Author Topic: Rear pinion angle  (Read 1851 times)

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Offline neale_rs

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Rear pinion angle
« on: January 18, 2012, 04:07:54 PM »

I finally got around to actually measuring the rear pinion and drive shaft angles (CV rear shaft).  The pinion is pointed about 3 degrees above the drive shaft angle.  I'm not getting any noticeable vibrations, neither when accelerating nor when compression braking.  Do you think it is worth setting the angle to the typically recommended 1 or 2 degrees down?  Will having it 3 degrees up make it any more likely to break a u-joint under torque when the pinion rises?

I mostly would like to leave it like it is because it is not causing vibrations and has no angle shims in place right now, but would adjust if it could cause a reliability problem.

Thanks

'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline sharpxmen

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Re: Rear pinion angle
« Reply #1 on: January 18, 2012, 04:16:45 PM »
ideally you'd want them lined up but i think the 1 or 2 deg down is recommended for 2 reasons - when applying gas the axle wrap would push the yoke upwards, secondly the u-joint needs a bit of movement to keep the needle bearings lubricated - but this is just what i heard, i can't tell you for sure.

in your case the second one is covered but the first is actually adding to the angle rather than reducing it - dunno how much if any this would harm your setup, so i can't help with that.
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Offline neale_rs

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Re: Rear pinion angle
« Reply #2 on: January 18, 2012, 04:46:18 PM »
Thanks. 

In general I don't think these 3 degrees up will contribute to u-joint breakage because it is not all that much, .... but it's better to hear from anyone who might have experience with this.

From my experience it seems the CV shafts avoid vibration even when the angles are not perfect, maybe the angle can just be set by eyeball with good results.  I've had it in the range between 4 degrees down and now 3 degrees up with no noticeable vibrations.



'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline Jeffy

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Re: Rear pinion angle
« Reply #3 on: January 18, 2012, 05:32:11 PM »
I don't think 3* is that big of a deal.
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Offline neale_rs

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Re: Rear pinion angle
« Reply #4 on: January 19, 2012, 10:37:30 AM »
Ok, I'll run it as is and let it prove itself out on the trail (when I get a chance again).  Thanks for the replies.

'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline neale_rs

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Re: Rear pinion angle
« Reply #5 on: October 11, 2012, 01:32:29 PM »
The YJ has been out on three fairly demanding trails with the pinion 3 degrees higher than the DS angle and has had no problems.  So it looks like 3 degrees up, although not ideal, works fine with the SUA suspension.

'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch