junkyardjeep

So i put a 4.5 zone aal and getting some bad vibes. But after installing I drove 100 miles to offroad and 100 miles back. I wheeled her pretty hard. Now after getting back I cleaned her all up and changed diff fluids. Now im getting bad vibrations starting at 20mph. Once i build speed it seems to smooth out but definitely still there. Also if i back off the throttle it goes away. Now i thought it was pinion/carrier bearings and was about to buy a jy rearend. But i forgot that ever since i put lift on i had a bunch of weight in the back( 4/super swampers,hilift,chain, tools, etc.) than after offroading i clean everyhting out. Now im thinking my jeep raised back up a little and pinion angle is off. Now before i buy a rearend what kinda of test should i run. Heres some specs: 2001 xj np231, transfer case drop,no shims, dana 35

tvarney26

do u got sye?, a tc drop? if so check ur u joints

Red82

You should look into an SYE. I recommend Iron Rock Offroads hack n tap and get a front driveshaft from a JY part. If you've got a dana 35 I'd go ahead and replace it if you've got the cash. Just grab an 8.25 out of one in the JY that looks good.

Red82

I would also look at replacing U joints as well. They've probably been a bit abused by the lift.

blankdeluxe

I don't want to be that guy but seriously... just search. This has been covered a hundred times. SYE. I know its not a cheap fix but its well worth the investment.

junkyardjeep

Ok I just bought hack n tap from ironrock. Im gonna try to pick up jy driveshaft tomorrow.

96FourOh

Just a little heads up, make sure your TC output shaft isnt bent before you cut it. Mines was and still is. Took about 90% of the vibes out but cant do anything better with it. Good luck!

flyn289

Id go ahead and do a rebuild on the jy front y while its out

VhoffXJ

Same lift, same problems, starts around 20-25 but mellows out, I have vibrations mostly from my meats. I can be going 20-25 and let my hand off the wheel and you can see it shake a little but any other speed no, Also I have the same t case with out a drop, nor shims and my pinion angle is ****, with a C.8.25 ***. SYE would do the trick, Cheapest one I've found with shafts is 400$.
Also I'm installing long arms so the crossmember they have gives the t-case a drop so hopefully that helps too.

junkyardjeep

Just picked up jy front drive shaft. $43

NHL_bullitt

Sounds like you are moving along quickly to fix the problem. Nice. It is a shame Jeep didn't do a double cardan shaft for the front and rear from the beginning.

junkyardjeep

i pulled the rear dive shaft and test drove and vibe went away. well there was some shaking in front but nothing compared to before. I still have get alignment and reclock the steering wheel though. So hopefully this hack n tap goes smooth and ill be driving again. Im moving fast cause i dont wanna be down when we get snow.