Correct pinion angle

[Learpilot]

My '40 has a TCI (Total Cost Involved) Chassis with  leaf springs with a 8" Maverick Rear End and Mustang II front end.
I have been chasing vibration for some time and it is getting better. The first thing was to get new tires as mine were 8 years old. they had good tread depth, but I was having some issues with tire scrub on the rear inner fender wells. Smaller tires fixed that problem. The next thing was a bent left rear axle. The wheel had a runout of .060" with my dial indicator and it was the same with either rear wheel and only .005 on the right. I still had a bad vibration. Had the drive shaft checked and it was bent and out of balance. I elected to get a new one with a Chevy front u-joint and a ford on the rear. The vibration almost went away. Then I checked the pinion angle. The rear end yoke was pointed up 7 degrees and the driveshaft was up a few degrees ( I don't remember what it was). My '40 was on a level 4 post lift. I put some wedges under the spring perch to point the pinion down, and I also had to lengthen the spring bolt to locate the rear end. I now have the pinion pointed down 1 degree with the driveshaft level.  
My question is this correct or do I need the pinion pointed down more ?
I don't to eat up a u-joint because the angle is not enough to spin the bearings in the joint cups.
My vibration is almost gone it only shows up between 64 and 69 mph. otherwise it is smooth below or above those speeds. I am going to take it back to the tire place and have them re-balance the tires.
Thanks for your answers !!!
Rick

[Harry]

Have the tires checked for being out of round.

[Charlie Chops 1940]

A good web site for drive shaft angles is Inland Empire Driveline. Look at the education portion.

Essentially, if your crank center line is down, say 3 degrees, then the pinion should be up 3 degrees. The u-joints need to be in proper phase also.

Charlie

[Glen]

Essentially, if your crank center line is down, say 3 degrees, then the pinion should be up 3 degrees.
Charlie

good advice.... remember Equal and opposite.

What kind of vibration is it? a shimmy or a buzzing vibration?


find a shop that can road force balance the tires to check runout on them and the wheels themselves.

[Learpilot]

Essentially, if your crank center line is down, say 3 degrees, then the pinion should be up 3 degrees.
Charlie

good advice.... remember Equal and opposite.

What kind of vibration is it? a shimmy or a buzzing vibration?


find a shop that can road force balance the tires to check runout on them and the wheels themselves.

Thanks for the info !!!  
I can go up real easy, just take out 3 degrees of wedges under the read end perch. I though you should have the pinion angle lower than the driveshaft. I will do that.
The vibration is just a vibrating not a shimmy. I hope it is just it is a out of balanced tire.
I will look up the web site and do a lot of reading.
THANKS AGAIN !!!!
P.S. One thing all the reading on the web about pinion angle was on racing and not the street. I guess the writers think the street is not worth writing about.
Rick

[Fat Cat]

There is also a drivelines explained article right here on this site which includes pictures. It can be accessed through the tech section at http://www.roddingroundtable.com/tech/articles/driveline.html