WahooSteeler Posted January 13, 2008 Posted January 13, 2008 The 87 2.5L, 2WD, AX15 truck I recently picked up has a driveshaft on it that is as big as any full size V8 truck I've seen. Yet, my 88's 4.0, AW4, 4x4 driveshaft is probably almost HALF the circumference of the 4cyl 2WD. Anybody know the explanation on this? Just curious........
WahooSteeler Posted January 15, 2008 Author Posted January 15, 2008 Bueller? Bueller? Anyone? Bueller?
Geonovast Posted January 15, 2008 Posted January 15, 2008 Surplus parts leftover from the J-series they had to use up? I dunno... Yeah, I was suprised when the first time I looked under my red 4 cyl MJ and saw that the D/s was as big around as my J-10 with the 360...
Duner Posted January 15, 2008 Posted January 15, 2008 it has to do with twist versus length. The 2wd shaft is longer and prone to twist that is why its diameter is so large. On the 4wd comanches most of cherokees and all of the wranglers, jeep was able to use the small diameter shafts.
Pete M Posted January 15, 2008 Posted January 15, 2008 I bet if you look at the axle end of the driveshaft you'll see the big rubber isolator. Helps with vibrations I'm sure.
tjbliley Posted January 15, 2008 Posted January 15, 2008 The rubber isolated shafts suck for making adjustments. You have to retube them completely. Can't just cut to size.
WahooSteeler Posted January 15, 2008 Author Posted January 15, 2008 I had thought at first it could have to do with torque being transferred that far, but I don't think that's a concern on a 2.5L, LOL. I'll say this, it be worth getting one from a JY dawg and cutting it down for a 4x4, it's a hoss!
Pete M Posted January 15, 2008 Posted January 15, 2008 The rubber isolated shafts suck for making adjustments. You have to retube them completely. Can't just cut to size. Sure you can. Just cut the t-case end of the shaft. I'm running a cut down isolator shaft on my 88. :thumbsup:
tjbliley Posted January 15, 2008 Posted January 15, 2008 The rubber isolated shafts suck for making adjustments. You have to retube them completely. Can't just cut to size. Sure you can. Just cut the t-case end of the shaft. I'm running a cut down isolator shaft on my 88. :thumbsup: How did you cut it down? I have been told a few times that the heat from cutting and rewelding it will degrade the rubber and make it likely to fail.
Pete M Posted January 15, 2008 Posted January 15, 2008 Don't cut that end! :D You can do pretty much whatever you like to the other end, after all it's 40+ inches away. If you're concerned at all, you can go slowly or just throw a wet towel on the isolator end. I paid a shop to cut/reweld mine so I'm not sure what they did. :dunno:
JeepcoMJ Posted January 16, 2008 Posted January 16, 2008 :P that truck has a nice ax15 swap in it then. check the tranny, if it's the factory trans it's gonna be a ba10/5. (all MJ 4.0 5 speed were ba10/5 until sometime during 1989...although it's a mixed year)
CEThomas Posted January 16, 2008 Posted January 16, 2008 The rubber isolated shafts suck for making adjustments. You have to retube them completely. Can't just cut to size. Sure you can. Just cut the t-case end of the shaft. I'm running a cut down isolator shaft on my 88. :thumbsup: How did you cut it down? I have been told a few times that the heat from cutting and rewelding it will degrade the rubber and make it likely to fail. I took ours to a DS shop. He cut off from the other end balanced it for $40. Told me he has done many with the isolator, and NO need to retube.
DirtyComanche Posted January 16, 2008 Posted January 16, 2008 it has to do with twist versus length. The 2wd shaft is longer and prone to twist that is why its diameter is so large. On the 4wd comanches most of cherokees and all of the wranglers, jeep was able to use the small diameter shafts. Bingo. The 2WD MJs, praticularily the LWBs, have a driveshaft that is rather impressivly long. It's actually pretty near the limitations of what can easily be balanced to an acceptable level. If you look at most of the other mini-trucks you'll find they use a steady bearing and a 2-peice setup to reduce the length of the shaft, making it easier to balance, and to allow a reduced size to be used.
HOrnbrod Posted January 17, 2008 Posted January 17, 2008 Bingo. The 2WD MJs, praticularily the LWBs, have a driveshaft that is rather impressivly long. It's actually pretty near the limitations of what can easily be balanced to an acceptable level. If you look at most of the other mini-trucks you'll find they use a steady bearing and a 2-peice setup to reduce the length of the shaft, making it easier to balance, and to allow a reduced size to be used. Exactly right Dirty, 66" to be exact. I think that's why the local shop couldn't balance it.
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