want the best of both worlds, install an automatic with an overdrive.  The THM200r4 or THM 700r4 will do the job.  Then go with a 3.55 gear set.  It will get more acelleration off the line, and improve highway mileage.  But that's a lot of cash and work.




Rear end repair - Advice & opinion needed

Posted: 4/1/06 3:15pm Message 3 of 10
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East Hanover, NJ - USA
Joined: 9/25/2004
Posts: 525
Vette(s): '68 Black Conv. Matching 327/300 4 Spd. P/S, P/B, P/W, Tele, A/C

Kevin,

A friend was very happy with the work done @ http://www.nostalgiamotors.com/ in Boonton, or you can PM Warbird.  He has had a lot of work done at a shop in Layton (Sussex County).

Good luck,

Anthony




Rear end repair - Advice & opinion needed

Posted: 4/1/06 5:53pm Message 4 of 10
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
If bearings will cure the noise, then that's all I would do. If you don't correct the bearing problem soon, then you'll have your chance to change the ratio, 'cause the gears will be damaged.
In '81, the only ratio available(factory) for the auto trans was 2.87.1


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Rear end repair - Advice & opinion needed

Posted: 4/2/06 7:25am Message 5 of 10
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Tecumseh, MI - USA
Joined: 9/14/2003
Posts: 221
Vette(s): 1980 all org. with 18000 act. miles dk claret with matching interior..Eagle alloys ..loaded..excellent cond.

Just a thought but, have you checked your fluids?




Rear end repair - Advice & opinion needed

Posted: 4/2/06 8:22am Message 6 of 10
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BINGHAMTON, NY - USA
Joined: 7/19/2003
Posts: 3808
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Yup, I'd Check the grease ,or lack of same,B4 I tore it down, Might just be time to drain and refill with grease and additive,much cheaper than a rebuild


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Rear end repair - Advice & opinion needed

Posted: 4/2/06 7:29pm Message 7 of 10
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WEST SENECA, NY - USA
Joined: 12/3/2001
Posts: 2379
Vette(s): 1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

A couple years ago I swapped out the 2.72 diff on my '81 for a 3.08 diff out of an '80. Made a slight improvement on take off and didn't really affect fuel economy.

Here are the I.D. markings that tell which axle ratio was originally inside for 1981.

2.87 w/AT.....OJ

2.72 w/MT.....OK

Have you ever changed the gear oil in the rear end? Try that first and see if the noise changes or goes away.

Sarge





GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




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Rear end repair - Advice & opinion needed

Posted: 4/8/06 5:07am Message 8 of 10
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Holland, OH - USA
Joined: 11/29/2004
Posts: 217
Vette(s): 1978 Silver Anniversary Edition

    Friends of mine had similiar noise in thier diff. Tried everything to calm noise. Went to three different shops with no help. Called a Vette repair shop in Detroit, they told them to have the posi clutches looked at. They had the posi checked, found the clutches worn aand had them repaired. No noise. I think the repair cost them about 600 bucks. I hope this helps.

Jim




Rear end repair - Advice & opinion needed

Posted: 4/8/06 5:50am Message 9 of 10
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Kendall Park, NJ - USA
Joined: 3/9/2005
Posts: 789
Vette(s): 1981 - 59 Beige over Cinnebar leather. Edlebrock top end, 2200 stall w/shift kit, 3:55s, Mufflex maniback exhaust, nice stereo, 16 in AREs w/BFGs
Jim, You are right on the money.  Thats what it was.  Found out last night.  Im debating about having the whole thing done (clutch pack, gear change to 3:23, bearings, etc)..  Keep you all posted. 


Rear end repair - Advice & opinion needed

Posted: 4/8/06 6:04am Message 10 of 10
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sussex, NJ - USA
Joined: 11/15/2002
Posts: 299
Vette(s): 1969 L71 riverside gold convertible on frame restoration numbers matching motor 4:11 factory rear 4speed with hooker side pipes
just did my 4:11,complete rebuild, just about 1000 bucks.


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