Newbie pinion angle primer

[GTX]

Ok, I admit that I don't know much about all of this (I'm still learning much after many years) and I'll bet a few others don't either but don't want to speak up.

So, Ron or Neil or someone, would it be asking a lot to jot down a basic primer for pinion angle and it's effects?
I've read a few posts here and there on the topic but nothing that really explains everything.

Anyone care to write a primer? What is optimal and why, what happens if you are not in that range?


Thanks!!!

[Blown70]

Not sure if this will help but the pinion angle will depend on the suspension your are running.  Leaf, Ladder, 4-link. 

Now for the others to tell you the degrees

[Chryco Psycho]

to give the basic idea as power is tranmitted to the diff the pinion will try to climb the ring gear , & the best way to transmit power is through a straight driveshaft so no power is lost in the U jiont with it being at an angle so as the power is applied & the diff twists on the springs & end up in a straight line with the driveshaft.   The actual degree is dictated by how much torque you are making , How much traction you have & how soft the leaf springs are or how much they will deflect , clamping the front section of the spring tight with a Square top U bolt with allow less distortion in the spring . Having the spring deflect & snap straight will cause wheel hop , & I have seen some high torque cars wind the spring up enough that it stays bent after 1 run on slicks , generally if you are bending the springs you serious need to lok at Ladderbars or 4 link

Having the pinion sit too high say 2 * nose up can cause heavy vibration , too low wil vibrate too but not as bad

Generally a std street setup will have the pinion 4-7* nose down from the driveshaft angle & under load the pinion should rise so the driveshaft & pinion are very close to being in line

With 4 link & ladder bar systems the diff cannot rotate without lifting the whole body which is why these systems are used to use the full weight of the chassis as leverage & as the body lifts the driveshaft is still kept in line with the diff so the angle can be 1*- 2* nose down  

[firefighter3931]

  Generally speaking, the stiffer the front segment....the less negative pinion angle required. Springs flatten out and weaken over time so what works on a fresh set of springs might not be enough for more "seasoned" leafs. It's something that should probably be looked at every couple of years depending on use/abuse.

Ron

[Ghoste]

There is a bit of a primer on this over at that other Mopar site.

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

[Kern Dog]

Years back before i knew much about pinion angles, I wanted to lower my 70 Charger after installing new XHD leafs. I bought some SS spring hangers at a swap meet and drilled holes as high up on the bracket as i could without having the front spring eye hit the body. I dont recall ever having any vibration problems until....
I installed a GV unit. This required me to use a shorter drive shaft. It apparantly didn't play well with the pinion angle because it now had an annoying vibration that I incorrectly blamed on the trans mount, the driveshaft, the U joints....
Anyhow, recently I decided to raise the rear up a bit since the springs have softened up and sagged a little. I put the original spring hangers back in and on the first test drive, the vibration was GONE. It was then that I had the "light bulb moment." Pinion angles are tricky.