Driveline Vib

[BlackYJ]

So I finally got my lift finished today and took her for a drive and now I am getting a low vibration that I am guessing is coming from the rear driveshaft.  Should I have installed some shims?  The reason that I did not was because when I had my 8.8 installed, they turned my pinion up a little.  I only went up about 1-1.5" in the rear.

Also if I install the shims, should I get new u-bolts again?

Finally, I should take it for an alignment so where should I go.  I don't need a 4-wheel alignment because there is nothing to align in the rear and I don't have to worry about caster and that stuff I there were no control arms to adjust.  Would any trusted place work?

[cotaman]

I just had a wheel alignment done on my ZJ after I installed my Xfactor  steering and they had no problems doing it.. drive nice and straight ... this is the second time  they have done a alignment for me on a modified vehicle and they have not charged me a ridiculous amount....

xj was 60-70 ( stock steering )
zj was 95( including tax ) Rock Krawler XFactor steering

Calgary Industrial Automotive - 403-279-4300
Fax : 403-279-0290
6-7139 40 Street SE, Calgary, AB T2C 2H7

[Bnine]

You could give it a shot first doing a driveway alignment. The lift has caused you to toe in a touch. Set that back to spec and you should be good. I think Stu's site has the specs.

You can install shims, I would make it temporary until you do a CV. Shims have a tendency to spit out and wreck things. Mike lost his shims on his second run.

After doing a CV the most reliable way to set it up is to cut the perches, rotate and reweld them at the right angle.

One more use on the ubolts should be fine as long as you didnt over torque them the first time around. 40-70lbs.

Have fun.

[BlackYJ]

So bill, you would suggest taking it in for an alignment before installing the shims?  Also I torqued the u-bolts to 90 ft-lbs so they are probably toast then because I think they stretched.

Here is a pic of the rear DS at ride height, but when I do the SYE kit, with the shims I think that it will be pretty close to aligned at the yoke.  You need to be with in 1-2 degrees below right.

[Bnine]

I wouldnt worry about an alignment before or after the shims, they wont effect anything up front.

Both joints need to be as close to each other as possible in angles.

If total shaft angle was 10 degrees, you want each joint to be at 5.

Unlike a CV where you just point the pinion straight (minus 1-2 degrees) and let the CV take all the angle.

The max operating angle of a single joint is around 5-7 degrees. Looks like you are pushing that limit. But I wouldnt recommend more then about a 3 degree shim, else the pinion will come up to much, throwing the difference between the 2 joints to far out of whack.

[BlackYJ]

I have 2.5 degree shims, but i think i will invest in an angle finder to take a few measurements.

Yeah I was looking at the picture and the t-case joint looks a little steeper

[sloria]

if your looking for a place to do allignments on jeeps with non OEM tires, i had great luck at

Tire Pirates
6112 30st SE
279-5559

Grant or Loyd


S.

[BlackYJ]

if your looking for a place to do allignments on jeeps with non OEM tires, i had great luck at

Tire Pirates
6112 30st SE
279-5559

Grant or Loyd


S.

Thanks but I would prefer somewhere in the NW as I am in Arbour Lake

[Asia]

90 ft/lbs is the factory torque spec (and Skyjacker's (my springs)) for the axle U-bolts.

If you only added new springs and shackles do you need an alignment?  Your steering wheel is likey off center but I don't think the direction of the tires is changed, was the tie rod touched?  Assuming you have the stock YJ steering system.  Was your alignment good prior to the new lift?  I also heard that you should get an alignment after a lift, the alignment will check that you are in spec and they will realign your steering wheel,  but you could easily align the steering wheel by adjusting the drag link.  My $.02

[Brink]

I gotta wonder the same thing.  Unless you messed with the tierod your alignment should be pretty close.  

Also with that driveshaft pic.....   All the "this angle and that angle should match" stuff tends to make my head hurt.  I'm sure Bill is steering you in the right direction.  But bottom lineis that DSI always told me, with a non cv shaft, the pinion should point about 2deg below the top joint.  Your's sure looks well below that.  The 2 deg below allows it to rotate up with a little axle wrap that is natural.  I've always set up pinion angles using nothing but "my good eye", and had excelent results, and even with just my bad one looking at the screen I would think that is aimed quite a bit too low.

Bill can you explain the angles thing a bit better?  Reading it leaves me feeling like it totally contradicts my "good eye" method.  Maybe I'm way off.

 :wink:

[Rookie]

What brink said is right for a CV shaft but not for a non CV shaft

Here you go this explains it all

http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html

Hope u got some spare time

Steve

[BlackYJ]

Yeah I think my driveshaft angle is a little steep.  I will be installing so shims in the very near future and then I guess fix the issue when I get a SYE shortly.

As for an alignment, I never really understood some of that stuff, but it has not had an alignment since i have owned it, so now is a good time

[Brink]

CV I'm sure of.  But standard I have little experience with.  I must have something confused.  

Might be time to look for a SYE though.  That's the number one upgrade in my opinion.  It fixes so many issues all with one shot.

[BlackYJ]

I got my shims installed last night and it seems that it fixed 90% of the vibration.  I only get a slight vib at about 35-40 km/h, but no big issues as the SYE kit is on order.

[Brink]

Got a new pic?  I'd be interested in having a peek at the new angles.