pinion angle

[chuky]

Hi guys need your help with my pinion angle of my 69 f100 swb, after a year and a half of owning the truck and buying parts i finally decided to start partially my project so in the last month i put in power steering,power brakes, a used modified 390 FE engine and lowered the truck now im in the process of swapping a 3 sp top loader for a mustang 4 sp top loader (installed already) and here is where i got stuck i have to shorten the drive shaft but first i want to get my pinion angle right, so the question is if my transmission is 4 deg negative and my pinion is 12 deg positive what size shim do i need ? since its recommended to be under 3 degrees i can put a 8 degrees 4-12=8 but that would leave me with a 4 degrees each way or im i wrong?

[hazelnut]

the factory set the engine angle at 4.54*, I don't remember what the rear angle is but would think that 5* would work fine.

[HIO Silver]

It is typically recommended that pinion angles match... or as a rule of thumb no more than 2° difference.

[chuky]

Thanks guys for your help. right know i have flexo-matic leaf spring i;m going to try to find the other kind of leaf spring in the junk yard or at least buy the number 1 leaf too see if i can loose another inch or two (28" from floor to btm of wheel opening) on the back and then i;ll recheck the pinion angle and figure out what size shim i need.

Thanks again.