Pinion angle....with pics

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GARRETTECH

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What do all the more knowledgeable members here think. The way I measured was to jack up the rear until I got the transmission level. I measured off the balancer to get the zero. Car is a 440 with 727 and dana 60. Also has SS rear springs. Car is primarily a drag car with light street use. Do you think I should shim the pinion to drop the nose another 3* or so?

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Also, the way I measured pinion angle was to put the angle finder on the rear yoke. I rotated driveshaft to get the yoke level in the yaw direction, the used the bottom surface of the toke to measure. Seemed only place I could get a flat. And I forgot to say I also have a pinion snubber
 
Measure off the output shaft of trans and pinion. Compare... That's it.

Leveling the car doesn't matter. IMO, leave the car on the ground. When you jack it up on the center section, you may be altering the angle the rear actually sit at in a static state.

Put the angle finder where the pinion snubber would mount to get that angle. Hopefully it is machined properly.

Nice Fish!!!!
 
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Ok, so I took off the snubber and put the angle finder on the mounting surface. I get perhaps a 1* difference as opposed to the side of the pinion yoke. I then put the car on its own weight and checked all the angles and they worked out to the same math as before....except factoring in the difference between the yoke and machined snubber mtg surface. So here is 2 new pics

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You want the car at ride height with the suspension loaded when checking the final angle. There is some math you can do. I measured my original pinion angle with the spring perches and the yoke and then just welded my new perches to the same angle. If you set your pinion angle with no weight on the suspension when you lower the car back down it's gonna change. I can't remember the numbers now. I think was something like 6 degrees no weight and 2 degrees with weight. So it moved 4 degrees. (In theory) like I said I can't remember the numbers. I'm sure it's in a thread here somewhere
 
if trans is at 0, the pinion is pointing 3* down, you have a -3* pinion angle.
 
If you need to raise the car to get under it, either come up with some ramps/ blocks, even 2x4's to put under the tires, or use jackstands under the rear axle and suspension. IT IS important to have the car somewhat level because you want the car weight distribution in some sort of order as it would be on the ground. As Cracked says, measure the angle of the engine/ trans in such a way that it is accurate to the crank/ trans shaft centerline, and then measure your pinion angle and compare the two. Neither has to be level to do that, you only need to compensate for how far off level the two are, IE the difference between the two.

If you end up with actual 2* I would guess that is a starting point.
 
crackedback said:
if trans is at 0, the pinion is pointing 3* down, you have a -3* pinion angle.
Click to expand...

Yes, I agree that I am at -3* pinion angle. Do you think that is enough? Should I add 2* shim to get to -5*? Or even bigger negative angle?

I did put the car down on my 2 x 10 ramps and remeasure

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it's OK there. If it's a drag car, you may need more, but that will not play nice on the street driving portion of use.
 
Maybe if you could find it in your heart to tell us what you're doing with the car it would make the ultimate answer more accurate. Street car? -3 degrees is ok, as Rob said. Hot street/drag or drag only? Then you want what the MP manual says. 5-7 degrees. Technically with SS springs, that's where it "should" be anyway, 5-7 degrees. But again, if only a street car, then what you have is fine.

The car's position doesn't amount to a hill of beans when you measure. As long as you have the weight on the tires. You could theoretically flip the car upside down and take the measurements, as long as the the wheels and suspension were still in the "loaded" position. It sounds like you get that part, though. I like how you leveled it up to make the math easier. That's how I always do it, too.
 
Hey rusty....I did say in first post....Car is primarily a drag car with light street use.

That being said, maybe to make it more clear, the street use would be prob 5 mile trips on local roads to a cruise in or ice cream run. I can't imagine any highway drives or anything the way this is setup. Other than that, just dragstrip
 
GARRETTECH said:
Hey rusty....I did say in first post....Car is primarily a drag car with light street use.

That being said, maybe to make it more clear, the street use would be prob 5 mile trips on local roads to a cruise in or ice cream run. I can't imagine any highway drives or anything the way this is setup. Other than that, just dragstrip
Click to expand...
Ok my bad. Somehow I missed that. You might try it like it is. I think it could hook harder with more pinion angle, but who knows?
 
I level the car with the jacks under the rear axle tubes and on the frame rails up front. I measure the ATI damper for the front reading. Whatever that is, I try to get equal but opposite at the rear, measuring off the rear end yoke. Has always worked on my street Dart 340 Sport and my circle track S10.
 
I saw a utube vid where first they want you to add the drivers weight in the drivers seat & the fuel weight in the trunk. (FWIW)
 
GARRETTECH said:
Yes, I agree that I am at -3* pinion angle. Do you think that is enough? Should I add 2* shim to get to -5*? Or even bigger negative angle?

I did put the car down on my 2 x 10 ramps and remeasure

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Do u also have the same amount of wood under the front wheels? If not start over again.what is the trans angle at with the wood under all 4 tires? If u had to jack the rear up to level the motor/ trans angle to zero then u would have to have a negative trans angle.
 
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