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Vibes-where to start!?

P

philagony94xj

NAXJA Forum User
Location
Schererville, Indiana
ok let me start out by stating that i did some research on this issue and found LOTS of possibilities that could solve my problem.

so start out by informing that i have a 94 xj with np231 with auto trans. i have lifted it 2 inches front and rear by means of lift blocks in rear and zj coils and insulators in front. i've had this on for about 8 months now. and never any vibs until lately. this is my DD so riding smooth on road is prefered. i have gone to Badlands a few times already this past summer. no issues with vibs until this last time i came back.

the problem starts at 50mph while slightly accelerating. when i let off the throttle it goes almost completly away. i coast down to 45 and its gone! as soon as i accelerate and hit 50 its back and stays for higher mph. feels like its from the rear drive line, axle somewhere. i also feel a bucking and pulsating in the brake pedal when braking from 35 to 50mph. different prob?

things i've checked replaced so far..... rear DS u-joints, front hub assemblies, changed front and rear diff. fluid and checked bearings(OK). oh and btw the front hub assemblies helped cure the roaring noise and steering vibs from the front.

now i have been thinking i should replace the front DS u-joints seeing as the front DS also rotates when the vehicle is in motion. it must engage in the T-case and not in the front axle. is this a possibility?

the other thing is possibly outer rear axle bearings? closest to the backing plate for the rear drums and shoes. maybe something in the rear brake assemblies worn or inop?

any input would be appreciated. i just dont wanna start throwing lots of $$$ at the problem. but thats what everyone says. but yet its sooo true!
 
What is your pinoin angle in the rear? First thing I would do is ditch those lift blocks & check your rear pinion angle. Also sounds like your getting axle wrap as well.

philagony94xj said:
ok let me start out by stating that i did some research on this issue and found LOTS of possibilities that could solve my problem.

so start out by informing that i have a 94 xj with np231 with auto trans. i have lifted it 2 inches front and rear by means of lift blocks in rear and zj coils and insulators in front. i've had this on for about 8 months now. and never any vibs until lately. this is my DD so riding smooth on road is prefered. i have gone to Badlands a few times already this past summer. no issues with vibs until this last time i came back.

the problem starts at 50mph while slightly accelerating. when i let off the throttle it goes almost completly away. i coast down to 45 and its gone! as soon as i accelerate and hit 50 its back and stays for higher mph. feels like its from the rear drive line, axle somewhere. i also feel a bucking and pulsating in the brake pedal when braking from 35 to 50mph. different prob?

things i've checked replaced so far..... rear DS u-joints, front hub assemblies, changed front and rear diff. fluid and checked bearings(OK). oh and btw the front hub assemblies helped cure the roaring noise and steering vibs from the front. Sorry I can't answer your other questions but this would be a good place to start.

Billy

now i have been thinking i should replace the front DS u-joints seeing as the front DS also rotates when the vehicle is in motion. it must engage in the T-case and not in the front axle. is this a possibility?

the other thing is possibly outer rear axle bearings? closest to the backing plate for the rear drums and shoes. maybe something in the rear brake assemblies worn or inop?

any input would be appreciated. i just dont wanna start throwing lots of $$$ at the problem. but thats what everyone says. but yet its sooo true!
Click to expand...
 
well to be honest i havent checked the rear pinion angle but the blocks dont have the taper like most blocks 2-4" have. could i shim the rear with blocks in? i know which way they have to go in to get the angle of the rearend straighter with the shaft but i am weary about putting them in with the blocks.

oh and this winter i plan on doing a rear bastard pack and t-bird front spring lift. and i will be doing a PORC SYE kit with front xj DS. and all the other goodies that go along with lifting ~ 3.5 to 4.5"

but back on track here, how do most folks check the angle on here?
 
oh and i did completely removed the rear sway to get more artic. when offroad so maybe that has something to do with the axle wrap. since the leafs are acting as swaybars now. hmmmm...... they might be worn out by now.
 
If you don't have enough degrees of shim, I had a machine shop mill more taper on a set of blocks to take away the vibes
 
rmm727 said:
If you don't have enough degrees of shim, I had a machine shop mill more taper on a set of blocks to take away the vibes
Click to expand...

that is brilliant! :cheers: i dont know why i didnt think of that! oh yeah thats why i love this site, everyone is so engenious with their methods to solve problems in the simplest way possible!

i am gonna give that a shot and i'll let ya know how it feels.

and with the pinion bearing thing, that was another one of my thoughts but i haven't seen it leaking "yet", "knock on wood" but that doesn't mean it still isn't bad. i'll do the block taper method first since it is the easiest and that way i get the angle correct, then i will try the bearing solution.

thanks for the ideas guys!
 
WhY deal with BLOCKS????
That seems like alot of work for somethen thats not that great in the 1st place.Why not just get some longer shackles instead of going to machine shops????
 
well i am gonna redo what i got this winter and will do it all correct. this is just to keep clearance for the 31's i plan on getting before "winter" hits. so 31's and 4"-5" lift will function and look good with the larger tires. but for now its the cheap way.

if i replace the blocks with lift shackles, i will still have to shim the axle to keep the pinion angle correct? or will it be ok without shims?

i guess if i get the lift shackles then when i do the bastard pack i wont have to use more leafs to lift it so much and make it stiffer.

what shackles would you recommend then?
 
Ebay has some Rough Country adjustable shackles for 45 bucks!! Iv beat mine to heck and there way nice just search shackles for xj.
 
ok, so say i get these so called "adjustable" shackles and nix the lift blocks, would i still have to shim the axle to get the pinion angle set correct? or would the shackles in a sense keep the angle right seeing as they lift the rear of the leaf pack and the front of the leafs dont move the mounting point at all. i know how the lift shackes work but my question again is will my pinion angle stay the same as stock with them installed?
 
Its only 2" of lift, on a pre-96 XJ....you shouldnt have to shim or have problems with vibs at all....

also, have you checked your brake pads and rotors - and also have your tires balanced and see if that cures any problems. sounds like the bucking/pulsating you get when you apply the brakes could be warped rotors...
 
well when i replaced my front hubs i checked the rotors for uneven wear or anything out of ordinary and found nothing visual. but i looked at the pads and they are wearing at an angle across the length of the pad as opposed to wearing straight and true. could that be a sign of warped rotor? if so i am planing to do brake job soon anyway seeing as the pads have about 1/3 left on them. so maybe i should replace the rotors. last time i did brakes i replaced the rotors (about 2years ago) because the book says never to resurface cherokee rotors and only to replace them! has anyone resurfaced their rotors and worked ok? or should i just replace them?
 
Hes right man i have a 4.5" lift and i didnt mess with the angles.
Im telling you blocks SUCK leave out please im begging you haha
Just replace the rotors
 
ok, so i went to work yesterday to help my dad find a truck to buy cause he has a 93 1/2 ton silverado w/ 215K miles. he is looking to get something new. so anyway, i had a few extra minutes and i took out the front D.S. just for sh**s and giggles and took it down the frontage road by the highway and as luck would have it the crazy vibes i had disappeared! and to think i was gonna start tearing into my axles. but hey, on these trucks there are soooooo many possiblities of what could cause a vib. so you are pretty much taking an educated guess with what could be wrong.

but thanks guys for all the help and advice you have given so far. from now on i wont be so hesitant to ask questions in the future.

oh and by the way, as for the blocks, i decided that i am gonna buy some lift shackles from quadratec for the time being. so i can fit the 31's for the winter. and then in springtime, on goes the 4.5" lift! i was thinking Rough Country w/full leaf packs, T&T HD Track Bar, PORC Sye w/front shaft out of XJ. what you guys think of that setup? should be ok right? oh and the tires i wanna get for street are BFG A/T 31-10.5-15
 
Well happy to help...
Iv got the 4.5 rough country
First thing is make sure that tracbar is adjustable it helps a ton.
I personaly think 32" would look better underneath iv now gone to a 33" bf allterrian on my rougher country then i thought it would be. Not a bad starter lift But if i could do it all over again i would have saved my money for rubicons 4.5" lift much better Suspension:yelclap:
 
tjmwr7 said:
Well happy to help...
Iv got the 4.5 rough country
First thing is make sure that tracbar is adjustable it helps a ton.
I personaly think 32" would look better underneath iv now gone to a 33" bf allterrian on my rougher country then i thought it would be. Not a bad starter lift But if i could do it all over again i would have saved my money for rubicons 4.5" lift much better Suspension:yelclap:
Click to expand...

yeah i was hoping to get someones opinion on RC. i do think it would be a good beginner lift seeing as thats the catagory i am in. mostly drive the xj on the street and will take it offroad about 1 every 1-2 months and i wanna be able to hang with the rest of the guys. so in that sense i think it will work out just fine for my needs.

and yes the track bar will be adjustable, i wouldn't do it any other way.

i think the 31's that i am soon to put on will work fine i hope, cause i dont really wanna regear to be able to put on 32's or 33's........yet. thats another time. plus i wanna keep my gas mileage as good as i can while prices skyrocket!
 
Man dont do it I regret
even putting on 32" never planned on ever goin bigger.... But gas didnt change that puch i have never regeared and now i run 33"s love em
 
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