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TruTrac Install in a 1031 axle

They are pretty darn tight by design for the rear D30 version, but that's also what keeps both tires going.

Screeching sound doesn't sound normal though, never heard one do that. What oil did you put in it? I've had better luck with M1 than Redline actually, but I only run full syn. Some places say not to, others say it's fine, I've run it in both of mine, had no issues in either, with around 90k on the wagon so far, with more than it's share of abuse.

Going from used to new bearings can change things. Most overhaul instructions I've seen have a different preload spec for new vs. used, with new usually being a little tighter.
 
no noises coming from the blue car, re-shimmed the carrier bearings and left the rest alone
 
I used the old bearings. As for gear lube, just some basic GL5 conventional 75w-90 from O'rielly. I will see if I can get a video posted by tomorrow.
 
I say, run it for a while and then see what happens. Mine made some nasty noise too when it was brand new and not broken in. Went away after a week or two.
Now a good year later, one oil change and about 20k covered, still going strong. Only replaced the carrier bearings when I did the swap. Left pinion alone, except for a new seal.

Happy with the performance. Surprised by how good it is in the snow.
 
In the video, I did not show the passenger side wheel spin but it makes the identical noise as the driver side. None of this can be heard when driving the car and putting power down while in a turn. Roughly a hundred miles on the TT as of the video....time will tell if there is an issue, however for the meantime it is mildly unnerving.

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I installed the TT in my 87 wagon today thanks to information on this thread and Dave Barton's Volvo rear end page. Install went relatively smoothly. Carrier bearing preload was a wee bit tighter than the factory diff and the backlash was right at .006". My only concern was after having the axle on the bench and all set up, I could not get the axle shafts to spin in opposite directions. I used a pry bar on the shafts and they would not budge. The axle felt 100% locked which was not what I was under the impression how this unit operates. Especially when compared to my '77 Scout which I installed a TT in the rear years ago, you lift the tires of the ground and spin one, the other spins in the opposite direction....

I contacted Eaton and they informed me this unit's 'high preload' will result in the symptoms I was experiencing. They blindly said to install the axle in the car and apply some real torque with the driveshaft. So I did and the unit performs as I expected and is a very predictable limited slip. After 40 miles of driving, I came back and lifted one rear tire while securing the rest of the car. The engine struggled but eventually spun the air born tire. It made an awful screeching sound but I still am wondering about the setup on this unit. Anyone else have issues with their TT's being this 'tight'? Eaton also said they will break in over time....

Also this is a 12 tooth tone ring car, I used a G80 ring and cut 36 teeth out. I welded it on after cutting the ring to get it to fit. The speedo was dead on with how it was on the factory diff. Shimmed the pickup with a washer for clearance and it was good to go. Just for info for the 12 tooth tone ring cars.

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....? the 940? I dunno whatchu talkin' bout now.

Naw dude. The guy quoted above you. Crossed wires, lol
 
In the video, I did not show the passenger side wheel spin but it makes the identical noise as the driver side. None of this can be heard when driving the car and putting power down while in a turn. Roughly a hundred miles on the TT as of the video....time will tell if there is an issue, however for the meantime it is mildly unnerving.

<iframe width="560" height="315" src="https://www.youtube.com/embed/MmkXLyRJrPg" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

That sounds like a dying bearing to me:


https://youtu.be/sE1sAIsrSHY
 
Sounds like the little helical gears, as there usually isn’t that much of a speed differential under most circumstances. That’s also putting a lot of wear on the helical gears and the housing when one wheel is lifted and spinning while the other is stationary. I wouldn’t worry about it, unless it’s making noises while going in a straight line.
 
I'd agree with ^^^^. Might try some better fluid as well, that can make a world of difference and operation. I had some strange, almost chunky operation on mine with valvoline syn, redline was better but I had some gear noise, M1 seemed to be silent operation and helped with the gear noise. Some of the house brand stuff from the chain stores is pretty bad, barely even meets, IF it meets the specs for the grade.
 
Okay cool, that sounds about right. No noise under any of the driving conditions. I used the house brand gear lube to do install and then will drain it soon to wash the contaminants out. Sounds like I might have to try some of that redline. Thanks for the input.
 
The 588 in my car is locked with both wheels in the air, just like in your description. It is the high-preload version, so that wasn't unexpected.

As far as the video applying power with one wheel in the air and the front wheels blocked, it looks like it is trying to do what the high-preload version is supposed to, apply the power to the wheel on the ground with traction. From what I've seen/heard the low preload ones will usually spin the wheel in the air, and you have to apply the brakes some to get it to transfer power to the wheel on the ground.

Heres what their literature says about lube;
"Detroit Truetrac:
High quality mineral gear lubes are required for use in Detroit Truetrac differentials. Regardless of the lube type, always use a GL5 rated lube with the least amount of friction modifier. Mineral lubes lacking friction modifiers (limited-slip additives) were historically recommended for all Truetrac applications because friction modifiers can slightly reduce the bias ratio (limited-slip aggressiveness) of Truetrac differentials. However, to address the continually increasing power outputs of modern powertrains, many vehicle manufacturers have switched to synthetic lubricants as a counter measure for increased axle temperatures and prolonged service intervals. In general, consult the vehicle owner's manual for the manufacturer's recommendations for lubrication type, weight and fill volume. This will ensure lube compatibility with the seal materials and bearings used in the axle. Eaton Performance technical support is available for any concerns in lube selection."

I used some Castrol non-synthetic 80w-90, I felt a little binding/vibration around the first one or two turns and haven't heard or felt anything noticeable after that.
 
finally found this thread again. toying with putting one in the black wagon (a TT), but then remembered I do have an annoying issue with the one in the blue 242.. that may be due to lack of miles on the unit... it's essentially locked 24/7, as in I can't even coast into a parking spot without it trying to scrub tires and make all kinds of racket.. at low speeds it's a whole lot like a welded diff, which is annoying tbh.

What are the actual real-world implications of using the low-preload version (585 I think?), I definitely don't want the same behavior from the wagon
 
Locked while coasting sounds like a possibly defective unit, or perhaps you have the longer axles in both sides forcing it to lock? By design locking under coasting doesn't make sense. All of mine are completely silent, open under coast, even on the big D60 in the Dodge and the Yota as well. The Yota, bombing dirt roads out here, you can definitely feel it transition from open on coast to locked when you get into it again in a turn.

The low preload you won't get the same transfer to both sides, but when they lock should be at the same point. The preload is more the percentage they will transfer when you have a traction issue, at least from my understanding. The 588 will do better in an autox situation than the 585, just as an example. When I did autox mine you could hear a little scrubbing on the inside but it never once lit up the inside completely, where I've heard from several that the 585 would unload the inside.
 
so longer axles, that's interesting. did 240's have different length axles? I did recall on the g80 install in sam's car eons ago we shortened one axle a little (1/4 inch or something like that), but I don't recall there being a similar need when I put the diff in the 242 (using a 92 rear end/1031, not the 1030), everything went together and just "worked" or at least seemed to.
 
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