Bad Vibes

[Schmo]

Probably pinion angle. Take some pictures of your pinion angle. Did you guys take time to adjust the rear upper control arms?

Vibrations on acceleration usually mean too high of an angle.

The kit I used only came with lower control arms (fixed). Can the stock uppers be adjusted? I was expecting to get around 3.5" overall seeing that I had a 2"BB and 31's with about 25% tread left and now have the 4" lift and new 33's...but I noticed that the difference is actually more like 4.25". Could it need a bit of time to settle?

Here's some pics of the new driveshaft:

[SIZED]http://i272.photobucket.com/albums/jj173/schmojoe/DSC00440.jpg?t=1207541529[/SIZED]

[SIZED]http://i272.photobucket.com/albums/jj173/schmojoe/DSC00441.jpg [/SIZED]

[SIZED]http://i272.photobucket.com/albums/jj173/schmojoe/DSC00442.jpg?t=1207541636[/SIZED]

[Geebo]

Joe, Looks like a totally different Jeep...Looks great..sorry I didn,t make it over today my empty day with no plans got filled up quickly somehow(girlfriend) anyway I,m glad you,re ready to get back out on the trails..Great work all you guys...Geeb..

[maddmike]

with that height lift i believe you will need to adjust the pinion angle, i believe upwards but you should consult someone who actually knows.

i also believe that in order to properly adjust everything you will need both adjustable lowers and uppers, because as you make the uppers longer than stock to point the pinion up, you will also need to pull the bottom of the axle in so that you retain the correct wheelbase and driveshaft length. i don't think it will work with only the uppers, and i also believe you will destroy your pinion gears if you leave it the way it is for more than a short while.

but - i'm not an expert. someone who has done this before can probably chime in and advise.

regarding the height of the lift, it will definitely settle out and break in, but it may not go all the way down to 3.5". each lift has a different "break-in" period. mine broke in after a few heavy wheeling trips and i could notice a definite difference in the springs and they became less "jittery". now, after about 16 months, they ride very well without any weight in the vehicle. overall they have hardly settled and i'm still at about the same height i was when i put it on (well...the winch has weighed the front end down a bit but that's not the lift)

[Shadly1]

Yeah, pinion angle. CV shafts don't like that. You may need to pick up some adjustable upper control arms to dial that thing in a little better.

[womb raider 940]

He said before was acting this way as well. So I dont think it has anything to do with what was installed. I drove it after and is a little noticeable around 25 mph and 2800 rpms. The new driveshaft is a woody a tom woods that is.

[Schmo]

i also believe that in order to properly adjust everything you will need both adjustable lowers and uppers, because as you make the uppers longer than stock to point the pinion up, you will also need to pull the bottom of the axle in so that you retain the correct wheelbase and driveshaft length. i don't think it will work with only the uppers, and i also believe you will destroy your pinion gears if you leave it the way it is for more than a short while.

Is this right? Most the kit's I've looked at, unless you buy the most expensive option, offer the lower fixed control arms and either reuse the stock uppers, or for a price, come with adjustable uppers but still come with fixed lowers. At this point, I'll have to do whatever is needed, but know several guys with the same basic set up . . . 4" lift w/ stock uppers running 33's without any issues, which was why I was hoping it was just something having to do with the alignment, new tires, or just needing some weight on it for more than 15 minutes to settle a bit.

He said before was acting this way as well. So I dont think it has anything to do with what was installed. I drove it after and is a little noticeable around 25 mph and 2800 rpms. The new driveshaft is a woody a tom woods that is.

I noticed the same vibration with the stock driveshaft after the lift and new tires were installed and the vibration is still there now with the new driveshaft.

[maddmike]

you should consult someone who actually knows.

joe, i wasn't sure, i was hoping someone that knew would chime in

everyone's jeep is different so it's possible that yours will not perform similarly with the same mods as someone else's. the vibes do not have anything to do with the tires or the alignment, they are exclusively caused by the pinion angle being incorrect. true that after "settling", it will change the pinion angle, but it will only change very very very slightly and probably won't be enough to get rid of the vibes. if you already had them with the 2" BB then you will continue to have them until your lift "settles" to less than 2", which is not ever going to happen.

[mrchips]

Looks great, will make all the difference on the trail.

[Schmo]

the vibes do not have anything to do with the tires or the alignment, they are exclusively caused by the pinion angle being incorrect. true that after "settling", it will change the pinion angle, but it will only change very very very slightly and probably won't be enough to get rid of the vibes. if you already had them with the 2" BB then you will continue to have them until your lift "settles" to less than 2", which is not ever going to happen.

I did not have the vibes with the 2"BB...just since the new lift and tires were installed.

[Materdaddy]

My uncle is using his stock upper arms with a 3.5" lift. To adjust his pinion angle they 'wollowed out' the frame mounted bracket holes. I don't like this approach, but it is an option if you don't want to spend a little more on upper adjustable arms.

Your pinion angle looks low from the picture, but again, ask an expert, not me!

[womb raider 940]

My uncle is using his stock upper arms with a 3.5" lift. To adjust his pinion angle they 'wollowed out' the frame mounted bracket holes. I don't like this approach, but it is an option if you don't want to spend a little more on upper adjustable arms.

Your pinion angle looks low from the picture, but again, ask an expert, not me!

I wouldn't hollow out the bolts. I am waiting for someone to throw up some affordable used ones on the forum. I too have a lower control arm lift with no probs though. I just want to change to aftermarket ones.

yeah pictures are never that great. Joe read up on this. also ask tom woods CR and see if they can point you in the right direction. after all they are in that business.


ALSO REMEMBER LIKE WE SAID THE LOOSER THE BOLTS THE MORE FLEX YOU WILL HAVE :wink:

[womb raider 940]

hey joe can you get a better side pic not tilted. I don't remember it being that bad.

[dadasjp]

Here's my two cents: First, get a professional opinion from someone who actually can see the jeep in person. Second, here's my best guess of what you might be facing: often times when a kit of your size is installed you see the shop/owner also doing a tcase drop to re-create the angle b/n the tcase and diff as it was when stock. You said you noticed no issues with the 2" BB lift, which I am assuming was a body lift? If so, when you did the lift no angles were changed b/n the tcase and diff and therefore no binding. If it was 2" longer springs or spacers, you might still have been okay, but closer to the edge of a tolerable angle change and the new kit may have pushed you over that edge. This would also explain why you had issues with both drive shafts. Often times the kit manufacturers don't point out that a t-case drop may be needed b/c then you'd buy someone else's lift kit with the adjustable arms, especially since after installing the kit to get clearance you give it right back with a t-case drop. They're more of the mind of do what fits the bigger tires for looks or mud, not that you're going rock crawling and are really concerned about clearance. Sometimes you'll also see a new driveshaft help the problem, but you've already done that, so you may just have to pop for control arms or do the drop. FYI, Currie sells a full kit of adjustable control arms with re-buildable joints, kind of pricey, but it's cheaper than buying another lift. Just my two cents....

[Shadly1]

This is from Tom Woods' site.

[womb raider 940]

This is from Tom Woods' site.

BB stands for budget boost not body lift.
yeah I just left his house. he does need upper control arms will fix his problem. we found that diagram with the driveshaft instructions.