I just installed a RC 6.5 long arm lift. I already had an AA sye with a front shaft in the rear. I put an 8.25 and d30 with 488s under the truck and around 40 mph I'm feeling some slight vibes. Here are pictures of then pinion angle to see if you all think there are good

Thanks,

Mike

 

From my knowledge over this it looks way to steep, like your axle should be more parallel to the ground. I may be wrong on that but search on here for some info I think I have seen something like this before

 

Front is too high, rear looks good as far as the picture looks

Edit: maybe front is too low? I can't make it out quite right, but it's off one direction or the other

 

did you ever get a slip yoke eliminator?

 

*Insert I dunno smilie here*

 

when putting a big lift on a XJ, people always recommended to install a slip yoke eliminator....i dont have too much knowledge but its also been said to eliminate the vibration or something

 

.

 

mine does the same thing but then clears up, its ur tires there probably outta balance and im in the same boat with 6.5" and a sye

 

Bad DS angle and tires both can cause vibe patches. If your arms are adjustable, get the pinion angle right before balancing tires since it's free to do it. The front pinion should point basically straight up the DS, it doesn't have to be below to account for axle wrap since there isnt any. If that doesn't work, tire balance.

 

You cant tell if the operating angles are correct from a picture. You need to put an angle finder to it and read the measurements.

It also appears your using a front driveshaft in the rear as well? Is it fully extended? Does it have slop where the two pieces join? These issues will transmit a vibe as well.

 

I do agree with you on the pictures, because i have another picture of the rear and the angle of the shaft and pinion look lower as a whole. But i figured a ball park angle couldnt hurt. Also your second point strikes me as well. Does anyone know the full extended length of a front shaft? or should i just take it off and see how much more it will go?

I am also going to probably pull the rear shaft as a whole and drive it in 4wd and see from then on. The truck has only been up to about speeds of 40-45 mph because of the break in period with the new gears. I am trying to take it nice and easy

Thanks,

Mike

 

I will probably throw some more pictures up of the angles and the driveshafts later too for some more input. Couldnt hurt I suppose, everyone is very helpful on this forum.

Thanks,

Mike

 

I know the pic is shotty, but i think its a little lower, Which i think is better because you want it slightly lower so there is some tension on the ujoints.

I think i think i think lol

Thanks,

Mike

 

The front is ok to point straight at it. Depending on how low it is though it may be fine. I can't really tell from the pic. Mine vibes a bit and once I got the front pretty much dead on it stopped.

 

Axle angles look good from the pics. how about the angles at the t-case though?
Rotate the tires and see if it changes.
Also be careful with front pinion angle, you have to remember you are changing castor as well.
Are all the joints nice and tight?