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89 xj rear driveshaft noise?

bcmaxx

NAXJA Forum User
Just installed a procomp 4" kit. The kit came with add a leafs which sagged within a day, so I added 3 " trailmaster tapered blocks to obtain even rideheight. Now I have a bad noise when just stepping into the throttle or just letting off the throttle at most speeds. There is about 2 5/8" inch of shiny driveshaft where it used to go all the way into the rear of the transfer case,I think this is where my noise is occuring,It is definately driveline noise. If I grab the front of the rear shaft where it goes into the t/case it has very slight wiggle, I assume this is normal. Any Ideas?
 
since you said you had a "shiney" part where the driveshaft goes into the t-case, that means you didn't put a Slip yoke eliminator on. i recommend you get yourself one.

what you're hearing/feeling is driveline vibs due to the u-joint angles being off. i'm assuming you didn't shim the axle to correct the angles??? also with the blocks you're probably getting some axle wrap.

how in the world did your add-a-leaf sag in one day??? were your old springs so bad that they were inverted or something??? and why didn't you contact the company and complain so they could replace the possibly faulty add-a-leaf.

personally i would highly recommend removing the block and putting in a complete new leaf spring pack. 3" is a little high for blocks.
 
Thanks for the reply, who makes a slip yoke eliminator for my xj??, Yeah within a day or two the back of the truck was draggin, crap kit. The kit was purchased through a third party shop so I cant go back to them. My leafs were almost straight or flat, when I added the extra add a a leaf it looked fine but sacked out fast. The 3 " trailmaster blocks were tapered as to angle the front off the rear diff up and towards the t/case. I have also heard of a t/case mount kit that lowers the t/case for better angle, is this recommended?
 
a transfercase drop. most kits come with them. you can make your own out of some steel square tubing or other stuff. do a search on transfercase drop and you should be able to find a few tips and ideas.
it is recommended if you have driveline vibrations. but if you get a Slip yoke eliminator, then you won't need to drop the t-case.

what t-case do you have in that XJ??? i got an Advanced Adapters Slip yoke eliminator for my NP231. you will have to either buy a new driveshaft to go with that, or try to find yourself another front driveshaft with the double cardan and you can use it as your rear driveshaft once you get the Slip yoke eliminator installed.
 
Ditto, you will be supprised what a good SYE/CV Shaft combo will solve. If you have a transfer case that has a part time 4wd setting that menas you have a NP242 Transfer case and really your only choise is a Hack n' Tap Kit. You can get them from Rubicon Express for around $200. If you have a jeep with only a full time transfer case (2H, 4H, N, 4Lo) you have a NP231 and can install a full replacement tailhousing kit for anywhere between $170-$300. No matter what kit you get, you will need a cv driveshaft. These can range anywhere from $270-$400. Some people will try to take an used from driveshaft and reuse it, but it's really only worth it if you can find a driveshaft the exact length you need. I tried to do this and have the shaft lengthened and between the driveshaft, lengthening it, buying adapters for both ends (HnT at the top, 8.8 behind) and replacing only one of the 3 u-joints, I've already spent almost as much money as a new shaft would cost, and I've still got mine covered in used parts (both ends and 2 old u-joints) and still not 100% completly right. well I hope this helps man!
 
Thanks for all the input, I now realize that a sye and modded driveshaft is the only true way to correct vibration. I guess I'll bite the bullet and do the right thing.
 
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