Akula69 Posted July 19, 2013 Share Posted July 19, 2013 OK - on the 89 resto to 99 swap I have a drive shaft question: The application is a 242J TC and a Cryco 8.25 rear The Tom Woods website suggests measuring the rear driveshaft from the back of the transfer case to the center of the u-joint on the differential (specifically: from the front of the rubber boot at the rear of the TC to the center of the u-joint yoke on the differential). In measuring this distance we got 53 1/4 inches. We decided to use the 89 MJ driveshaft, as it is a larger tube and has new u-joints already. I took it yesterday and the company cut it to 53 1/4 inches. They cut it correctly, I have measured it numerous times, both the vehicle and the shaft measurements are the same, but the shaft is still about 3 3/4 inches too long. The TC output shaft mates up perfectly with the slip joint on the driveshaft, and the slip joints are identical from the MJ and the old rear XJ shaft. We are fully engaging the slip onto the TC output shaft. We have measured the output shaft and the inside of the slip joint and the output shaft is fully seating (no internal obstructions). Can anyone tell me why the measurements are correct but the shaft doesn't fit? :hmm: Please - no tape measure jokes...I've tried several measuring tapes and had other folks confirm the measurements. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 19, 2013 Share Posted July 19, 2013 Is the TC slip joint yoke fully splined internally, end-to-end? Some are not. Also it the MJ sitting on the floor, not jacked up with the rear axle hanging? Link to comment Share on other sites More sharing options...
Akula69 Posted July 19, 2013 Author Share Posted July 19, 2013 Is the TC slip joint yoke fully splined internally, end-to-end? Some are not. Also it the MJ sitting on the floor, not jacked up with the rear axle hanging? Thanks - The MJ is down on all fours, and the TC output shaft is fully splined from end to end. I need to check the slip joint itself to ensure it is fully splined on the inside.... Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 19, 2013 Share Posted July 19, 2013 Is the TC slip joint yoke fully splined internally, end-to-end? Some are not. Also it the MJ sitting on the floor, not jacked up with the rear axle hanging? Thanks - The MJ is down on all fours, and the TC output shaft is fully splined from end to end. I need to check the slip joint itself to ensure it is fully splined on the inside.... Yep, that's what I meant. Link to comment Share on other sites More sharing options...
Alexia Posted July 19, 2013 Share Posted July 19, 2013 Tom Woods recommends measuring from the back of the transfer case tail cone because then Tom Woods subtracts the measurements of the slip or fixed yoke they use from the measurement provided. 3.75" too long is just about the additional that should have been taken off.Measuring for a standard Jeep drive shaft with slip yoke.Please note that is a rough guide and that ideally there should be 1.5" of slippage allowance inside the slip yoke to accommodate suspension travel. Always double check your measurements.1.) Measure from the length from the center of the u-joint at the differential yoke to the edge of the tail cone on the transfer case. This has to be done in a straight line and not at an angle. Hanging pieces of string from the two points down to the floor to measure between works well.Example: 50" - This will be measurement A.2.) Slip the slip yoke all the way bottomed out on to the transfer case output shaft. Measure the length of the slip yoke from the back of the transfer case tail cone to the center of slip yoke u-joint. Add 1.5" to this measurement to allow for slippage.Example: 4" + 1.5" = 5.5" - This will be measurement B.3.) Final u-joint to u-joint length is A - B.Example: 50" - 5.5" = 44.5"NOTE: If the slip yoke hits the output shaft seal before bottoming out on the output shaft then the slip yoke is too long and may damage the transfer case if the entirety of the 1.5" slippage allowance is used during suspension travel. Simply cut the slip yoke down 0.5" to compensate or buy a shorter slip yoke. Link to comment Share on other sites More sharing options...
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