Driveshaft Angle?

[techno1154]

On a 4.5" lifted XJ, what pinion angle and driveshaft slope is acceptable?

My XJ have a pinion angle of 0*, drive shaft slope of 7.5* and caster of 6*.

This is on a JK D44 front differential. They have a built-in caster to pinion angle of 6*.

 

[XJlimitedx99]

With a double cardan driveshaft, the operating angle of the u-joint at the pinion should be no more than 3 degrees. You can probably get away with slightly more, but more angle will produce more driveline vibrations.

The JK axles have very little pinion/caster separation. I recently cut/turned the inner C's on a JK 44 that I am putting on my XJ. Its nearly required on these axles. The JK's get away with it because they run a Rzeppa CV joint rather than universal joints. I ended up with about 13 degrees separation which should give me about 6.5 degrees of castor with very little u-joint angle at 4" of lift.

 

[techno1154]

With a double cardan driveshaft, the operating angle of the u-joint at the pinion should be no more than 3 degrees. You can probably get away with slightly more, but more angle will produce more driveline vibrations.

The JK axles have very little pinion/caster separation. I recently cut/turned the inner C's on a JK 44 that I am putting on my XJ. Its nearly required on these axles. The JK's get away with it because they run a Rzeppa CV joint rather than universal joints. I ended up with about 13 degrees separation which should give me about 6.5 degrees of castor with very little u-joint angle at 4" of lift.

Unfortunately, I found that out late. Had I known that before I would have done that before putting it under the XJ and keep fiddling with it for weeks trying to get to get it to an acceptable castor and pinion angle.

My other choice would be trying the get the pinion as close as possible then get some angle correction ball joints.

 

[RCP Phx]

Try reducing the castor, remember the driveshaft angle will be reduced also.

 

[XJlimitedx99]

Unfortunately, I found that out late. Had I known that before I would have done that before putting it under the XJ and keep fiddling with it for weeks trying to get to get it to an acceptable castor and pinion angle.

My other choice would be trying the get the pinion as close as possible then get some angle correction ball joints.

FWIW, doing the cut and turn wasn't as difficult as I had imagined it being. It sounded awfully daunting, and very invasive. However, once I got into it, it wasn't so bad. I had the luxury of not having coil buckets or any other brackets in the way.

 

[XJEEPER]

I rotated the inner C's on my HP D30 back in 2008 https://www.naxja.org/forum/showthread.php?t=913774&page=10 and since then, I have performed this mod on several XJ and JK front axle housings, with great success. Artec makes some great gussets, trusses and reinforcement bracketry to beef up the housings as part of the project.

Definitely worth the effort for a rig that is lifted over 4" and driven regularly at freeway speeds. The end result is caster angles which elicit proper handling and precise front driveline/pinion angle for minimal vibration. :thumbup:

 

[maxbraketorque]

On a 4.5" lifted XJ, what pinion angle and driveshaft slope is acceptable?

My XJ have a pinion angle of 0*, drive shaft slope of 7.5* and caster of 6*.

This is on a JK D44 front differential. They have a built-in caster to pinion angle of 6*.

I'm curious why you are asking. 6 deg of caster is good. 1-2 deg pinion angle is desirable to keep the u-joint needle bearings spinning, but 0 deg is probably ok because of constant suspension movement affecting pinion angle. So overall, your numbers look good to me.

 

[XJlimitedx99]

I'm curious why you are asking. 6 deg of caster is good. 1-2 deg pinion angle is desirable to keep the u-joint needle bearings spinning, but 0 deg is probably ok because of constant suspension movement affecting pinion angle. So overall, your numbers look good to me.

He's saying the pinion is 0 degrees to the ground. The u-joint is operating at 7.5 degrees.

 

[maxbraketorque]

He's saying the pinion is 0 degrees to the ground. The u-joint is operating at 7.5 degrees.

ok, that's a bit much pinion angle. I think its worth seeing whether reducing caster angle down to 4 deg to get pinion angle to 5.5 deg gets the job done. That's about where my XJ was at when it had a D30LP, and it drove fine. No obvious vibes, and return-to-center was ok.

 

[techno1154]

FWIW, doing the cut and turn wasn't as difficult as I had imagined it being. It sounded awfully daunting, and very invasive. However, once I got into it, it wasn't so bad. I had the luxury of not having coil buckets or any other brackets in the way.

Having no brackets on the axle would have been the best time to do a cut and turn. It will be a bit more difficult now that it is completely assembled.

I rotated the inner C's on my HP D30 back in 2008 https://www.naxja.org/forum/showthread.php?t=913774&page=10 and since then, I have performed this mod on several XJ and JK front axle housings, with great success. Artec makes some great gussets, trusses and reinforcement bracketry to beef up the housings as part of the project.

Definitely worth the effort for a rig that is lifted over 4" and driven regularly at freeway speeds. The end result is caster angles which elicit proper handling and precise front driveline/pinion angle for minimal vibration. :thumbup:

I do have some brackets and gussets from Artec but no truss. Instead, I installed some inner sleeves.
I have not taken the XJ out since the front diff was installed. I spend plenty of time adjusting and trying to adjust the caster and pinion angle to something I think will be vibration free and an acceptable angle on the drive shaft. Now, I find I am fighting a losing battle. There may be just 2 options left.

1) Get the driveshaft as close as I can then get some offset lower ball joints
to add more castor.
2) Cut and turn the C's. That means removing the diff and partially dismantle
it, at least the outer ends.

 

[XJlimitedx99]

I think its worth seeing whether reducing caster angle down to 4 deg to get pinion angle to 5.5 deg gets the job done. .

I agree with this. Not ideal on either side, but you might be able to get away with it. Would be an easy first step.

 

[XJEEPER]

Having no brackets on the axle would have been the best time to do a cut and turn. It will be a bit more difficult now that it is completely assembled.



I do have some brackets and gussets from Artec but no truss. Instead, I installed some inner sleeves.
I have not taken the XJ out since the front diff was installed. I spend plenty of time adjusting and trying to adjust the caster and pinion angle to something I think will be vibration free and an acceptable angle on the drive shaft. Now, I find I am fighting a losing battle. There may be just 2 options left.

1) Get the driveshaft as close as I can then get some offset lower ball joints
to add more castor.
2) Cut and turn the C's. That means removing the diff and partially dismantle
it, at least the outer ends.

I've rotated Inner C's with the diff still on the rig and several more with the diff on the stand. Off the rig makes it easier, but it's not a requirement to do the job.

 

[techno1154]

I've rotated Inner C's with the diff still on the rig and several more with the diff on the stand. Off the rig makes it easier, but it's not a requirement to do the job.

That decision is weighing heavy on my mind. I want it done right and not worry about it again, but I am a bit hesitant to make that first step of cutting the C. I will go back under there with my angle finder then make decision based on what it looks like.

 

[techno1154]

With a double cardan driveshaft, the operating angle of the u-joint at the pinion should be no more than 3 degrees. You can probably get away with slightly more, but more angle will produce more driveline vibrations.

The JK axles have very little pinion/caster separation. I recently cut/turned the inner C's on a JK 44 that I am putting on my XJ. Its nearly required on these axles. The JK's get away with it because they run a Rzeppa CV joint rather than universal joints. I ended up with about 13 degrees separation which should give me about 6.5 degrees of castor with very little u-joint angle at 4" of lift.

13 degrees sounds plenty compared to what the JK have which is reported to be 6 degrees. :dunno: What is the separation pinion to castor on the XJ D30?

 

[RCP Phx]

Go jeep reports 9* for a hp d30 and 12* for a lp d30 but it is easy to check for yourself.

 

[maxbraketorque]

Go jeep reports 9* for a hp d30 and 12* for a lp d30 but it is easy to check for yourself.

That's an interesting tidbit.

 

[XJEEPER]

That decision is weighing heavy on my mind. I want it done right and not worry about it again, but I am a bit hesitant to make that first step of cutting the C. I will go back under there with my angle finder then make decision based on what it looks like.

When you installed the inner sleeve, did you weld the sleeve to the axle tube......and the inner C? If so, this makes the C rotation project more complex.

 

[techno1154]

When you installed the inner sleeve, did you weld the sleeve to the axle tube......and the inner C? If so, this makes the C rotation project more complex.

I have not thought of that. Good call. It was done by someone else who did the gears. IIRC, the inner sleeve was welded to the tube only, but I will look at it closely when I am ready to tackle this project.

I spent some more time under the XJ trying to find a happy medium. There is no happy medium. Quite a bit of mechanical changes needs to be made. Here is where things stand as of yesterday.

Pinion angle 5*
Driveshaft slope 5* (perfect or near perfect)
Caster 1*

I could try one or more of the following options to fix this negative issue.

1) Reduce the overall height of the XJ. 3 inches is my preferred height.
2) Install some ball joints with as much offset as I could get my hands on.
3) Cut and turn the inner C's.

Turning the inner C's are by far the most desirable. I could do the welding. That part is not a problem. Cutting the C's off will result in plenty of metal dust that will look bad on the driveway the next time it rains, or the lawn sprinkler goes off.

I need to start looking for someplace to take it to get it cut. :banghead:

 

[maxbraketorque]

...

I spent some more time under the XJ trying to find a happy medium. There is no happy medium. Quite a bit of mechanical changes needs to be made. Here is where things stand as of yesterday.

Pinion angle 5*
Driveshaft slope 5* (perfect or near perfect)
Caster 1*

...

You tried values in between your initial values and these values, and those weren't acceptable? There is no need for 0 deg angle between the pinion shaft and DS. 3 deg is perfectly acceptable.