Eaton Posi rebuild - Page 2 - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

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post #16 of 26 (permalink) Old Sep 21st, 14, 12:04 PM
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Steve Johnson
 
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Re: Eaton Posi rebuild

Been having burnout issues with this unit.


Tom at Tom's Rear ends says this posi was only used two years and to throw it away So I'm at the "now what" stage. Bite the bullet and buy a 3 series Eaton?

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1970 SS with a .030 over 454 LS6 crate engine, 14096188 open chamber rect. cast iron heads, 3933163 intake, Quick Fuel Q850PV, Summit 110gph FP, Holley 12-803 fuel pressure regulator set to 7.0 psi, Bullet cam (238/245 @ .050, lift 540/540, LSA 109), Gm HEI 93440806, TH400, FTI 3500 convertor, Hedman headers, 2.5" exhaust with H-pipe, Pypes Race Pro mufflers, 3.55 gears, KYB gas shocks, UMI adjustable upper control arms and UMI boxed lowers, pinion angle negative 1-2 degrees), 245/60/14 BFG's and M/T Pro Bracket Radials, timing total 37 degrees.
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post #17 of 26 (permalink) Old Sep 29th, 14, 2:23 PM
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Kevin
 
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Re: Eaton Posi rebuild

So what about too much axle end play? Mine definitely have a lot of play and I had never really put a lot of thought into it.

Should I try to find some thicker C clips somewhere?

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post #18 of 26 (permalink) Old Nov 19th, 14, 6:47 AM
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Re: Eaton Posi rebuild

cool video,

Here is my deal, i had my posi unit rebuilt with 400# springs and during slow driving (parking lot maneuvering) the rear clunks real bad -- it sounds like a lockright unit but at the track i've done quite a few one leg burnouts. What gives?

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post #19 of 26 (permalink) Old Mar 6th, 15, 11:37 AM Thread Starter
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Re: Eaton Posi rebuild

Quote:
Originally Posted by thunderstruck507 View Post
So what about too much axle end play? Mine definitely have a lot of play and I had never really put a lot of thought into it.

Should I try to find some thicker C clips somewhere?
Sorry I didn't see this earlier. You probably just need to shim or replace the clutches to reduce the axle end play. The axle end play will increase with clutch wear.
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post #20 of 26 (permalink) Old Mar 6th, 15, 11:39 AM Thread Starter
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Re: Eaton Posi rebuild

Quote:
Originally Posted by turbopowered68 View Post
cool video,

Here is my deal, i had my posi unit rebuilt with 400# springs and during slow driving (parking lot maneuvering) the rear clunks real bad -- it sounds like a lockright unit but at the track i've done quite a few one leg burnouts. What gives?
Did you use the GM limited slip oil additive? If you didn't then put a bottle in and drive it for a while. The clunk should go away. If the clutches were not shimmed correctly that could also cause it. Did you use the 18 disc steel clutches when it was rebuilt?
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post #21 of 26 (permalink) Old Mar 6th, 15, 12:36 PM
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Re: Eaton Posi rebuild

Quote:
Originally Posted by big gear head View Post
Sorry I didn't see this earlier. You probably just need to shim or replace the clutches to reduce the axle end play. The axle end play will increase with clutch wear.
it's only on the driver side...but it moves enough that it pushes my brake piston into the caliper during a right hand turn (or at least I am fairly sure that's what's going on...no brake pedal pressure after a right turn unless I hold the pedal during the turn)

Pro Touring 1971 Chevelle SS clone
head/cam LS2, 4l60e, 3.42 12 bolt
1.61 60ft 7.17@95 1/8th 11.33@117 1/4
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post #22 of 26 (permalink) Old Mar 10th, 15, 9:12 PM Thread Starter
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Freddie
 
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Re: Eaton Posi rebuild

Quote:
Originally Posted by thunderstruck507 View Post
it's only on the driver side...but it moves enough that it pushes my brake piston into the caliper during a right hand turn (or at least I am fairly sure that's what's going on...no brake pedal pressure after a right turn unless I hold the pedal during the turn)
I would remove the differential and check the clutches. Watch the video and follow it's instructions.
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post #23 of 26 (permalink) Old Mar 11th, 15, 10:24 AM
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Re: Eaton Posi rebuild

That's the plan, I have a whole clutch, shim kit from EATON along with brand new C Clips

Pro Touring 1971 Chevelle SS clone
head/cam LS2, 4l60e, 3.42 12 bolt
1.61 60ft 7.17@95 1/8th 11.33@117 1/4
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post #24 of 26 (permalink) Old Feb 11th, 16, 3:48 PM
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Re: Eaton Posi rebuild

Ok it's been rebuilt for a while now and for the most part it seems to be working.

But it still pops in reverse and on real light right hand curves. Pretty sure at the track last week it wasn't even fully engaging and letting one tire spin sometimes.

I've have 2 bottles of limited slip additive in it. Kinda figured it would have broken in by now.

Any ideas?

Pro Touring 1971 Chevelle SS clone
head/cam LS2, 4l60e, 3.42 12 bolt
1.61 60ft 7.17@95 1/8th 11.33@117 1/4
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post #25 of 26 (permalink) Old Apr 16th, 16, 10:30 AM Thread Starter
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Freddie
 
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Re: Eaton Posi rebuild

Quote:
Originally Posted by thunderstruck507 View Post
Ok it's been rebuilt for a while now and for the most part it seems to be working.

But it still pops in reverse and on real light right hand curves. Pretty sure at the track last week it wasn't even fully engaging and letting one tire spin sometimes.

I've have 2 bottles of limited slip additive in it. Kinda figured it would have broken in by now.

Any ideas?
Sorry I'm late getting here. I hadn't noticed that you posted again. If this is a drag car then it's best not to use the additive in the oil. The additive makes the clutches slip easier, which is not what you want when drag racing. If it's being used for auto cross then the Eaton Posi is probably not the best differential to use. As for the popping, I don't know what's going on there. Did you use the GM additive?
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post #26 of 26 (permalink) Old Apr 18th, 16, 3:54 PM
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Re: Eaton Posi rebuild

I've been meaning to pull the cover and look for other issues like broken spider gear teeth or something.

I haven't been able to observe personally from outside the car but bystanders who noticed the popping when it was first built said it appear the axle was twisting then popping to unload like what happens with a car with a spool? It occurs in situations where the car is only slightly trying to turn, such as real wide curves on the highway.

The car is used for both and the original Eaton served me very well for nearly 10 years with no complaints. And yes, after a couple years I stopped using the additive in it.

I have 1 bottle of GM additive and I think the 2nd bottle was the Ford equivalent. Seems to work when the fluid is fresh and again got better when I very first added the 2nd bottle of additive.

Pro Touring 1971 Chevelle SS clone
head/cam LS2, 4l60e, 3.42 12 bolt
1.61 60ft 7.17@95 1/8th 11.33@117 1/4
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