Bad Vibes

[Shadly1]

Seeing that this thread has taken a down turn from happy new lift pics to bad vibes:poop:, I guess I'll start up a new one under a more appropriate heading:mad: The input is appreciated . . . please keep it coming as I need to get my Jeep back on the road ASAP . . . riding my motorcycle to work sure is risky in rush hour traffic!

Hey Schmo... you're jeep looks damn good You'll get it dialed in, don't worry.

[Schmo]

Bad Vibes

Well, I guess I was too quick to get excited and post up pics of my new lift as the discusson quickly turned from how cool it looks to bad vibes. I have a 2006 TJ Rubicon . . . over the weekend we installed a Full Traction 4" lift with new lower fixed control arms (keeps the stock uppers), springs, adjustable track bar, F/R track bar brackets, drop pitman, etc . . . we also put on 33" tires on 15" wheels, and a Tom Woods Rubicon Rear Driveshaft (double cardan). I noticed that once the lift and tires were installed that there was vibration when accelerating above 25 MPH with both the stock and new driveshafts. I took it to the shop today, hoping (but sensing otherwise deep down) that the required alignment and a little adjusting here and there would do the trick. My driveshaft angle is apparently the culprit. Looking at it now, the angle of the driveshaft and where it connects with the diff are not the same (the diff is angled up creating a slight "V" shape). I've got the Rubicon Express rear upper adjustable control arms ordered and will hopefully be able to have them installed on Friday and am just hoping that will be the final cure. I'm waiting for a call back from Full Traction on whether or not I'll have to install the transfer case drop as well . . . I really hope I can avoid this as lowering my belly goes completely against what I was trying to accomplish in the first place, why I bought the new drive shaft, etc. Does anyone know if the new upper adjustable control arms will correct the problem? It seems (but I'm no expert) like it would correct the angle issue where the diff connects to the driveshaft, but that won't address the angle from the trans to the driveshaft where the double cardan is . . . I'm not sure if that matters or not. If anyone knows about this and could shed some light on it, that would be great!!!

[Schmo]

This is how it is supposed to look . . .



This is what my new driveshaft looks like . . . you can see the pinion angle is off. So it looks like I need longer uppers to kick the front of the diff up and get it to match the angle of the driveshaft. I need to know if the angle at the Trans to the Driveshaft also needs to be addressed or if that's fine.

[RAT]

Joe,
I've not read here where anyone has mentioned the FRONT drive shaft. It's angle has changed as well. Do this simple test: Take the front drive shaft off at the front Diff, wire it up out of the way and go for a drive.

Kurt

[Shadly1]

Does anyone know if the new upper adjustable control arms will correct the problem? It seems (but I'm no expert) like it would correct the angle issue where the diff connects to the driveshaft, but that won't address the angle from the trans to the driveshaft where the double cardan is . . . I'm not sure if that matters or not. If anyone knows about this and could shed some light on it, that would be great!!!

Those adjustable UCAs should correct your vibe issue. When the back end of a CV shaft is out of align, the whole shaft has a tendency to flop to one side or the other and create an unbalanced load. The double cardan portion of the driveshaft can handle much more angle than you're giving it. It's the single cardan portion at the rear that needs fixing. If I was in your position, I would have done the exact same thing you did and ordered those adjustable UCAs. My feeling is that it will be a night and day difference when you get that diff angle handled.

[Schmo]

Those adjustable UCAs should correct your vibe issue. When the back end of a CV shaft is out of align, the whole shaft has a tendency to flop to one side or the other and create an unbalanced load. The double cardan portion of the driveshaft can handle much more angle than you're giving it. It's the single cardan portion at the rear that needs fixing. If I was in your position, I would have done the exact same thing you did and ordered those adjustable UCAs. My feeling is that it will be a night and day difference when you get that diff angle handled.

Keeping my fingers crossed and hoping that does the trick. I contacted Rubicon Express who I ordered the UCAs from and Tom Woods who I got the drive shaft from and they seem to think that the Adjustable UCAs will do the trick without lowering the belly pan. Tom Woods didn't think that the angle from the trans to the shaft should be a problem as the double cardan can handle an angle up to about 35 degrees before binding and said that the shaft I have can be used up to a 5.5 inch lift.

Just spoke with Full Traction and he shed a bit more light on the issue at hand . . . apparently when you go to a double cardan drive shaft, it requires that you also change the pinion angle as this type of drive shaft requires the angle of the pinion to match the angle of the shaft instead of matching the angle of the trans like in traditional set ups. Therefore, it will require the longer upper arms to kick pinion up. At this point, the only question is whether or not the adjustable arms will be long enough, but according the folks I've spoken with, they should, in which case I will not have to drop the T-Case.

Too bad I need it to actually run . . . sure looks great!!!

[womb raider 940]

Joe,
I've not read here where anyone has mentioned the FRONT drive shaft. It's angle has changed as well. Do this simple test: Take the front drive shaft off at the front Diff, wire it up out of the way and go for a drive.

Kurt

should the front driveshaft have the same angle as well as the rear?

[Shadly1]

should the front driveshaft have the same angle as well as the rear?

Single cardans are more forgiving as far as angle but you're limited to about 15* max. The front shaft is nice and long so it won't bind as easily as that rear. It would be nice if the front pinion was pointed right at the T-case, but proper caster is more important than perfect pinion angle.

[Schmo]

Single cardans are more forgiving as far as angle but you're limited to about 15* max. The front shaft is nice and long so it won't bind as easily as that rear. It would be nice if the front pinion was pointed right at the T-case, but proper caster is more important than perfect pinion angle.

Yeah the whole Caster issue came up too when I had it aligned . . . it was at 5.2* which I guess is not good, but I've got bigger fish to fry with the driveshaft issue! It sounded like the Caster being undesirable will not mess up the Jeep, but affect the quality (or lack there of) in handling and make the Jeep wander a bit. Does this sound right? The guy at the shop didn't seem too worried about it and didn't seem to think there was a whole lot I can do about it . . . kinda like the fact that one of my rear wheels is towed in a bit . . . uhhhh how'd that happen???:dunno:

[Shadly1]

Yeah the whole Caster issue came up too when I had it aligned . . . it was at 5.2* which I guess is not good, but I've got bigger fish to fry with the driveshaft issue! It sounded like the Caster being undesirable will not mess up the Jeep, but affect the quality (or lack there of) in handling and make the Jeep wander a bit. Does this sound right? The guy at the shop didn't seem too worried about it and didn't seem to think there was a whole lot I can do about it . . . kinda like the fact that one of my rear wheels is towed in a bit . . . uhhhh how'd that happen???:dunno:

Caster should be somewhere between 7* and 9*. 5.2* won't kill ya, but it will wander around a bit. 8* will snap to center pretty nicely. You can deal with that later with adjustable front control arms.

The toe was off due to the lift. The angle of the drag link and tie rod changed because you have that goofy TJ setup You'll probably have to set the toe again in a few months after it settles.

[scherf68]

Upper control arms are needed to adjust the pinion angle in the rear. That was my problem when I went to sye and it corrected it.

[Schmo]

The toe was off due to the lift. The angle of the drag link and tie rod changed because you have that goofy TJ setup You'll probably have to set the toe again in a few months after it settles.

It's my rear driver that is toed in 0.38* the rear passenger is at 0 . . . very wierd! Musta hit a big rock on that one

[mrchips]

Schmo, if you have to have the alighnment done again, Find a Firestone tire shop, They offer a lifetime free alighnment for you rig for about $180. It is a great deal

[Schmo]

Schmo, if you have to have the alighnment done again, Find a Firestone tire shop, They offer a lifetime free alighnment for you rig for about $180. It is a great deal

You know I'd heard that from someone, but then heard you have to find the right shop/guy as some won't do it quoting some technicality about bigger tires or off road vechiles or something . . . which one have you had good luck with?

[Shadly1]

Schmo, if you have to have the alighnment done again, Find a Firestone tire shop, They offer a lifetime free alighnment for you rig for about $180. It is a great deal

Jeeps are just a front toe set. A Jeep alignment shouldn't be more than $55 or so. I guess if you are always going to go to that Firestone shop and you plan on keeping that Jeep for a long time, it's a good deal. It will be a lot of years before you break even or come out ahead with that one.