Quadratrac ?

Quadratrac ?

Rusty Shank

Chino California
1978 cj7 golden eagle
304 with a automatic trans, Quadratrac w/Hi-Lo BW 1339 transfer case
3.5 lift. Rear locker 32in tires
Power steering. Front disk breaks drum in the rear.
3 core radiator
If my jeep is full time four wheel drive what does the little knob in the glove box do.

Actually it is a all wheel drive until you activate the switch which locks the center differential making it a true 4x4
a bit of 4x4 knowledge here
2 wheel drive, is a system where only one set of wheels, either front or rear, gets power, it has a diff there that splits the power so you can turn smoothly
full time 4x4, or all wheel drive has power to 2 sets of wheels with a diff in each axle. it also has a center diff in the tcase, that way power can be delivered to all wheels but it will suffer no driveline bind as only the wheel with the least amount of resetence will be driven.
4x4 has either no center diff, or a locked center diff so each axle has a wheel with the least resistance being powered. You can get driveline bind and break stuff on low shear surfaces such as a road with this so in order to make FULL TIME 4x4 they include the center diff.
Full time 4x4 is best as a road system, part time 4x4 is best off road, a full time 4x4 with a center locker does as well as a part time 4x4 when it is in 4x4 offroad. Most all wheel drives do not have a low range, most part time 4x4s do, so a part time 4x4 is desirable as an offroad vehicle as it can go places the full time will not.
Another thought, a diff, splits the torque between each wheel 50/50 always, however the wheel with the last resistence is the one that tells how much torque is required, if one tire is on a road requiring 50 pounds of torque to turn, and 1 is in the mud requiring 10 pounds, then only 20 pounds will be developed and the mud tire will spin and the pavement tire will stay still, to overcome this we have Limited slip diffs, and diffs with lockers, the diff with a locker makes sure both tires turn at the same time, so the torque will have to be 100 pounds and it will walk out of the above situation with ease, the diff with a Limited slip will transfer either through a clutch pack or a gear pack the resistance from the stuck wheel to the turning wheel until 100 pounds of resistance is developed and it walks out. This could take a second or two and is kinda like turbo lag, not only that but depending on how well cared for the diff is, it may not do it at all.
Hope this helps about the Quadratrac question
Thanks for the info Baja you going to make it up to Big Bear this weekend for the jeep Jamboree. Had plans to check it out but i found out i have to work Saturday so its out of the picture for me.
Thanks for the info Baja you going to make it up to Big Bear this weekend for the jeep Jamboree. Had plans to check it out but i found out i have to work Saturday so its out of the picture for me.
I am currently in recovery mode from a surgery, want to get out around the first of June however, We can hook up then.
Oh, by the way, does the quadratrac you have in that jeep have a low range? They came both ways, with or without
Yes it did come with low range. And o would like to put the part time in it.
Yes it did come with low range. And o would like to put the part time in it.
do you mean you would like to transfer the entire system over to a Part time system, or learn to use the entire system?
Are you in love with that particular Jeep?
To tell you the truth, Quadratrac, as much as it was a great innovation in 4x4 technology, is not a real good system for the trails, kinda a weak link.
It is not bad under a lot of wheeling situations, but when you start to push it, well.............. If you want to take advantage of a lot of the SoCal terrain then you will want to either get another Jeep, or mod a new transfer case into it. There are a few things to consider when doing such if that are specific to the Quadratrac if you are considering that.
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The plan for the quad is to take it out and use it and when i start to out grow it start looking at maybe switching the trans and diff out with with a better T-case. Is their a better way of doing this?
well this is a noble idea, but that is why I asked how much you really like that jeep
You see there is a third thing that may have to be changed, the rear end.
If you look under the rear of the jeep you will notice that the rear pumpkin is offset to the passenger side. Only the quadratrac and the pre 72 jeeps used this type of axle as it is related to the transfer case they used.
The D18 tcase from a early Cj is not a bad tcase. but it is Limited to how low it can be set up for. So be prepared to go shopping for a new axle or adapt a D18 into the system. There are many reasons to want to get a new rear axle for that jeep with the t case you want as going with a D300 or a Dana 20 would be a nice upgrade for the unit easily adapted. Remember now most upgrades are going require new drive shafts. Updating to a newer tcase such as a NP231 or such means having to change out both axles to get both the pumpkins correct.
The other decision is to look for a CJ7 with with a non quadratrac system. However I hate to see guys part with a CJ, there is just something about them that tugs at your heart, and they become part of the family.

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