I'm putting together a project. (picture was at the beginning, its progressed a long way since this picture) I'm using a modified frame from a 91 Dakota. I've installed a 9 1/4 from a 77 Dodge truck on the leaf springs, so I relocated the spring perches on the axle. Now that I'm close enough to actually get the correct angle readings with the weight on the frame, I find I have the axle pinion up at 5 degree angle to the trans center line. Is the 5 degrees going to cause problems on a street driven truck that will probably never have more then 200 lbs in the box? This is not ever going to be at a drag strip, while I own it.

I can get correcting shims in 2 degree and 4 degree angles that I can use to decrease the angle, but I'm not sure the 5 degrees I currently have will even be a problem.

What do you guys think? Thanks, Gene

You want the angles to be (1) minimal (1-1.5, maybe 2) & (2) parallel but in different planes (if one is up from horizontle the other needs to be down from horizontle) (3) plus the pinion a slight bit down further from parallel cuz it will rise on accell & that depends on the app, how much it is expected to rise (not much in your app). First with the truck reasonably level side to side (which it should be, just sayin), see what the trans output shaft angle is at & post it

The old Mopar chassis manual for leaf springs calls for between 3 to 7 degree difference from the drive shaft and pinion shaft with the pinion shaft pointing down towards the ground and the driveshaft pointing up towards the tranny forming a V, not a ^ or inverted V
I've use that spec on a lot of drag cars as well as on my own street cars
As far as tranny angles and other angles I don't worry about them nor try to use those angles in setting my pinion angle to the driveshaft angles

gene, i see another cool project from your fertile mind ! any more pics you can share ?

Here a good video that might help. The issue is the rear angle changes as the rear end moves. http://www.dragstuff.com/techarticles/pinion-angle.html

This link is right here on Moparts as the very first pic shows a good pic of pinion angle. Bottom line is you want the trans centerline and the diff centerline to be about the same when on the gas but on different parallel lines. So on a leaf spring car if you set the pinion say 3 degrees down in relation to the trans it will move up about the 3 degrees when on the gas to be a parallel line to the trans but not the same line. Easy way to look at is if the trans centerline is 0 then the pinion centerline should be about 3 to 4 down on a street driven car so it will move up to be about 0 when on the gas. Ron

Here is the link: http://www.moparts.org/Tech/Archive/axle/8.html

RapidRobert & Cab_Burge, I've built a few cars & trucks. The truck sits as level as my garage, and driveway cement allows, certainly real world close enough to level. The motor mounts were built with the throttle body level in forward/backward and side to side, should give me about 3 degrees trans down. Of course the angles for the pinion angle were checked with the front end up on jack stands, my fat butt doesn't fit under this thing if its not jacked up. I checked the angles with a degree finder placed on the drive shaft yoke in the trans and against the u joint mounting flange on the rear axle. The angles were position corrected. I figure the difference in the angle from a 90 degree setting should be the same, and the difference was all I was concerned about. The side to side angle is good. The trans center line and pinion center line are parallel with each other side to side, and the trans is on a higher level then the rear axle, about 2" higher with a 45" long driveshaft.
When I welded the axle perches on the axle, the axle was on my bench with 2 pieces of 2" x 4" steel tube under each of the perches. I took an educated guess at the pinion angle before I welded them on because the bare frame was sitting on jack stands on my driveway. I'm really pretty happy they are as close as they are. Thank you for your input.

Moparx sorry, not much in updated pictures just one of the painted frame with the motor sitting on it. I've done a bunch of stuff to it, I probably should update the photos.

FurryStomp, that video blew me away. I knew things were moving a lot down there, I guess actually seeing it changes one's perspective.

383man, since I'm at 5 degrees pinion up, I better go with the 6 degree wedge to at least get me back to 1 degree down. It will be better then what I have now. Thanks for that video. Gene

6 degrees is a lot to correct with wedges. The limiting factor will be the locating pin must protrude through.

I know we all use the Performance manual as gospel. I too agree with a relatively weak leaf spring 7 nose down works pretty well on a drag car but it's way too much if smooth operation is the goal.

I believe the 6 degree and the 8 degree wedges both require the center bolt to pass through them.

If it would have been 5 degrees nose down I would have given it a shot, but since it is 5 degrees nose up, I need to do something. The 6 degree and the 8 degree are both the same price, I might go with the 8 degree which will give me an end result of 3 degrees nose down. Gene