Pinion Angle... again
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
Pinion Angle... again So, I'm trying to set my adjustable torque arm.
I am using a magnetic angle finder... I'm using a straight edge as well.
So, I understand the need for around a 2 degree different in the angles of the driveshaft front to rear, with the trans being greater by about 2 degrees than the rear. Wonderful.
Now the question is, how do I get accurate measurements for those two angles?
I am putting the straight edge on the crank pulley and measuring it. It looks to be about +2.5 degrees. Now where is my second measurement? Is it the driveshaft itself? Do I put the straight edge against the trans edge where the driveshaft slides in? Do I measure the u-joint?
Same for the rearend. Can I use the bottom of the pumpkin? Or the bottom of the torque arm bracket? Then do I take the second measurement from the driveshaft or somewhere else? Also, does it matter if I'm measuring on the x or y axis? With the straight edge on the balancer, I'm measuring it's relation to 90 degrees on the device and is essentially a y-axis measurement.
I am using a magnetic angle finder... I'm using a straight edge as well.
So, I understand the need for around a 2 degree different in the angles of the driveshaft front to rear, with the trans being greater by about 2 degrees than the rear. Wonderful.
Now the question is, how do I get accurate measurements for those two angles?
I am putting the straight edge on the crank pulley and measuring it. It looks to be about +2.5 degrees. Now where is my second measurement? Is it the driveshaft itself? Do I put the straight edge against the trans edge where the driveshaft slides in? Do I measure the u-joint?
Same for the rearend. Can I use the bottom of the pumpkin? Or the bottom of the torque arm bracket? Then do I take the second measurement from the driveshaft or somewhere else? Also, does it matter if I'm measuring on the x or y axis? With the straight edge on the balancer, I'm measuring it's relation to 90 degrees on the device and is essentially a y-axis measurement.
Last edited by JakeFusion; Aug 24, 2014 at 11:32 PM.
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
Okay, I found a picture from Driveshaft shop that helped me figure out some things...
My angles are as follow:
Front of crank is +2.5 degrees (pointing down)
Driveshaft is -1 degrees (pointing up)
Rearend (measured off the flat bottom of the torque arm mounting bracket) is -1 degrees (pointing up).
So does that mean I have 3.5 degree front angle and 0 rear? Which means I need to adjust the rear to shorten the TA? Initial measurement was 0 and 0 on the torque arm bracket and driveshaft. Meaning I was at 2.5 and 0 for a 2.5 degree difference...
Is the torque arm mounting plate a good place to measure?
My angles are as follow:
Front of crank is +2.5 degrees (pointing down)
Driveshaft is -1 degrees (pointing up)
Rearend (measured off the flat bottom of the torque arm mounting bracket) is -1 degrees (pointing up).
So does that mean I have 3.5 degree front angle and 0 rear? Which means I need to adjust the rear to shorten the TA? Initial measurement was 0 and 0 on the torque arm bracket and driveshaft. Meaning I was at 2.5 and 0 for a 2.5 degree difference...
Is the torque arm mounting plate a good place to measure?
The front of the crank is a good measuring point. For the rear, the most accurate would be straight edge off the flange where your driveshaft mounts. Or the bearing cap if you're able to. Then I'd aim to get your rear to measure about .5 degrees for the 2 degree difference. Honestly, you could probably take your car out now and be completely happy with the driveline relations. If you're on rubber bushings the 3 degrees will be compressed under load to about 0 degrees, which is what you want. Poly bushings are happiest with 1-2 degrees since they won't compress as much under load.
Hope that helps! I think the Pinion angle discussion is so frequently over-analyzed. Often times at the shop we'll throw it together with an approximate pinion angle, drive it and adjust accordingly. Every car reacts differently, so to go for an exact number isn't always going to be ideal.
Hope that helps! I think the Pinion angle discussion is so frequently over-analyzed. Often times at the shop we'll throw it together with an approximate pinion angle, drive it and adjust accordingly. Every car reacts differently, so to go for an exact number isn't always going to be ideal.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Why anyone measures at any spot other then the u-joint cap is beyond me. You only measure the driveshaft for working angles not pinion, so that being said get rid of that figure. The simplest way for me to describe it is match the u-joint angles, that is, make them identical. It really doesn't matter which way your driveline in angled, just match them. You're at zero pinion. Now nose your rear end down how ever many degrees you want your pinion to be negative. Couldn't be simpler. Reading threads here about setting pinion angle is downright painful because of how overly complicated it gets.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Its recessed, so no. Put a socket of the correct diameter to use as a spacer between your joint cap and your straight edge. As crude as it sounds it works well. Putting the straight edge up to the yoke won't get to the cap.
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Joined: Aug 2007
Posts: 24,241
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From: Turnin' Wrenches Infractions: 005
And obviously you will be measuring the yoke caps, not the driveshaft caps so you may have to roll the wheels around to get the yoke caps to face down.
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