pinion angle.

I don't know of any wrieups, but it's pretty simple. It's in relation to your crank.Find the angle your crank is at, what ever it is, setup your rear from that. MIne was something like ten, and I set it at -2.5

tylerrocks said:

I am getting ready to build a 9" rear end for my car now that the motor is complete. I am having a housing shortened from an F-150, I will buy the centersection and axles new. What I need to know is if there is any good writeups (or advise) about measuring and setting pinion angle, as well as the specs. I would like to weld my spring perches as close as possible to the correct angle.

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I have heard that any angle over 6% is going to cause premature U Joint wear.

The stock angle is 3 degrees

Check you engine/driveline angle by first getting your car level, referenced off the rocker panels. Check both rockers to make sure you don't have a "frame twist". If your engine/driveline angle is at or less than 4 degrees, and this is the combination you are going to stay with, then go ahead and match the perches to this angle. If you think you might change later, my suggestion would be to weld the perches at the 3* stock angle.
If the engine/driveline angle is greater than 4 degrees, I'd suggest correcting this first.
From my experience, car drivelines start to get vibrations above 4 degrees. I've also had vibrations start when the difference in the two angles reaches between 1/4 and 1/2 degree. Your experience may differ. I've had very good results staying between 3 and 4 degrees, and matching the angles to less than 1/4 degree difference. I use a jeweled movement inclinometer (for building model airplanes). It is very accurate, and was cheaper than the professional tools. The down side is you have to be careful not to damage it.

HTH,

Scott

thehueypilot said:

http://www.baselinesuspensions.com/info/pinionangle.htm

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With due respect, I would ignore that link entirely. Try this thread for how you want to setup a vintage mustang.

http://forums.stangnet.com/showthread.php?t=471744

I like the first article link

This one

http://www.drivetrain.com/driveline_angle_problem.html

I didn't care for the second one. cheap inclinometers from Sears, Home depot etc can be off by as much as 1/2*. In my opinion they don't have a smooth enough movement to give good repeatable results closer than 1/4*.
I picked up jeweled movement incidence meter used in building remote control airplanes. It is wicked acurate and about $30.00. It also comes with a nice long beam usable to level the car using the rockers as your guide. This is a good option if you are only doing one rear end, or are careful handling it (I've had this last one for almost 8 years).