pmedicj

Ok,

2010 2dr rubicon

Ever since installing a Teraflex 2.5 coil lift (4dr springs) I have had some bad rhythmic driveline vibrations at around 40mph and then again at 50-65 mph!

Had this problem with stock driveshafts tried adjusting the Teraflex front lower control arms with no effect.

Replaced driveshafts with Coast shafts = Same driveline vibration.

U joints all seated correctly also

when I replaced them I took a drive with the front DS out and smooth no vibes! Put the front in and vibes are back. Adjusted control arms to no effect and my front lowers right now are set to stock length 22 5/8"

I had the tires balanced x2 and had an alignment done x2 no effect!

Axles are centered perfectly! Could shifting them one way or the other correct this problem? it seems to get worse at a half tank of fuel which I think is weird.

I am at a complete loss at this point and desperately need help!

attached rear and front pinion angles, sorry for the sideways photos. rear = 12 degrees at pinion and 12 at DS angle

front is set with angle finder right now at 5 degrees caster LCA are set to factory lengths 22 5/8" and can only go 2 turns shorter on control arms when they were set at 22 3/4" with stock DS caster was 4.2 and 4.4 why does it seem like the caster grew when I went shorter with the LCA?

Also I did notice that I have some slight side to side up down movement on the yoke at the front output of the transfer case and was told that a slight play is normal?

pmedicj

it happened with the stock driveshafts also, So I can't blame the coast shafts yet.

If I lengthen the control arms that is going to put more of a negative angle on the u- joints and cause a worse vibration tired that.

mkjeep

Well, if you take the ds out and that takes the vibe away, it's the shaft or yolks. Are your yolks to proper torque? It is pretty common to have to either re-balance these aftermarket shafts.took me 4 different shafts from two different companies to get a properly balanced front shaft.
U did mention up and down movement in the tcase yolk, how much? Is it minute or obvious?

pmedicj

I just checked the play in the front yoke against a new jeep on the lot and it is not much more than one with 0 miles on it.

Funny thing is that it has done it with the stock driveshafts and the Coast shafts with replacement yokes.

the only thing I can think of is that I need to decrease my caster and point the front pinion up more, but I am already under stock control arm length now ( a hair under 22 5/8")

Or maybe my trackbars are placing a horizontal bind on the shafts? Axles are centered but maybe favor one side over the other?

mkjeep

Thats very odd. You shouldn't have to go with a shorter than stock length on those arms for the amount of lift you have. When you've adjusted your arms before, did the vibes move to a higher/lower speed than before you adjusted? Thats one way to tell if the castor is affecting the vibes.

pmedicj

yes they did move a little bit.

I have no idea where my caster is now but when I had the control arms set to 22 3/4 I had a caster of 4.2 dr 4.4 pa and had the vibes

I changed DS and have adjusted the lengths/angles with no help and am currently at stock lengths on LCA's

I think I can go maybe 2 more turns in on them now, Funny thing is my angle finder reads between 4 and 5 degrees for caster even with my arms at stock length it seems like with the shorter arms my caster grew from when i had them set at 22 3/4 and my angle finder was on with the alignment shop. maybe the springs have settled a bit but it has done nothing for the vibes. or maybe by taking the bolts out so many damn times I actually grew the bolt holes

I am going to set it shorter and shoot for 3 - 3.5 according to my angle finder tomorrow and get some better tolerance bolts.

mkjeep

Hmm, all in all, I'd still get the ds checked for balance.
Did you go through this many adjustments with the stock driveshaft and end up with the same results.

Edit: nevermind, I re-read 1st post.

pmedicj

yeah same issues with stock and aftermarket DS and only started after lift.

The lift consists of Teraflex 2.5 (4dr) coils, 1/2" rear spacer, bilstein 5100 sized for the lift, Teraflex monster track bars, front LCA and Rear UCA, still on stock rubi tires and wheels with spidertrax spacers. (yes I removed all of the retainers on rotors)

my rear is dead nuts on, but do you think that slight angle on the front looks like it may cause vibes?

even though my axles appear to be centered, I wonder if I have any horizontal misalignment, could that cause my vibes?
what's the best way to check that? measure from the frame to the center of the output on both tc and pinion?

mkjeep

I will also re-interate again, I went through 4 drive shafts before getting a good one. Castor adjustments would move the vibe abit, but it was still there until I got a nicely balanced one. What throws me off is the fact your stocker did it, they are pretty forgiving as far as vibes go. BUT, removing the front ds takes away the vibes, its the culprit if you can't adjust the vibes out and still have descent castor, I run 4.5 degrees by alinement machine on a 4in TF lift, no vibes.

Also, those angle finders accuracy can vary daily.