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Old 08-15-2017, 06:53 PM   #1
Duramaxfan03

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Suspension blocks and pinion angle

So far this season I have been running 2" blocks in my truck and I want to take them out to lower the back down to stock. My question is, is my blocks are tapered 1/4" from end to end making the rear end point more towards the ground making the pinion angle, if I take them out should a run a wedge to keep that angle or don't worry about it? Idk what kind of pinion angles you guys are running or what not so I'm a little curious.
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Old 08-15-2017, 09:08 PM   #2
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Less angle on ujoints is more good!
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Old 08-15-2017, 10:02 PM   #3
Duramaxfan03

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So if I would take the block completely off and my rear end would point more towards the trans would be best?
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Old 08-15-2017, 11:26 PM   #4
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Originally Posted by Duramaxfan03 View Post
So if I would take the block completely off and my rear end would point more towards the trans would be best?
Yes, but pinion angle rises as power is transferred through the driveline. That's why you want to start with a slightly negative angle and not pointed directly at the trans, ideally when you are putting all the power down it'll then climb up and be at a perfect angle and be more efficient at transferring power.
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Old 08-16-2017, 09:45 AM   #5
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Yes, but pinion angle rises as power is transferred through the driveline. That's why you want to start with a slightly negative angle and not pointed directly at the trans, ideally when you are putting all the power down it'll then climb up and be at a perfect angle and be more efficient at transferring power.

Of course a good set of traction bars will help eliminate this.
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Old 08-16-2017, 10:38 AM   #6
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Less angle on u-joints is more good!
Just wanted to clear some things up. Less angle isn't 'more good' exactly. These are phased, u-jointed driveshafts, so they basically move forward and backwards over and over (it's kinda amazing the bearings in the u-joints and seals in the t-case last as long as they do!). If you don't match the angle of the t-case, you toss a TON of vibration and harshness into everything. It'll also pulse your output to your axle which isn't good for traction or axle shafts, or tire life for that matter.

Check out this picture:
Click the image to open in full size.

Ideally you want more than 2deg of angle (to keep the bearings/caps spinning and supplying grease), and less than 4deg of angle (to keep wear down in the bearings/caps).
On a double cardan setup, like in the front driveshaft, you want to match the driveshaft angle with that 2-4deg angle in mind (close to the 2deg if you can).

All that said, just measure your t-case angle, and then make some shims to match it on the pinion and you're good to go!

This is cool too:
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Last edited by CorneliusRox; 08-16-2017 at 10:40 AM.
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Old 08-16-2017, 10:50 AM   #7
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Yea I made a set of bars that I have been running this year that are 2" OD and 1/2" wall and 6' long. So those are not allowing a ton of movement
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Old 08-16-2017, 11:44 AM   #8
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So if I would take the block completely off and my rear end would point more towards the trans would be best?
Quote:
Originally Posted by 1stgensleeper View Post
Yes, but pinion angle rises as power is transferred through the driveline. That's why you want to start with a slightly negative angle and not pointed directly at the trans, ideally when you are putting all the power down it'll then climb up and be at a perfect angle and be more efficient at transferring power.
Not true. Please read my post :-)
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Old 08-16-2017, 01:08 PM   #9
Duramaxfan03

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On your last post you said to check the angle of the t case and have your pinion angle match, but then you said I should have a 2-4 degree difference. Should the pinion match the t case or no?
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Old 08-16-2017, 03:02 PM   #10
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Originally Posted by Duramaxfan03 View Post
On your last post you said to check the angle of the t case and have your pinion angle match, but then you said I should have a 2-4 degree difference. Should the pinion match the t case or no?
So your 2-4 degrees can come from lateral change too (left to right). I added the 2-4 deg statement mostly because it sounds like your ladder bars hold it pretty fixed. Typically you'd aim for perfectly in line and the rocking of the pinion angle would be enough to lubricate the bearings in the u-joints.

In theory, you'll get the best performance going down the track and driving if it's completely parallel.
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Old 08-17-2017, 06:42 AM   #11
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Ok thanks for all the help guys!
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Old 08-17-2017, 12:02 PM   #12
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I run about 2 degrees down on pinion compared to the angle of the tranny/TC to the drive shaft. Even with ladder bars, the rear will twist up, especially with a diesels torque. You may have to go even more down angle if it is not hooking. Might want to stick a gopro under there and watch the rear axle, then you'll have an idea of what is happening on your setup.
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