FSJ Noob - QT questions

[J-Roc]

Hey, this is my first post and I hope yall don't flame as bad as pirate . Wanted a FS Chev but a FS Jeep with Chev parts came along my way . Anywho I have done some research on the QT tcase, I sort of understand how it functions, I read the tech articles posted on the main page and they helped a lot. Researched on here and found out about part time 4wd kits that are availible (some with over drive as well which is a bonus). However my question is fairly simple and noob and I didn't find it in my search...

The truck is a J10 it will mostly be street driven with some mild wheeling (hard pack, gravel pits, maybe mud). I am wondering if I can just convert the front hubs to manual hubs. That way I can run a half *** 2wd on the street. The front output would still spin obviously but the wheel(s) will not be engaged in the front. Is this possible, or would I be better to convert to a part time kit? I'll keep searching but so far nothing has come up.

The reason I want to do this is because I want to lock the rear diff in the future...and I don't want the front end to bind on the street

[J4GRAND]

You can install front hubs on the J10 but would have to be in Emergency Drive (E-drive) with the hubs unlocked. If you forgot to lock the hubs and took it out of e-drive, you would burn up the clutch cones in the case and go nowhere. My suggestion if you are wanting to lock up the rear is to go to a part-time kit where you will have a true 2wd-4wd and not run the risk of burning up the case.

[will e]

I think you have to get a part time kit.

You can lock the rear end even if you have QT, it won't bind. You just don't want a locker on the front if you are running full time four wheel drive.

Welcome to the board.

[J-Roc]

hmm, this is a head banger for sure
At the moment Warn's website isn't working for me so there hub conversion kit isn't come up. The cheapest PT kit I have found so far is $500 USD. Do we have any local vendors on the board?

Regarding the truck being in E-Drive is that so the QT is not constantly sending power to the front wheels only and going no where because the hubs are free wheeling? I'll look into the PT kits more... still not exactly sure how the engagement works on them...

[J4GRAND]

Regarding the truck being in E-Drive is that so the QT is not constantly sending power to the front wheels only and going no where because the hubs are free wheeling? I'll look into the PT kits more... still not exactly sure how the engagement works on them...

The QT WILL be sending power to the front driveshaft in e-drive but like you said earlier, with the locking hubs, the wheels won't be engaged. In normal mode, the QT sends more torque to the axle with the most grip. In e-drive, the front and rear outputs are locked together sending an equal amount of torque front and rear. With a part-time kit, you are replacing the limited-slip unit (differential made up of clutch cones) with gears to get a true 2wd-4wd selectable transfer case. Instead of a shifter to engage 2-4wd, the part-time kit uses the vacuum shifter of the e-drive to select 2 or 4wd.

[Frank in Norway]

The QT works like a limited slip. When it's in normal mode, it sends power both to the front and the rear axle. But insede the case there's clutches that allow one output shaft to rotate at a different speed than the other.
This meens that you can drive with 4 wheel drive at any surface. Very good on winter roads.

When you engage emergency drive, you lock the front and the rear output together. This is for use in terrain, you can't use it on hard surfaces without putting much stress on the case.

So, if your clutches are good I would recommend that you keep the case like it's designed from Jeep. There's nothing to gain on the PT kit as far as mpg and you won't find a new kit under $500.

[J-Roc]

So does that mean I lose the ability to lock the Tcase 50/50 with the E-drive switch when a part time kit is installed? If so that is a hell of a sacrifice for 2wd

Edit: Frank you posted while I was typing a reply to J4Grand. Thanks for the clarification on the case, I wasn't hoping to gain any MPG, that will only happen with a light foot, a brick will always be shaped like a brick . So you really think I should just leave the case alone... I was just thinking 2wd would be better if I ran a locker or if I wanted to have some fun in the snow...donuts etc. Maybe a little less wear and tear on the drive train as well...

[J4GRAND]

So does that mean I lose the ability to lock the Tcase 50/50 with the E-drive switch when a part time kit is installed?

No, that's all you will have with a part-time kit is a 50/50 torque bias between the axles. That is the beauty of the full-time QT, the ability to act like a limited-slip and send power to the axle that needs it most or the ability to equally split the torque with e-drive.

[fulsizjeep]

Welcome to the IFSJA forum J-Roc. I am not sure why you are after a 2 wheel drive mode. Maybe that will help us respond to your query. The Mile Marker kit was designed for 2 basic reasons. One, people were destroying QT differentials from improper maintenance, improper fluid and using Edrive mode on hard surfaces (which it was not designed for). Two, a true 2 wheel drive mode supposedly gives you better gas mileage. Then there is the 16% OD discussion which I am not going there in this response. One is true. QTs were failing. The kit gives the owners another option where you can run true part time case with ATF in it instead of the liquid gold the dealers sell. Two, these things are as aerodynamic as a brick. Running 2wd or 4wd hardly makes a difference in the amount gas you use. So, it is your truck. Do with it what you think best. In my opinion there is hardly any advantage to changing the QT if everything inside is working as originally designed. That being said and the fact that all QTs are around 30 years old and have been treated with a variety of understanding, maybe it is not working as designed.

Edit: To your question about the manual hubs on front axel... There is nothing wrong with doing that to get 2wd from your truck. Just remember to switch to Edrive when the hubs are unlocked as previously mentioned.

There is good feedback here and many people who have personal experience with Quadratrac transfer cases have something to share.

Originally Posted by J4GRAND

In normal mode, the QT sends more torque to the axle with the most grip.

Not to start a debate, but I don't agree with the quote above... Depending on the condition of the cone washers and brake cones, the axel with least grip or traction will get more power everytime unless the differential is bound up and locked. The differential should have around 85-140 lbs torque bias to be considered in normal operating parameters. The less torque bias, the more likely the axel with least grip will have the power from the skipping action in the QT differential. The more torque bias, the more likely both axels will get similar power until the differential starts to slip. The QT is not so sophisticated that is understands, knows and has technical design to send power to the axel with most grip. You can fake the driveline out by feathering the brakes or even using the Ebrake to give you some traction control to the axel that does have better grip as long as the differential is in good working order. Once you get to this point, using the Edrive is probably a good idea and will send equal power to both axels if the QT is working properly. Then it will be up to the axel differentials to distribute power from there. Notice I keep referencing "if it is working properly".

[J4GRAND]

I always thought that too but found out differently when I bought a factory QT pamphlet from 73. Here is a link to some other factory literature:
http://www.arcticboy.com/Pages/arcticboysjeep7.html
Scroll down about 2/3s of the way. It would seem to me that the wheels with more grip get more torque and that's how it's explained in the pamphlet.

[Lindel]

Sorry Patrick, all I see are little red "x" where the pictures go.

[fulsizjeep]

I understand Patrick and also believed the propaganda in the sales literature until I actually saw the inside of a QT differential almost 6 years ago. It is a limited slip differential very much like that used in axels. Mechanically speaking, when the differential is working properly and begins to slip, the shaft with least resistance (or grip) will get more power applied.

Edit: I don't mean to say that all the power goes to the shaft with least resistance. It is true that until the differential has significant slip, both shafts will be getting power applied. That is how they can advertise what they did. One axel can be in mud or ice and still have power to the axel that is on more solid surface.

[J4GRAND]

I fixed the link in my previous post; I guess they wouldn't allow me to post pics from the site.

[JeepinPete]

Flint, I have to disagree with you. Start with an open axle. Once the traction limit is reach at either wheel, that is the limit of power than will be delivered to both wheels. Any more power applied by the engine will simply increase the speed of the tire with less traction. Now add a limited slip into the equation. Assume that the limited slip produces a ~100ft lb torque difference. This adds that 100ft lbs of torque to the tire with more traction.

Now lets go back to the QT. A differential is a differential. It does indeed work the same as a limited slip in an axle. So when one of the tires reaches the limit of traction, an additional 100ft lb of torque is available to the other (higher traction) axle. Of course this assumes that the QT is in factory condition. If the cones are shot, then it is an open differential.

I am an fan of the cone clutch limited slip design. But that being said, IMO BW got it wrong in the basic design. That a look at Auburn Gears website. They produce cone clutch limited slips. The major difference between their units and the differential in the QT is the QT has a fixed bias. If it takes 100 ft lb to turn the input, then the bias is set at 100 ft lb. The auburn design has a variable bias. It uses the separation forces of the spider gears to increase the bias. So apply the brakes a bit to load up the spinning wheel, and you get a disproportionate about of torque increase at the wheel with more traction. It would have been very easy to design the QT this way...

[fulsizjeep]

Pete - Your explanation of the limited slip differential is certainly easier to see than my babble. I think we are saying the same thing basically. Maybe Patrick was also saying the same basic thing too. You get one spinning faster than the other, the other one has a fixed amount of bias powering it as well. You end up getting power to the traction axle... No more debate from me. The Auburne variable bias design is pretty interesting and would have been a killer setup in the QT. Thanks!

Krista's 76 Wag has a LSD in each axle along with the QT. It is a good comination of LSDs... 3 of them.

[J4GRAND]

I found the pamphlet from Jeep I was looking for. It was issued by Jeep but is a reprint of a Dec 72 PV4 magazine article on full time 4wd systems. It describes the New Process as well as the QT system and gives the best explanation (I believe):

"So what happens with the Quadra-Trac in action? A loss of traction at one wheel would bring the unloading type differential (which is described earlier in the article) into action and power will continue to be delivered to both front and rear in proportion that each will accept it without breaking traction. Where the traction is, that's where the power will go."

[crazydog]

Originally Posted by JeepinPete

Flint, I have to disagree with you. Start with an open axle. Once the traction limit is reach at either wheel, that is the limit of power than will be delivered to both wheels. Any more power applied by the engine will simply increase the speed of the tire with less traction. Now add a limited slip into the equation. Assume that the limited slip produces a ~100ft lb torque difference. This adds that 100ft lbs of torque to the tire with more traction.

Now lets go back to the QT. A differential is a differential. It does indeed work the same as a limited slip in an axle. So when one of the tires reaches the limit of traction, an additional 100ft lb of torque is available to the other (higher traction) axle. Of course this assumes that the QT is in factory condition. If the cones are shot, then it is an open differential.

I am an fan of the cone clutch limited slip design. But that being said, IMO BW got it wrong in the basic design. That a look at Auburn Gears website. They produce cone clutch limited slips. The major difference between their units and the differential in the QT is the QT has a fixed bias. If it takes 100 ft lb to turn the input, then the bias is set at 100 ft lb. The auburn design has a variable bias. It uses the separation forces of the spider gears to increase the bias. So apply the brakes a bit to load up the spinning wheel, and you get a disproportionate about of torque increase at the wheel with more traction. It would have been very easy to design the QT this way...

If the Auburn design is better, maybe a variation of it could be used to increase the performance of the LSD in the QT. Might be something to look at if progress is made in this thread.

http://www.ifsja.org/forums/vb/showthread.php?t=54604