skep419
5.9 Magnum 4 speed afficionado
The trans is -1 and rear pinion is +1 What would you do to fix it. Have the 3" inboard kit but didn't plan on installing it until next year when I can afford wheels and tires.
installed SS springs and pinion angle is at 0
- Thread starter skep419
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Locomotion
Well-Known Member
Pinion angle is the difference between the pinion yoke/shaft and driveshaft. That needs to be measured and adjusted - if needed.
-1* between the trans and driveshaft is good. Mopar book says 2.5* or less, but not "0".
-1* between the trans and driveshaft is good. Mopar book says 2.5* or less, but not "0".
but...and I ask with all due respect...
Myron...
is the pinion NOT to be at a positive angle?... hence you would want to adjust the rear pinion downward with shims (4 degree) to a total of -3 degree minimum....
Denny
Myron...
is the pinion NOT to be at a positive angle?... hence you would want to adjust the rear pinion downward with shims (4 degree) to a total of -3 degree minimum....
Denny
Locomotion
Well-Known Member
Wording can get misunderstood, but this exaggerated representation should help. Looking from the side with the trans on the left, the driveshaft is usually at a "down angle" from the trans to the rear and then the pinion would be angling up - relative to the driveshaft.
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When talking about "pinion angle", it is the angle at the bottom, between the pinion on the right and the driveshaft on left (represented by the downward slashes). The angle difference between the trans output shaft and driveshaft is not used in pinion angle computations. But adjusting the pinion angle can slightly alter the trans-to-driveshaft angle.
Hope this makes sense. It's past my bedtime! lol
Gosh darn, heck. Couldn't get the lines and slashes to stay where they need to be.
_______
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\
\_____
When talking about "pinion angle", it is the angle at the bottom, between the pinion on the right and the driveshaft on left (represented by the downward slashes). The angle difference between the trans output shaft and driveshaft is not used in pinion angle computations. But adjusting the pinion angle can slightly alter the trans-to-driveshaft angle.
Hope this makes sense. It's past my bedtime! lol
Gosh darn, heck. Couldn't get the lines and slashes to stay where they need to be.
Locomotion
Well-Known Member
pishta
I know I'm right....
If the trans is 0 the pinion should be -3 down. (leaf, 4 link and IRS are all different values) As the rear end wraps up on acceleration, the pinion rises, and 0 delta between output shaft and pinion angle minimizes HP loss and parasitic loss. Shims are cheap at 4X4 shops. One way to figure it out is lay a level on the valve cover and jack up rear diff until its bubble up, jackstand rear axle then measure the diff yoke straight up and down with an angle finder. figure how far your off and buy the appropriate shim. You dont want 0 at cruise, supposed to be bad for your U-joint as it doesnt spread the load over enough roller bearings. Any believers?
64physhy
Well-Known Member
It should be slightly down at about 3 degrees. If you plan on drag racing, go down a little more to 4 or 5 degrees.
skep419
5.9 Magnum 4 speed afficionado
skep419
5.9 Magnum 4 speed afficionado
Locomotion
Well-Known Member
Yes.
Using the actual floor as a reference can get confusing. But basically it is the difference between the driveshaft and the pinion shaft. I like to use the ones with a magnetic base. Getting a good surface to measure on the pinion or yoke can be a little difficult.
I was tired in my previous post. I should havej ust said add shims ander the spring pas to get the angle down to where you want it and make sure the trans-to-driveshaft angle stays right around the 1* you have.
Using the actual floor as a reference can get confusing. But basically it is the difference between the driveshaft and the pinion shaft. I like to use the ones with a magnetic base. Getting a good surface to measure on the pinion or yoke can be a little difficult.
I was tired in my previous post. I should havej ust said add shims ander the spring pas to get the angle down to where you want it and make sure the trans-to-driveshaft angle stays right around the 1* you have.
skep419
5.9 Magnum 4 speed afficionado
the -1 was a measure of just the transmission. I will get the trans to driveshaft measurement tonight. Along with the pinion to driveshaft measurement
According to the Mopar Performance chassis book on page 252, the trans to driveshaft angle should always be 2.5 degrees or less (but not zero). On page 253 all the pictures showing how to adjust rear pinion angle show only the rear axle pinion and the driveshaft. No trans pictured or any reference to it for the rear pinion angle adjustment. And the chart says 5-10 degrees nose down (5-7 preferred) for a leaf spring setup. There are other measurements if ladder bars or 4 link is used.
skep419
5.9 Magnum 4 speed afficionado
The transmission measurement is to get the centerline. The reason to adjust the pinion to -5 below centerline is because the leaf springs are going to allow the rear end to lift 5 degrees. After they lift 5 degrees it should be parallel to the trans. Right now my trans is at -1 and the rear end is +1 meaning it is a perfectly parallel. In order to get -5 down pinion angle the rear end will have to be positioned to -4 degrees down instead of +1 (1-5= -4) Once the -4 degrees is reached when I smash the gas and the pinion lifts 5 degrees the driveline is parrallel.
The transmission measurement is to get the centerline. The reason to adjust the pinion to -5 below centerline is because the leaf springs are going to allow the rear end to lift 5 degrees. After they lift 5 degrees it should be parallel to the trans. Right now my trans is at -1 and the rear end is +1 meaning it is a perfectly parallel. In order to get -5 down pinion angle the rear end will have to be positioned to -4 degrees down instead of +1 (1-5= -4) Once the -4 degrees is reached when I smash the gas and the pinion lifts 5 degrees the driveline is parrallel.
That's the way I do it. There have been times where it didn't work out well and the chassis book method was employed.
If you go more than about 4* down on a street car you run the risk of some vibration issues. I've had SS sprung cars that needed more than 8* down to work well, but they weren't street driven, race only.
pishta
I know I'm right....
driveshaft angle has little to do with this, its is the relationship between the output shaft of the trans and the input shaft of the yoke. look at a 4X4 with a 30 degree shaft to yoke angle, still goes. like I said, level to the flat valve cover and an angle finder on the diff yoke at ride height, find what you need for 3-5 pinion down from trans output and your done.
skep419
5.9 Magnum 4 speed afficionado
3 inch inboard kit is getting installed. Done with doing things twice. Even though there isn't snow on the groung it will still be april before its out to play. Garage burnout break in 2 weeks
The pinion angle is just that. The angle of the center line of the pinion gear relative to horizontal.
The angle you are referring to is called the "working angle".
Woods74
Broke Senior
It happens.
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