driveshaft angles

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If the centerline of trans-engine is 2 degrees down then to have the pinion line right it should be 2 degrees UP. I would do rear at 0 degrees then under acceleration it moves up 2 degrees for perfect alignment.
 
Ceedawg said:
If the centerline of trans-engine is 2 degrees down then to have the pinion line right it should be 2 degrees UP. I would do rear at 0 degrees then under acceleration it moves up 2 degrees for perfect alignment.
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Now we have some understanding. But see, you cannot tell these guys a damn thing.
 
I guess some guy's haven't slapped a snubber on the floor board. lol
 
fishmens67 said:
I guess some guy's haven't slapped a snubber on the floor board. lol
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Evidently not. There's no way in HELL I would even set the working angle to zero on any type of performance car. Not even a factory 340 car. In fact, I'd love to see where they came set from the factory. Setting one up at zero sitting static assures the drive line angle goes negative on acceleration. That's not good.
 
RustyRatRod said:
Evidently not. There's no way in HELL I would even set the working angle to zero on any type of performance car. Not even a factory 340 car. In fact, I'd love to see where they came set from the factory. Setting one up at zero sitting static assures the drive line angle goes negative on acceleration. That's not good.
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When you say "goes negative" is that relative to the ground, the crank centerline, or some other reference point?
 
RustyRatRod said:
Evidently not. There's no way in HELL I would even set the working angle to zero on any type of performance car. Not even a factory 340 car. In fact, I'd love to see where they came set from the factory. Setting one up at zero sitting static assures the drive line angle goes negative on acceleration. That's not good.
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Don’t u mean positive as the pinion will rise. Kim
 
92b said:
When you say "goes negative" is that relative to the ground, the crank centerline, or some other reference point?
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Going negative means the pinion goes "up" in relation to the drive shaft. That's never good and will cause serious vibration and can even break u joints. The correct position for the pinion is to point down in relation to the drive shaft under acceleration, even if only 1 degree.
 
RustyRatRod said:
Now we have some understanding. But see, you cannot tell these guys a damn thin
Ceedawg said:
If the centerline of trans-engine is 2 degrees down then to have the pinion line right it should be 2 degrees UP. I would do rear at 0 degrees then under acceleration it moves up 2 degrees for perfect alignment.
Click to expand...
Wrong wrong wrong. Kim
Click to expand...
 
RustyRatRod said:
Going negative means the pinion goes "up" in relation to the drive shaft. That's never good and will cause serious vibration and can even break u joints. The correct position for the pinion is to point down in relation to the drive shaft under acceleration, even if only 1 degree.
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At what degree is the pinion at when it is what you call "up" from the driveshaft?
 
92b said:
At what degree is the pinion at when it is what you call "up" from the driveshaft?
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It could be anywhere. See if this helps. The top picture shows correct pinion angle when running a front constant velocity joint. It shows the pinion angle "UP" relative to the drive shaft, which is correct.

The bottom shows the correct pinion angle for conventional u joints like what we have. The pinion angle is "DOWN" relative to the drive shaft, which is correct for our cars. The specific angle will vary, dependent on WHAT you are doing. The hotter the car and harder the launch, the more downward pinion angle relative to the drive shaft you will need. As I've been preaching all along. All of this is covered in DEPTH in the Mopar suspension and chassis manual. @Oldmanmopar posted the exact text with pictures very recently.

DRIVE SHAFT ANGLES.jpg
 
92b said:
At what degree is the pinion at when it is what you call "up" from the driveshaft?
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what degree do you think the pinion is at when the snubber hits the floor board.
The pinion moves up more than everyone thinks under acceleration as it's climbing up the ring gear.
 
RustyRatRod said:
It could be anywhere. See if this helps. The top picture shows correct pinion angle when running a front constant velocity joint. It shows the pinion angle "UP" relative to the drive shaft, which is correct.

The bottom shows the correct pinion angle for conventional u joints like what we have. The pinion angle is "DOWN" relative to the drive shaft, which is correct for our cars. The specific angle will vary, dependent on WHAT you are doing. The hotter the car and harder the launch, the more downward pinion angle relative to the drive shaft you will need. As I've been preaching all along. All of this is covered in DEPTH in the Mopar suspension and chassis manual. @Oldmanmopar posted the exact text with pictures very recently.

View attachment 1716050765
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So the bottom is correct? It looks like the crank centerline and the pinion are both at zero degrees relative to the ground.
 
92b said:
So the botom is correct? It looks like the crank centerline and the pinion are both at zero degrees relative to the ground.
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Yes, but as I've said, for performance applications, you need to shoot for parallel under acceleration. How much pinion angle is a guess totally dependent upon "how much" the car pulls the pinion up on cruise acceleration for a street car, or hard launch for a drag car. There is no ONE answer for everything. Drive shafts will ALWAYS vibrate somewhere in the RPM range. The trick is to get the vibration OUT of the operating range of a given application.
 
RustyRatRod said:
Yes, but as I've said, for performance applications, you need to shoot for parallel under acceleration. How much pinion angle is a guess totally dependent upon "how much" the car pulls the pinion up on cruise acceleration for a street car, or hard launch for a drag car. There is no ONE answer for everything. Drive shafts will ALWAYS vibrate somewhere in the RPM range. The trick is to get the vibration OUT of the operating range of a given application.
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The reason I said 0, rise to 2 for a street car only, it will need more downward for a race car (very stiff springs or snubber can change the ammount). I was trying to draw up a picture but your pic showed it much better than I can draw lol
 
92b said:
So the bottom is correct? It looks like the crank centerline and the pinion are both at zero degrees relative to the ground.
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Nothing should be "relative to the ground"! All the angles are supposed to be measured compared to the other driveline angles. ( the above drawings don't include the normal down at the rear angle of the engine/trans.)
 
RustyRatRod said:
**** if I know. I haven't measured it yet. The 9" swap has yet to be done. Setting the pinion at 5 degrees is how I've done it for forty years and I've always been damn close.......right on the money a few times. Everybody's scared of 5 degrees initial pinion angle, but they fail to realize, that backs off a hair when you install the rear end on the leaf springs.
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When you set your pinion at 5 degrees, is that measured relative to the ground? If not what is the 5 degrees relative to?
 
92b said:
When you set your pinion at 5 degrees, is that measured relative to the ground? If not what is the 5 degrees relative to?
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I think he is referring to the factory setting. Mopar welded the spring pads at a nose-down 5° angle, to account for the angle of the front segment of the leaf springs.
 
33IMP said:
I think he is referring to the factory setting. Mopar welded the spring pads at a nose-down 5° angle, to account for the angle of the front segment of the leaf springs.
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So with rear end out of the car and the spring pads level to the ground the front of the pinion is angled down 5 degrees relative to the ground?
 
Perch angle and installed angle are two different things. The springs get in the mix when installed.

A set of +3, 0, and -2 ride height springs will likely have pinions point at different angles.
 
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