Eaton True-trac - Chevy Impala SS Forum
 
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post #1 of 9 (permalink) Old 07-16-2012, 08:21 PM Thread Starter
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Eaton True-trac

Has anyone had any problems with an Eaton Posi continually grinding in turns...this is after an AAMCO total rebuild ....and several times back to the shop before warranty expired. It would stay quiet for about 3 months and then the clutches seemed to start sticking. Tried multiple bottles of friction modifer to no avail. I'm considering changing to an Eatom True -trac. Any problems with the true-trac?
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post #2 of 9 (permalink) Old 07-16-2012, 09:00 PM
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I did when using synthetic gear lube.
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post #3 of 9 (permalink) Old 07-20-2012, 04:11 PM
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The Eaton Tru Trac uses spherical gears and is a Torque Multiplying/ Biasing Diff much like the Torsen T2's operation.
They will not grind in a turn and I like them so much that, that is all I use in my vehicles if I have any choice.
Plus the effect of more managed power to the ground, you can feel the difference in the seat of your pants in certain driving situations. IMHO
Cons of the units are they Don't Like shock loads well. They have no way of shunting excessive energy and can fail if you rev your motor high and Dump the Clutch hard or drop the Tranny into drive from Neutral.
If taking one to the drags you need to preload the diff and they work great.

The Stock Auburn Units and the Eaton Brute #400 diffs use slip clutch plates and springs to drive the axles so yes they will bind and pop in a turn, some more than others depending on friction on plate, modifier in the oil and type of oil. Just a side effect of the design.

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post #4 of 9 (permalink) Old 07-21-2012, 02:54 PM
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I have been rebuilding diffs for quite some time and one thing i can say about the tru-trac is that the tolerances between the gears inside the unit are a little excessive i feel. I build ford 8.8 kits to swap into CTS-V's and i can tell you that with the 2 piece driveshaft and the clearance between the tru-trac gears there is quite a clunk when going from reverse to drive or drive to reverse. This is with the backlash at .008. With all of that said i still have a tru-trac in my impala and dont notice it as much.

94 Impala SS with a decent amount of work
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post #5 of 9 (permalink) Old 07-21-2012, 04:09 PM
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Quote:
Originally Posted by iceman View Post
Has anyone had any problems with an Eaton Posi continually grinding in turns...this is after an AAMCO total rebuild ....and several times back to the shop before warranty expired. It would stay quiet for about 3 months and then the clutches seemed to start sticking. Tried multiple bottles of friction modifer to no avail. I'm considering changing to an Eatom True -trac. Any problems with the true-trac?
aamco = iffy job quality

eaton recommends a good mineral based gear oil and using a friction modifier.
you might try the ford limited slip additive if the gm stuff was used with no success.

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post #6 of 9 (permalink) Old 07-22-2012, 09:34 PM Thread Starter
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Thanks for the replis and information. I am now considering changing the 400# springs to the 200# light duty springs hoping to lessen the chattering/binding/popping noise. The car is stock, and I probably will not use on drag strip unless I modify it....that may be later down the road. Has anyone changed to the 200# springs and noticed a change in the chattering/popping noise in street driving?
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post #7 of 9 (permalink) Old 07-22-2012, 09:39 PM Thread Starter
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Mr Pogo - I agree with aamco = iffy job quality. Don't think I'll be seeing any of their shops in the near future. I should have done the rebuild myself....but hindsight is 20/20.
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post #8 of 9 (permalink) Old 07-22-2012, 10:45 PM
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Eaton True-trac

When I started using Pennzoil/Shell gear lube with two GM posi additives,my chattering was gone. Synthetics are a big no no with the Eaton.
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post #9 of 9 (permalink) Old 07-24-2012, 12:39 PM
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fwiw I have the Eaton with 400# springs using dino oil and Ford friction (came with unit) modifier.

...and clutch dumps with a tire are not a problem nor have I experienced any clutch noise on tight turns. have been down the track about 200 times with it and no noise under any driving condition

your rebuild could be suspect or fluid/additive

I did have the "clunk" with the stock auburn unit on tight, low speed turns..even with dino fluid and GM additive. this was when the car was stock. went with the eaton limited slip

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