IRS Eaton True Track

[chmhasy]

I have a quick question, I rebuilt my Lincoln Mark VIII pumpkin with 3.55 gearing and a Eaton True Track. The true track comes with a spacer that fits within the True track, I wanted to button up the pumpkin with the back cover before I install it within the frame. but if I install the spacer before installing it in the frame the space can fall out through the axle holes, Did anyone here not install the spacer or did you install the space after you got the pumpkin and axles installed?

Thanks

[karlos]

Same exact setup I'm running. The cylindrical spacer shown in the center of the photo, correct?

Sure, it's possible to install the spacer and button everything up prior to mounting the center section in the frame. But you really want to confirm you have some small amount of clearance between the spacer and the ends of the axle shafts with the axles fully seated in the center section. In some instances the spacer is too thick to fit in the available space, and if it's installed before the axles the axles won't be able to click into place.

I was also tempted to install the spacer and final install the differential cover before mounting the center section. Because the cover is part of the attachment to the frame, wasn't sure how to keep the RTV in place as the cover was jockeyed into position. Maybe you're wrestling with the same issue. The second photo shows one possible solution. This will allow you to install the spacer after the center section and axles are in place, confirm you have the proper clearance, then install the diff cover with no worries about leakage due to the RTV getting disturbed.

[CraigS]

Is your TrueTrac specific to the IRS application? I just looked at Summit and couldn't find a separate listing. Reason I ask is that my solid axle trueTrac had that spacer and it was absolutely needed as it locates the axles. It serves the same function as the big pin in the Ford lim slip unit. I wonder if it is even needed in an IRS diff since the axles are located by the snap rings. Seems to me it would need to be just a few thousandths of an inch smaller than the final space between the axles so they could push in and allow the snap rings to expand into their grooves. So then what would be it's purpose? Just some questions that I don't know the answers to.

[karlos]

Yeah, good questions. I don't recall the differential being IRS specific. Don't believe it is. Part number is 912A562 if you're interested.

The snap rings limit the outboard displacement of the axles, and the spacer limits the inboard displacement. Is the spacer absolutely required? Probably not. And in some cases it will be too wide to fit it the available space anyway. But if it does fit I'd put it in.

*Edit*

Near as I can tell, Eaton includes the spacer as a way to limit/adjust the axle end play in the event that tapered roller bearings are used. Not the case for an IRS, so I believe the spacer is extraneous. But I've also read that cornering forces are intended to be transferred from one wheel to the other via a load path through the axles and the spacer. Don't know if that's true or not, but I put the spacer in just in case.

[chmhasy]

Yes 912A562 is the one I got from summit racing. I was planning to install the spacer but was wondering how to but it in there ether before installation into the frame or after installation. Looks like I will have to wrestle with it after installation, and remove the cover ones its in the frame, Arrrr

I did get the Reusable Axle Cover Gasket from mustangsunlimited.com


Thanks

[CraigS]

I know it's a little unusual but you could install the axles into the pumpkin while it is on the floor. At the least as a test fit. But I would think seriously about leaving them in there while you install the diff. The knuckles would need to be removed but... A couple of bungees from the frame to each axle could be arranged to take most of the weight of each axle as you jack the diff into position. Keep re-adjusting the bungees as you go up.

[bansheekev]

I used the Eaton TrueTrac P/N 912A562 in an aluminum 8.8 case for the T-Bird style IRS. I did not install the pin, per guidance from the rear end shop who assembled the differential. Just a data point. 4,000 miles later its perfect.

Kevin

[1932]

The 15 and newer IRS is super 8.8, parts are different.

[bansheekev]

The 15 and newer IRS is super 8.8, parts are different.

You are correct as the newer IRS is a totally different ballgame. Not sure there are any aftermarket options available for a TrueTrac/Torsen style differential other than getting the factory one which is pretty expensive. For this thread, the original poster was inquiring about the older generation IRS though...

Kevin

[chmhasy]

I used the Eaton TrueTrac P/N 912A562 in an aluminum 8.8 case for the T-Bird style IRS. I did not install the pin, per guidance from the rear end shop who assembled the differential. Just a data point. 4,000 miles later its perfect.

Kevin

Kevin, the only issue I would foresee is that the half shafts would rub against the seals pre-wearing them out

[CraigS]

I just had a thought and checked to see if the large pin is still used in the 8.8 T-bird irs diff as it is in the solid axle. According to this it seems it is.
http://www.tccoa.com/articles/mn12-t...action-lok.htm
I have not been able to find a pic of an irs diff w/ the cover off to verify further. Thinking that, if the pin is there in the Ford lim slip, then maybe it is a good idea to use the spacer in the TrueTrac.

[Bob Cowan]

I never used a spacer in there. I'v never even seen a spacer for that. 12 years and thousands of miles without trouble. My Exocet uses the same diff, and there's no spacer there, either.

[chmhasy]

I never used a spacer in there. I'v never even seen a spacer for that. 12 years and thousands of miles without trouble. My Exocet uses the same diff, and there's no spacer there, either.

Bob, here in this picture is the spacer that comes with the true track dtl-913a481_w_ml.jpg

[rich grsc]

That spacer is used with the solid axle to hold the axles in place. Without it, the axles would slide in and out, and the keeper would drop out. IRS axles don't have side loads on them, the are held on place by the snap ring on the stub that slides into the differential. No reason to use it on an IRS that I can see.

[chmhasy]

That spacer is used with the solid axle to hold the axles in place. Without it, the axles would slide in and out, and the keeper would drop out. IRS axles don't have side loads on them, the are held on place by the snap ring on the stub that slides into the differential. No reason to use it on an IRS that I can see.

Yes, that is what I was thinking and was wondering what others have done with the spacer.