Driveline Angles

[punkin]

Hello all,

Working on a 69 F-body. I've installed a 4l80e and ford 9" and I'm struggling with wrapping my head around some of the angles. I did this conversion on a 68 about 2 years ago and there were no adjustments required. For some reason, things aren't as straight forward this time go round. Maybe my head is a little vapor locked. I could use some advice.

With digital angle finder;
Measured engine/trans at crank pulley and zero'd out the angle finder (viewing the angle finder from the driver's side of the car.
Measured the driveshaft (again viewing from the driver's side) the driveshaft points upwards toward the transmission at 6.3 degrees.
Measured the differential/pinion (from driver's side), the pinion points upwards toward the transmission at 7.4 degree.

I've got a little bit of room still under the trans tunnel to raise the transmission if necessary but not much. I don't think this really matters but the engine/trans is currently pointing tailshaft down with reference to the chassis approx 4 degrees. In my mind, I'm thinking raise the transmission as much as practically possible then put approx 4 degrees additional pinion angle in the differential.



Am I on the right track? Thoughts? Thanks in advance.

[punkin]

A slight update, you may consider ignoring previous data. I have a couple different transmission mounts to work with. I installed a taller trans mount. Also rather than zeroing out the angle finder on the crank pulley, I simply zeroed it out on the floor. Here are my current measurements;

Crank pulley; engine/trans pointing down hill toward the tail housing at 5.3 degrees
Drive shaft; down at 1.1 degrees
Differential; up at 2.1 degrees.

Again, thanks for any advice or recommendations.

[Hotwire]

Engine working angle 5.3-1.1=4.2 working driveshaft angle
Diff working angle 1.1-2.1=1.0 working driveshaft angle

You need these 2 angles to be as close together as possible that they'll equal each other out, you're 3.2 degrees out. Also with leaf springs you want the pinion angled around 2 degrees down so that when the torque hits and the axle wraps you don't bind the u joints.

[punkin]

I thank you for the reply. I appreciate the help with the sanity check. I didn't want to muddy the water from the start but I'm also running caltracs. This will be mostly street driven. My understanding with the caltracs is because it will further limit the diff rotation I can get away with a little tighter front and rear u-joint angles. I'm thinking additional 2 degrees in the diff should get me there. Does that sound right?