Weird metal piece included with the new truetrac diff

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DaisyDart

DaisyDart

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Hello everyone,
After recently purchasing a detroit truetrac diff, i went thru the manual and everything but cannot find what this metal piece is for?? I'm hoping someone on this forum has experience with these diffs and can help me out with identifying its purpose. Its not listed anywhere in the installation guide.
Thanks!
 

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Whats the size of that?

But to me it looks like its the pin that goes in the center of the diff. Look thru the splines on the locker and is there a hole the same size as that? Most people remove that pin from the sure grips when they replace there axle shafts. Just my opinion...
 
gdrill said:
Probably the spacer to run adjustable tapered bearings. Hard to tell with nothing to compare it's size to.
Click to expand...

That's what it is (it's called a thrust shim spacer or something like that). You need to slide it in the tru trac if you are running axles with adjustable bearings.
 
Yep. That is the thrust block that usually comes in a plastic bag with the Eaton TrueTrac.for use with tapered axle shaft bearings.
It is slid into the diff (where the axle shafts go in) prior to fitting the 3rd member into the axle casing.
 
DaisyDart said:
Hello everyone,
After recently purchasing a detroit truetrac diff, i went thru the manual and everything but cannot find what this metal piece is for?? I'm hoping someone on this forum has experience with these diffs and can help me out with identifying its purpose. Its not listed anywhere in the installation guide.
Thanks!
Click to expand...

When I bought my differential I got one of those as well. What you are supposed to do is bolt your rear axles into the rear end and see if you can slip the plug between the axle ends. It's purpose is to provide a means of checking axle clearance to prevent crushing the center section internals. If the fit is too high you are supposed to shave off the ends of you axles until they plug fits.
 
retroron said:
When I bought my differential I got one of those as well. What you are supposed to do is bolt your rear axles into the rear end and see if you can slip the plug between the axle ends. It's purpose is to provide a means of checking axle clearance to prevent crushing the center section internals. If the fit is too high you are supposed to shave off the ends of you axles until they plug fits.
Click to expand...

How exactly are you supposed to do that with an 8.75" rear end?

I too believe it is the thrust block that is only used on an 8.75" with the old adjustable bearings.
 
If you have green bearings don't worry about it. If you have the tapered rollers put the slug in the center. Install the non adjustable axle. Slip the adjustable axle in so you can back off the adjuster and slowly snug it up without bending the retainer/adjuster base. You may have to back off the adjuster some more. Then adjust the bearing load per spec.
 
As others stated above. For tapered bearings. My mechanic lost mine and had to get a replacement. For my installation, I had to shave the thrust block to get the end play correct (1962 tapered axle, bearings).
 
69_340_GTS said:
How exactly are you supposed to do that with an 8.75" rear end?

I too believe it is the thrust block that is only used on an 8.75" with the old adjustable bearings.
Click to expand...

What I was told by the rear end shop was to bolt the axles in place with the center section removed and check the clearance between the axle ends using the plug --I haven't got there yet.
 
Thats what I had to do, when my axles came back,cut too long, for my narrowed rear end,from the same shop.
Thankfully, nothing was yet installed. Instead of machining the "slug", I shaved the axles. That way I didnt have to mod every single chunk I had(7).
 
AJ/FormS said:
Thats what I had to do, when my axles came back,cut too long, for my narrowed rear end,from the same shop.
Thankfully, nothing was yet installed. Instead of machining the "slug", I shaved the axles. That way I didnt have to mod every single chunk I had(7).
Click to expand...

Having thought about this for a bit, does anyone see a reason to leave the plug in the center section after you check for clearance? I don't see any value leaving it in the pumpkin after you verify clearance.
 
Hold on there BubbaLoey
I have a feeling that the slug just represents the spacer in the TruTrac, making it a tool to determine any axle length adjustment(cutting) that may be required to fit it.Afterwards the slug is worthless to you.
Now shine a lite down into the center of your new TruTrac. If your new trutrac has a spacer in the center, then the the slug is just used beforehand as a set up tool to verify that the axle end-play will remain adjustable after the install.
If there is nothing in there, and you are using tapered timkin wheel bearings,then you must install that slug as a spacer in the new TruTrac.If you do not install it you will be unable to adjust the axle endplay, the axles will slide down the tapered races and the brakedrum will jam up on the brake shoes.
If you are running the green,ballbearings, then, after the measuring and adjusting,the slug serves no more purpose and may in fact prevent the bearing retainer plates from seating; so leave it out.
 
retroron said:
Having thought about this for a bit, does anyone see a reason to leave the plug in the center section after you check for clearance? I don't see any value leaving it in the pumpkin after you verify clearance.
Click to expand...

You don't need it if you have the non-adjustable "Green" axle bearings.
 
AJ/FormS said:
Hold on there BubbaLoey
I have a feeling that the slug just represents the spacer in the TruTrac, making it a tool to determine any axle length adjustment(cutting) that may be required to fit it.Afterwards the slug is worthless to you.
Now shine a lite down into the center of your new TruTrac. If your new trutrac has a spacer in the center, then the the slug is just used beforehand as a set up tool to verify that the axle end-play will remain adjustable after the install.
If there is nothing in there, and you are using tapered timkin wheel bearings,then you must install that slug as a spacer in the new TruTrac.If you do not install it you will be unable to adjust the axle endplay, the axles will slide down the tapered races and the brakedrum will jam up on the brake shoes.
If you are running the green,ballbearings, then, after the measuring and adjusting,the slug serves no more purpose and may in fact prevent the bearing retainer plates from seating; so leave it out.
Click to expand...

The slug is needed at least on earlier tapered axles or endplay cannot be set. I just set up my Eaton rear end and putting just the axles in and torquing down the brake backing plates led to large amounts of end play on both sides. This was before I realized the slug was missing. I shaved the slug down to the dimensions of the spacer in the open differential that I took out, refit the axle and endplay was spot on. Granted the axles could be shortened instead of the spacer but this is a one and done as I don't plan on swapping the third member out again.
If you are running green bearing then it is not needed.
 
Supershafts said:
You don't shave the block, you adjust the axle
Click to expand...

What would be the down side to shaving the block? Everything on my rearend was reused except the differential. The original open differential has a piece of squared tube that set end play of the axles. All I did was make the dimensions of the new spacer the same as the old one. Whether the axles are cut or the spacer cut, the distance from end to end remain the same.
 
Ok so I spent a couple of minutes on line And I see how the TruTrac works.
The slug is a spacer.
If you're using the tapered bearings, use it to to determine if the adjusters will work. Adjust the slug length if necessary, slam it together with the slug inside the trutrac
If you're using the Greens, throw it away.
Yes its just that simple.
 
It had nothing to do with adjusting or trimming anything (in a stock housing anyway), and you are supposed to leave it I in if you run tapered bearings.

In the 8 3/4, outside- wheel cornering load is carried by the opposite wheel bearing. There's a button in the stock diff for this purpose. That slug allows the trutrac to transfer cornering load in similar fashion, THROUGH the axles and diff.

This was covered in mopar action about the time the trutrac came out. Iirc, Rick and crew had to make their own slug because their diff didn't come with one. This might have been the bold beeper Road Runner?
 
Well to all, thank you!! If anyone needs this piece let me know and I'll send you mine, I have "green" bearings.
 
'64 and newer 8.75" rears came with 1.5" wide thrust blocks. Pre '64 OPEN rears came with 1.25" wide thrust blocks and longer axles.
 
DoctorDiff said:
'64 and newer 8.75" rears came with 1.5" wide thrust blocks. Pre '64 OPEN rears came with 1.25" wide thrust blocks and longer axles.
Click to expand...

jos51700 said:
It had nothing to do with adjusting or trimming anything (in a stock housing anyway), and you are supposed to leave it I in if you run tapered bearings.

In the 8 3/4, outside- wheel cornering load is carried by the opposite wheel bearing. There's a button in the stock diff for this purpose. That slug allows the trutrac to transfer cornering load in similar fashion, THROUGH the axles and diff.

This was covered in mopar action about the time the trutrac came out. Iirc, Rick and crew had to make their own slug because their diff didn't come with one. This might have been the bold beeper Road Runner?
Click to expand...
Hello i realise this is an old thread but the trust spacer or slug for the truetrac do you know how it is inserted i'm hoping you are able to go through the axle tube as i;ve just realised that mine also is missing and hoping i'm able to remove one axle and slid it in with out going through and pulling the diff down again
 
440RTSE said:
Hello i realise this is an old thread but the trust spacer or slug for the truetrac do you know how it is inserted i'm hoping you are able to go through the axle tube as i;ve just realised that mine also is missing and hoping i'm able to remove one axle and slid it in with out going through and pulling the diff down again
Click to expand...
I'm sorry, I don't own a Trutrac so I can't tell you what specifically to look for. Have you tried contacting Eaton?
 
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