Pinion angle double check...

[macleanflood]

So 157.4 on the Dana 35...167.6 on the double cardin with SYE...stock skid plate, no mm lift, 4" lift of questionable origin installed by PO... installed adjustable upper control arms... getting a slight vibration and noise... assuming I need these within 3 - 4 degrees and I need to shorten the arms to lower the pinion...that sound correct?

 

[taylormade73]

Measure your pinion on the flat spots on the rear of your diff and on the driveshaft tube and report back.

 

[macleanflood]

Measure your pinion on the flat spots on the rear of your diff and on the driveshaft tube and report back.View attachment 293300

103 even

 

[Daryl]

103 even

View attachment 293302

So your pinion is at 13 degrees. 103-90=13
Now set your fancy little gauge on the driveline tube. Do the math.

 

[macleanflood]

12.8 actual... what's the formula? Or am I .2 off and therefore ok? Thanks for the assistance!

 

[Daryl]

12.8 actual... what's the formula? Or am I .2 off and therefore ok? Thanks for the assistance!


View attachment 293318

Edit: it looks like your gauge is resting on the weight. Move the gauge to the bottom of the tube.

Now you know that doesn’t work for you. Adjust it one degree and take it for a drive. Worse? Same? Keep playing with it until you feel the least amount of vibration.
Before you adjust anything, check your transmission mount. Driveline looks new, so u-joints and slip yoke tight, no movement?

 

[macleanflood]

Good spot...15.1...i'll attempt to lengthen the arms a turn and try a drive.

Transmission mount looked decent but it's probably the original and therefore shot.

I'll try 2-3 degrees and then throw a transmission mount at it if it's still complaining.

Thanks!

 

[taylormade73]

Good spot...15.1...i'll attempt to lengthen the arms a turn and try a drive.

Transmission mount looked decent but it's probably the original and therefore shot.

I'll try 2-3 degrees and then throw a transmission mount at it if it's still complaining.

Thanks!

There is no target angle to achieve that produces/reduces vibes. Measuring just provides you with a starting point. Raise the pinion angle .5 deg (lengthen upper arms). Does it lessen or increase vibes? If it lessens, then keep raising until eliminated or reduced as much as possible. If it worsens, then lower you pinion until same.

The pinion and drive shaft dont care what angle measurement theyre at. All that matters is you keep adjusting until you find the sweet spot; whatever angle that happens to be is what it is.

 

[JMT]

I start with the pinion 1* lower than the shaft. Your pinion is slightly high in the original post. Adjust from there if you still have vibes.

If you still have vibes, you might detach the front driveshaft at the pinion, tie it off at the frame, and see if you still have vibes. That will rule out the front shaft as causing the vibes.

 

[Blackjack]

I start with the pinion 1* lower than the shaft. Your pinion is slightly high in the original post. Adjust from there if you still have vibes.

This is a good place to start. With a double cardan shaft you need to make sure the pinion is just below the center of the driveshaft tube. Easy thing to remember if you think the driveshaft angle is the issue is if it it too high it will vibrate on acceleration and if too low vibrate on deceleration.

 

[macleanflood]

Any suggestions on how to effectively change the angle with single adjustable upper control arms?

I can see putting a jack under the diff close to the pinion to raise it...I assume I need leverage somewhere to lower it.

Thanks!
Mac

 

[macleanflood]

Been sweeping angles the last couple of days...this video helped the most... basically on a double cardin...231/241 withe the SYE...you want the pinion angle within 2-3 degrees of being parallel with the driveshaft.

 

[Shawn at Tom Wood's]

What a crazy coincidence, I just emailed someone with a very similar question and setup. I had to double check the photos to make sure it wasn't the same person. I'm going to for the most part copy and paste my email answer below.

The pinion should be about 2 degrees less than the angle of the drive shaft. This is mainly said as a general rule to accommodate for axle wrap in leaf spring vehicles such as a YJ. Because you have a TJ and coil springs the fact that the pinion is high actually shouldn’t matter, unless for some reason you have some sort of unusual flex in your control arms (like from bad control arm bushings or something like that). For the most part though no I do not see anything in you angles that I think should be causing a vibration. There are different types of drive shaft vibrations though. There are angle related vibrations and there are dynamic vibrations. Dynamic vibrations are things like a bad balance, vibrations that are a product of weight and speed. I’ll go over the symptoms of each below.

1. Angle related. These are typically felt at lower speeds, from 0 to about 40 mph. These are also worse on heavy throttle and load, when accelerating or going uphill. Angle related vibrations are often described as a shudder and usually get better or go away when letting off the gas.
2. Dynamic vibrations. These are worse at high speeds, usually 50 mph and up. The faster you go the worst they get. Letting off the gas either makes no difference or it makes it worse. If letting off the gas makes it worse it usually means that there is a loose part which is rattling around when unloaded.

If your symptoms seem angle related you may want to adjust that rear pinion, although it appears to be adjusted correctly already.

If it seems more like a dynamic vibration it could be any of the following.

1. A poorly balanced shaft. Though I don’t expect this on an Adams shaft. It is possible though, even we sometimes get it wrong.
2. A loose part. This shouldn’t apply to the rear as everything looks new but lets not rule it out. It could definitely apply to the front shaft though. Even in 2WD the front shaft is spinning passively. A good test for loose parts is to set your park brake and/or chock the wheels then scoot underneath your jeep. Give each drive shaft a good hard shake up and down. If you can feel anything moving and/or hear a knocking sound then there is something loose that needs to be replaced or tightened.
3. A bad transfer case yoke. This is not common but it does happen. The yoke on the SYE could be machined a little off center which would cause the entire drive shaft to run off center. I think wonky is the technical term for this. It looks like you have maybe a Teraflex SYE, I’ve had people report bad yokes with that SYE (again not common). Really any brand yoke has a possibility of being defective and wonky.
4. Something else entirely. There are a lot of moving parts on a jeep and a lot of things that could be making noises and vibrating. Many times it is not a single source but a vibration will actually be a combined result of several factors.

Hopefully that helps. If you have other questions, please give us a call.