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Drone at Hwy speeds, long.

Angus

NAXJA Forum User
Vehicle:
2000 XJ, 6cyl, Auto, 231 w/SYE. Frt HP D30 w/Trutrac,
Rr 8.25 w/Powertrax, 4:11 gears, 5" hybrid OME lift w/OME shocks.
BFG 31 AT's

Problem:
Slight vibration above 50mph, but loud drone above 70mph. The drone is low frequency that
ocilates every 2-3 seconds. The original LP D30 and 3:55 gears had same condition, just at different
speeds of course. Drone is in the rear.

Treatment to date:
Removed front then rear shafts. Front had no effect,
noise is all but gone when the rear shaft is removed (rear is the
problem). Have installed (2) Tom Woods and (1) stock front shaft
mounted in the rear. The front shaft installed in the rear is the best
(Sorry Tom)? Swaped 2 then 4 degree rear shims along with longer
shackles. No real effect other than tone.

Possibles:
Having eliminated the front end I am working at the back. I am
now looking at the yokes and the SYE rear shaft. I am the original
owner and the rear axle yoke has not taken any hits. I have a
BayouGeep SYE setup that looks and installs like any heavy duty
replacement rear shaft kit. The TC yoke was new in the kit.

Help?? Anyone have a yoke that was out of round from the factory?

Thanks
 
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I'm gonna keep an eye on this one...sounds exactly like mine, but I haven't isolated the problem yet. Only difference being 4.56 gears,a full detroit, and bigger tires.
 
Angus said:
Anyone have a yoke that was out of round from the factory?

Thanks

Had the RE rear DS and hack 'n' tap sye. DS was both out of balance and too much runout. After balancing things were better, but still had cyclic vibration. Checked RE sye and found runout. Replaced the works (Tom Woods DS and sye/yolk) and things are fine. Might want to go through the motions found at

http://www.babcox.com/editorial/us/us50126.htm

like that this guy gets down to pulling the wheels and tires.
 
Had this same issue on my 99 XJ whe nit was stock. Mine I think was tires or wheels, or bearings. Sorry not sure cause it went away after I lifted/sye'd/new tires/wheels/gears/bearings on my Jeep.
 
Did you check the ring gear for "run-out" when you did the install? I set up rear ends and I'm thinking something in the diff. Also, Woods builds different shafts for different uses, If you got one, say for crawling, it would be smaller diameter and thicker tubing and harder to balance. The one I installed on my 96' was built more for street and light trail use, thus having larger diameter and thiner tubing, easier to balance.

I'm not being critical just trying to find a solution.

You have a very similer set up to my 96'. Except the front is open and Tru-Trac in the rear(4.10 and 30"), and I'm running mixed bag OME/ACOS/TeraFlex 4.5" lift.

p10001330kb.jpg
 
yes, sounds like its in the Chry8 1/4 itself. Check bearings and run out like xjtrailrider said.
 
skyjackedxj96 said:
yes, sounds like its in the Chry8 1/4 itself. Check bearings and run out like xjtrailrider said.

These things drone stock in my experience.

Time for a 9"? you know you want it.

:D
 
The 8 1/4 has adjustable collars on them for the back lash. Sometimes the carrier bearings wear out and the colars need to be tighting, that might fix the problem..
 
recycledxj said:
The 8 1/4 has adjustable collars on them for the back lash. Sometimes the carrier bearings wear out and the colars need to be tighting, that might fix the problem..

Interesting. This would be consistent with what I have seen (higher mileage means more noise).
 
Well to add more info, I have 103,000 miles on the XJ. Vibration was noticable after my first lift of 2" at 5,000 which was expected. I bought the SYE at 20,000 shortly after I went to 3", this solved the vibration, but the drone was now present. My Woods shaft are the heavy type but not the pure rock crawler unit. Keep in mind I have used three shafts, one being a stock front shaft with no major change. Since I lifted early and the vibration was present I cannot rule out the drone from day one. I am on my second set of BFG's with the same noise. The gears were done with all new bearings a year ago at 90,000 miles. With those changes I am confident in eliminating the tires, bearings, shaft, and gears since the drone has stayed the same. I am now considering taking the yokes off with the shaft and sending them to the driveline shop to spin as a unit.
 
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Mine turned out to be the brake pads having wear were they mount to the braekets. I added the little tabs that clip onto the pads and fill the gap to the brackets and no more drone.
 
this thread is worthless without posting driveline angles :banghead:
 
My 99 used to have that drone at highway speeds. (8.25) When I replaced the pinion, the noise went away. I also replaced carrier, and pinion bearings at the same time.
 
Guys, I've replaced all the bearings with no change! The angles are great, but since you asked Max the CV is at 6 and the pinion is at 1-2. I have played with the shims, but the drone has never changed.
Angus
 
I havnt thought of that? It has remained constant in all these tests. I need to reseal my TC anyway so I will check it very thouroughly.
Thanks!
 
I'm curious to see what you find. I have a '98 and as speed increases it drones from the rear until it is nearly deafening at 80.

While off the ground I listened to it with a stethascope. From inside the vehicle it sounded like it was the rear end (8 1/4) but from outside, the closest place it could be pinpointed to was the output shaft on the t-case, which makes me think either the output shaft bearing or the driveshaft itself
 
couple of things... Thanks Max for pointing out the need for pinion angles.
the pinion should point about 1-2 degrees below parrallel of the cv driveshaft.
next you need to double check that the driveshaft is indexed correctly. the yoke ears between the 2 ends of the straight slip section need to line up.
0I0=====----===0
and not
0I0=====----===[
check that first, i've seen it messed up before from the axle builders.
also try rotating the u-joint 180 degree's in the diff yoke.
 
Thanks for the help, but please read my post and info. The pinion is at 2 degrees. I mentioned 1-2 just for the sake of the flex in the springs. The Woods shafts are indexed properly and the ujoints have been changed. Now after a total of three shafts, and four ujoints (three that were fine) and several adjustments at axle shims I am confident that the rear shaft is not the issue. I realize that I am the one that asked for help, but please understand that I am beyond the basics here. I have eliminated the rear shaft and the front driveline, trust me! I am fustraited and don't mean to bite the hand that feeds, but I was just wondering if anyone else had issues like this. At this point I am leaning toward the rear TC bearing.
 
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