Drive Shaft Help!

cloudswimmer · Sep 12, 2005

Ok I posted here last week but the photo didn't show up.Could you guys do me a favor and click on the link to my photo and tell me where you think I outta start in degrees for a shim.I've had a few people look at it in person and so far I have been told different degrees by all of them from 3 to 4 to 5 to 7 to don't worry about it :scared: The drive shaft is a J.E. Reel CV on an Advance Adapters shortshaft kit.Thanks!

http://www.pbase.com/cloudswimmer/image/49114244

ChiXJeff · Sep 12, 2005

Not gonna be able to tell from that pic. Go get yourself an angle finder, and figure out the difference between the pinion yoke and the driveshaft.

cloudswimmer · Sep 12, 2005

ChiXJeff said:
Not gonna be able to tell from that pic. Go get yourself an angle finder, and figure out the difference between the pinion yoke and the driveshaft.

Stupid question here, Where do I place the angle finder on the yoke?
Thanks for the help!

ChiXJeff · Sep 12, 2005

I'm mildly surprised that you don't this, considering the extent of the mods on your XJ.

For a little theory, a standard single cross u-joint (like the axle end of your rear driveshaft,) needs to have a (practically) zero operating angle. This means that the pinion yoke and the driveshaft needs to be parallel. When the angles diverge, assuming a constant input rotation speed, the output shaft rotation speed will vary in a sine wave twice per revolution. This is where the driveline vibrations come from.

Place the angle finder on the driveshaft and find the inclination. For the most accurate reading on the yoke, remove the driveshaft and read the inclination by placing the angle finder against the flats on the pinion yoke. In an ideal world, you'll shim the pinion up (or down) until the angles match. In the real world, most folks go for 0-3 degrees down on the pinion yoke to allow for axle wrap under acceleration.

Your traction bars are going to make your life difficult. You're going to need to cut and adjust them once you get your pinion angle dialed in.

MaXJohnson · Sep 12, 2005

ChiXJeff said:
I'm mildly surprised that you don't this, considering the extent of the mods on your XJ.

For a little theory, a standard single cross u-joint (like the axle end of your rear driveshaft,) needs to have a (practically) zero operating angle. This means that the pinion yoke and the driveshaft needs to be parallel. When the angles diverge, assuming a constant input rotation speed, the output shaft rotation speed will vary in a sine wave twice per revolution. This is where the driveline vibrations come from.

Place the angle finder on the driveshaft and find the inclination. For the most accurate reading on the yoke, remove the driveshaft and read the inclination by placing the angle finder against the flats on the pinion yoke. In an ideal world, you'll shim the pinion up (or down) until the angles match. In the real world, most folks go for 0-3 degrees down on the pinion yoke to allow for axle wrap under acceleration.

Your traction bars are going to make your life difficult. You're going to need to cut and adjust them once you get your pinion angle dialed in.

what he said...

except, in the real world, most guys don't have a traction bar. Since you do, you shouldn't have to worry about axle wrap, so the pinion should be very close to parallel with the driveshaft.

Because you have the traction bar, you can adjust the traction bar first or shim first. If you adjust the traction bar, loosen the U-bolts first to relieve binding. Once the pinion is in line with the driveshaft, you should be able to see how much shimming will be necessary between the leafs and spring perch. If you shim first, you should undo the front of the traction bar. After shimming the pinion to be in line with the driveshaft, adjust the front of the traction bar to fit without binding.

When it comes to measuring the pinion angle, I like to clean off the cast circle on either side of the diff cover and measure from there. Very easy. Hardly enough time to crack open a beer.

ChiXJeff · Sep 12, 2005

Uh....... maybe you're seeing something I'm not....... where's the adjustment in his traction bar? I'm seeing cut and weld again.

MaXJohnson · Sep 12, 2005

ChiXJeff said:
Uh....... maybe you're seeing something I'm not....... where's the adjustment in his traction bar? I'm seeing cut and weld again.

I can't see enough of the front mount to determine whether it is capable of adjustment or not. The point is the traction bar will dictate pinion angle, not shims. If it isn't designed with adjustability, then "cut and weld" will have to be the plan.

cloudswimmer · Sep 12, 2005

ChiXJeff said:
I'm mildly surprised that you don't this, considering the extent of the mods on your XJ.

You mean don't know this?I just learn things as issues come up.

ORGS did my driveline (post Hinkley)and said i was good to go.It wasn't till Rawbrown drove my rig and pointed out the vibe (I still don't notice it driving)I just wish I had figured it out before the ladder bar as now I'm going to have to cut and re-weld, plus I have raised lower shock mounts that I'm a little worried about after axel rotation.Another thing I'm wondering about is I have a gas tank skid going on as well as a Detours USA bumper.Now thats going to add a bit of weight in the back, now add in the 33" spare in the rear cargo along with all my prospecting tools and camping gear and the rear is gonna sag which I assume is going to change that driveshaft/pinion angle relationship a bit?The longest trips I make are when its loaded down of course, I drive it a couple times a week local unloaded.So logic seems to dictate setup driveline loaded correct?Thanks for taking the time to help.Wish they had done that at ORGS

ChiXJeff · Sep 12, 2005

MaXJohnson said:
I can't see enough of the front mount to determine whether it is capable of adjustment or not. The point is the traction bar will dictate pinion angle, not shims. If it isn't designed with adjustability, then "cut and weld" will have to be the plan.

Exactly my point. The front point on the traction bar doesn't change the pinion angle, only the attachment points on the axle. And all else being considered, he'll be better off taking the traction bars off completely while he's dialing in the pinion angle. Traction bars should keep the angle, not dictate it.

While you're at it, see as you're now telling us how much more weight is going on, yes, make sure you dial in the angle as it'll be customarily loaded.

Dookie · Sep 12, 2005

that's the first XJ i've seen with traction bars...

what are the front of them mounted to? the crossmember?

cloudswimmer · Sep 12, 2005

Dookie said:
that's the first XJ i've seen with traction bars...

what are the front of them mounted to? the crossmember?

Its mounted to the Currie crossmember via a shackle and Johnny joint.Quite a few of the middle and So.Cal. guys run em.Farmer Matt, Goatman, Porch Puppy etc.

Drive Shaft Help!

cloudswimmer

NAXJA Forum User

ChiXJeff

Curmudgeon

cloudswimmer

NAXJA Forum User

ChiXJeff

Curmudgeon

MaXJohnson

NAXJA Forum User

ChiXJeff

Curmudgeon

MaXJohnson

NAXJA Forum User

cloudswimmer

NAXJA Forum User

ChiXJeff

Curmudgeon

Dookie

NAXJA Forum User

cloudswimmer

NAXJA Forum User

Similar threads