Pinion angle shims

[Darter6]

Question, If installing 6* shim to lower the pinion angle at the spring perch,will that give me 6* at the pinion, or more ?

 

[Budnicks]

I'd assume it'll be far more than 6*
they usually have about appr. 2* down {could be more},
if you installed them so it adds neg. degrees {front of the pinion down}
that'd be appr. 8* down, {too much IMO}
if you went the other way
it'd be up 4*, that's the wrong direction {unless something is far different}
the factory had it really close, built in/welded perches from the factory
at min. 2*-3* + or - usually the front of the pinion pointing downward
in relationship to the engine/trans crankshaft centerline

it was mainly for wear issues of the universal joints
to spin the little needle bearing, for staving of wear

generally a drag car set up is about 4* down {+ or - a degree},
in relation to the crank, to help it bite some
when the suspension works it goes up some in the front of the springs
the extra pinions angle helps with bite, but you don't want to go wild either

I don't know what you have {you may need it, I don't know}
but I'd think the 6* shims are swinging for the fences

 

[493 Mike]

Question, If installing 6* shim to lower the pinion angle at the spring perch,will that give me 6* at the pinion, or more ?

It would give you 6*. Imagine if you had a 90* shim. The pinion would look straight down. What is the current angle and what do you want?
Mike

 

[Sixpactogo]

It would give you 6*. Imagine if you had a 90* shim. The pinion would look straight down. What is the current angle and what do you want?
Mike

It depends on what you had for angle before adding the 6 degrees. If you add more than 3 or 4 degree shims you don't have much left for your spring perch to sit over the stud holding the leaf spring together. If your driveshaft is angled down from the transmission (as most are) you add that angle to the pinion angle to get the true pinion angle. 6 degrees seems like way too much without knowing what the rest of the drive line is. From what I've learned about mopar pinion angles with leaf springs, you want 5-7 degrees angle at rest. Say your drive shaft is angled up 2 degrees from pinion to transmission and your pinion is nosed down 3 degrees. You would have a 5 degree pinion angle. You probably don't want much more than that.

 

[67belvedere/225]

since were on the subject , since i swapped my 82 dodge 8 1/4 diff
the car has driveline vibration at 65 - 70 mph. now that i have the new 700 r4 tranny on . i need to address this issue
did or does anybody use the tremek app. on there i phone ? and what is the engine or out put shaft angle need to be as a starting point ???
i watched a few vids on how the angles need to add . I'm going to try the app on my friends pick up that has no issue and see if the app works or get it to work. and also there is the issue of side to side not just up and down now
thanks

 

[Darter6]

Thanks to all, The car was put together 15 years ago and has angle shims in it now that are unknown. Reading with all things level the pinion is at +7* up.Trans yoke is +3* up. Bad vibration at 45 to 60 MPH. Can't do much with the engine/trans side would like to work with pinion angle leaf spring shims to correct the problem. I will remove what is in there now and start from there with a new reading. I have read several different ways of adding A to B and getting a total of C etc. etc. What would be nice is to get +3* at the trans yoke and -3* at the pinion in a perfect world.

 

[Sixpactogo]

lThere is a lot of confusion out there on how to set pinion angles. Spicer has a site that says the pinion should be parallel with the transmission.It sounds like your pinion is nosed up and that is the wrong direction. Who ever set yours up years ago probably already has 6 degree shims but installed them backwards raising the pinion up that high.
My engine/Trans has a 3.4 degree angle down so using their directions, I shimmed the pinion up 3 degrees making them parallel thinking that would fix my vibration. It got worse!
Then I found another site that really didn't take into account the engine/trans angle at all. They were only concerned with the angle at the driveshaft / pinion. I tried that and it fixed my issue. They are probably all correct to a point but IMO, you keep playing with it until you get it right. Here is the one that worked for me.
http://www.quickperformance.com/Pinion-Angle-Measurement_ep_45.html

 

[383man]

I found I like how the first section of this tells about pinion angle. You need to remember its about the difference in the trans/crank centerline angle and the rear pinion angle. Basically you want the trans/eng centerline and the pinion centerline the same when on the gas but different parallel lines. Leaf spring cars can move up about 3 to 5 degrees when on the gas so that's why you set the pinion angle down some. When the pinion moves as you step on the gas hard it will move up to make the trans/eng and pinion centerlines about the same but still different parallel lines when on the gas. That way the driveshaft has some angle so the U-joints will work and stay well lubed. Ron

http://www.moparts.org/Tech/Archive/axle/8.html

 

[67belvedere/225]

on my car there was a real bad vibration , the diff yoke was pointing down i shimmed it up some more and it did help , about half the vibration as before. i will try quick performance one and see what i get.