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1G Is it safe to derust & paint propeller shaft?

XC92

Proven Member
1,428
300
Jul 22, 2020
Queens, New_York
I removed nearly the entire rear end of my '92 Talon TSi AWD, including the prop shaft, to replace some wear parts & clean, derust & paint everything. I was just wondering if it's safe to do this to the prop shaft as well.

I thought that if I didn't do this uniformly, it could potentially imbalance the shaft and lead to whipping and even catastrophic failure, or damage to the t-case or rear diff.

I'm guessing not, that it doesn't spin quite fast enough for this to be an issue, compared to say the crankshaft, flywheel or turbo, but I just wanted to make sure.

I was planning to use the same methods to derust it, die grinder with various wheels, and a rotary tool for hard to reach areas. As for paint, it would likely be either primer and Rustoleum, or POR-15. Does it matter?
 

Dusty Landrum

Supporting VIP
509
458
Jul 15, 2019
Denver, Colorado
I removed nearly the entire rear end of my '92 Talon TSi AWD, including the prop shaft, to replace some wear parts & clean, derust & paint everything. I was just wondering if it's safe to do this to the prop shaft as well.

I thought that if I didn't do this uniformly, it could potentially imbalance the shaft and lead to whipping and even catastrophic failure, or damage to the t-case or rear diff.

I'm guessing not, that it doesn't spin quite fast enough for this to be an issue, compared to say the crankshaft, flywheel or turbo, but I just wanted to make sure.

I was planning to use the same methods to derust it, die grinder with various wheels, and a rotary tool for hard to reach areas. As for paint, it would likely be either primer and Rustoleum, or POR-15. Does it matter?

You could just do what I did and take the entire thing apart, take it to a powder coater and have them chemical strip it then coat it. It was cheap and looks amazing.
 

XC92

Proven Member
1,428
300
Jul 22, 2020
Queens, New_York
You could just do what I did and take the entire thing apart, take it to a powder coater and have them chemical strip it then coat it. It was cheap and looks amazing.
Is it possible to take just the 3 sections apart using a ball/U-joint kit and remove the 2 yokes and 3 journals w/o taking apart the 2 bearing assemblies too, to make it easier to clean, derust and paint everything and avoid potentially damaging the bearings by doing this to an intact prop shaft?

And if I do take it apart, are there any parts that need to or should be replaced, like the journal bearings or snap rings?

Also, while I have it off the car, what am I supposed to do to "fix" that t-case oil leak issue with the sleeve yoke? I took mine in for a recall way back in '98 and they said it was fine and didn't need a replacement, but I figure that with it off the car I might as well take a precautionary measure. Do I need to replace that freeze plug or is cleaning it and then applying black RTV good enough?
 

Mech Addict

Supporting Member
988
426
Jun 9, 2019
Jackson, Wyoming
I believe the recall had to do with improper hardening on the seal-wearing surface of the yoke shaft end (outer surface where the splines are on the inside). I think if yours looks unworn, that is, still a fairly perfect cylinder without any "hourglass" wear, then I doubt you'll have any issues. If it's worn, replace it now.
As far as I've determined, the only service for the U-joints is replacement as a unit. They're expensive, and there are three. They should move smoothly through their range of articulation. If notchy, then definitely replace the joint. I believe the FSM designates these are "never re-use" parts once their removed, though I'm sure folks re-use them, just like the large locking nuts that are used to secure the yokes on the d.s. I suggest you replace the rubber isolators on the carrier bearings mounts. If the bearings themselves turn smoothly, their probably fine, unless the rubber donut is disintegrating/ heavily cracked. I'm not sure how to remove these w/o damage, as I was replacing mine per plan. I did the lobro boot, as well, though it was probably fine. But after 30 years, how much life does a rubber component have left....?
Nothing especially complicated about it all, though I found that remounting the assembled shaft went way easier by temporarily wiring everything to a 2x4 with some spacer blocks to hold it all pretty straight. Otherwise it's wrestling with a somewhat heavy 3-piece snake.
I did a total strip/derust and repaint on all the parts, and didn't worry about the minute amount of change in the balance. It's back in the car and running (so far) without issue. If your ujoints, lobro, and carrier bearings seem ok, then just try to mask off any exposed bearing points with masking tape before strip and paint. You'll get 90+% of the full tear-down result with about 25% of the effort(and @10% expense).
 

steve

DSM Wiseman
14,579
1,470
Feb 3, 2002
Boulder, Colorado
Mark the phasing of the segments so they can go back the same way and maintain the balance. The Lobro joint is what allows the length to change as the suspension moves. It may need to be rebuild too.
 

XC92

Proven Member
1,428
300
Jul 22, 2020
Queens, New_York
I believe the recall had to do with improper hardening on the seal-wearing surface of the yoke shaft end (outer surface where the splines are on the inside). I think if yours looks unworn, that is, still a fairly perfect cylinder without any "hourglass" wear, then I doubt you'll have any issues. If it's worn, replace it now.
As far as I've determined, the only service for the U-joints is replacement as a unit. They're expensive, and there are three. They should move smoothly through their range of articulation. If notchy, then definitely replace the joint. I believe the FSM designates these are "never re-use" parts once their removed, though I'm sure folks re-use them, just like the large locking nuts that are used to secure the yokes on the d.s. I suggest you replace the rubber isolators on the carrier bearings mounts. If the bearings themselves turn smoothly, their probably fine, unless the rubber donut is disintegrating/ heavily cracked. I'm not sure how to remove these w/o damage, as I was replacing mine per plan. I did the lobro boot, as well, though it was probably fine. But after 30 years, how much life does a rubber component have left....?
Nothing especially complicated about it all, though I found that remounting the assembled shaft went way easier by temporarily wiring everything to a 2x4 with some spacer blocks to hold it all pretty straight. Otherwise it's wrestling with a somewhat heavy 3-piece snake.
I did a total strip/derust and repaint on all the parts, and didn't worry about the minute amount of change in the balance. It's back in the car and running (so far) without issue. If your ujoints, lobro, and carrier bearings seem ok, then just try to mask off any exposed bearing points with masking tape before strip and paint. You'll get 90+% of the full tear-down result with about 25% of the effort(and @10% expense).
Thanks. I'll have yet another look but I think it's good. I suppose that some RTV wouldn't hurt though just in case. I don't think it needs a rebuild at this point at just over 78k miles. Plus this rear end restoration has turned out to be way more work than I'd expected. Took forever to remove some of the bushings and there's just so much damn rust to remove.

Thankfully removing the prop shaft is relatively easy and doesn't require doing anything else except I suppose dropping the exhaust and I've gotten used to that. So I can always revisit that someday. But for now I'll just clean, derust and paint, and maybe replace the external grease with fresh stuff. Any recs on what to use that isn't OEM?

Mark the phasing of the segments so they can go back the same way and maintain the balance. The Lobro joint is what allows the length to change as the suspension moves. It may need to be rebuild too.
I probably won't take it apart this time but I did mark where the rear prop shaft flange meets the rear diff flange. I forgot the do the same for where the latter slides onto the diff shaft but that's probably less important.
 

XC92

Proven Member
1,428
300
Jul 22, 2020
Queens, New_York
If your not replacing the U-joints and Lobro there's less to worry about WRT phasing and the balance.
I don't plan on taking anything apart or replacing anything at this point, unless I notice serious issues with one or more of the joints, like binding, notching or too-free play. I basically removed the entire shaft and plan to clean, derust and paint it, then reinstall it with some fresh grease in the u-joints, and maybe put some RTV on that sleeve plug.
 

XC92

Proven Member
1,428
300
Jul 22, 2020
Queens, New_York
I'll have to ask Phil Swift. He'll probably say it can replace a broken u-joint.
 

XC92

Proven Member
1,428
300
Jul 22, 2020
Queens, New_York
So I checked my driveshaft, and there's definitely something notchy going on with at least the rear u-joint. It moves smoothly, except when it's going straight back. There's no resistance, it's just not smooth.

To be safe I think I should replace all three u-joints. The bearings seem ok. Might as well replace the insulators while I'm at it, and this will give me a chance to take it apart to clean, derust and paint it, probably with POR-15.

I'm aware of the difficulty in obtaining OEM u-joints, and their expense. Amayama has one available right now and another two on backorder that might not arrive till October. I can probably wait that long, in fact I kind of prefer to as I'm pretty burnt out from this rear end restoration, and I think the existing u-joints can hold up till then.

One alternative that would be a lot cheaper and faster is a sealed Moog that RTM has. This is the one without a zerk fitting. Does anyone know if it's any good, or is OEM the only way to go on these?

Again, I can wait and am willing to pay what it takes to get a good unit, but faster and cheaper's always better IF the quality is up to par.

Also, are those Torque Solutions insulators any good, and are they aluminum or poly? I'm not looking to race or anything like that so I prefer comfort over power, in case they're aluminum and create vibrations.
 
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