pinion angle shims

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345man2

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just put a new rear in my car and setting the pinion angle to find out it is 8* cal vert racing recommends -2 to -4 for there set up so by my math I had 8 on the pinion and 0 on the driveshaft, so by my measurements if I got a 6* shim it should be 2 on pinion and 6 on shaft which would equal -4 does this sound rightand is a 6 degree shim to thick :blob:
 
when you launch, your pinion will come upwards.
your driveshaft will slide slightly into the trans at the slip yoke.

ideally, the pinion will rise slightly & be inline exactly with the driveshaft during a launch.

so calvert is recommending that it is down between 2 and 4 degrees below level with the driveshaft so that when you launch their setup allows the pinion to only raise that amount.

i'm not aware of shims that work perfectly for this. there are shims you use beween the hangers and the frame on one side or the other left/right to make the axle straight with the car's alignment, but not to angle the pinion up or down

you may have to reweld the perches. someone else may know of a different approach.
you might want to call calvert on Monday to ask them also.

there is a bunch of in-depth info on rear suspension & axles etc here:
http://www.moparts.org/Tech/
http://www.moparts.org/Tech/Archive/rearsusp.html

this one has a good picture:
http://www.moparts.org/Tech/Archive/rearsusp/13.html
 
EIGHT degrees???? You sure you are measuring that right??

There most certainly ARE shims. However, some are pot metal (alloy) and I've never figured out why. I got some in Spokane at a traditional "spring and brake" truck place, both shims and leaf spring clips.
 
67Dart273 said:
EIGHT degrees???? You sure you are measuring that right??

There most certainly ARE shims. However, some are pot metal (alloy) and I've never figured out why. I got some in Spokane at a traditional "spring and brake" truck place, both shims and leaf spring clips.
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yes ^... go with STEEL only... everything else will crack with bad results and i believe against NHRA rules.

ive always just measured the pinion angle and made sure it was -2 to -5 but after some reading i was corrected to measuring the output shaft angle as your base number. so if the driveshaft is 0 you want 4* difference. the idea is setting the pinion to the trans, not the ground. body rake can change these numbers and does affect results.

now some guys like upwards of 10* for SS springs but its what the car likes...
 
so is the steel better thanthe aluminum ones?:blob:
 
Calvert sells steel shims,but I would,nt add 6* maybe 3* tops.Yes use steel ones,they have holes in the center to sit between the spring and perch.
 
Sounds like you are measuring from the driveshaft. This is not the correct method to determine pinion angle.

Ideally, you want the pinion to become relatively parallel to the transmission as the pinion wraps up under power.

With the vehicle's weight resting on its suspension, make the pinion parallel to the transmission as a base-line, then tip the pinion downward an additional 2-4 degrees. The result is a true 2-4 degree negative pinion angle.
 
DoctorDiff said:
Sounds like you are measuring from the driveshaft. This is not the correct method to determine pinion angle.

Ideally, you want the pinion to become relatively parallel to the transmission as the pinion wraps up under power.

With the vehicle's weight resting on its suspension, make the pinion parallel to the transmission as a base-line, then tip the pinion downward an additional 2-4 degrees. The result is a true 2-4 degree negative pinion angle.
Click to expand...

he has spoken! :prayer:

daredevil said:
Every car can be different depending on how the perches are welded on.
Click to expand...

this is kinda like the degreeing in a cam deal lol... it may take + or - 6 to get what you want!
 
The OP is installing Cal-Tracs. I would shoot for 2-3 degrees, as pinion rise is constant.

BTW, I make billet steel pinion angle wedges.
 
the pinion measured at 8* and the driveshaft was at 0 :blob:
 
345man2 said:
the pinion measured at 8* and the driveshaft was at 0 :blob:
Click to expand...


Forget about the driveshaft for now. Pinion angle is relative to the ground, not the driveshaft. Imagine a line extending from the front of your engine, through your crankshaft and through your output shaft in the trans. Now imagine a line through your pinion. Those two lines should run parallel for a good start.

Example:
 

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Adjust your angle with adjustable perches and shackles.

You can stand your springs on end and turn the rear but will the springs work correctly.

Shims are for lifted 4x4's
 

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Bad Sport said:
Forget about the driveshaft for now. Pinion angle is relative to the ground, not the driveshaft. Imagine a line extending from the front of your engine, through your crankshaft and through your output shaft in the trans. Now imagine a line through your pinion. Those two lines should run parallel for a good start.

Example:
Click to expand...

right, to the tranmission. your assuming the output shaft is parallel to the ground.
 
Yup. Your "zero reference" is the crankshaft/ transmission shaft centerline. Don't forget that the engine pan rails are parallel to both these. So is the (TF) trans pan rail. The trans pan, though, might be warped on the bottom
 
now the adjustable hangers and smaller shims could work , hadn thought of them any one else run them?:blob:
 
345man2 said:
now the adjustable hangers and smaller shims could work , hadn thought of them any one else run them?:blob:
Click to expand...
changing the height of the front eyelet changes the centerline of force, or what ever its called i have forgotten... just get steel shims and be done.

measure pan rail and make sure pinion is -4 compared to that...
 
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