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Discussion Starter #1 (Edited)
EDIT WITH FINDINGS FOR FUTURE SEARCHING: A Standard 8.25 rear diff for 29 spline axles works in the commander, verified and installed in mine.



There is so much conflicting info on the rears on our Jeeps, mine is starting to make some noise so I was going to put in a true-trac.

A know ARB lists the 8.25 air locker as fitting our vehicle, here is what Eaton sent me through their tech lines...

My Email:
I have a 2006 Jeep Commander. The rear end housing is a standard Chrysler 8.25, 29 spline axle. I would like to run a TrueTrac in the rear. The ring gear on the newer Chrysler products is a 213mm outer diameter, as opposed to the older 210mm outer diameter. Are the bolt patterns for the ring gear the same / can I use the standard 8.25" differential? The rear end is also a floater style, no C clips. I see no reason why you couldn't use the C clip style differential in a non c clip style rear, correct? Thanks for any insight, looking at part number 912A553. -Jared


Response:
Thank you for the interest in Eaton differentials. Actually, the axle is not the 8.25” old school style. It is a metric corporate rear that is completely different (aside from the ring and pinion being interchangeable). Unfortunately the differentials will not interchange between the two applications, which means that all traction aid options are dealer items only at this time


Just sharing some info...
 

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ford 9", problem fixed. Or a dana 60 swap. . .
 

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Discussion Starter #4
Yes they are saying they dont make a locker/LSD for our rear.

ARB obviously disagrees as they list the one for the 8.25 as fitting the commander.

Anyone have a clue what a "metric corporate" rear is? The 8.25 (210mm) and 8.375(213mm) ring gears are interchangeable, same bolt patterns so our ring gear will bolt up to that diff. (similar to GM 7.5 and 7.675) If the gear sets are interchangeable, that also means the pinion placement as far as depth is the same, so you could get a good pattern. Diff bearing size or diff ring gear offset is the only thing I see which would change things?

Does anyone have any case measurements or a diff from a Commander they could measure a few things?
 

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Discussion Starter #5
Just crossed OEM jeep, to aftermarket, to old school 8.25. Pinion head and tail bearings, and diff bearings are all the same bearings. I think Eaton is wrong, I may just try and wing this...
 

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Discussion Starter #7
Well, mark one up for Eaton being flat out wrong.

Purchased a true trac, installed today. No problems, cant wait to test it out. :)
 

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Well, mark one up for Eaton being flat out wrong.

Purchased a true trac, installed today. No problems, cant wait to test it out. :)
Sweet! Let us know how it goes!
 

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Yes please let us know how it works out for you the more options we have the better. The guy at eaton is not an expert and with a vehicle like ours with very little after market support he probably did a little internet search or asked someone before responding to you. I was in email contact with ARB about there locker and threw there test fit on an XK in which we have a thread on it.
 

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Discussion Starter #10
Initial impressions are great. No problems with stability control as some people suggested, took it out in a parking lot and swerved hard enough for it to engauge and seemed like it responded normally. Ill know for sure once winter hits.

Zero noise, zero chatter/binding when turning. :banana_hitit:
 

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What was the true trac model number and what was the basic installation procedure? I've been thinking about putting a no-slip in mine, but haven't jumped the fence yet.

I'm assuming the read diff in a 2010 5.7 w/ QTII is the same..........
 

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Discussion Starter #12
Havent looged on in forever. I believe the QT2 cars are a completely different animal...
 

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Havent looged on in forever. I believe the QT2 cars are a completely different animal...
Are you running QT1?

I think the rear diffs should be the same between QT1 and QT2 - Only the Transfer case is different. FYI - this assumption comes only from reading mostly on this board.

When you did the install did you have to pull off a wheel and pull out an (or both) axle, or could it all be done from the diff case?

Any info on the installation procedure would be greatly appreciated.
 

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Still slightly confused

Was on Summit Racing website today and had to call the company. They List an Eaton/Detroit Truetrac for my 2006 Commander 8.25", however their Eaton book didn't list one for the 8.25" but did list one for the 8.375".??

When I asked the Summit guy what what was going on he gave me a "wait over". He called one of his tech guys and this is what is going on from their POV

The R&P from a 8.25" and fits on the 8.375" and the carrier bearings for a 8.25" and a 8.375" are the same part numbers, so they are saying that all is good.

Found another website that lists the TrueTrac for both the 8.25/8.375
http://www.iwerearendsonly.com/product_details.php?id=247

So maybe all is good in the world!!!

Altjar any second Impressions on the TrueTrac and what was the part number? I am working with the following number 912A553, please correct me if u used a different number.

Still a little confused and gun shy, $800 plus labor is a big chunk of change to drop on something that "might " fit
 

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In the 60's & 70's Chrysler had several different differentials, open, lsd, etc, that were totally different designs, had nothing in common, other then the external critical dimensions that allow them to be interchanged in the Chrysler Axles. I'd think the same was true of GM and Ford as well.

Could the Eaton rep have been fooled by that fact, thinking old and new corporate axles were different enough, that only the ring & pinion gear carried over, NOT the differentials?

If other differentials carry over from the old and new corporate axles, that would give me more confidence. I.e. if brand x differential works in old & new corporate axles, and brand y differential works in old corporate axles, shoudn't it fit a new corporate axle as well?

Don't forget the driveshafts on each side, they often change the spline count or diameter of the driveshafts. So its possible an older differntial could fit in the axle, but when you go to put the driveshafts into the axle, they won't fit.
 

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Discussion Starter #18 (Edited)
Still working great for me. No noise, no binding. This winter has been SUPER mild, so still havent had it in any kind of deep snow. But as a dailty driver, I dont notice it at all (which is a good thing)

And I used part 912A553. Its for 8.25 with 29 spline axles. This should work in all the rear commander setups except those with the electronic lockable diffs from the factory.
 
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