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-   -   Pinion angle (http://www.wranglerforum.com/f282/pinion-angle-239393.html)

037jeff 04-30-2013 10:38 PM

Pinion angle
 
I have investigated and read up on and asked and PM'd Jerry. I have come to the conclusion my pinion angle needs to come down by 2 degrees to match my TC angle. Long story short a little vibration I feel and after investigating seems my angles are a smidge off. It's either that or a bad u joint anyways. So my million dollar question.... I want to lower my rear pinion angle. Today I took both rear control arms off after placing jack under rear pinion to hold it in place. When I went to lower the jack a little to lower the pinion NOTHING moved! I pulled on the drive shaft to see if I could get the pinion angle to change and nothing. Granted I have never done this before and looking online I think I was doing it right. Everything online says to lengthen rear CA to lower pinion angle. To do that u need to take them off. ( I have RE adjustable rear CA) So I expected after taking off the CA the pinion/axle would want to move. It didn't budge. So how do I get the pinion angle to move down 2 degrees. PLEASE I am open to all suggestions, criticism and ridicule. Thank u!

JKralph 04-30-2013 10:43 PM

hmm if I hit that problem I think the first thing I would do is loosen all of the control arms and the track bar to make sure they aren't binding while you are trying to adjust your angle.

037jeff 04-30-2013 10:51 PM

I didn't think of loosing everything else up I figured the upper CA. would be enough. I forgot to mention my TC angle is 7* the driveshaft is at 10* and the pinion angle is 8/9*. It's a 05 Rubicon LJ with 28000 miles lite off roading. I am second owner. It has 4" RE short arm lift with RE rear CV drive shaft.

Patrick H 04-30-2013 11:06 PM

If you have a double cardan shaft (most people mistakenly call them CV joints) you need to raise your pinion angle. It needs to point straight at the transfer case basically, or 1 degree down; one degree lower than the drive shaft angle.

JKralph 04-30-2013 11:18 PM

patrick brings up a good point

OP, does your rear driveshaft have one or two u joints where it meets the tcase? Or do you have a picture of it?

037jeff 05-01-2013 09:24 AM

It's a double cardan joint. That's what I wanted to do was move the pinion angle 1* below the TC but I can't get it to move. I was under the assumption loosening the upper CA would do the trick but it didn't. That's where I need help.

037jeff 05-01-2013 09:37 AM

5 Attachment(s)
Here's some pictures



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Attachment 243689

Water Dog 05-01-2013 09:43 AM

Quote:

Originally Posted by 037jeff (Post 3705496)
It's a double cardan joint. That's what I wanted to do was move the pinion angle 1* below the TC but I can't get it to move. I was under the assumption loosening the upper CA would do the trick but it didn't. That's where I need help.

As mentioned above, with a double cardan shaft, your pinion angle should match your drive shaft angle, not your tc angle. Perhaps some info got left out in your previous conversation.

The track bar is probably holding it from moving. You are going to need to loosen all rear suspension components and retighten anyway so they won't be in a bind once the pinion angle is reset.

Jerry Bransford 05-01-2013 09:48 AM

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With an aftermarket CV driveshaft, the kind that has two u-joints at the front & one u-joint at the rear, the pinion angle must be the same as the driveshaft... as below. I.E. the pinion shaft must point directly at the CV joint. :)

037jeff 05-01-2013 10:02 AM

Thanks everyone for your responses. I am going to loosen all rear suspension components to get the pinion angle to match the rear driveshaft angle. I will repost the results.

Jerry Bransford 05-01-2013 10:09 AM

As a fine point, make sure the pinion shaft angle ends up equal to or no more than 1-2 degrees under that of the driveshaft. It cannot be any higher at all. Under acceleration, the pinion angle tries to lift a tad so don't have it too high to begin with or vibes will be the result.

037jeff 05-01-2013 10:15 AM

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Another question. When I measure the pinion angle, I am measuring off the flange on the passenger side. Which is telling me the angle is at 9*. If I measure off the flat part on rear of axle near the fill hole I get an angle of 16*. Which should I go off.

Attachment 243702

The passenger side flange.


Attachment 243703

Or this flat part I am pointing at

Jerry Bransford 05-01-2013 10:22 AM

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Don't worry about the angle numbers themselves, just get the pinion to the same angle as the driveshaft.

I measure the pinion angle off one of the two flat surfaces on the back of the axle on either side of the diff cover as below. Those two round machined surfaces are exactly perpendicular to the pinion angle so the angle finder can easily compare the two angles as shown.

037jeff 05-01-2013 10:43 AM

Thank u! At that spot the angle is 16* and my driveshaft is at 10*. So I need to come down no more than 7*. This hopefully will explain the vibes I have been getting.

Water Dog 05-01-2013 03:46 PM

Quote:

Originally Posted by 037jeff (Post 3705800)
Thank u! At that spot the angle is 16* and my driveshaft is at 10*. So I need to come down no more than 7*. This hopefully will explain the vibes I have been getting.

Actually, you will probably only have to come down somewhere close to half of that, as your driveshaft angle will also change as you come down.

JKralph 05-01-2013 03:53 PM

yup, as previously stated, don't worry so much about the numbers, just try to get the driveshaft and pinion as close to parallel as you can without going over.

037jeff 05-01-2013 09:53 PM

Your were absolutely right. I brought the pinion angle down and when I adjusted the CA's they were all the way in. I was a little nervous, however the driveshaft angle increased to 12* and the pinion angle is at 12* now. Vibration is GONE! Thanks to all.


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