Quadratac fulltime 4X4 on old jeeps?

Anyone ever heard of qudratac fulltime 4 wheel drive on older jeeps? I was told it was in a few late 60's and 70's models... found a cj7 (i know, i know) that has it. I know the new models have it. I am guessing with full time 4X4 you end of with more wear and tear on components. I need some help here because I may buy this jeep; good condition, great price, etc. Any suggestions? THANKS!

 

Skip it I had quadratrac on a CJ7. Then I put a doug nash part time conversion in it, then I got smarter and just put a dana 20 with a centered dana 44 rear in it...

The biggest problem I saw with it was chain stretch. The chain could give up the ghost (it is Halloween) at the worst moment. The chain drove both the front and rear wheels so when it started banging on the case your either stopped right there and fixed it or ran the risk of the chain banging a hole in the case.

My quadratrac jeep was also horrific on gas. It also required special lubricants in the transfer case. If not used it lead to premature wear on the transfer case differential.

If I were to buy a jeep with one in it I would be prepared to swap it out at some point. Some didn't even have a low range unit on them. There will be a high low shifter on the floor if it has it.

The vacuum lines could also be problematic...

All that said, my neighbor and I share a plow jeep (wagoneer) with quadratrac in it and it has held up well. Also, it does have a turbo 400 auto with an AMC bell pattern in it which is a decent trans.

The new quadratrac is different than the older ones.

 

Thanks for the input. I appreciate the honestly, versus the bull from the seller. It still amazes me to this day what people will say to sell you something. THANKS! R)

 

I would not consider it a selling point, but if the price was right I wouldn't dismiss it either.

 

I had Q-trac in a 78 fullsize Cherokee and loved it. It is true that it requires special lubrication, and parts for it are increasingly difficult to find, but when everything is working properly it makes a great setup (in a fullsize, I have no knowledge of how well they work in a CJ).

Oh, and it's not 60's models, the Borg-Warner 1339 Quadratrac transfer case first entered life on Jeeps in 1973 on J-trucks and Wagoneers, 74 for Cherokees and in 76 was offered on the first CJ-7's. It was never offered in a CJ-5 (which never had a factory automatic tranny of any kind, the only choice with a Q-trac). It was discontinued for the 1980 model year when Jeep made a major change in transmission and transfer case suppliers and went from the GM TH-400 to the Chrysler TF-727. Jeep kept the Quadratrac name and still uses it, but all subsequent "quadratrac" transfer cases are much different from the original BW1339.

 

Quadratracs are fine if well maintained (no offense to those who got a lemon). My buddy's went over 200K miles and was fine at trade-in time. I'd rather have the Quadratrac than the Dana 228 that grenaded on me at 90K miles.

Don't worry too much about the extra wear and tear from full-time 4wd. I never took my Grand Wagoneer out of full-time, sold it at 189K miles, and the next owner retired it at well over 200K miles because of body/accessories issues, not the drivetrain.

 

Oh, and as far as gas mileage goes, my Cherokee with a 360 4bbl, TH-400 and Quadratrac and 3.08 gears would get 15-17 mpg highway consistently. Word is that those who convert to part-time see at most a 1 mpg increase.

Driving on snow-slick roads it was incredible.

 

It is true that the chain stretches on the B-W Quadratrac. However, chain life is at least 50,000 miles, and typically twice that. You must check the chain slack occasionally, and use the Morse chain, the quality US-made brand, for replacement. Imported chains are entirely unsatisfactory.

The proper fluid is also a requirement. It's some kind of specific oil with a friction modifier, that makes the clutches work properly. Still available across the dealer parts counter, or from Crown automotive.

Here's an article on Flint Boardman's site that will tell you more about the Quadratrac: http://jubileejeeps.org/quadratrac/index.htm

 

I had a 76 CJ with quadratrac when it was only about a year old, one of the most go anywhere with Surburbanites XG's hard charging with the V8 that I have ever owned I especially liked the lock in the glove box. Had it in a J10 pretty much the same after a new chain at 80K both had low range...

 

it was the best system and way ahead of it's time...
the front d/shaft CV joint and the chain were the only high maintenance items on the original Q-Trac.
it was great for driving mountain roads

 

I'm another believer that they're junk if you intend to do a lot of offroading. They were nice to get up a snowy road to a cabin or for a snow plow on a flat parking lot, but I saw way too many failures in rigs that spent more time on rougher trails or in deep snow. On top of that, they're extremely heavy and I believe they all came behind TH400 transmissions. I think there are much better combo's available. Personally, I wouldn't own a Quadratrac equipped vehicle again.

 

Just a comment - if I were presented with a cool CJ-7 or FSJ from that era with a QT, I would not let that prevent me from owning the vehicle. I believe that, if they are maintained properly, they can be durable and reliable. They are quiet, and the full-time feature works really well.

That said, the BW1339 has a few very specific issues that owners and potential buyers should be aware of. The newest of these was last produced in 1979, 28 years ago, and time and abuse has taken its toll on many of these. Good hard parts for the BW1339 are getting harder and harder to come by, so if you own one, you probably want to find and set aside a couple of good parts units for a rainy day. The main problems I see are the splines on the side gears, and the cone washers. If the PO uses anything but the special oil, the cone washers will wear out. For some reason, the splines in the side gears will strip out - the cure for this is another good parts unit, or a part-time conversion.

So, while I agree with Jim that these units work great and were revolutionary in their day, they aren't without their problems now. I'd still own one if part of the right vehicle, however. :driving:

 

that's true Tim
if I knew the vehicle history, or I knew it was an original owner vehicle that hadn't been messed with, I too would be tempted.
But too much time has gone by now, and too many shade tree DIY mechancis out there working on these for my blood...

 

I think that's the key, where you're from and terrain. Works great in mud and low traction situations. Not many rocks and mountains around here, but we have mud and slick hills....

 

Once locked the quadratrac functions the same as any other transfer case. Unlocked without lockers if one wheel lost traction that wheel and only that wheel will spin.
I think someone looking for an older jeep unless it was an exceptionally good deal I would recommend to avoid that transfer case. I think the bad points of this case far out weigh the good points. It isn't a good case to consider for conversion to part time either.

However a Dana 20 and a centered flanged 44 is a very easy swap. It can even be done with factory parts. Many will say the factory turbo 400 to dana 20 is a weak adapter but that held up well for me behind a powerful 401. The worst part of that swap is taking the automatic apart to swap tail shafts. I think I even reused the stock drive shaft.

Bone stock and fairly new my 78 quadratrac CJ7 was a serious gas hog. But I think gas mileage is the luck of the draw. My green jeep used to do 20MPG on the highway. My black jeep is a pig. Hard to convince me that a full time 4X4 is going to be as good on gas as a part time.

The target market for the quadratrac was the individual that wanted the advantage of four wheel drive all the time. It was a great transfer case for someone that had to travel a muddy drive way or a snow packed road. Was also good for someone that didn't want to have to worry about when to shift into 4 wheel drive. In theory the only time you would lock the case was after you were stuck.

 

I disagree. The NP203 used in Chebbies and Dodges would do that but not the BW1339. Furthermore it's simple enough to test this. Jack up one wheel of a Q-trac equipped Jeep and attempt to drive away. If it was as you said you would sit on the jack and that wheel would spin. However, having done this very test with my Cherokee I guarantee you the Jeep will drive off the jack with no problem.

Here's one source of evidence to support this:
"What made the original unit different from other full-time xcases at the time was the differential that drives the output yokes. This chain driven diff. contained a mechanism similar in theory to a "posi" rear differential in an axle. However, instead of the clutch packs with which you may be familiar, the QT diff. uses a brake cone arrangement in each end of the diff. which is preloaded by Belleville springs and thrust washers.

This enabled the QT to drive both axles with a constantly varying division of torque between the two axles. Other full-time units of the era such as the NP203 had what was essentially an open diff. in the center of the unit. In certain traction conditions it is possible to immobilize a truck with a full time xcase which is driving open axle differentials, but not the BWQT.

The QT's posi-style diff allowed it to "sense" which end of the truck had better traction, and would bias the torque output of the QT to the wheel which was not slipping. (Note: The QT didn't actually sense anything, but rather would accomplish the torque biasing through a phenomenon of physics.) "

From: http://home.off-road.com/~jseries/BWQT.html

 

You are correct sir. It's these very cone clutches that are no longer made and hard to find good ones. Last one I rebuilt it took 5 to make one good unit because of this. This unit works very much like the cone clutch limited slips in differentials. The Q-trac unit isn't bad and under mild use holds up quite well providing they are maintained properly and the correct fluid is used. Under very heavy use the chains have a tendency to stretch. IMHO the worst part about them is parts availability and the cost of the special fluid required. Nickmil

 

keep in mind Roger Mears and several others used Q-Tracs in their class 8 Jeep trucks running the SCORE events back in the 70s and 80s...course, they didn't have to worry about maintainence, just bolt in a new one before every race.
I think that says something about the tuffness and durability of the Q-Trac units.

 

I agree the quadratrac has about the same clutch setup as many posi rear ends. Even with a posi rear end, unlike a true locker, if you lift one tire that tire is the one that spins. The posi clutches are not tight enough to provide much traction when a wheel is lifted. Sure if your on flat ground the clutches may be tight enough to drive it off a jack stand. (I don't recommend you try this at home)

If the cones in your quadratrac are too tight then there is something wrong with it. It is sticking and that will lead to drive train bind. They must give to allow for speed differential between the front and rear end when cornering. A sticking quadratrac will load the front axles when turning into a parking spot leading to premature failure. That was the whole purpose of the Extreme Pressure Concentrate (EPC) and special fluid that they required. It was to insure the cones or clutches or brakes or whatever you want to call them didn't stick. As I recall, (been a lot of years ago) testing a quadratrac required driving in a tight circle in a parking lot. The transfer case was to release smoothly with no binding.

I will agree to disagree. I will also agree that the quadratrac has been successfully raced. Any of the guys around the Rapid City area could wander over to Off Road West and chat with one of the designers of the system. He also raced it successfully in a commando behind a 401. I will also agree it was a good case for someone that wanted or had a use for a full time 4X4. I won't agree that it is a good transfer case for someone looking for a CJ to take off road, cruise topless around town or drive down a paved highway. Off road I want a positive locking manually shifted transfer case. Driving on city streets I want a part time transfer case and unlocking hubs.

I think there are enough CJs around with a better part time transfer case that I could shop around and find something better than a full time 4X4 CJ7. If I found an exceptional deal on a CJ with quadratrac in it I would plan on swapping the quadratrac out of it and would consider that cost when determining purchase price. I wouldn't at all consider a part time conversion to a quadratrac. For the cost of conversion you would be very close to the cost of swapping to a dana 20. Unless you had to pay someone to swap the automatics tailshaft. I have no desire to drive a full time 4X4 CJ. If I want four wheel drive I would prefer to reach over and push a shifter. I don't even mind getting out and having to turn a locking hub. I certainly don't want to depend on a vacuum operated shifter off road. Especially in mud. I guess that is just my personal preference.

Here is an excerpt from JPs praise of the quadratrac taken from here http://www.jpmagazine.com/techarticles/23658_original_jeep_quadra_trac/index.html ;

"Only four areas of the Quadra-Trac case usually cause problems: the low-range reduction unit mainshaft and sun gear, the vacuum-operated shifting mechanism, the limited-slip differential, and the normal wear of the drivechain."

Geez, only 4 problem areas. I would stick with the dana 20 or dana 300 also offered in the CJ7. But to each their own.