Quadratrac

[Formula 40PC]

I have a 1976 Quadratrac question if anyone has knowledge.
1. where was the vac hose route to? manifold? carb? and where at exactly? When I purchased the CJ it was not connected.
2. I have the mile marker kit that a PO installed, I know nothing about this kit and there are very few instructions online and even those are very vague. What all do I have to do to engage 4 wheel drive? Disengage? I know there is the turn dial in the glove box and hubs on the front axle but I dont know what to do & when and I definitely do not want to damage anything.
3. The turn dial in the glove box will not turn, I have pulled it out of the glove box while the vac hoses are still attached to get a strong grip and the dial wont move either way. Can I add a little lubrication to this without hurting anything? I would think that since it is just a pressure switch/dial that it should move fairly freely.
Thanks

 

[Peanut Butter]

The Quadratrac transfer case is a very unique piece of equipment. It was the first chain driven transfer case, which led to the development of all other such transfer cases. This led to the AWD craze in vehicles today.

The Quadratrac transfer case contains an internal differential that allows it to transfer power to either axle as is needed. (AWD) The switch found in the glove box is a vacuum switch that locks the differential forcing power to both axles equally. This should only be done off-road. in snow, in mud, etc. to prevent the damage of the internal of the transfer case. TCL-1 fluid is the only fluid to be used in the transfer case.

The Quadratrac is only found in CJ7's from 1976 to 1979. FSL (full size Jeeps) had it during this time frame too. The CJ7 was designed so that an automatic transmission could be an option for the first time in a CJ. From 1980 to 1986 a Chrysler transmission was used with the DANA 300 as the transfer case. '76 to '79 the TH400 was used. The first TH400's were either Chevy or BOP transmissions used with an adapter plate to bolt to the AMC engines. These were found mostly in the FSJ. In my case however, I have this setup in my CJ7. Shortly after the first automatic transmissions came out the TH400 was produced specially for AMC with a different bell housing. For more information see my article: http://www.jeep-cj.com/forums/f2/jeep-th400-technical-information-24384/

At some point Mile Marker developed a part-time kit for the Quadratrac. This removed the internal differential and replaced it with a solid gear. They also included lock out hubs for the front axle. This kit turned the transfer case from an AWD to a full / part-time case. It also allowed the use of ATF instead of the TCL-1 fluid. Moving the vacuum switch to the emergency mode locked the gearing into full time 4 wheel drive. Front hubs also needed to be locked in.

To use the part-time kit, lock front hubs, move the vacuum switch to the emergency position. You are now in 4 wheel drive. Do the reverse to go back to 2 wheel drive.

How do you know if you have the part-time kit installed. PO's can do some crazy things. Some put locking hubs on the front axle without the part-time kit. This only wears and damages the internal differential. So start by jacking the Jeep up and put jack stands on all four corners. Lock the front hubs. Make sure the vacuum switch is in the normal position. Start the Jeep up and give it a little gas. If only the rear wheels turn, you have a part-time kit. If however the front and rear wheels turn, you do not have the part-time kit. Please make sure your vacuum switch is working first.

You should also have a lever under the front of the driver's seat. This is for the low range unit. All the way forward is no low range, half way back is neutral, and all the way back is low range. This can be used in 2 wheel drive. You do not have to be in 4 wheel dive or the emergency switch engaged to use low range. If you do not have this lever, look underneath your Jeep. If you have the low range you should see this big round housing attached to the driver's side of the transfer case.



If you only have a round cover, you do not have low range:



There is only one supplier of USA made parts for the Quadratrac: BJ's Off-Road All other chains and parts are made in China and are made from cheep steal. The will last maybe 15,000 miles. A good USA chain should last 30,000 to 40,000 miles with proper care.

Have you checked the amount of slack in your chain lately? Do What? Put something under the transmission to support it. Remove the skid plate. On the bottom of the transfer case is a pipe plug. Remove this and drain the fluid. Not insert a screwdriver until you push on the chain. Measure the amount of travel. 1/4 to 1/2 inch is ok. Anything 1/2 inch and over requires a new chain. This is one of the biggest failure point in the transfer case. Keeping a good chain in is a must. But only a USA chain. Now replace the fluid you drained out with new fluid. If you have a low range unit, fill it first, then then main body of the transfer case.

Here are some links you can read for more information:

Jeep QuadraTrac

Removal, disassembly, assembly and re-installation of a Quadra-Trac transfer case in an SJ series truck.

Quadra-Trac Transfercase Rebuild - Jp Magazine

QuadraTrac BW1339-BW1305 Parts

Good luck and be sure to ask questions. This was a lot of information to absorb at one time. Rod

 

[Formula 40PC]

PB, I am only judging that I have the part-time kit by visuals. I have the part-time label in the glove box with the switch and I have hubs on the front. At first I saw the hubs and started to investigate and then I saw the part-time label and would think that someone wouldnt just add that for decoration.
I have low gear on the T/C and the handle on the floor tunnel but someone broke the linkage and it was laying in the back of the CJ when I bought it. I have a spare that I was going to install.
I too have the 1976 CJ7 with TH400 & quadratrac, I like the idea of all this because my wife will using this as her daily driver soon and it seemed like a better system then manual tranny and regular 4wd. I kind of wish I did not have the MM kit so I could experience the full quadratrac experience.
I am just getting things going but intend to take the CJ in to have my trans guy look it over, I also just bought a TH400, Quadratrac T/C and a front axles with disc brakes off a guy for $150, he had a whole stockpile of trannys and axles and was selling everything cheap. I am going to have the trans & T/C gone over so I have a spare when needed.
I still have 2 questions that need answering, where does the vac pressure tube connect in the engine compartment? carb? manifold? which outlet?
Also, I cannot turn the dial in the glove box, can I add some lubricant to this without hurting anything?

 

[Peanut Butter]

Manifold vacuum. Lube may not fix it. The switch is only plastic. Might want to buy the switch BJ's has. Good idea on getting the extra parts. You can easily change back to AWD with a rebuild of the extra transfer case. They are heavy, but not hard to remove and install. You can rebuild one yourself by doing some reading and studying. My build thread has where I rebuilt mine. The links are really good information. If you do switch back to AWD, you will need to keep the front hubs always locked. The TH400 is one of the easiest automatics to rebuild. I plan on rebuilding my extra myself. Just Make sure you use only parts from BJ's. Don't let some mechanic tell you anything different. Yes their stuff costs more money, but not in the long run.

 

[Formula 40PC]

Do you have a picture where your QT vac pressure hose hooks to the manifold?

I have attached pics of my QT switch from the glovebox It must be different then the one you have, this one is all metal. Works good, I thought it wasnt turning but it was the way I was holding it when it was installed so I took it out and it turns and works correctly.

 

[Peanut Butter]

That one is a little different from mine:



Here is how the vacuum lines run:



Hope this helps. Don't forget to check the chain. Here is an example:

http://www.jeep-cj.com/forums/f2/driveline-popping-binding-sound-video-26982/

 

[Formula 40PC]

Does anyone have knowledge of or pictures of what the front axles hubs looked like on a CJ7 with quadratrac? I have a part-time kit that a PO installed but may think someday of switching it back, I really like the idea of the fulltime 4wd.

 

[Peanut Butter]

The only difference is the outer hub. In stock form it is a solid connection to the axle and the wheel.



The piece I'm talking about is top left in between the snap ring and the axle nut. By keeping your locking hubs locked all the time you are doing the same thing, if you were to replace the TC to an OEM Quadratrac.

Here is what it looks like all together:



Hope that helps some.

 

[Formula 40PC]

Does anyone know the gearing ratio of the quadratrac system axles?
I am confused on how the gearing system goes. Are the axles the same ratio as the trans/transfercase setup? I know the TH400 has three gears therefore 3 ratios. Could someone help explain? Thanks

 

[007]

PeanutButter probably knows but www.grimmjeeper.com has it for sure.


Sent from my iPhone using Tapatalk

 

[007]

PeanutButter probably knows but www.grimmjeeper.com has it for sure.


Sent from my iPhone using Tapatalk

Here's what I see with 31" tires...

HI LOW
1 8.78 22.91
2 5.24 13.67
3 3.54 9.24

 

[Posi]

It did not have a low range.
If it came with the optional low range it would be 2.57

 

[Peanut Butter]

If you go to this page you can figure everything out. Gear Ratio Calculator

You can select the GM TH400, the Borg Warner 1339 (or Quadratrac), you need to know the axle gearing, if you don't there are was to figure that out.
Once you have input all the data, you can compare what different axle gears will do, it will give you highway speeds at certain RPMs and what RPMs you should have at a particular speed. Very handy tool.

 

[Posi]

or you can multiply trans 2.48 BW 1339, 2.57, axle 3.54. assuming you have standard factory axle gear ratio.

Your crawl ratio is 45.1

 

[Posi]

or you can multiply trans 2.48 BW 1339, 2.57, axle 3.54. assuming you have standard factory axle gear ratio.

Your crawl ratio is 45.1

To expand on the above quote, your gear ratio would be 23.1, your crawl ratio as mentioned is 45.1

I didn't read the ratio calculating website posted in this thread, but most, if not all don't include realistic crawl ratios for autos because they don't use the torque multiplication factor of the torque converter.

The t-case will increase the output torque by approximately two times, making the actual crawl ratio almost double.

Because the multiplication factor is a variable one, and it changes as the RPM moves up it's best to calculate your crawl ratio with an auto trans by multiplying the nominal result by 1.5 up to 2. I just doubled the first gear ratio in the 400 to get a 45.1 crawl.

You can get a more actuate crawl ratio by factoring in the torque at the flywheel, and tire size as well.

 

[Peanut Butter]

or you can multiply trans 2.48 BW 1339, 2.57, axle 3.54. assuming you have standard factory axle gear ratio.

Your crawl ratio is 45.1

To expand on the above quote, your gear ratio would be 23.1, your crawl ratio as mentioned is 45.1

I didn't read the ratio calculating website posted in this thread, but most, if not all don't include realistic crawl ratios for autos because they don't use the torque multiplication factor of the torque converter.

The t-case will increase the output torque by approximately two times, making the actual crawl ratio almost double.

Because the multiplication factor is a variable one, and it changes as the RPM moves up it's best to calculate your crawl ratio with an auto trans by multiplying the nominal result by 1.5 up to 2. I just doubled the first gear ratio in the 400 to get a 45.1 crawl.

You can get a more actuate crawl ratio by factoring in the torque at the flywheel, and tire size as well.

Thanks for this information, It was something I never considered. With regards to the torque converter is the oem unit sufficient for everyday normal on and off-road use?

 

[007]

Posi can chime in but it's my understanding that absolutely is a good answer.

The whole driveline is rated for 3/4 ton use and it's in a 1/4 ton vehicle. As you well know, it's the exact same driveline found in the Wagoneers in Cherokee's and pick up trucks including the 3/4 ton ones.


Sent from my iPhone using Tapatalk

 

[Posi]

Thanks for this information, It was something I never considered. With regards to the torque converter is the oem unit sufficient for everyday normal on and off-road use?

Absolutely!

 

[Formula 40PC]

I should have been a little more specific in my question because it was a much simplier answer.
What was the factory axle ratio in a 1976 CJ7 with quadratrac? Or was there multiple axle ratios with the quadratrac?

 

[Posi]

"Standard" axle gear ratio 1976-79 was 3.54 regardless what drivetrain you had.

Jeep Axle: AMC 20