Quadratrac replacement advice needed

Modified FSJ Tech Area
Post Reply

Topic author
cpfeifffer
Posts: 81
Joined: Mon Nov 26, 2018 6:03 am

Quadratrac replacement advice needed

Post by cpfeifffer »

I have been going through this site over the past several months and really appreciate everyone contributing. It has made my project so much easier.
All that said, I finally need to post a question.

My Jeep is a 1978 Cherokee Chief. It currently has the 360, TH400, and Quadratrac. I am doing a 5.3 L33/4L60E swap and intended to keep the Quadratrac. While removing the QT, I discovered that the top driver’s side mounting tab was broken off. That was the straw that broke the camel’s back, so I am investigating other transfer cases.

I have also read a lot about the offset rear differential. Some posts say don’t worry about it – the angle is acceptable. Others say I will have vibration issues. I have heard differing statements depending on if you have a WT or NT. Obviously, I'd prefer to keep the existing axles.

1. What is a good passenger drop TC that is readily available? Where should I look for one? How much is a good price?
2. What do I need to do about the offset rear differential? Swap it with a centered axle? What is a good donor vehicle?
3. Please educate me on a slip yoke eliminator. Is the main goal on this to shorten TC and improve the angle?

Thanks in advance!
1978 Cherokee Chief
5.3L L33, 4L60E, Atlas II 5.0

rocklaurence
Vendor
Posts: 2565
Joined: Sat Mar 30, 2013 6:53 am

Re: Quadratrac replacement advice needed

Post by rocklaurence »

Id look for a donor vehicle that would have the trans', Tcase and rear axle you need and swap it all. You could do this with the olde Passenger side Tcase or even a Driver's side with 727 and NP229. Depends on what donor you purchase.

sonoraed
Vendor
Posts: 673
Joined: Sun Apr 07, 2013 7:38 am
Location: Sonora,Ca
Contact:

Re: Quadratrac replacement advice needed

Post by sonoraed »

I used a Dana 20 because that's what was there before the swap, go to Novak up in Logan Utah and read their tech articles and adapters for sale, also Tom Woods drivelines has several good articles

will e
Posts: 5096
Joined: Sat Aug 18, 2012 8:21 am

Re: Quadratrac replacement advice needed

Post by will e »

Depending on your wheeling plans, and budget, an aftermarket Atlas is an option. You get twin shifts and there is a 4 speed transfer case option. They do either driver or passenger swaps.
81 Waggy 'WILL E' Retired
82 Cherokee WT - SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau XRS Baja & 5 point retractable harness/Hella Aux lights/tuffy console/killer32 sliders/Evil Twin bumpers, rack and roll cage/WARN 8000/TT Fabworks steering brace/dual batts/custom TC skid plate/ARB fridge
User avatar

Cecil14
Posts: 727
Joined: Mon Oct 01, 2012 6:40 am

Re: Quadratrac replacement advice needed

Post by Cecil14 »

An 80s Chevy NP208 or NP241 are probably your easiest solution. The offset rear diff shouldn't make that much difference, and it will help keep things clear of your fuel tank.


aa
1983 J-10 - 4.6L(MPFI)/CS130D/Hydroboost/NV3550/D300/44/44/3.54/Disc-Disc/32s/42 gallon 'burb tank
User avatar

derf
Posts: 1403
Joined: Mon Jun 04, 2012 9:10 am
Location: Littleton, CO
Contact:

Re: Quadratrac replacement advice needed

Post by derf »

Cecil14 wrote:An 80s Chevy NP208 or NP241 are probably your easiest solution. The offset rear diff shouldn't make that much difference, and it will help keep things clear of your fuel tank.


aa
This. All Chevrolet trucks through 1988 (I think) used a passenger drop NP208. Find one from a 1/2 ton truck/K5 Blazer/Suburban and it will bolt right up to your intended 4L60E. The K5 Blazer (and I think the Suburban) kept this configuration through 1991 or 1992. The NP208 changed to the NP241 in that time. Pickup trucks starting in 1989, as well as the full size Tahoe and Suburbans after 91/92 switched over to a driver drop configuration that won't work with your Cherokee easily.

Note that the NP208 from 3/4 and 1 ton trucks will more likely have a 32 spline input shaft that won't work with the 27 spline shaft that the 4L60E transmission has. So be sure to get the right donor.

Keep in mind also that your donor drivetrain will need an electric speed sensor where the speedometer is on the NP208. There are several different approaches to this. If you're going full electronic on your speedometer you can just put in a sending unit, tie it to the computer, and use the computer's speedometer output in the dash. If you want to run the electronics for the drivetrain but keep your mechanical speedometer, you can get a piece that bolts between the speedometer cable and the transfer case. It will provide the electric signal and your stock speedometer can work. Either way, be sure your vehicle's computer knows not only that you are in low range but also what the low range of the transfer case is. It figures out transmission shifting based on the speedometer sensor and needs to be "in the loop".

An aftermarket Atlas transfer case can work too. It's pretty easy but it's not cheap. You can get some pretty good low range out of it, especially if you go with a 4 speed. But the more you build it up the more it costs.

If you have some money to spend and want something different, you can get creative. You can adapt the 4L60E to a Dana/Spicer 18 transfer case. It has the same front and rear offset output as the Quadratrac. When you get the right donor and build it properly, it's fine behind a 5.3. It's also pretty unique which would be cool. But it will require a significant effort to make it work. That means it's not cheap, nor is it easy.

As far as the rear output shaft, Jeep had an offset rear axle even with the center output Dana 20. It seemed to work fine.

But you're putting in a longer transmission and, if it has the slip yoke as many Chevys do, you're dealing with a shorter driveshaft. Adding a slip yoke eliminator with a CV joint to the transfer case will both make the shaft a little longer and go a long ways to reducing potential vibration.

4bz
Posts: 32
Joined: Wed Mar 08, 2017 12:15 pm

Re: Quadratrac replacement advice needed

Post by 4bz »

Just like Cecil14 said "and it will help keep things clear of your fuel tank." If you run a centered rear differential with a centered output transfer case, the driveshaft will strike the coffin style stock fuel tank. The Dana 20 transfer case is a very nice unit - the best part is they are still plentiful and inexpensive. They were factory installed in many cherokees, so you may be able to find a factory driveshaft and fsj shifter for one. (And avoid the cost of a custom rear driveshaft and shifter unit when you do your swap) Dana 20 transfer cases are also notorious for dripping small amounts of oil, so be forewarned.
Post Reply