Locked QT in snow/ice

[9.3x62]

Anybody drive a full time quadra trac with a rear auto locker in snowy/slick conditions? I understand the thing is great in the snow, but wonder if it's performance would be severely hampered by an aussie or detroit out back? I have heard from Land Cruiser guys with the AWD series 80 that snow performance was still good with a rear lunch box, and that it posed no real issues, so I started to wonder...

[sierrablue]

I wouldn't think so. I don't have one but idk how it could hurt--the snow itself handles a lot like sand (depending on the snow), and for ice, you basically get a mechanical ABS because you can't lock up the rears w/o locking up the fronts, or the individual rears w/o locking up the other one.

[9.3x62]

Yeah, to my mind, in a normal 4x4, it's 50/50 to both axles, so if one end busts loose on the slick stuff, there's no differntiation and that end just keeps swinging until it don't. But the QT is a limited slip, so if the rear with the locker busts loose, it sends the power to the front, stopping the slide. Of course, if there were no locker in the first place the slide wouldn't have happened at all.
Does my rambling make any sense???

[OldFarmTruck22]

I have a lunchbox locker in the rear. Works great. Been through 16" of snow with this jeep, it loved it and wanted more.
360, Turbo 400, Quadratrack, High and Low range, 32 x 11.50

[9.3x62]

Good to know! I definitely want my rig to be good in snow and slick hard pack, but want a locker for the trails, but don't want to shell out gonzo bucks for a selectable just yet. I figure a lunchbox behind the QT should be a good compromise?

[OldFarmTruck22]

It's a great unit. Just be prepared for a little clicking when you go around hard turns. It's normal to the way they function.
The dana 44's are great diffs too.

Just wish I had a 4th gear in there! lol

[ghcoe]

From my reading QT and lockers don't mix. That is why you could not get a QT equipped Jeep with a locker from the factory. I would suspect the lockers would put a lot of stress on the clutches in the QT and cause premature failure.

[Anvil-3]

I had a Detroit locker in the rear and open front and thought it was worse than just having open diffs on snowy roads.


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[OldFarmTruck22]

From my reading QT and lockers don't mix. That is why you could not get a QT equipped Jeep with a locker from the factory. I would suspect the lockers would put a lot of stress on the clutches in the QT and cause premature failure.

I don't have to read about it ... I actually drive it. Lunchbox unit. Works great.

[Stuka]

For the QT, they were not available with any traction units from the factory. No limited slip or anything. And that's because it does put more stress on the clutch cones. Sure, you can put it back there, but be aware that the QT may not live as long.

As for snow...

Lockers are terrible in the snow (be it automatic or something like a spool). You lose lateral traction. With an open diff, and a tire spines, the other tire is still holding the vehicle from moving sideways. But with a locker, that is no longer the case.

Detroits can be especially bad in hard pack snow because of the way they can snap lock. This is due to detroits can be between open and locked, and soon as one tire spins a bit, they can suddenly lock. That shock of suddenly locking typically results in both tires losing traction. I had detroits in my Cherokee and J10 and it made them very tricky to drive in the snow because they could snap oversteer.

Ratcheting lunch box lockers typically don't have have the snap lock issue detroits do. But you still lose lateral traction.

Can you drive them in the snow with a rear locker, sure. But know that you need to pay special attention to knowing its there. If you have inexperienced people also your Jeep, I would suggest not having it there.

Also, the loss of lateral traction becomes a larger issue if you live in a mountainous area. In flat areas like the mid west it won't be as much of an issue. But in places like the west coast, or Colorado where you are on a lot of steep roads, it becomes a much larger issue.

Yeah, to my mind, in a normal 4x4, it's 50/50 to both axles, so if one end busts loose on the slick stuff, there's no differntiation and that end just keeps swinging until it don't. But the QT is a limited slip, so if the rear with the locker busts loose, it sends the power to the front, stopping the slide. Of course, if there were no locker in the first place the slide wouldn't have happened at all.
Does my rambling make any sense???

That's not how a QT works. Viscous coupler systems can work this way. But the QT is not able to distribute power that way. If the rear loses traction completely, you will still get some power to the front, but not a full 50%.

For a part time 4wd (Or QT with e-drive on), if the rear loses traction, you still have full power to the front axle because both front and rear axles have to spin at the same speed.

[OldFarmTruck22]

Hey ... guess what? Under list of Factory options in the 1978/79 Chief brochure
Optional Trac-Loc rear differential with Turbo 400 and Quadratrack system.

I'll bet you could even choose what axle ratio you wanted if you sat with a good salesman and were having one built for you.

So yeah, it was available from the factory with a locking rear diff and Borg Warner 1339. Optional

Free Wheeling Front Hubs - Optional too

Damn, Learning something new every day.

[sierrablue]

I would think for snow specifically (especially if you want to drive it normally and have no clicking on turns), a limited slip would be the way to go. Still allows some slip, which can be helpful on the hard packed (also I would like to point out that if you want any chance of getting moving on the hard packed, you need some traction control for the diffs), yet still not letting you get stuck on the trails and stuff.

For deep snow I wouldn't worry too much about the open diffs. Unless it's packed, and/or you're ok with taking on some pretty serious body damage from the snow, you're not gonna get it stuck unless your tires are bald. I've put the stock height, 225/75r15 (and the absolute worst rated modern all season tires for snow), open diff '71 through drifts that are well over 2' deep, pushing 3'. Only time I want lockers/limited slip, really, is on the ice/piles of hard packed snow. I realize that's with the D20, but still.

[OldFarmTruck22]

I would think for snow specifically (especially if you want to drive it normally and have no clicking on turns), a limited slip would be the way to go. Still allows some slip, which can be helpful on the hard packed (also I would like to point out that if you want any chance of getting moving on the hard packed, you need some traction control for the diffs), yet still not letting you get stuck on the trails and stuff.

For deep snow I wouldn't worry too much about the open diffs. Unless it's packed, and/or you're ok with taking on some pretty serious body damage from the snow, you're not gonna get it stuck unless your tires are bald. I've put the stock height, 225/75r15 (and the absolute worst rated modern all season tires for snow), open diff '71 through drifts that are well over 2' deep, pushing 3'. Only time I want lockers/limited slip, really, is on the ice/piles of hard packed snow. I realize that's with the D20, but still.

That's all great sierrablue, my research shows that the engineers at AMC, DANA, BorgWarner seemed to thing it's Ok to have a Trac-Loc in the rear, coupled with a 1339 and a Turbo 400. How or where somebody drives with all that gear is really up to the individual owner. We can't make blanket statements that say "this is no good in snow". I can drive a motorcycle in snow and have many times. It's really up to the driver skills to keep their vehicle on the road or not.

[Stuka]

I would think for snow specifically (especially if you want to drive it normally and have no clicking on turns), a limited slip would be the way to go. Still allows some slip, which can be helpful on the hard packed (also I would like to point out that if you want any chance of getting moving on the hard packed, you need some traction control for the diffs), yet still not letting you get stuck on the trails and stuff.

For deep snow I wouldn't worry too much about the open diffs. Unless it's packed, and/or you're ok with taking on some pretty serious body damage from the snow, you're not gonna get it stuck unless your tires are bald. I've put the stock height, 225/75r15 (and the absolute worst rated modern all season tires for snow), open diff '71 through drifts that are well over 2' deep, pushing 3'. Only time I want lockers/limited slip, really, is on the ice/piles of hard packed snow. I realize that's with the D20, but still.

That's all great sierrablue, my research shows that the engineers at AMC, DANA, BorgWarner seemed to thing it's Ok to have a Trac-Loc in the rear, coupled with a 1339 and a Turbo 400

This is false. You were only able to buy an 73-79 FSJ with a Trac-Lok limited slip when a manual transmission was equipped.

[OldFarmTruck22]

1979-Jeep.pdf

[sierrablue]

I would think for snow specifically (especially if you want to drive it normally and have no clicking on turns), a limited slip would be the way to go. Still allows some slip, which can be helpful on the hard packed (also I would like to point out that if you want any chance of getting moving on the hard packed, you need some traction control for the diffs), yet still not letting you get stuck on the trails and stuff.

For deep snow I wouldn't worry too much about the open diffs. Unless it's packed, and/or you're ok with taking on some pretty serious body damage from the snow, you're not gonna get it stuck unless your tires are bald. I've put the stock height, 225/75r15 (and the absolute worst rated modern all season tires for snow), open diff '71 through drifts that are well over 2' deep, pushing 3'. Only time I want lockers/limited slip, really, is on the ice/piles of hard packed snow. I realize that's with the D20, but still.

That's all great sierrablue, my research shows that the engineers at AMC, DANA, BorgWarner seemed to thing it's Ok to have a Trac-Loc in the rear, coupled with a 1339 and a Turbo 400. How or where somebody drives with all that gear is really up to the individual owner. We can't make blanket statements that say "this is no good in snow". I can drive a motorcycle in snow and have many times. It's really up to the driver skills to keep their vehicle on the road or not.

As my parents like to tell me: "Just because you CAN doesn't mean you SHOULD."

Also these are the same engineers who were still running drum brakes in the back, and in order to make their engines run "cleaner" they basically detuned them so they'd make less power and thus use less gas. I'm not saying they were stupid by any means but I am saying that they didn't always know what the best way to do things was, and if they knew, they didn't bother with it. And the Qtrac isn't exactly known for being long lasting; in their mind, if that's going to give out first, what difference does it make whether or not you put the locker/limited slip in the back?

And you can make blanket statements saying "This is no good in the snow" (which, rereading my post, I did not actually do). Sometimes it might depend on the kind of snow, but if for instance you said that 2 wheel drive is no good in the snow, I don't know anybody that would argue with you.

Note: I'm not trying to be aggressive or mean here, so please do not take this as an attack. More of a debate. And NOT in the 2020 presidential election sense of the term.

[OldFarmTruck22]

I would think for snow specifically (especially if you want to drive it normally and have no clicking on turns), a limited slip would be the way to go. Still allows some slip, which can be helpful on the hard packed (also I would like to point out that if you want any chance of getting moving on the hard packed, you need some traction control for the diffs), yet still not letting you get stuck on the trails and stuff.

For deep snow I wouldn't worry too much about the open diffs. Unless it's packed, and/or you're ok with taking on some pretty serious body damage from the snow, you're not gonna get it stuck unless your tires are bald. I've put the stock height, 225/75r15 (and the absolute worst rated modern all season tires for snow), open diff '71 through drifts that are well over 2' deep, pushing 3'. Only time I want lockers/limited slip, really, is on the ice/piles of hard packed snow. I realize that's with the D20, but still.

That's all great sierrablue, my research shows that the engineers at AMC, DANA, BorgWarner seemed to thing it's Ok to have a Trac-Loc in the rear, coupled with a 1339 and a Turbo 400. How or where somebody drives with all that gear is really up to the individual owner. We can't make blanket statements that say "this is no good in snow". I can drive a motorcycle in snow and have many times. It's really up to the driver skills to keep their vehicle on the road or not.

As my parents like to tell me: "Just because you CAN doesn't mean you SHOULD."

Also these are the same engineers who were still running drum brakes in the back, and in order to make their engines run "cleaner" they basically detuned them so they'd make less power and thus use less gas. I'm not saying they were stupid by any means but I am saying that they didn't always know what the best way to do things was, and if they knew, they didn't bother with it. And the Qtrac isn't exactly known for being long lasting; in their mind, if that's going to give out first, what difference does it make whether or not you put the locker/limited slip in the back?

And you can make blanket statements saying "This is no good in the snow" (which, rereading my post, I did not actually do). Sometimes it might depend on the kind of snow, but if for instance you said that 2 wheel drive is no good in the snow, I don't know anybody that would argue with you.

Note: I'm not trying to be aggressive or mean here, so please do not take this as an attack. More of a debate. And NOT in the 2020 presidential election sense of the term.

You think I should remove my transfer case or my Trac-loc? It's been working fine for 44 years but if it's a 'mistake' from the factory, I had better sell it.
All the snow that I drive through and the 60, 70, 75 mph on the highway with this combo, it probably just a timebomb waiting to explode. It's a real shame cause it all works so good together. But, if you guys say it's not possible, I had better take it apart.

[sierrablue]

Most Qtracs only last 50k or so per rebuild, 75k if you're lucky and easy on it. Nobody said it was going to explode, and maybe you got one wit the absolute best of the best internals from the assembly line, so it lasts longer than the others

[9.3x62]

Wow, I didn't look at this thread for a couple weeks. Didn't know you guys were having such a rigorous discussion. Thanks for all the input!
I guess I'll have to try things out for myself. Luckily, lunchbox lockers are cheap, so if it doesn't worktoo well, no biggie.
If I could just get this thing on the road...

[tgreese]

My experience at the dealership in the mid-70s confirms what Stuka wrote above. All the QT equipped vehicles were sold with open differentials, front and rear. Only the Dana TracLock was available from the factory, and was limited to vehicles without the QT.

Realize that the Borg-Warner QT was revolutionary in its day. I think there have been better passive systems built since then, sp. Quadradrive used in the Grand Cherokee ca 2004, which has "lockers" front and rear. Modern vehicles are no longer passive, instead relying on the computer to distribute power when the wheels slip (like my KL, and I presume the modern Wranglers), or selectable lockers.

The original QT was very very well behaved under all conditions; people really liked it for driving in the snow specifically. Lots of owners bought it because they could better get to their chosen ski areas more reliably. You would not know that you were driving a 4WD car, regardless of the weather ... except that you could keep going when other cars were forced to put on chains. Performance on snowy highways sold Jeeps. I speculate the factory engineers tested cars with the TracLock, and decided it was better to appeal to the bigger market that wants an all-weather SUV without surprising performance in icy conditions. Or maybe adding posi really does damage the cones/plates ... that's not obvious to me.

My copy of the '79 TSM - footnote (3) says the TracLock is NA (not available) with the Quadratrac.