From: DonS4x4 (Original Message) Sent: 11/30/2003 4:04 PM
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QUADRA-TRAC BW-1339 update 11-30-03
The QTs with the part time kit installed should be noted as BW-1339PT.
The QTs with the PT Over Drive kit should be noted as BW-1339PT16%

RUMORS
‚Ä¶ There are many models of the "Quadra Tracs" and there have been rumors about weaknesses in the QT units. These rumors are about the cheap IMITATIONS of the BW-1339 that were used in Fords, Dodges and Chevys and the later models in Jeeps up through 2003 models. The BW-1339s were raced in stock condition in the Baja California races for years with no problems. The BW-1339 was the first and best QT. The later models only ruined the name.

http://autos.groups.yahoo.com/group/cfsja/message/41600 Message below

quote
My opinion: The BW-1339 Transfer case is the best full time case ever designed,Hands down. The 1339 was actually a military prototype that was put into civilianProduction. Awesome design, very dependable (when correctly cared for), awesome Function, etc.
‚Ä¶ Even the offset design is wonderful, allows a clear path for obstacle Clearance without worrying about slamming a differential. It has great low range Gearing, can handle an incredible amount of torque and HP. The chain is larger than nearly any other transfer case chain ‚Äì equating to a much stronger case overall.
‚Ä¶ Let‚Äôs face it, the people with QT problems are dealing with a very old transfer case, in most cases never rebuilt, probably never had the fluid changed (read: neglected), and with very high mileage pulling around a very heavy vehicle.
‚Ä¶ They are quiet, have much better gearing than most stock gear driven cases, have the ability to lock and provide for all the functionality of a part time case, really don‚Äôt draw gas mileage down very much in comparison to the advantages you have with a full time case. My QT‚Äôs have gotten me around in situations where a part time case would have left me with wheels spinning.
‚Ä¶ J.C. Jones 1979 Jeep J-10 ‚Ä¶
J.C. Jones is a respected member of the Full Size Jeep community in Colorado.

BW-1339 QT Transfer Case Theory and Testing
‚Ä¶ The out put shaft of the GM TH 400 automatic transmission is longer than usual and goes through the transfer case into an optional sun-gear equipped two speed reduction gear box. From the upper sprocket driven by the two speed gear box a wide heavy duty chain drives the lower sprocket between the front and rear output shafts. The output shafts are on the passenger side of the truck.

‚Ä¶ In the center sprocket is a differential with a steel cone clutch system acting like an all steel limited slip differential in a rear axle. As with most LSDs the center differential will send a limited amount of power (least amount) to the axle with the most traction. But in the transfer case situation it is to the front or rear axle.

‚Ä¶ Without the LSD or a locking device in the transfer case or the axles, if one tire were on ‚Äòblack ice‚Äô and the others had good traction the truck might not move. The cone clutch system helps supply some torque to both front and rear axles. The front and rear torque may not be equal but they both do get power sent to them. The center sprocket differential clutch system allows for speed difference as the front axles wings a larger arc (more distance) than the rear axle when turning. Both front and rear axles get power all the time and the cone clutches between them allow this to happen with out torsional windup and excessive wear to tires and running gear.

‚Ä¶ A vacuum operated locking feature (emergency drive) will lock the center differential. When engaged, both front and rear output shafts are locked together and forced to rotate at the same speed. The center differential and clutches are locked and operate as a part time transfer case.

‚Ä¶ So "e-drive" should only be used in conditions where the tires can easily slip on poor traction surfaces because the axles need to be able to rotate at different speeds.

"E-Drive" rotary switch.
‚Ä¶ There is an EMERGENCY-Drive rotary vacuum switch located in the glove box. Vacuum is applied to the front ‚Äònipple‚Äô of a vacuum motor on the transfer case to slide a locking ring forward into position to lock the two output shafts together. Vacuum can be applied to the other side of the vacuum motor to slide the ring back to unlock the system. A limit switch has been installed so the vacuum motor shaft will operate a light in the cluster gauge indicating if the e-drive is engaged.

‚Ä¶ The vacuum motor on the transfer case needs a fair amount of vacuum to slide the locking ring back and forth. At high altitude engines are producing less vacuum. There are occasions when there is not enough vacuum to lock and unlock the transfer case. The usual cause is vacuum leaks.

‚Ä¶ Some of the systems have a round vacuum reserve tank on the firewall and a hose feeding it from the base of the carburetor. The chamber helps the system to perform with fewer failures. A rubber line goes from the chamber through the firewall to the switch in the glove box then returning through the firewall two metal lines go down to the vacuum motor.

http://www.fullsizejeeps.com/jeeps/files/Parts-Junkyards/bwqt_vac.jpg VIEW VACUUM DIAGRAM

COOLING AND OILING
‚Ä¶ When replacing the BW-1339 oil use Crown TCL ‚Äì 1 and it will use a little over two quarts. Fill the two-speed reduction gearbox first then fill at the oil check plug. Use a squeeze bottle with a rubber hose that runs through the top and down to the bottom. When draining the oil check for steel debris in the magnetic plug. The debris could indicate Cone clutch wear, stripped clutch spline or chain wear.

‚Ä¶ When the truck is moving the QT oil is spinning in the aluminum case in the direction that the chain is rotating and this helps all the parts cool. In the upper end of the chain case there is a small piece of metal that act as a oil slinger that forces oil into the reduction gear housing. The oil then continually exits the gear housing flowing back into the chain case.

‚Ä¶ Excessive wearing of the chain would be related to crud in the oil and sudden power and backlash loading. The chain can‚Äôt tell where the force came from other than the sprockets, just the amount of the force exerted on it.

TESTING CONE CLUTCHES
‚Ä¶ When testing cone clutches the transfer case should not be in e-drive. With the front wheels locked and blocked, the engine off and the transmission in neutral, disconnect the rear drive shaft. Be sure to mark all parts so they can be reinstalled exactly as they were removed.
‚Ä¶ Use a strong torque-wrench on the rear yoke-retaining nut. Measure the torque to the point the cones clutches start slipping by turning the wrench clockwise. If the torque is between 80 and 170 foot pounds the cones are in good shape. Over 170 foot pounds would indicate a lubrication problem.

http://www.slidingdelta.com/fsj/xfercase/826.gif CONE EXPLODED VIEW

Test the CHAIN SLACK
‚Ä¶ If you can accelerate from a stop briskly up a 30 degree hill in 4low without the BW-1339 transfer case chattering and the truck seeming to be jerking then the QT chain is in good shape. If the chain just jumps while remaining on the sprocket it‚Äôs not good but if the chain jumps and slips off the sprocket you will need a new case.

‚Ä¶ One way to check chain slack is by parking the Jeep front end up on a 5degree grade. Put the Th-400 Transmission in park and let the truck roll back until all the drive line slack is tight against the parking pall. Lightly block the wheels in case the parking pall should fail. In this position the chain will be tight across the top and the slack will be on bottom. When you remove the chain check plug oil will run out if it had the correct amount. Check the slack by lightly measuring from the check hole edge to the chain. Next push the chain upward until it is tight and check the measurement again. Three quarters of an inch would indicate an undesirable amount of slack.

‚Ä¶ Some chose to wait until the first time the chain jumps and then replace it. The chain will jump the sprocket in proportion to the amount of power applied against how loose the chain is.

Testing the "Emergence-Drive engagement"
Simply engaging e-drive then jacking all four wheels up and watching wheel rotation doesn‚Äôt work.
Engaging e-drive then jacking rear wheels up off the ground and attempting to drive up an incline would be difficult and unsafe but would probably work.

#1... One safe way to check the ‚Äòe-drive‚Äô is to find a large graveled parking lot and do some tight figure 8‚Äôs. Listen closely to the noise level of the tires in the gravel. Then put the transfer case into e-drive, a red indicator light should come on in the gauge cluster. You may have to go straight and travel forward or back a bit due to drive-line windup. Do the figure 8‚Äôs again. The gravel noise should be louder if e-drive is working and the FSJ should buck and snort a little more. If not the system may have problems.
‚Ä¶ If the case went into e-drive then straighten the wheels, turn the e-drive switch off and travel back and forth 50 feet a few times or until the indicator light goes off. If your light does not work do the figure 8‚Äôs again and see if the gravel noise is less. Don‚Äôt drive on dry pavement in e-drive. If you have a bad situation known as ‚Äôslip-stick‚Äô it means the clutch packs are very strong or not properly lubricated. In such case the gravel noise would be nearly as noisy as when it was in e-drive. Slip-stick will cause a little more wear depending on the severity of the condition.

#2‚Ä¶ Put the truck in emergency-drive, remove the front or rear drive shaft. Be sure to mark all parts so they can be reinstalled exactly as they were removed. If the e-drive is working you will be able to drive the truck.
‚Ä¶ Do not drive the truck unless all axles and wheels are capable of taking power and driving because this will damage the cone-clutches. Unlocked locking hubs while in standard-drive will damage the cone-clutches.

http://www.slidingdelta.com/fsj/xfercase/821.gif BW-1339 EXPLODED VIEW

TOWING THE BW-1339
It has been recommended to remove the front and rear drive shafts if towing over 50 miles because it will damage the cone-clutches. Be sure to mark all parts so they can be reinstalled exactly as they were removed.

http://www.slidingdelta.com/fsj/xfercase/815.gif VIEW REDUCTION ASSEMBLY

A MECHANICAL NOTE
‚Ä¶ The front and rear snapring and bearing replacement can be completed with the transfer case in the truck. When dealing with the snaprings remember the case is made from cast aluminum and very soft. The front half of the transfer case need not be removed in order to replace the chain. These items can be done under the truck. A quarter inch spring and detent ball can jump out and get lost during the removal of the vacuum motor. The e-drive signal limit switch hides one of the case splitting nuts.

Important Disclaimers - Please Read http://groups.msn.com/JEEPTECH101/jeeptech.msnw?action=get_message&mview=0&ID_Message=19&LastModified=4675398801218699942

Here are three great LINKS

http://www.t-r-j.com/Auto/QT/quadratrac.htm QT

http://home.earthlink.net/_riverbeast/qt01.htm RBs QT

http://www.ifsja.org/ubb/ultimatebb.php?ubb=get_topic;f=2;t=009894 e-drive SWITCHES

This is an original T-O Jeep Club & JEEP TECH 101 document

This subject will be expanded when more time is available. If you have a correction or addition please

post a reply. Unfortunately replies are deleted when this subject is updated... Sorry

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