Simply put, I need help from the guru's!
I've looked around but cannot really find the answers to my questions...

I removed the rearend and leaf springs from my 54 f100 to install my rear axle flip and c notch kit, but I need help on how to properly line up the spring perches....

I know that the frame needs to be leveled, everything needs to be reassembled with the axle over, and the pinion angle needs to be set to 0 before I can weld the perches in place, but...

I don't know the proper way to level the frame, and where to mount my angle finder to set everything to zero before a tack weld the perches in place...

Any help, suggestions, feedback would be awesome!

 

Did you purchase some sort of kit with new springs and perches?

I have read that the pro's set pinion angle only after 'ride height' has been established. That would mean having your front suspension height set where you want it as well as the rear. Then, if you are on a level surface, use a level to determine side to side and adjust accordingly. This is the process that I used.

I have been through many pinion angle changes with my leaf spring setup as I tried the recommended 'engine angle down/ pinion angle up'. That did not work for me and burned through too many u-joints, apparently due to 'spring wrap'. I also have my axle 'flipped'. I think 0 is a good starting point but also think it would depend on the type of leaf springs you are using. I am still with the stock, narrow type with 2 leaves removed which I think are more inclined to said 'spring wrap' than a wider, stronger spring pack.
Steve

 

i've got the kit from Midfifty parts... factory leaf pack with all new bushings, zirc fittings, and pins... this truck is an unmolested original with the 223 6 cylinder/ 3 speed column shift tranny/ and original rearend... there has been absolutely no modifications to it up until this point... it is still 6 volt...

could i put a 6 foot level across the bed board mounts to level the frame?
do i put the magnetic angle finder on the drive shaft and set to zero to determine 0 degrees?
would it make more sense to determine the angle when i'm all done with the front as well, or does it not matter because that won't affect how the tranny and rearend are lined up?

 

As far as leveling your frame your main concern should be across the rails and not front to back. You should make sure the the frame is supported in front of and behind your your "C" notches so the frame does not droop when you cut it, also do one side at a time to help prevent the frame from sagging after cutting. As far as pinion angle goes it should never be zero on a leaf spring set up unless you are running ladder bars with sliding perches. Typically leaf spring pinion angle is 4 deg. neg (the difference between the drive shaft and the pinion flange) to allow for spring wrap on acceleration. If you run a special stiff spring or some type of rotation limiter you can reduce the angle. The idea is when the spring wraps your pinion u-joint angle does not exceed zero (0) deg. And like said, pinion angle should not be set until ride height is established and the truck has its normal load on it. My rear end is currently only u-bolted into the spring perches until I can get the cab and bed back on the frame to establish ride height and then I will loosen the bolts and set pinion angle, re-tighten and mig the perches to the diff. housing. When setting rear pinion angle don't be concerned or worry about the front u-joint. Measure the angle of the drive shaft when installed and set your pinion angle 4 deg. below the angle of the drive shaft. When you accelerate the springs will wrap up slightly and change the angle to (hopefully) no more than a 0 deg difference between the pinion and the drive shaft.

Hope this helps.

 

Actually the pinion angle at ride height should be the same as the engine angle. Most engines are installed on a 3-4 degree downward slope (so the carb flange is level). Fortunately they make tapered shims for pinion angle adjustment if you miss by more than a degree or two.

 

I have to add that I'm not by any stretch an expert on this stuff; my replys are based on my own experience and knowledge. Much of what I read re: correct pinion angle turned out to be untrue when applied to leaf sprung rear ends.

Steve

 

Steve, I understand finding a solution by experimentation, and your solution may have mitigated your problem, but it isn't the right solution. The rule that the pinion angle must match the transmission angle is derived from the pure physics of how a pair of U joints work. With miss-matched angles the joints will bind twice per revolution, no other result is possible.
We (personally and most of the factory racers, Ford, Chrysler, etc) drag raced rear leaf sprung vehicles well into the 70's, and never miss-matched the angles. Yes, when drag racing leafs, you do have to control pinion twist, spring wrap up at launch, or you will blow out U joints. That's why traction bars, ladder bars, and pinion snubbers were invented and used with this suspension. The Ramchargers were one of the pioneers in perfecting the control of spring wrap/
pinion angle in the 60's with their SS and then their FX cars with slapper bars and pinion snubbers.
If you are dealing with a race only chassis the springs likely don't completely unwrap, especially if not controlled and using soft springs, for most all of the trip down the strip, so you may need to compensate for the average (mean) effective pinion angle. But on a street driven chassis you need to set for the at rest (no spring wrap) position since that is the state the vehicle will be driven in 99.x% of the time. Slightly miss-matched angle U-joints may not fail frequently enough to be noticed on an occasional driver, (especially compared to the failure frequency at the drag strip due to spring wrap) but they will fail significantly earlier than ones where the angles are matched.