Rubicon Express Lift Made Incorrectly?

alexgalexg

New member
1998 Jeep Cherokee XJ Sport 4wd AMC 4.0 I6

Rubicon Express 3.5" Super-Flex short arm with monotube shocks
IRO track bar
advance adapters SYE with 6*shims under leaf springs

Adams extreme series rear drive shaft

Flowmaster Super 44 High glow exhaust



So I have noticed some annoying vibes when going over 63 mph. This is with my sliders maxed out with no spacers. :dunno: Did I mess something up? Or do they sell us kits with useless parts that are one size fits all. I would believe that from Rough Country but not Rubicon Express.

(Yes it is my front drive shaft making vibes I removed it and have nothing even during a test going up to 85mph)



So did I botch something, any tricks to fixing this issue? If not a recommendation for a solid set of adjustable lower controls that can survive off road and winter salt would be appreciated.
 

Tim_MN

Freakish Hand Strength
NAXJA Member
It would be logical to suppose that the front pinion angle is incorrect, leading to front drive shaft vibes. Measuring the front pinion angle and the caster angle will prove or disprove this theory. Your lack of knowledge or lack research prior to buying your lift kit parts is not the fault of any lift kit company.
 
Last edited:

alexgalexg

New member
It would be logical to suppose that the front pinion angle is incorrect, leading to front drive shaft vibes. Measuring the front pinion angle and the caster angle will prove or disprove this theory. You lack of knowledge or lack research prior to buying your lift kit parts is not the fault of any lift kit company.

Its a kit... The controls are not adjustable.... They dont ask about angles and wouldnt do anything with that information. They are Rubicon Express lower control arms that came in the same entire lift kit that I installed. They are designed to work with the exact lift I put on the car. The only thing that is my problem would be rear drivetrain angles which I resolved just fine by measuring for shims and ordering a custom drive shaft after installing my shims and sye.
 

ljobbins

New member
Yeah he needs to measure and post the angles, but he did say he changed the arms position with the adjustment bolts. Not sure if he did it right though.
 

alexgalexg

New member
Yeah he needs to measure and post the angles, but he did say he changed the arms position with the adjustment bolts. Not sure if he did it right though.

Pinion angle is visibly off. But I will post the angles on wednesday when I can next get under the truck.
 

RCP Phx

New member
Your lack of knowledge or lack research prior to buying your lift kit parts is not the fault of any lift kit company.
You going to hate the lift more when you find out that you should have purchased adjustable arms. Since you really didn't buy a "complete" kit and you took on yourself to select the components............
 

alexgalexg

New member
You going to hate the lift more when you find out that you should have purchased adjustable arms. Since you really didn't buy a "complete" kit and you took on yourself to select the components............
I dont hate the lift. Rides a little harder than stock but that could also be the fact that the old had 206k and this lift has only a few thousand. And again it was a kit. They do not sell a kit at 3.5 with track bar, sye, driveshaft and shims. The kit came with brakeline, sway bar links with disconnects, springs front and back, shocks, pucks and lower controls. I didnt order these things individually and the kit is not customizable.



You are the second person that has told me I have taken the liberty to go out of my way and not do things as intended but im failing to see at which point I did anything like that. Please explain
 

RCP Phx

New member
As already stated, if you did your homework right you probably would have purchased differently. I don't think any company sells a "all inclusive" kit that they will "guarantee" perfect results from. You could have purchased the individual components of your choice but in a "kit" price from someone like Dirk.
 

IslanderOffRoad

NAXJA Member
NAXJA Member
I ran the same kit on my 94 with no issues.

Every Jeep is a little different. That’s why the factory LCA adjusters exist. To get them into spec.

How’s the front shaft look overall? Bad joints could contribute to the vibe.
 

IslanderOffRoad

NAXJA Member
NAXJA Member
I would have suggested something like that, but considering it's a new shaft. I don't have any experience with that company though. TW I've dealt with many times.
The rear shaft is new.

He says the Jeep has 260k+, so if that front shaft has never been rebuilt it could be causing the vibe. Especially if removing it made it fine up to 85
 

trippled

NAXJA Member
NAXJA Member
The rear shaft is new.

He says the Jeep has 260k+, so if that front shaft has never been rebuilt it could be causing the vibe. Especially if removing it made it fine up to 85
Agreed. Especially since it is running at a higher angle now, it's very likely it has sticky u joints or double cardan joint. If it's all good you may just need to fine tune your angles.
 

Jim Malcolm

New member
I know absolutely nothing about the exact parts you have, but the fixed LCAs that I have from another company are slightly longer than stock to recenter the wheel after lifting it. At lower ride heights like where I'm at now (3.5"), it pushes the axle forward, extending the driveshaft. At stock height, there's ~3/4" of spline engagement in the front driveshaft with a NP 231 and about 1/2" engagement if you have a NP242. Take the front shaft and bottom it out completely. You'll see that the seal sits just about where the shiny metal stops and the rust starts, or where the two large diameter sections almost hit. Now install it on your XJ and measure the gap between the two. Subtract your measurement from 3" and that's how much engagement you have. It gets less when the suspension compresses. Kind of scary if you ask me. The aftermarket shaft I replaced it with has 6" splines (iirc) so no more worries about a driveshaft coming apart and getting shoved up my rear. No more vibes either. As a warning, I tried to have my oem shaft rebuilt, straightened, balanced etc. Spent more on that than I did the aftermarket shaft I had not choice but to buy after realizing the true problem.
 

alexgalexg

New member
As you can see, the angle is visibly off even from this crappy picture I took. Since it's not on the double cardon side it cannot have an angle to it. When I say the sliders are maxed out I mean they are pushed back all the way. Towards the rear if the vehicle. I am at work so I cannot get dirty on my back to measure it out today but here are some pics of what I'm talking about.


Sent from my SM-G950U using Tapatalk
 

alexgalexg

New member
I ran the same kit on my 94 with no issues.

Every Jeep is a little different. That’s why the factory LCA adjusters exist. To get them into spec.

How’s the front shaft look overall? Bad joints could contribute to the vibe.
Front drive shaft is good. I bought it certified pre tested. While I was waiting on my custom rear I was running stock front drive shafts front and rear. I was asking if the lower controls not fitting was due to my own error or if they made them all size fits none.

Since they are not proper fitting I now either need adjustable upper or lower controls. I was wondering if anyone had advice on how to either remedy this problem or a solid recommendation for some quality controls

Sent from my SM-G950U using Tapatalk
 

VAhasnoWAVES

New member
check your yokes at the axle and case for slop, if those are solid id look into adjustable uppers and possibly a castor measurement.

install the adjustable uppers without the driveshaft installed and remove castor (point the pinion up) until you get undesirable on road wandering (typical of too little castor). reinstall the driveshaft and see how it is. if you still have vibes, you can use the adjustable uppers and factory castor adjustment on the lowers to push the axle forward to help with the driveshaft angle.

as stated, every vehicle is different. youll have to play with it to get things perfect.
 
Top