Went to Lowes and got one of those angle finders. I got the magnetic one and it was only $7.94.

Anyway, measured the angle on my output shaft from the Tcase with a 1.5" drop on it (galvanized washers to get that extra .5")...it was 7.5 degrees. The pinion shaft was 11 degress

So, I lengthened the lowers to 16 3/4" and got the pinion angle to 7.6 degrees. Then went for a test drive. Bad vibes (worse than bdfore). Even though the angles were equal, i think the angle of the driveshaft between the ujoints was just too much.

Then, I checked some lift sites and looked at the suggested control arm length for 4" lifts....just to get some ideas.

I ended up with my uppers at 13 3/8" and the lowers at 16" Now my pinion angle a little over 12 degrees but the vibes aren't nearly as bad. Go figure. Why is this?? I could just buy an SYE but that would be too easy....besides, i could get the hack n tap now or save for the HD AA ....figured i'd save and try to knock the vibes down with my control arms.

what is the angle of your driveshaft relative to the pinion angle?

Fawk, you had to ask something I don't know off hand...have it all written on a sheet on the coffee table at home. It was pretty nasty though. If I stuck the angle finder on the driveshaft, it was in the high 20's after I made the two shafts parrallel. So if the pinion was at 7.6 then that would mean close to 20 degrees in relation to the pinion.

Something close to that.

Originally posted by geauxTJ
Fawk, you had to ask something I don't know off hand...have it all written on a sheet on the coffee table at home. It was pretty nasty though. If I stuck the angle finder on the driveshaft, it was in the high 20's after I made the two shafts parrallel. So if the pinion was at 7.6 then that would mean close to 20 degrees in relation to the pinion.

Something close to that.

If am understanding you correctly , that is your problem. Are you running a CV drive shaft?

Not just yet,
Saving for the AA HD and was trying to minimize the best I could. I'm driving three hours to go wheelin' Sunday and wanted to be as smooth as possible for the haul. I am going to get the SYE...I just recently got the control arms and now I am working toward the rest...you know how it goes.


I rember reading somewhere that even if the pinion angle is parallel to the output shaft angle, those two in relation with the angle of the driveshaft can only differ a certain number of degrees. I must have surpassed that.

Way surpassed that..how much lift are you running? If its too much without a SYE (more than about 4 inches or so) You will probably NEVER get all the vibes out.

Originally posted by geauxTJ
Went to Lowes and got one of those angle finders. I got the magnetic one and it was only $7.94.

Anyway, measured the angle on my output shaft from the Tcase with a 1.5" drop on it (galvanized washers to get that extra .5")...it was 7.5 degrees. The pinion shaft was 11 degress

So, I lengthened the lowers to 16 3/4" and got the pinion angle to 7.6 degrees. Then went for a test drive. Bad vibes (worse than bdfore). Even though the angles were equal, i think the angle of the driveshaft between the ujoints was just too much.

Then, I checked some lift sites and looked at the suggested control arm length for 4" lifts....just to get some ideas.

I ended up with my uppers at 13 3/8" and the lowers at 16" Now my pinion angle a little over 12 degrees but the vibes aren't nearly as bad. Go figure. Why is this?? I could just buy an SYE but that would be too easy....besides, i could get the hack n tap now or save for the HD AA ....figured i'd save and try to knock the vibes down with my control arms.
aperently you didnt take into acount the pinion riseing under acceleration. thats why it is usualy sugested to have the pinion point 3+ degrees down from parrallel.

I'm not an SYE expert, but I went wheeling with a YJ that had a 4" lift and not SYE. Keith you drove around him at the gate keeper after he :nuke: his tail shaft. The gate keeper is the first obsiticle on the Rubicon.
That seems like a bigger issue than the vibrations.
Bring spares and some gear oil.

Originally posted by MellowYellow
I'm not an SYE expert, but I went wheeling with a YJ that had a 4" lift and not SYE. Keith you drove around him at the gate keeper after he :nuke: his tail shaft. The gate keeper is the first obsiticle on the Rubicon.
That seems like a bigger issue than the vibrations.
Bring spares and some gear oil.


:laughing: I remember that, i felt bad cause you seemed pretty frustrated :(

I was told by the local driveline guy that there needs to be atleast 2 degree difference in operating angles of the d-line and the pinion. I told him that my pinion pointed straight up the shaft to the t-case, he told me that was part of the reason I was at his shop getting a new d-line. he explained it to me like this.......when you have a striaght shot at the shaft on one end and not on the other, one u-joint is trying to spin faster or slower than the other, hence I twisted the ears off the driveline.

-Scott

Originally posted by T1H5_TA3

aperently you didnt take into acount the pinion riseing under acceleration. thats why it is usualy sugested to have the pinion point 3+ degrees down from parrallel.

You would be correct! I tried reading up on all the proper ways to set the angles, I think I got the general idea....but I don't remember seeing anything about the 3+ degrees down from parrallel.

I'm running the RE 3.5" springs with other pieces and parts on a TJ. If I blow the tail shaft, the wife will be forced to let me divert funds to the Jeep:D Maybe I ought to get it bouncing as i drive down the road;) :nuke: Umm Honey, we have a problem!!
Heh Heh!

Just pull the shaft out and tell her "look it's broke" leave the axel end connected;)
Cord

Originally posted by SCOTTS_4X
he explained it to me like this.......when you have a striaght shot at the shaft on one end and not on the other, one u-joint is trying to spin faster or slower than the other, hence I twisted the ears off the driveline.

-Scott

This is absolutely correct. When a standard driveshaft is installed correctly (TC output and pinion shaft parallel) the 'shaft' part of the driveshaft actually speeds up and slows down twice per revolution. Since the ends are 90 degrees out of phase with one another, they cancel one another out making for a smooth spinning driveshaft. If only one end of the shaft is doing this it leads to horrible vibes and worn out U-joints because the other yoke isn't canceling out the vibes.

In order to have the pinion pointed at the TC output, you NEED a CV on the TC end of the shaft. A CV assembly is basically just another (very short) 'shaft' that takes the angle while the rear U-joint is pretty much just along for the ride.

HTH,
Jake