I was wondering if you guys can tell me if I measured this the right way and if numbers are correct.

99 F-150 Reg. Cab ShortBox XLT 2-wd stock.
Factory shocks were replaced by Koni's.

First, I put the angle finder on the endcap of the U-joint (don't know how you would call that but you get the idea looking at the picture) that's attached to the differential like this.



I measured 1.5 degrees nose up.

I did the same thing on the endcap of the U-joint that is attached to the slipyoke.
I measured 2 degrees nose down.

Finally, I put the angle finder on the endcap of the U-joint that's attached to the driveshaft.

I measured 5 degrees nose up and of course 5 degrees nosedown.

Summary:

Differential: 1.5 degrees nose up
Slipyoke: 2 degrees nose down
Driveshaft angle: 5 degrees.

Did I measure the pinion angle correctly and is there something to say about these angles.
I am having a driveline vibration and am looking into every possible thing that is mentioned on this great messageboard.

TIA

 

I think you are on the right track. You come out to have only a half of a degree difference, very good in my opinion. Check out this link.

Good luck.

 

Thanks for posting that pic, Le Pew.

I guess, mine is pretty much parallel.

It is normal for a stock truck that the differential is pointing up and the tranny pointing down.
I read in the Lightning forum that you don't want your differential pointing up, that's not a good thing.
Maybe because of the racing they do but can someone comment about that.

Also about the angles (1.5-2.0 degrees, this is not the pinion angle), is it normal for a stock truck.
Remember I wrote I put new Koni's under my truck.
And maybe I am having some bad motormounts.
That could change the angle of the outputshaft as well pointing up, am I right.

 

You are welcome F150Europe. Yes your setup is pretty much parallel. You are showing 1/2 of a degree more down on the pinion than on the output shaft, this is good because under acceleration the leaf springs allow the pinion angle to deflect upwards to some extent depending on how hard you accelerate. If you accelerate real hard and your pinion rotates upward by a whole degree you will still only have a half of a degree difference from the output shaft.

IT does not matter which direction the differential or the tranny points so long as they are on the same parallel line, note the second illustation. The ideal line can only be attained with the vehicle at rest. When you load the truck or go over bumps the rear suspension is always moving up and down but as long as the two angles stay parallel the stran on the U-joints should be only moderate.

It's only when the pinion rotates upwards on (hard acceleration/pulling a heavy load) or downwards during (hard braking/decelleration) that they come out of parallel. The racing guys either rotate thier pinion angels extremely downward to compensate for the deflection of the pinion angle during a hard launch or use some type of traction control device like traction bars to keep the proper geometry and leaf springs for wrapping up and allowing the pinion angle to rotate upwards too much.

For the most part, unless you are attemting to move a heavy load in a big hurry or accellerating like an animal I doubt that your pinion angles are of any concern judging by the measurements you obtained. I dont think that the Koni shocks affected it at all. It is possible that the transmission mount is allowing the tail of the transmission to move arround. That would affect the alignment of the two angles somewhat.

Check out
this atricle to see wat axle wrap is and how it relates to pinion angle.

Hope this is helpful. Good luck.

 

Thanks.