QuadraTrac Fluid in Part-Time TC?

[Country Jeep]

See sig for specs, minus transfer case. Trying to determine if my tc is still QuadraTrac, or if it's already been converted to part-time. The truck has front locking hubs (Warn), but problem is, the fluid that's remaining in the tc is milky and hard to discern if it's ATF or TCL-1 / a QT mix, and there's only about a quart left, so I'm not keen on trying any of the usual tests until I have it full of one fluid or another. Which is a problem since I don't know if it's QT or part-time

I know you can't use ATF in a QuadraTrac, so no worries there. But would it be safe to use TCL-1 or a homemade QT mix in a tc that's already been converted to part-time? At least long enough to do some testing to see if it behaves as a part-time should.

Alternatively, I've been looking for an excuse to buy this for other projects. If it's possible to feed this through either the drain or fill plugs in the tc and identify if it's QT or part-time that way, I'd have no issue doing that - one more toytool for me to use on other things.

Also can refer to images below for fluid color, if anyone wants to hazard a guess.

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[Country Jeep]

I decided to go ahead and get the probe camera, even if it doesn't prove helpful for this project. Video is uploaded here. I can't make heads or tails difference between what QT or PT is supposed to look like based on the schematics from the install instructions I found on JubileeJeeps. Is there anything of note in the video?

[tgreese]

Cool to get the flexible probe camera, regardless. Hard to say what the outcome will be, if you don't know what the Quadratrac and Mile Marker conversion output sprockets look like in advance. Understand what I mean? The Mile Marker kit would replace the limited slip part of the Quadratrac with a selectable output sprocket. You might look at existing pictures of what the factory Quadratrac sprocket looks like. Maybe there are pictures of the Mile Marker sprocket online somewhere for comparison. Seems like the torque bias test (section 2D in the '79 TSM) would tell you more.

[Country Jeep]

Cool to get the flexible probe camera, regardless. Hard to say what the outcome will be, if you don't know what the Quadratrac and Mile Marker conversion output sprockets look like in advance. Understand what I mean? The Mile Marker kit would replace the limited slip part of the Quadratrac with a selectable output sprocket. You might look at existing pictures of what the factory Quadratrac sprocket looks like. Maybe there are pictures of the Mile Marker sprocket online somewhere for comparison. Seems like the torque bias test (section 2D in the '79 TSM) would tell you more.

Makes sense, I’ll try to find a reference. Not opposed to doing the test, just hoping to avoid using the old (and now less) fluid to do so. Got a physical copy of the 79 TSM as a Christmas gift from in-laws, which was neat

IMG_3780.jpeg

[Dusty]

All the info, and pictures for a Quadratrac you could ever want,

https://jubileejeeps.org/quadratrac/openmmkit/index.htm

[seventynine]

So this is not a definitive answer to your question…but the part time kits come with a new decal that is supposed to go over the original Emergency Drive decal in the glove box to describe the new operation. People probably don’t always apply this…but if it’s there…I’d say it’s pretty certain it’s been changed.

See attached image.

[Country Jeep]

All the info, and pictures for a Quadratrac you could ever want,

https://jubileejeeps.org/quadratrac/openmmkit/index.htm

Much appreciated! I got back up under there with the camera again and went through all four possible avenues - the fill port, drain port, the tiny secondary port on the bottom driver side of the tc housing, and the low-range port - but was never able to spot anything that would let me definitively identify if full-time or part-time, at least inasmuch as I can tell.

So this is not a definitive answer to your question…but the part time kits come with a new decal that is supposed to go over the original Emergency Drive decal in the glove box to describe the new operation. People probably don’t always apply this…but if it’s there…I’d say it’s pretty certain it’s been changed.

See attached image.

No dice; mine still has the original full-time decal. In fact, I looked everywhere for any sort of indication that something had been modified, including around the tc housing. Absolutely nothing.

So with all that said, I bought four quarts of new, clean TCL-1. So once it comes in this week, at the very least I'll use it to do the torque bias test, see if this thing is full-time or part-time, then I can change the fluid out if I find it is in fact part-time. If for some reason it's still full-time though, I wouldn't be surprised if the clutch cones were burned up by this point, as it's been driven between the PO and myself at least 10k miles with the front hubs unlocked (in e-drive per the dash light - no remaining vacuum hoses going to the tc intact in the engine bay).

Here's some potentially pertinent info in the meantime: Back when I first bought this in 2022, and mentioned early in this thread here, there were either a new or old Quadratrac belt and control diaphragm lying in the bed of the truck deteriorating from the elements for who knows how many years. Clearly someone was going to do some work on the tc at one point, or had done some work but stopped, I'm not sure. But there were no parts indicative of a part-time kit. Whoever bought those parts came before the PO, as PO really didn't know anything meaningful about the truck or its history, and seemed to be flipping it after finding out how much work needed to be done on it. Perhaps they were going to replace the belt because the current one is slack, and the diaphragm is broken?

Either way, I did confirm that the belt has at some point been slapping around the inside of the tc; see photos below. I just don't know if the belt that's in there is the old one or the new one in that set of parts I found.

EDIT: I recalled also being told at one point there was a split somewhere in the tc housing, but I couldn't find anything for the life of me. Uploaded a video to the shared Dropbox folder just going over it all.

Screenshot 2024-02-11 152008.jpg

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[tgreese]

I'd go ahead and do the torque bias test without putting any new fluid in. You'll need to shift the transfer case out of e-drive somehow. Once out of e-drive, the test in the book will spin the rear output more-or-less freely if you have the part-time kit. With the Mile Marker unit out of e-drive, the front driveshaft disconnects completely from the rear drive shaft.

If you still have the Quadratrac LSD differential, it will take something like 80 ft-lbs to turn the differential against the front drive shaft. That will take some muscle, and should be nothing like the Mile Marker conversion turning the more-or-less free output shaft of the transmission in neutral. Indeed, if the rear output turns easily, you can put the rear driveshaft back and turn the front output as an added test. It should turn even more easily.

If you have the Quadratrac differential, there will still be oil between the plates. If it's short on oil, it will be harder to turn and the test will even more strongly confirm that the differential is in there. You don't really care whether it's in spec and properly being bathed in oil. It will turn easily, or not ... the difference from the Mile Marker kit should be like night and day.

[Country Jeep]

I'd go ahead and do the torque bias test without putting any new fluid in. You'll need to shift the transfer case out of e-drive somehow. Once out of e-drive, the test in the book will spin the rear output more-or-less freely if you have the part-time kit. With the Mile Marker unit out of e-drive, the front driveshaft disconnects completely from the rear drive shaft.

If you still have the Quadratrac LSD differential, it will take something like 80 ft-lbs to turn the differential against the front drive shaft. That will take some muscle, and should be nothing like the Mile Marker conversion turning the more-or-less free output shaft of the transmission in neutral. Indeed, if the rear output turns easily, you can put the rear driveshaft back and turn the front output as an added test. It should turn even more easily.

If you have the Quadratrac differential, there will still be oil between the plates. If it's short on oil, it will be harder to turn and the test will even more strongly confirm that the differential is in there. You don't really care whether it's in spec and properly being bathed in oil. It will turn easily, or not ... the difference from the Mile Marker kit should be like night and day.

Understood. Just to be sure, this doesn’t mean anything, does it? Rear driveshaft doesn’t move by hand at all currently. And if I’m going to manually attempt to disengage e-drive without the truck’s vacuum system, is this the type of Mityvac I need?

[tgreese]

Watched your video.

Are the hubs locked? That spins like there is nothing connected to the front driveshaft, either in the axle or in the transfer case. Again, to me, that spins waaay too easy. The oil and weight of the gears spins harder than that. But maybe not.

This implies that you have the Mile Marker kit, but the front driveshaft should not spin like that if the transfer case is in e-drive mode (dash indicator on). This is not adding up to a normal condition. Possible the gears have been removed from the front axle (BTDT - not my truck).

I would test the front axle next. With the hubs locked and both front wheels off the ground, the differential action in the axle can be seen. If you hold the driveshaft and turn one wheel, the other wheel should turn in the opposite direction. If you hold one wheel and turn the other wheel, the driveshaft should turn.

[tgreese]

Watched it again. I can see the axle u-joint turning on one side. You should lock the hubs and try this again.

[Country Jeep]

Watched it again. I can see the axle u-joint turning on one side. You should lock the hubs and try this again.

Uh. Think this is bad then - see here.

I don’t have a jack or jack-stands tall enough to lift it off the ground, so that would have to wait until I can get it to someone with one or a friend of mine with a lift. When we changed out the front and rear axle oil, everything appeared intact. That was around the time we were trying to confirm if the rear axle was open or not, which it was.

[tgreese]

Yeah, not what you'd expect. With both tires on the ground, the driveshaft should be prevented from rotating when the hubs are locked in. The rotational motion has to go somewhere. Something is broken, either an axle shaft or one of the hubs.

You understand how the front axle differential should behave? The rotation has to go somewhere. If you turn the driveshaft, one or both of the axle shafts has to turn. The locking hubs should connect/disconnect the axle shafts at the very outboard end of the axle shafts, in the hubs.

In your first video, you can see the hub-end u-joint turning on the right side. If you have a helper available, you could leave the hubs locked in and watch the u-joints at the hub end on both sides. You could also block the hub u-joint with a bar or such and see if the other side turns.

Also, not familiar with the Mile Marker hubs, but the Warns I have turn the long distance, counter-clockwise between free and lock, the opposite of what you showed. Dunno, maybe that's right for those hubs.

[Country Jeep]

Yeah, not what you'd expect. With both tires on the ground, the driveshaft should be prevented from rotating when the hubs are locked in. The rotational motion has to go somewhere. Something is broken, either an axle shaft or one of the hubs.

Phooey. Alright then, not the end of the world at least. Will this have any impact on the torque bias test working correctly?

[tgreese]

I added a lot to the above post - suggest you read it again.

[tgreese]

... Will this have any impact on the torque bias test working correctly?

Yep. The test depends on the driveshaft locking the front side of the differential in the Quadratrac using the brakes.

Kinda think you have something broken and a PO did enough to make it run and drive. I don't know how else to reconcile the e-drive light and the free front drive shaft, other than some breakage that's being jury-rigged to run and drive. People sell cars for a reason. You'll need to find what's up with the front axle.

[Country Jeep]

…

Okay, read through everything. I thought the rotation was supposed to go somewhere; when I had my CJ7 20 years ago, I couldn’t recall ever being able to move the front driveshaft freely like that, and it seemed odd that the hubs made no difference. In any case, I’ve come this far with the truck, I definitely don’t mind having to resolve any issues with the axles or transfer case.

I’ve gone back outside one last time to really put the hubs through their paces. Bear with me, this video is eight minutes long, but I was able to get the driver side hub to do something when the passenger side hub was locked with a bar. I was never able to get the passenger side hub to change behavior. There also may be some damage to the passenger hub visible, not sure. Comprehensive video here.

[tgreese]

Broken hubs would be an easy/cheap fix. You said you inspected the gears in the housing, and they look ok. I'd look for a broken axle shaft; not uncommon. (Sorry, mixed up with another post. '79 is a 44 front.)

[tgreese]

Watched your last video - very thorough. Seems clear that the right side hub does not lock. I would not hesitate to take the allen head screws out and pull the hub off. A broken axle shaft on the passenger side inside the hub (the Jeep's hub not the locking hub) would do the same thing, but a broken locking hub seems way more likely.

A Quadratrac Jeep came from the factory with "slugs" that connected the splines of the hub to the splines of the axle shaft.

hubslug.png

I'm sure most of them were thrown away when locking hubs were installed. You might find some used ones anyway.

[Country Jeep]

Watched your last video - very thorough. Seems clear that the right side hub does not lock. I would not hesitate to take the allen head screws out and pull the hub off. A broken axle shaft on the passenger side inside the hub (the Jeep's hub not the locking hub) would do the same thing, but a broken locking hub seems way more likely.

A Quadratrac Jeep came from the factory with "slugs" that connected the splines of the hub to the splines of the axle shaft.


hubslug.png


I'm sure most of them were thrown away when locking hubs were installed. You might find some used ones anyway.

Video of the hubs disassembled, actuating, and the effects on the axle found here (10 mins).

Short version:

The driver side, which seems to be working: The O-ring is intact and holds a tight grip, and the center of the hub is dry while the rest of the hub, inner and outer, is filled with grease. Sprocket actuates in and out, except for on one side, which gets partially hung on the way back to the free position, but otherwise pushes all the way in easily for the locked position. The switching part of the hub operates appropriately, springing the teeth firmly outward when switched away from free to lock. When holding the switching part against the sprocket while set to “lock,” there is good tension being pressed outward, and the axle does indeed lock. Likewise, when freed, there is no tension, and the axle moves freely.

The passenger side, which seems to be broken: The O-ring is intact, but does not hold a firm grip, and the center of the hub is filled with grease, as is the rest of the hub. Sprocket does NOT actuate in or out freely - currently sits recessed inward as if in locked position, and can only be partially moved manually with help of Allen wrenches. The switching part of the hub does push the teeth outward when switched to lock, but the spring, despite being intact, seems to do nothing against the thick grease. Holding the switching part against the sprocket in locked position does nothing; axle spins freely regardless.

Someone with more experience will have to tell me if any of this means something, but the takeaway I have at the moment is such: The reason I have not heard any meaningful actuation on the passenger side is because that sprocket is “stuck” (can technically move, but only with manual manipulation, which the switch does not do) in the lock position, regardless of what the switch is set to. It doesn’t however tell me why, when the switch is properly installed and set to lock, knowing that the sprocket is fully inset, and the teeth on the switch are protruding fully outward, why the axle is not locked… unless an axle shaft broke at some point because they thought they had set the passenger side to free, but the sprocket had not popped out to the free position as it should have, and they drove it like that not knowing? Or could the hub still be what’s busted?