YJ post lift question

[BIG]

OK - had the alignmen done and have added a SYE and TW drive shaft...... but still get vibes in 4th above 45 mph and in 5th till i get pas 60 mph??? In addiion to the SYE and drive shaft install - the guy did not have and 8 degree shims so he cut and welded the perches at the "correct angle" - this was done without checking with me... but at the same time the guy replaced the rear pinion seal and put on the new drop pitman - again without asking, or any charge.

What could be the source of he vibes still? What should I be looking for?

 

[JeepinMaxx]

Big - does your setup look like this? At rest the pinion angle should be a couple of degrees down from the completely straight line shown in the photo. 
At the speeds you mentioned - it could just wheel/tire balance. 
Also, you may notice some bumpsteer with that dropped pitman arm  :wink:





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[BIG]

Big - does your setup look like this? At rest the pinion angle should be a couple of degrees down from the completely straight line shown in the photo. 
At the speeds you mentioned - it could just wheel/tire balance. 
Also, you may notice some bumpsteer with that dropped pitman arm  :wink:

that's what the set-up looks like - I will keep on checking things

 

[xjmark]

Took me a while to find it, but this chart has some really good info to help you out.
Vibration troubleshooting guide

 

[NomadJeep]

damn....  I would hate see what he hit you up for...

Drop Pitman Arm, usually makes bump steer worse, on anything under 5"

As for the vibe...  process of elimination.  Front drive shaft.

My bet would be on improper rear drive angle.  A lot of shops that that move perches dont know that you dont measure the angles the same when you use a double cardin shaft.  Also, most shops that do set the correct way set the pinion at 1 or zero.  This works fine with a TJ, being they have control arms that do not allow for movement.  YJ's have leafs, and when you step on the gas, the spring acts like a spring board.  Turning into a slight S, that is why YJ angles should be set around 3 degrees below, so that it will allow for axle roll while under acceleration...

call me if you want a quick way to check where he set it at...  to much to type.

 

[hotrod]

Big: How big of a lift did you go? I will be lifting my YJ this spring and hope to avoid the vibes. Thanks

 

[BIG]

damn....  I would hate see what he hit you up for...

Drop Pitman Arm, usually makes bump steer worse, on anything under 5"

As for the vibe...   process of elimination.  Front drive shaft.

My bet would be on improper rear drive angle.  A lot of shops that that move perches dont know that you dont measure the angles the same when you use a double cardin shaft.  Also, most shops that do set the correct way set the pinion at 1 or zero.  This works fine with a TJ, being they have control arms that do not allow for movement.  YJ's have leafs, and when you step on the gas, the spring acts like a spring board.  Turning into a slight S, that is why YJ angles should be set around 3 degrees below, so that it will allow for axle roll while under acceleration...

call me if you want a quick way to check where he set it at...   to much to type.

I will take the front DS off tonight - but the vibes are worse than they were when I brought it in to him - just at a higher speed, so I am confident it is related to his "work"

The labor was not really that much - what bothers me is that instead of getting the correct shims - he cut and welded perches without checking with me.....and while I think the rear pinion seal replacement he did is OK, again I like to be checked with before work is done - and now he claims the vibes I feel are not much at all, and that BIG must have a sensitive butt!!!!!!!!!!! don't even get me F'n started about this now... I don't want to bad mouth any shop on a BB - but at the end of the day - I am very unhappy with the work, and his view on the situation simply let's me rule out ever doing business with him again, or recommending him to anyone.

Damon, what # should I call you at - shoot me a PM

If it is improper rear drive angle - can the perches be cut, moved and welded again - or should I go with new perches and start fresh with shims, and U-bolts? I am gonna get this Fawkin YJ right if it kills me (or us, for those of you who are nice enough to help out)....

 

[jon]

The labor was not really that much - what bothers me is that instead of getting the correct shims - he cut and welded perches without checking with me..  If it is improper rear drive angle - can the perches be cut, moved and welded again - or should I go with new perches and start fresh with shims, and U-bolts? I am gonna get this Fawkin YJ right if it kills me (or us, for those of you who are nice enough to help out)....

While it sucks that he didn't check with you,  Cutting and welding the perches is the proper way to set the pinion angle when doing a lift.  the shims are really the hack way.  I Know quite a few guys who won't do the shims for liability reasons. 

you can get new spring perches from dodge for $7.00/pair. 

honeslty figure out where the vibes are coming from.  is it speed sensitive or rpm sensitive?  pull the shafts.

 

[BIG]

The labor was not really that much - what bothers me is that instead of getting the correct shims - he cut and welded perches without checking with me..  If it is improper rear drive angle - can the perches be cut, moved and welded again - or should I go with new perches and start fresh with shims, and U-bolts? I am gonna get this Fawkin YJ right if it kills me (or us, for those of you who are nice enough to help out)....

While it sucks that he didn't check with you,  Cutting and welding the perches is the proper way to set the pinion angle when doing a lift.  the shims are really the hack way.  I Know quite a few guys who won't do the shims for liability reasons. 

you can get new spring perches from dodge for $7.00/pair.   

honeslty figure out where the vibes are coming from.   is it speed sensitive or rpm sensitive?   pull the shafts.

A given that if the perches are welded in the correct position it is the way to go (not even knowing this - it just sound like a better approach, with less to go wrong) - but if they are not, it is harder to correct. That said, the answer to your question is that it seems more speed sensitive as I can crank 1st, 2nd and 3rd out pretty good and no vibes - but in 4th once I hit 45 mph or more I get some vibes.... and again in 5th....

I will take off the F DS tonight just to double check...

 

[jon]

ok so its definately not a motor tranny issue (wanted to make sure)  I would pull each shaft individually and see if that changes anything.

Also,  did you swap the tires at the same time?

 

[BIG]

ok so its definately not a motor tranny issue (wanted to make sure)   I would pull each shaft individually and see if that changes anything.

Also,  did you swap the tires at the same time?

still has the same 31's running - they look kinda small!!!!

 

[tjcoastie20]

what about steering? can you feel anything in the wheel? possible stabilizer or a drag link joint gone bad letting the tires wobble down the road. maybe form when or if they dropped any or all of the linkage off the truck to facilitae the lift?  just some thoughts I had.  I know pickle forks can cause some pretty good damage when used improperly

 

[NomadJeep]

Perch moved is always better, I have even sheered center pins before myself.  However when you are not swapping an axle, and are putting the bolt on kit in, usually people don't take the time to cut off the perches, and move them.  What he did is a better choice, but only if he did it right....

Call me at 860-662-0999