lupinsea
06-23-2009, 03:58 PM
The linkage for my Jeep's transfer case had been messed up for ages but it "worked" so I had left it alone. Eventually, after futzing with the linkage one too many times it started popping out of place necessitating a repair. Nothing that would leave me stranded, but perhaps requring climbing under the rig in the dirt and mud to shift from 2WD to 4WD or back again.
Perhaps annoying but I prefer this. Pulled a Toyota Tacoma out of the snow this winter when it wouldn't shift into 4WD. I looked under the truck and it was some electrical solenoid that fried with no ability to manual shift the t-case into 4WD. At least with the Jeep I could shift the t-case manually with a wrench.
This write-up isn't necessarily for y'all here on Carmudgeons but I'd figure I'd post it in the tech forum anyways for laughs.
The stock linkage system is at once both crapy and quite elegant in its manufacturing simplicity. It's a contorted linkage system to get the 4WD shift lever in the cab to hook up with the range selector lever on the t-case. But it's interesting for any Rube Goldberg fans. The linkages have barbed metal fittings that snap into plastic bushings. it's easy, cheap, and quick to assemble with good sound and vibration resistance. And normally these linkages keep working for several hundred thousand miles and never give Jeep owners much hassle.
Transfer Case Linkage Write-Up
CONTENTS
1) Vehicle Setup
2) Performance Review
3) Installation Write-Up
4) Additional Resources
1) VEHICLE SETUP
- 2001 Jeep Tj 4.0L Automatic
- 1" Body Lift and 1" Motor Mount Lift
- Low Profile Skid Plate
- Skyjacker T-case Linkage Relocation Bracket
While this Jeep has extensive changes to the stock drive train / frame / body relationship, the concept of the write up is still valid provided measurements are taken off your own rig.
2) PERFORMANCE REVIEW
Difficulty With Transfer Case Shifter:
For many years the the Rube-Goldberg-esque shift linkage for the transfer case shift system has been very problematic on this Jeep and many others. Even before the installation of the Skyjacker relocation bracket the stock upper shift rod was bent for some reason. For years when ever the shift linkage was removed the rod would be re-straightened and reinstalled only to have it re-bend again in short order. Then, with all the removal and reinstalls of the linkage the plastic bushing in the 4WD shift lever finally wore out to the point that the linkage would pop out on it's own quite easily. This, coupled with a fussy adjustment block, yielded spongy, vague shifting, difficulty getting into 4WD, misaligned stop gates in the shifter, and difficulty accurately adjusting everything.
Solution:
The solution to this was to finally fix the upper shift linkage. A new shift linkage was built using quality spherical rod ends and a threaded rod. This required modification to the shift linkage system to accept the new rod ends which involved some welding and steel fabrication and re-using the factory 4WD shift lever.
Performance:
The new linkage has breathed new life into 4WD shift linkage system. By eliminating the old, bent rod and half the plastic bushings in the linkage system the shift feel is vastly improved. No more misaligned stops in the shift gate, no more spongy, vague shift feel. Now a simple pull on the lever results in a crisp, satisfyingly notchy, mechanical feel as the shift lever snaps with authority into each mode with the transfer case's range selector. And with proper jamb nuts and rod ends the linkage stays adjusted to it's proper length.
Cost:
Total cost for all the parts was approximately $25. This included rod-ends, all-thread rod, some regular nuts, some nyloc nuts, a few washers and a couple bolts.
Bottom Line:
If your shift linkage is working just fine then leave it be. But if you're having difficulty shifting, keeping the linkage in adjustment, or have bent or damaged linkage components then consider this modification as it greatly improves shift feel and accuracy with higher quality components that are stronger than stock.
3) INSTALLATION WRITE-UP
Gaining access to the linkage is not terribly difficult, nor time consuming, but there are several layers of the Jeep that need to be peeled back to access everything. More difficult is the welding that needs to be done for those without the skills or access to equipment. And careful measurement and calculation of the linkage length is needed.
Remove Shift Linkage System:
Shift the transmission into neutral and shift the 4WD lever into 4-Lo. Support the transmission and driveline. Remove the skid plate. The linkage system was originally snapped into place with barbed metal end tips so everything can be popped out for service. Using a screw driver or other implement, pry the adjusting block on the upper linkage out of the plastic bushings in the end of the 4WD shift lever. To preserve the life of any other plastic bushings, remove the whole linkage system by next unbolting the range shift lever from the side of the transfer case. Finally, remove the cross shaft. In stock applications this mounts to the transfer case one side and the body tub on the other.
Remove Center Console:
With transmission shifted to neutral and 4WD lever in the 4-Lo position, pull off the automatic's shifter handle. Just pull straight up to pop it off the detents. Do not twist, pull straight up. Pop out the shift lever bezel on the top of the console after feeling which side is easier to pry up. Disconnect the light bulb from the bottom of this bezel. Then feel under the forward edge of the bezel opening for the release tabs for the air bag on/off switch panel. Pop out the on/off switch panel an disconnect the wiring harness plug. Pull out the rubber cup holder trim, it should lift right out for full-console setups. For mini or half consoles you might need to take out the bottom rubber disk. Locate and remove the two 10mm screws holding the console in place (Fig 1) and remove console.
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/01consoleremoval.jpg
Fig 1. Removing the center console takes about 5 minutes
Remove 4WD Shift Lever:
Pry up the wiring harness from the side of the shifter bracket. Locate and remove the five 8mm screws holding the shift lever in place (Fig 2). Remove (Fig 3).
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/02shiftleverremoval.jpg
Fig 2. Removing the actual 4WD shift lever
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/03shiftlinkagelever.jpg
Fig 3. Bent linkage and bushing failure
Modifying 4WD Shift Lever:
With a hack saw or other blade cut off the protruding tapered side of the plastic bushing on the end of the 4WD shift lever. The rest of the bushing should pop out revealing a depressed lip around the mounting hole. Grind down to bare metal and weld on a pair of washers on either side of the hole to tighten up the tolerance for your rod-end fasteners. Grind down welds flush with the surface of the washers (Fig 4).
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/04shiftleverwashers.jpg
Fig 4. Modifying the stock 4WD shift lever with some washers and a welder
Modifying Cross Shaft:
For this particular set up I used two different rod ends, one was a eye-type rod end that would accept a bolt and tucked tighter to a flat surface and the other had a built-in threaded stud off one side of the spherical bearing with a greater offset. Both rod-ends used a carbon fiber bearing race liner. This arrangement worked well with the factory off-sets, though I could have used two studded rod ends, too.
A new lever arm was fabricated out of 1/4" x 1" steel flat stock by first drilling a hole sized to the rod-end fastener. Then careful measurements were made to determine how far off the cross shaft the stock hole was located. This distance was marked on the steel flat stock, about an extra 1/8" was added and the steel cut to length. With a grinder a radius was ground into the end of the new lever arm to match the curvature of the cross shaft. A few test fits and the proper distance was established. The new lever was rotated approximately 1/4" - 1/2" "backward" on the cross shaft. This gives better leverage for shifting in to 4Lo and gave the bulky rod-end more clearance so it wouldn't hit the cross shaft at it's maximum extent (fully shifted forward into 4-Lo). Rotating the lever backwards is fine but the length of the hole-to-cross shaft needs to be the same as the stock arm to maintain any shift ratios (Fig 5). The lever was also located along the length of the cross shaft such that it provided as close to stock (or straight) connection to the 4WD shifter lever after taking into account any fastener offsets. With the location and position noted, the new lever was tack welded into place. The old lever was then cut off and the shoulder ground down and cleaned up for better rod-end clearance. (Fig 6).
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/05newleverarm.jpg
Fig 5. Welding new lever arm onto cross shaft, position
optimized for better rod-end clearance
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/06leverarmpainted.jpg
Fig 6. Modified cross shaft with new lever arm
welded on and old arm ground off.
Reinstall and Measure:
Re-install the 4WD shift lever and the console in the reverse order they were removed. Likewise, reinstall the shift linkage and hook it back up on the transfer case (minus the top linkage, of course). Make sure the transfer case range lever is in the 4-Lo position and make sure the 4WD shift lever is in the 4-Lo position, too. These are the Factory Service Manual's recommended adjustment positions.
To measure the linkage length needed, loop a piece of string through the hole in the new lever on the cross-shaft and the hole in the end of the 4WD shift lever, pull taut. Using a fine felt tip pen or pencil, mark the near-edge of the holes on the string. Remove the string and measure the distance between the two marks. Add the diameter of one of the holes to this distance to get the center eye-to-eye measurement for your total linkage length. For example: my measured distance on the string was 7 1/4". To this I added 3/8" for my hole diameter to arrive at a 7 5/8" total center-to-center length. All applications are different so do your own measurements.
Linkage Length Calculation:
At this point there is some math calculations to work backward from the total needed rod length to determine how long you need to cut the all-thread rod. Refer to Fig 7 as I use my measurement for an example here.
Measure the center of your rod end (the eye or stud) to the end of the rod end body (1 9/16"). Do this for each rod end and write this down (I diagram everything so it's easier for me to follow).
Next thread on a jamb nut and fit the all-thread into a rod end until it bottoms out in the rod-end body. Snug the jamb nut to the rod end body and then remove the all-thread. This will show you how deep you can screw in the all-thread, measure this distance and note it (7/8").
Typically, you need to leave at least as much threaded rod in the rod body as the diameter of the rod (3/8" dia. all-thread). So subtract the diameter of the all-thread from the depth of the threads in the rod end body you just measured. This is your adjustment range for each rod end (7/8" - 3/8" = 1/2" adjustment range).
For adjustment sake, we want to be in the middle of this range. So, take half this remaining distance (1/2" divided by 2 = 1/4") and add it to the diameter of the all-thread you're working with (3/8"). This is how far in the all-thread should be from end of the rod-end body (1/4" + 3/8" = 5/8"). This is your initial engagement distance for each rod end.
Subtract the length of both rod ends (center of eye to end of body) from your total linkage length (7 5/8" linkage - (2 x 1 9/16") = 4 1/2"), then add both engagement distances to this number (4 1/2" + (2 x 5/8") = 5 3/4"). This should be the length of all-thread you need to cut. Whew.
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/07newlinkagecalcs.jpg
Fig 7. Calculations for new length of top shift rod.
Assembly, Installation, and Fine Tuning:
Thread on the jamb nuts to the proper depth, then thread the rod-ends onto the all-thread for your new linkage (Fig 8). Leave it a bit loose and install the linkage between the cross-shaft and 4WD shift lever. If it's a tad short or long make the necessary adjustments and tighten down the jamb nuts. Then bolt the linkage into place (Fig 9) using nyloc nuts and test out the 4WD shift lever making sure everything works properly. Use any washers for fine tuning the spacing between a rod-end and the lever arms they connect to to allow the rod-end body free movement.
Reinstall the skid plate and do one final test shift and you're good to go.
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/08newshiftrod.jpg
Fig 8. New shift linkage (top) vs. old bent linkage (bottom)
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/09linkageinstalled.jpg
Fig 9. New linkage installed on Jeep
4) ADDITIONAL RESOURCES
Rod ends can be sourced from:
McMaster-Carr
Grainger
or local specialty fastener suppliers
Make sure you get matching all-thread and nuts/jamb nuts.
.
Perhaps annoying but I prefer this. Pulled a Toyota Tacoma out of the snow this winter when it wouldn't shift into 4WD. I looked under the truck and it was some electrical solenoid that fried with no ability to manual shift the t-case into 4WD. At least with the Jeep I could shift the t-case manually with a wrench.
This write-up isn't necessarily for y'all here on Carmudgeons but I'd figure I'd post it in the tech forum anyways for laughs.
The stock linkage system is at once both crapy and quite elegant in its manufacturing simplicity. It's a contorted linkage system to get the 4WD shift lever in the cab to hook up with the range selector lever on the t-case. But it's interesting for any Rube Goldberg fans. The linkages have barbed metal fittings that snap into plastic bushings. it's easy, cheap, and quick to assemble with good sound and vibration resistance. And normally these linkages keep working for several hundred thousand miles and never give Jeep owners much hassle.
Transfer Case Linkage Write-Up
CONTENTS
1) Vehicle Setup
2) Performance Review
3) Installation Write-Up
4) Additional Resources
1) VEHICLE SETUP
- 2001 Jeep Tj 4.0L Automatic
- 1" Body Lift and 1" Motor Mount Lift
- Low Profile Skid Plate
- Skyjacker T-case Linkage Relocation Bracket
While this Jeep has extensive changes to the stock drive train / frame / body relationship, the concept of the write up is still valid provided measurements are taken off your own rig.
2) PERFORMANCE REVIEW
Difficulty With Transfer Case Shifter:
For many years the the Rube-Goldberg-esque shift linkage for the transfer case shift system has been very problematic on this Jeep and many others. Even before the installation of the Skyjacker relocation bracket the stock upper shift rod was bent for some reason. For years when ever the shift linkage was removed the rod would be re-straightened and reinstalled only to have it re-bend again in short order. Then, with all the removal and reinstalls of the linkage the plastic bushing in the 4WD shift lever finally wore out to the point that the linkage would pop out on it's own quite easily. This, coupled with a fussy adjustment block, yielded spongy, vague shifting, difficulty getting into 4WD, misaligned stop gates in the shifter, and difficulty accurately adjusting everything.
Solution:
The solution to this was to finally fix the upper shift linkage. A new shift linkage was built using quality spherical rod ends and a threaded rod. This required modification to the shift linkage system to accept the new rod ends which involved some welding and steel fabrication and re-using the factory 4WD shift lever.
Performance:
The new linkage has breathed new life into 4WD shift linkage system. By eliminating the old, bent rod and half the plastic bushings in the linkage system the shift feel is vastly improved. No more misaligned stops in the shift gate, no more spongy, vague shift feel. Now a simple pull on the lever results in a crisp, satisfyingly notchy, mechanical feel as the shift lever snaps with authority into each mode with the transfer case's range selector. And with proper jamb nuts and rod ends the linkage stays adjusted to it's proper length.
Cost:
Total cost for all the parts was approximately $25. This included rod-ends, all-thread rod, some regular nuts, some nyloc nuts, a few washers and a couple bolts.
Bottom Line:
If your shift linkage is working just fine then leave it be. But if you're having difficulty shifting, keeping the linkage in adjustment, or have bent or damaged linkage components then consider this modification as it greatly improves shift feel and accuracy with higher quality components that are stronger than stock.
3) INSTALLATION WRITE-UP
Gaining access to the linkage is not terribly difficult, nor time consuming, but there are several layers of the Jeep that need to be peeled back to access everything. More difficult is the welding that needs to be done for those without the skills or access to equipment. And careful measurement and calculation of the linkage length is needed.
Remove Shift Linkage System:
Shift the transmission into neutral and shift the 4WD lever into 4-Lo. Support the transmission and driveline. Remove the skid plate. The linkage system was originally snapped into place with barbed metal end tips so everything can be popped out for service. Using a screw driver or other implement, pry the adjusting block on the upper linkage out of the plastic bushings in the end of the 4WD shift lever. To preserve the life of any other plastic bushings, remove the whole linkage system by next unbolting the range shift lever from the side of the transfer case. Finally, remove the cross shaft. In stock applications this mounts to the transfer case one side and the body tub on the other.
Remove Center Console:
With transmission shifted to neutral and 4WD lever in the 4-Lo position, pull off the automatic's shifter handle. Just pull straight up to pop it off the detents. Do not twist, pull straight up. Pop out the shift lever bezel on the top of the console after feeling which side is easier to pry up. Disconnect the light bulb from the bottom of this bezel. Then feel under the forward edge of the bezel opening for the release tabs for the air bag on/off switch panel. Pop out the on/off switch panel an disconnect the wiring harness plug. Pull out the rubber cup holder trim, it should lift right out for full-console setups. For mini or half consoles you might need to take out the bottom rubber disk. Locate and remove the two 10mm screws holding the console in place (Fig 1) and remove console.
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/01consoleremoval.jpg
Fig 1. Removing the center console takes about 5 minutes
Remove 4WD Shift Lever:
Pry up the wiring harness from the side of the shifter bracket. Locate and remove the five 8mm screws holding the shift lever in place (Fig 2). Remove (Fig 3).
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/02shiftleverremoval.jpg
Fig 2. Removing the actual 4WD shift lever
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/03shiftlinkagelever.jpg
Fig 3. Bent linkage and bushing failure
Modifying 4WD Shift Lever:
With a hack saw or other blade cut off the protruding tapered side of the plastic bushing on the end of the 4WD shift lever. The rest of the bushing should pop out revealing a depressed lip around the mounting hole. Grind down to bare metal and weld on a pair of washers on either side of the hole to tighten up the tolerance for your rod-end fasteners. Grind down welds flush with the surface of the washers (Fig 4).
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/04shiftleverwashers.jpg
Fig 4. Modifying the stock 4WD shift lever with some washers and a welder
Modifying Cross Shaft:
For this particular set up I used two different rod ends, one was a eye-type rod end that would accept a bolt and tucked tighter to a flat surface and the other had a built-in threaded stud off one side of the spherical bearing with a greater offset. Both rod-ends used a carbon fiber bearing race liner. This arrangement worked well with the factory off-sets, though I could have used two studded rod ends, too.
A new lever arm was fabricated out of 1/4" x 1" steel flat stock by first drilling a hole sized to the rod-end fastener. Then careful measurements were made to determine how far off the cross shaft the stock hole was located. This distance was marked on the steel flat stock, about an extra 1/8" was added and the steel cut to length. With a grinder a radius was ground into the end of the new lever arm to match the curvature of the cross shaft. A few test fits and the proper distance was established. The new lever was rotated approximately 1/4" - 1/2" "backward" on the cross shaft. This gives better leverage for shifting in to 4Lo and gave the bulky rod-end more clearance so it wouldn't hit the cross shaft at it's maximum extent (fully shifted forward into 4-Lo). Rotating the lever backwards is fine but the length of the hole-to-cross shaft needs to be the same as the stock arm to maintain any shift ratios (Fig 5). The lever was also located along the length of the cross shaft such that it provided as close to stock (or straight) connection to the 4WD shifter lever after taking into account any fastener offsets. With the location and position noted, the new lever was tack welded into place. The old lever was then cut off and the shoulder ground down and cleaned up for better rod-end clearance. (Fig 6).
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/05newleverarm.jpg
Fig 5. Welding new lever arm onto cross shaft, position
optimized for better rod-end clearance
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/06leverarmpainted.jpg
Fig 6. Modified cross shaft with new lever arm
welded on and old arm ground off.
Reinstall and Measure:
Re-install the 4WD shift lever and the console in the reverse order they were removed. Likewise, reinstall the shift linkage and hook it back up on the transfer case (minus the top linkage, of course). Make sure the transfer case range lever is in the 4-Lo position and make sure the 4WD shift lever is in the 4-Lo position, too. These are the Factory Service Manual's recommended adjustment positions.
To measure the linkage length needed, loop a piece of string through the hole in the new lever on the cross-shaft and the hole in the end of the 4WD shift lever, pull taut. Using a fine felt tip pen or pencil, mark the near-edge of the holes on the string. Remove the string and measure the distance between the two marks. Add the diameter of one of the holes to this distance to get the center eye-to-eye measurement for your total linkage length. For example: my measured distance on the string was 7 1/4". To this I added 3/8" for my hole diameter to arrive at a 7 5/8" total center-to-center length. All applications are different so do your own measurements.
Linkage Length Calculation:
At this point there is some math calculations to work backward from the total needed rod length to determine how long you need to cut the all-thread rod. Refer to Fig 7 as I use my measurement for an example here.
Measure the center of your rod end (the eye or stud) to the end of the rod end body (1 9/16"). Do this for each rod end and write this down (I diagram everything so it's easier for me to follow).
Next thread on a jamb nut and fit the all-thread into a rod end until it bottoms out in the rod-end body. Snug the jamb nut to the rod end body and then remove the all-thread. This will show you how deep you can screw in the all-thread, measure this distance and note it (7/8").
Typically, you need to leave at least as much threaded rod in the rod body as the diameter of the rod (3/8" dia. all-thread). So subtract the diameter of the all-thread from the depth of the threads in the rod end body you just measured. This is your adjustment range for each rod end (7/8" - 3/8" = 1/2" adjustment range).
For adjustment sake, we want to be in the middle of this range. So, take half this remaining distance (1/2" divided by 2 = 1/4") and add it to the diameter of the all-thread you're working with (3/8"). This is how far in the all-thread should be from end of the rod-end body (1/4" + 3/8" = 5/8"). This is your initial engagement distance for each rod end.
Subtract the length of both rod ends (center of eye to end of body) from your total linkage length (7 5/8" linkage - (2 x 1 9/16") = 4 1/2"), then add both engagement distances to this number (4 1/2" + (2 x 5/8") = 5 3/4"). This should be the length of all-thread you need to cut. Whew.
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/07newlinkagecalcs.jpg
Fig 7. Calculations for new length of top shift rod.
Assembly, Installation, and Fine Tuning:
Thread on the jamb nuts to the proper depth, then thread the rod-ends onto the all-thread for your new linkage (Fig 8). Leave it a bit loose and install the linkage between the cross-shaft and 4WD shift lever. If it's a tad short or long make the necessary adjustments and tighten down the jamb nuts. Then bolt the linkage into place (Fig 9) using nyloc nuts and test out the 4WD shift lever making sure everything works properly. Use any washers for fine tuning the spacing between a rod-end and the lever arms they connect to to allow the rod-end body free movement.
Reinstall the skid plate and do one final test shift and you're good to go.
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/08newshiftrod.jpg
Fig 8. New shift linkage (top) vs. old bent linkage (bottom)
http://homepage.mac.com/jgreening/.Pictures/Jeepmods/shift%20linkage/09linkageinstalled.jpg
Fig 9. New linkage installed on Jeep
4) ADDITIONAL RESOURCES
Rod ends can be sourced from:
McMaster-Carr
Grainger
or local specialty fastener suppliers
Make sure you get matching all-thread and nuts/jamb nuts.
.