finished OME lift - vibrations?

I just finished installing my 3" OME lift tonite. After talking to a rep at ARB (sat REAL high in rear), I filled Jeep with 350# worth of boulders and proceded to beat on it . I did not have any vibration issues at ANY speed . I wheeled it a little and then took the boulders out and remeasured the height. It was now sitting at 34" from garage floor to bottom of wheel well moulding all the way around (with boulders it sat 1-1/2" lower in rear and 1/2" in front.
Now I go for another ride and at ~65mph I start to get a little vibration from rear. At 70mph to 75mph, it is more pronounced but not too noisy (it does pick up a little upon accelleration from 65 to 75 mph). At 80 to 85 mph it appears to be gone. I'm running 31 x 10.5 x 15 ProComp AT's (30" tall ) AW4, 242, and stock otherwise.
My question: Does anyone think that I may get away with a 1/2" TC drop vs going the full inch?....since my vibrations only appear between 65 & 75mph. This gives me an extra 1/2" clearance and doesn't change the front angles too much either. Has only 1/2" been tried before?

Thanx for your continued input,
BLUTO

BTW: LOVE that new OME lift :loveu: and steering stabilizer! Nothing seems to faze it now! The poly bushings make a little "flex" noise on the bumps and dips, but smooth and quiet otherwise

what year?

if it is post 97 then you might need to shim the rear springs and/or the full tc drop.


why did you use poly bushing?.. you are supposed to use OEM rubber bushings.

another option is too add a small spacer to the front and add some MJ shackles to the back.. that may rotate the pinion enuff to fix the vibe.

what year is your xj? what t-case/tranny/rear end combination do you have?
Also do you have shims in the rear? how does it look when you look at the tcase output vs the rear axle output angles? Kind of parallel but steep angles between each other? or not?

Kejtar

I'd try a 2° shim in the rear (thin end forward). Also be sure your tires are balanced (this is often the culprit)

RJ

Sorry,...forgot to post year and axle (2000 and 3.55,AW4, 242, and D30 front/D35 rear).
No I haven't shimmed it yet, I think that's where I try out several different shims 'till it's gone OR does somebody have a formula to take the guesswork out of it?
I didn't know that Urethane bushings were verboten!? Seems like a lot of other guys use them and like them. I figured there would be a little extra noise, but it shouldn't affect vibrations. I also plan on using them on my sway bars. The only time I hear them is on rough roads, 90% of my driving is on pavement.
Tires are brand new and balanced, though the tire guy said that one tire didn't balance-up perfectly, it is on the rear. I have my old stock tires/wheels still. I can put them back on to see if the vibrations go away (they are 2" shorter in diameter than my 30" tall new ones). Would that affect my pinion angle and fool my experiment to eliminate bad balance as cause?
The axle and TC yoke angles are fairly(by eye) close to each other in angle. Though, there is a slight bend in angle between pinion/axle yoke and driveshaft yokes. By shimming 2*or 3* I may be able to make everything straight? Any good technical write-ups (with pics) that you can direct me to?
Thankyou for your continued support, I'm going to send in my membership fee and become an "honest wheeler" :angel: ....hope you guys take PayPal,

BLUTO

I'm ran a 2° shim at 3 and 4" of lift, worked out for me very well. You can also get an angle finder from Home Depot and find out excactly what you need. I wouldn't think more than 4° but 2 is a nice starting point.

I hav a XJ withe teh same specs as yours (2000, AW4, NP242, 3.55). It has 3.5" in the rear. I tried several sets of shims and even tried to measure the angels to get the right set of shims. No luck.. vibes were still present. I got an SYE and that took care of it. Don't know if a TC drop would do it for you or not. I also drove around with vibes for about 6 montsh with no ill effects to date. BTW, you figure out how much lift you have by measuring from the lower edge of teh fender flare to the center of the wheel, than subtract those abount from stock measurements in the same locations. Stock measurements are 17.5" front, 17" rear.

-Chris

Very true, a SYE kit and CV driveshaft will indeed cure what ailes him, but there's a good chance he'll need to shim regardless.

TOZOVR said:

Very true, a SYE kit and CV driveshaft will indeed cure what ailes him, but there's a good chance he'll need to shim regardless.

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Oh yeah.. I didn't say he didn't need to shim... I have 2.5* shims in mine with teh SYE.

-Chris

finished OME lift

Did you guys have vibrations at most speeds or just at a certain speed? As I said earlier, I had NO vibrations at ALL speeds when vehicle was loaded down and dropped 1-1/2" in rear.
I can see how the driveshaft-yoke angles are a little off right now and hope the shims will bring it back in-line. Did adding the shims create any noise from vibration or rubbing?....Did you do anything special to them when you installed them?

BLUTO

BTW...can you describe the noise of your vibrations (ocillating? humming? grinding? high pitch?)
Mine occur under accelleration between 65 & 75 mph OR at a steady state speed of 70 - 75 mph.

I would call mine an "oscillating drone"!

I have a 2000 also and what worked best for me was to install an AA HD SYE and Tom Woods driveshaft before I even lifted. Best $500 I've ever spent too. :angel:

what is an OME lift? what does that stand for?

finished OME lift

OME .....(not to be confused with OEM: original equiptment manufacturer).... stands for Old Man Emu. They are the suspension division of an Australian company (ARB), that makes a LOT of quality aftermarket parts for 4wheel drive vehicles from all over. The OME suspension is top notch , in my 24 hours of driving on it....and many other peoples opinion on this forum. They are a little bit pricier than your average lift kit, but you definately get what you pay for!
BLUTO

Re: finished OME lift

BLUTO said:

They are a little bit pricier than your average lift kit, but you definately get what you pay for!
BLUTO

Click to expand...

Then I think you ought to pay more for an SYE.

Seriously I can't believe some folks have newer XJs lifted over 3" and no SYEs, especially when they spend extra $$ to get a OME. Plus you should see the AA output shaft compared to stock!

finished OME lift

I have read that some people NEVER have vibrations after a lift of >4", while some people get vibrations at <2" of lift .
Each vehicle is somewhat different than the next. I will START with $15 worth of shims and if they are still there, drop TC and if that doesn't work...SYE No need to go to the most expensive solution first, if the others do the job properly. My rig is not a "Bogger" or RockClimber....just a daily driver with a little offroad thrown-in on occasions.
If I can avoid having to install a SYE, then I'll be in a better $$$ position to get some posi's and gears.

BLUTO

Bluto, I have a 98XJ and I thought the same as you did.... now finally after I put on the SYE, I will have to say that it rides better then it did stock! Also if you got good droop in the rear, make sure that you're not going to drop the shaft when you articulate.

Kejtar

Re: finished OME lift

BLUTO said:

I have read that some people NEVER have vibrations after a lift of >4", while some people get vibrations at <2" of lift .
Each vehicle is somewhat different than the next. I will START with $15 worth of shims and if they are still there, drop TC and if that doesn't work...SYE No need to go to the most expensive solution first, if the others do the job properly. My rig is not a "Bogger" or RockClimber....just a daily driver with a little offroad thrown-in on occasions.
If I can avoid having to install a SYE, then I'll be in a better $$$ position to get some posi's and gears.

BLUTO

Click to expand...

Yes, but the SYE isn't only to elliminate vibes.. it is to relieve stress on teh transfer case's out put shaft and out put bearing.

-Chris

Just finished a 3" lift on my '01 XJ, and I too had a bunch of weird vibrations on the fore and aft sections of the driveshaft under accl. and decl. Trust me, add the T.Case relocation kit from Skyjacker and your troubles should be minimal, mine were. You could also make it with square box steel and save around $30. its simple. Good luck.

Kejtar is right on. I had my OME at 2.5" for awhile and I thought it was nearly silent on the road. After I went to 3.5", there was some noise, but it was tolerable. Once I got the SYE on I could not believe how much smoother and quieter it was. You get used to noise pretty easy driving a Jeep, so you probably think you have no vibes. The harmonic vibes that you don't 'hear' or 'feel' to be excessive are still slowly but surely shaking, and ruining, your driveline. Just get the SYE. I went with an RE hack and tap and got it with the shaft for about $350, and it is worth twice that much. You should pick something besides your driveline to cut corners on. My $1.73.