vibes driveline vibes or something

for reference i had bad vibes a year ago. since then ive swapped out my control arms twice, front and rear axles twice, and tires twice. also new steering ends and zj tie rod. hackntap sye, lengthend and balanced rear cv shaft.
new u joints.
swapped front axle shafts for newer used ones.
RE hd trackbar.
tons of other stuff.
every thing but the tcase basically, but i did do a hackntap...

alright. im kinda confused.
i didnt have vibes for so long. now they are back. yep. lame. just about anything over 65mph.
heres what i got so far.
adjusted toe in tonight
centered steering wheel(shouldnt make a difference but is nice)
pulling front shaft doesnt make a difference.
uppers are at 17"
lowers are at 18.5"
when uppers where at 17.5 i pretty much had no vibes but my trackbar was rubbing on the driver side uca mount when flexing. sucked bad. was loosening the trackbar nut.

front was about 5.5" or so at that point.
so i added another 1" of lift up front and adjusted the ucas back to 17".
it also straightened out my springs.
anyway the front lift is roughly 6.5"
the rear is somewhere between 3.5-4"
rear driveline angles are good.
front "castor" estimated angle in regards to gojeeps writeup is about 89-90* which is too much. it needs to be like 87.5 ish.
http://www.go.jeep-xj.info/HowtoAlignment.htm

i would like to actually drop the front about 1/2" (RE3.5 coils with 4 stock isolators)
and then add a leaf to the rear and maybe the commacnhe shackles i have too.
i know this would help stiffen my rear which is too soft.
it would bring the front down a bit and make control arm angles better.

but will it make castor better or worse?
could i be getting vibes from too much castor?
if so, how?
im also considering just going to a real sye kit and rebuilding the t case if getting the tires balanced doesnt fix it.

basically could too much castor and maybe a bad job on toe in cause vibes ???? or is that not possible?

im kinda at a loss for words.
the REcoils are old and very soft . the rear packs are probably worse.
but still it was on these same coils and same packs with no vibes a few months ago.

i also got some slight vibes for a bit from some loose uca nuts. but i locktighted them and tightened them back up. vibes went away for a while. drove all the way to santa cruz. on the way back got the vibes back.

Okay, let's see if I can help. I had Similar Issues at 5"s of Lift. I was Using an Adjustable Lower and Stock Uppers. I Set my Adjustable UCAs to 15 1/4"s and my Adjustable LCRs to 16 5/8"s and Centered my Assembly with the New Adjustable Track Bar. I have had Absolutely No Problems Since.

Your 89 xj, 4.5"s of Lift built to 6.5"s

"RE hd trackbar" = Check to make sure the body is centered over the axle.


"front was about 5.5" or so added another 1" of lift up front" = That would be 6.5"s of lift.


"adjusted the ucas back to 17"." = Adjust the upper adjustable control arms to a measurement of 15 5/8”s from center to center of sleeves.


Lowers are at 18.5"s = Adjust the lower control arms to 17 3/16”s from center to center of sleeves.


Remember to lubricate all bushings with a lithium grease or equivalent.

I would highly suggest taking your XJ to a 4x4 shop and have the suspension professionally checked and the front aligned just to be sure and so not to wear out your tires and/or steering components.

Good Luck.

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The purpose of the list is to give a good starting point to set the lengths of your arms to maintain the correct caster and try to achieve stock 7 degrees.

Lift...........Lower Control Arms / Upper Control Arms
********Decimal**Fraction***Decimal*Fraction
Stock........15.75.......15 ¾........15.00.......15
2”.............15.92.......16...........14.88.......15
3”.............16.09.......16...........14.92.......15
4”.............16.33.......16 3/8......15.03.......15
4.5”..........16.47.......16 ½........15.11.......15
5”.............16.62.......16 5/8......15.21.......15 ¼
6”.............16.97.......17...........15.44.......15 ½
7”.............17.36.......17 3/8.....15.74.......15 ¾
8”.............17.81.......17 ¾.......16.09.......16
9”.............18.30.......18 ¼.......16.50.......16 ½
10”...........18.82.......18 ¾.......16.96.......17


For 1/2" lifts take the difference from the one above and below. So for example a 4.5" lift would be LCA - 16.5" and the UCA - 15".
__________________

I did have Front Driveshaft Compression issues at Full Drop with my Short Arm Kit at 5"s of Lift... I suggest having the Front Driveshaft Shortened 1 3/4"s with a Short Arm Kit over 4 1/2"s. I had this done and it was about $50.

Before Shortening my Front Driveshaft... my Front Driveshaft Blew the U-Joint and Punched a Huge Hole in my Transfer Case after going OffRoad and then on the Freeway.

I Shortened the Front Driveshaft because I Do Not Use Control Arm Drop Brackets. I Do Not Like the Way Drop Brackets Hit on Limestone Ledges (even those Hidden in Sand or Mud) Let alone Rocks or Logs here in Florida.



Hope this Helps.

im gonna pull a 1/2" spacer outta each side hopefully tonight....

alright. did a few things.
added a leaf to the rear and some mj shackles.
tightened up the bolt that holds the yoke onto the rear ds.
helped a bit with the vibes.
gonna take in the tires to get balanced too.
measured rear pinion angle, its 14.5*
rear ds angle is 17.5*
i want to bring up the rear pinion a bit.
maybe 1-2* with some longer shackles.
as for the front the front pinion is at 1-1.5*
the front ds is at 11.5*.
but the front ds isnt engaged so i dont know if its a big deal to have such a huge difference in angles?

Your vibes sound like pinion angle is off on the Rearend, catser way off in the front (arms too long). Adjust the rear pinion to point directly at the TC output. Re-check the U-Joints. Recheck the tire ballance.

Adjust your front control arms as per cher96's chart. Your caster is way off, as is your rear pinion angle. Stop adding things to your suspension and adjust it as is. Adding things is just making your situation worse. You really should consider drop brackets or longarms for the hight you are at. It will solve a lot of your front end problems and ride MUCH better. Read cher96's post over and over and you will understand. That is probably the best info you are going to get no matter which chapter you post in.

thats what i needed to hear! thanks! ill get on that asap.

cool got it figured out. driver side front tire somehow got way outta balance in the last 2000 miles. test drove it no more vibes. also tightening the bolt on the yoke helped. i still want to point my rear pinion up a tad bit so im still gonna get some shackles but other than that its all good.
i guess at least for now the 18.5" lcas and the 17" ucas are good.
the purpose of the longer arms in my case was to better center the axle up front and also with the longer arms less of an angle for better articulation and handling on road.
plus the lowers were free.