Growl in the rear...

I recently installed a BB kit on top of my 3" kit in my 98 XJ. I then started to notice a slight growl coming from the back end. It only growls at slight slight acceleration or at the first instant of deceleration. I also notice it does it noticably less with a full tank of gas vs a almost empty tank. Theres barely any noticable vibe to it, but definately noise. Im thinking I need to do something along the lines of slip yolk modification. Any thoughts? I already have a t-case drop.

98XJSport said:

I recently installed a BB kit on top of my 3" kit in my 98 XJ. I then started to notice a slight growl coming from the back end. It only growls at slight slight acceleration or at the first instant of deceleration. I also notice it does it noticably less with a full tank of gas vs a almost empty tank. Theres barely any noticable vibe to it, but definately noise. Im thinking I need to do something along the lines of slip yolk modification. Any thoughts? I already have a t-case drop.

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those slip chickens might get irrate if you mess with their yolk (yoke, just kiddin, lol)
i shimmed my rear axle with 4degree shims & that helped w/ about 5.5" of lift i ran mine that way about a year but not all the vibe/bind was eliminated, it wasn't my daily driver so i didn't get to worried about it.
re & rusty's sells shims its a cheap fix but a sye is probly in your future or else the rear output shaft seal & bearing & the pinion seal & bearing will beginning to wear with to many miles

It gets a lot of miles, being my daily driver. Im wondering about something along the lines of an RE extended tailshaft thingy or one of the kits from RE that are only like a fraction of the more expensive SYE kits...

98XJSport said:

It gets a lot of miles, being my daily driver. Im wondering about something along the lines of an RE extended tailshaft thingy or one of the kits from RE that are only like a fraction of the more expensive SYE kits...

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bad plan - Hack and Tap just sounds bad...
sure people run them with no issues and all that - but when a HD sye is 170.00 - why would you run less? for 70.00 more, that kit is a stronger piece...

i dunno bout you but my hackand tap fit my needs fine.. i like it and it was easy to install

If the BB consists of a longer shackle, you will have tilted the pinion upwards a little. The center line of the pinion should be at the same angle as the center line of the transfer case output. If they aren't you will get torsional vibration. This can be corrected with degree shims up to a certain point. However, if you're lifted, you should check that the U/joints aren't binding especially at full drop if you go offroad. The front U/J on my rear prop was binding badly, even on the street so I replaced the slip yoke half of the joint with one from a Wrangler. this allows double the flex and sorted the problem for free. It's just done 2000 miles including a weekend of tough wheelin' with no problems.

It did consist of a longer shackle. I presume my problem is as you describe, with the center lines being off. It is so slight to the degree that i first thought i was imagining it, but now that I know to look for it I do notice it. Are shims the only way to fix this angle issue or is a hack and tap a good or better way (cost-wise) to go about it too?