tell me whats going on when i hear this noise

sorry i think this is common question but i searched and could only find stuff on driveline vibes, not exactly this problem

just put on 3.5 in lifton my 01 xj, drives good, minimum vibes, not enough to the point il pay $$$ for an sye

but when im going on the highway and i let off the gas, and im not pushing on the break or doing anything, i hear a weird rubbing type noise, sounds almost underneath the center of jeep not towards rear diff

doesnt worry me too much but can someoen describe what this is and if i need to do something asap or if it could hold off

thanks and again sorry prolly common question but i did search first

Theres no such thing a "minimal" vibes,sure sounds like a SYE kit is needed.

RCP Phx said:

Theres no such thing a "minimal" vibes,sure sounds like a SYE kit is needed.

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well i was told every jeep is different some are out of control and some is driveable

too me i barely feel it only way i tell it is vibrating is the rear view mirror is jumpy as i look into it, i dont feel it tho


im more worried bout the weird rubbing noise while not accelerating or breaking

If your rear view mirror is bouncing that is more than a little vibes...Vibes like that will wear out seals and bearings in your transfer case quickly...You either need the ghetto fix transfer case drop or the real fix and SYE...

dont mean to hijack but i have a very loud grinding noise whenever i let off the gas. kinda sounds like its in the same spot as the op

We did a re 3.5 (with full packs)on my old mans jeep without a sye. The front yoke was actually contacting the driveshaft yoke. We clearanced it and made it "better" . The horrible noise is probably the lack of spline engagement of the slip yoke into the trans. not good. save up for a sye.

Interesting thread, I'm going through the same stuff. RE 3.5 and TC drop but still a hum at 40-50 and loud flutter when easing off the gas. Sounds like we're having similar problems Heep. I have the RE hack and tap SYE but waiting on installer to have time for it. I'll post results once it's done.

im really hoping its the axle or gears and not the tcase because im swapping my axle out soon anyways and i dont plan on swapping a tcase anytime at all

After my 4.5" lift, 1" transfer case drop, and 32" tire install everything was smooth as silk. After about 3 months I started getting really bad vibrations. I noticed it most as I was coming to a stop.

One day after driving over a light colored dirt every other lug was clean on the inside of the tire. This was true of both front tires.

I went to the tire store and had them rotate and re-balance them. There wasn't anything they could do about the un-even wear, but moving the front tires to the back really helped the vibration problem.

Now after a year of driving on the tires the vibration has mostly gone away, it gradually got better as the rear tires wore even.

I get a cycling vibration at about 60 mph to 70 mph. It does vibrate the rear view mirror.

Do I think a SYE would help? Sure, do I think it would get ride of all the vibrations? No, new rear tires is what it will take to fix that.

Maybe a few burn outs.

NJblackdeath4x4 said:

im really hoping its the axle or gears and not the tcase because im swapping my axle out soon anyways and i dont plan on swapping a tcase anytime at all

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sounds like ujoints binding when the pinion changes.

lift doesnt have an effect on the gears or axle except changing the pinion angle. but when lifting the angle of the driveshaft changes and that has an effect on the transfercase seal and bearings along with the ujoints. i would say its not the gears or axle. if the sound is from the rear axle, it could be the pinion bearing.

Can someone please describe what mild driveline vibes sound like?

I recently install an RC 3" lift which is sitting about 3.75 inches lift right now, on a 2000.

I can't feel any vibes, nothing through the steering wheel, pedals, butt. No mirror shake. What I do get is a very low, almost subsonic, resonating hum that fades in and out. I seem to get it around 30-35 mph. Almost sounds like the exhaust at low RPM, but it doesn't change with engine rpm. Also happens more pronounced when I accelerate. Or seems to be. I might just be imagining the whole damn thing...

So some describe what driveline vibes sound/feel like!

I have had a 6.5 inch lift on my 98 for over a year and at least 30k miles with nothing done to the driveshaft or transfercase, which im about to drop, and i havnt had a problem with anything other than some vibration when accelerating.

Id bet it is a drive line vib. Make sure all your u-joints are tight, and the cv on the front shaft is tight. If you grease the cv and it temp. gets a little better then thats what it is.
If you have vibs put shims under the rear axle. If thats not enough get a t-case drop. With 3.5" even on a new model there is no reason for a SYE.

As promised, a post SYE install report: Had the RE hack and tap installed on my NP231. The "flutter" or "thump" on accelerator letoff, which presented immediately after RE 3.5 lift install, is now 100% gone. The shop had forgotten to remove TC drop spacers, but on first test drive zero vibes. Like butter. After TC spacers removed, maybe a little vibe, maybe my imagination. Flutter still 100% gone. Might need to shim pinion up a hair. Wish I could tell you what was thumping, but SYE kit killed it.

FWIW :dunce:

lokiju said:

As promised, a post SYE install report: Had the RE hack and tap installed on my NP231. The "flutter" or "thump" on accelerator letoff, which presented immediately after RE 3.5 lift install, is now 100% gone. The shop had forgotten to remove TC drop spacers, but on first test drive zero vibes. Like butter. After TC spacers removed, maybe a little vibe, maybe my imagination. Flutter still 100% gone. Might need to shim pinion up a hair. Wish I could tell you what was thumping, but SYE kit killed it.

FWIW :dunce:

Click to expand...

thumping may have been the slip yoke on the transfercase splines.