Hi Everyone,

I installed the OME LT kit purchased from David at Northridge. I don't have a lot of road time on the JK yet; but, so far it feels good to me.

There has been so much written about death wobble and its causes that I thought it might be interesting to know some particulars about those OME LT kits (and other 3" kits +/- 1/2") which might provide useful information to others setting their rigs up.

The biggest variable seems to be caster. Factory specs are 4.2 degress +/- 0.5 degrees. I currently have 4.2 (L) and 4.1 (R) on mine. I adjusted the eye-to-eye distance for the front upper control arms to 18-1/2" (from an OEM distance of 18-3/4"). Shortening the arms made up for the difference in caster caused by the lift height, or so it would make sense. I have read that caster greater than 5 degrees is preferred by many posters, even up to 6 degrees and above. But, there is always the concern that increased caster will cause driveshaft vibration problems, so it is a fine balance.

The following are questions that may be helpful to others if you have a similar lift, and if you have taken it to an alignment shop for validation. It should also be clearly stated if death wobble (or anything similar) and/or driveline vibration is a problem. (If either was a problem at any time, a brief explanation of the fix used by you would be helpful, too.) I will list my information below for reference.

1. Caster (Left and Right): 4.2 (L) and 4.1 (R)
2. Tire Diameter: 32" (Stock Rubi Tires and Wheels w/1-1/2" Wheel Spacers)
3. Tire Pressure: 37 PSI (Est.)
4. Adjustable Upper Control Arm Settings (Eye-to-Eye Distance): 18-1/2"
5. Lower Adjustable Control Arm Settings (Eye-to-Eye Distance) (If Installed): Not Installed
6. Toe-In Specification (If Changed from OEM): Not Changed

Based upon what I have been reading, I wouldn't be surprised if I experience death wobble (or related issues) when I go to 35" diameter tires and when I lower the air pressure.

I would really be interested to hear from anyone running a similar kit but who is running 35" tires at lower air pressures. The caster details would be especially great to know. (The information provided here could also be expanded to include the complete wheel and tire dimensions, as well as the backspacing of the wheel.)

Any feedback will be appreciated.

Thanks

Jeff

 

I have the 2" OME HD springs which gave me about 3.5" of lift with the following settings:

1. Caster (Left and Right): 6.0 (L) and 6.0 (R)
2. Tire Diameter: 35"
3. Tire Pressure: 30 PSI
4. Front Upper Adjustable Control Arm Settings (Eye-to-Eye Distance): stock
5. Front Lower Adjustable Control Arm Settings (Eye-to-Eye Distance): 23"
6. Toe-In Specification: Not Changed

I also have a JKS adjustable front track bar. I have never had any death wobble or driveshaft vibration issues at all and it rides great.

 

I'm curious about this statement:

As all the posts and comments I've seen about death wobble concerned bad/loose steering components (90+ percent of which seem to be trackbar related), I'm wondering where you got the info about tire size and/or pressure being a cause?

Pretty much the answers have been along the lines of - trackbar is loose, crank down the bolts. Trackbar bushings are bad, replace them and crank the bolts.

Anyway, old fashioned OME kit + spacers = 4" lift, and 34's. Tire pressure has been anywhere from 50lbs (from the shop new) to 30-35lbs (normal running pressure) down to 15-20 (offroad)

at stock caster with stock CA's - no DW (with lift, but before adj ca's added)
at 3.5 caster with adj upper CA's - no DW (very very flighty - shop installed and ignored my request for 6deg...)
at 5.5 caster - no DW (great handling)

The trackbar bolts were cranked down when I installed the lift, and I'm happy to report that I have not experienced the dreaded Death Wobble...

 

Hi nthinuf,

Thanks for posting your information.

I haven't read all of the death wobble threads in detail; but, I believe that I have read references to both of those factors (tire diameter and pressure) as contributing to specific instances. Because there are so many variables, maybe factors such as these only exagerated the problem, making it hard to ignore.

I am not saying that it will happen when I go to larger tires, or when I reduce my air pressure; but, I have mentally prepared myself for the possibility. If it happens I am planning on cranking the upper control arms in to get more caster. I just want to make sure that I maintain a balance between drivability and driveline reliability.

As difficult as it is to really crank down on the trackbar bolts with the JK on the ground, I can understand how those fasteners aren't always torqued to spec. Although I doubt I'll be wrenching like this into my late 60s or 70s, I am a lot more comfortable doing this kind of work myself as opposed to relying on a shop to do it the right way each time. I used to have a hard enough time just getting the tire dealer to torque the wheel lugs properly.

If I'm wrong about the tire size and pressure factors, I will edit my original post as I receive more feedback.

Thanks

Jeff

 

I have an '07 Unlmtd. 3" Zone lift. Running 35 x 12.5 x 18 Toyo MT's on 18 x 9 Procomps.

1. Caster (Left and Right): 7 (L) and 7 (R)
2. Tire Diameter: 35"
3. Tire Pressure: As high as 42 on hwy and as low as 20 offroad
4. Adjustable Upper Control Arm Settings (Eye-to-Eye Distance): Not installed
5. Lower Adjustable Control Arm Settings (Eye-to-Eye Distance) (If Installed): Curries set at 23 1/4", was at 23 1/8" moved them out a touch.
6. Toe-In Specification (If Changed from OEM): Not Changed

When I installed the lift I noticed the flightiness of the steering. Adding 35's made it worse. The adj LCAs made all the difference. Set the caster at 6 deg and handling was very good. Set it to about 7 deg. this past weekend and feel it is better. If I get any driveline vibes, I will adjust it back. I do not have an adj. trackbar, but am planning on getting one. Also planning a steering stabilizer. At this point, I feel my Jeep is as dialed in as it can get.