So I have a '69 F100 and I just flipped my rear hangers. I know I need to change my pinion angle. I'm at about 1.5 degrees on the drive line and 23 on the pinion. Any suggestions for an easy fix? The truck is NOT stock. I'm pretty sure I'm looking at about an 18 degree shim which is a lot so throw some ideas at me.

 

Are you sure you're measuring in the right places? You don't measure the angle on the drive shaft. You're actually measuring the angle on the output shaft on the tranny and the input shaft on the rearend. You have to put your angle finder on a flat spot on the tranny that is parallel with the out put shaft and same with the rearend. If you were to magically extend the output shaft and the input shaft the two should be perfectly parallel. If you google image pinion angle you'll find lots of info.
If you are out too much to use shims then you'll have to remove and reweld your perches.

 

Easy fix? NOT.

I flipped mine too (full flip on an LB with two-piece driveshaft) and ended up with 12° difference and there was no way I'm gonna stack that many shims. Instead, it's gonna be an axle flip and a C-notch from Fatman Fab... welded.

 

Thanks for the inputs. HIO Silver, I also have the LB with the 2 piece driveshaft. As soon as I looked at my angle... Found these, cheap and probably a lot simpler in my eyes.

Speedway Weld-On Spring Pad for 3 Inch Axle Tube - Speedway Motors, America's Oldest Speed Shop

Get my angle, weld, and BAM!

 

Yeah but.... does your rig have the Flexomatic spring set up? The angle at which the leafs are set basically negate the FOMs. Plus my rig is still gonna do some work so in the end the C-notch is a better option to maintain the FOMs, have some frame clearance, and maintain the look. I am yearning to shift its TKO-500!

 

Yes they are Flexomatic

 

.. then they'll just be along for the ride.

Here is Fatman's kit in case ya change yer mind. Comes with shock brackets so it can use stock-length shocks.

 

How much did that run you if you don't mind me asking? Not trying to sell an arm and a ******** here

 

One ******** was donated for $525... comes with shocks, shock adapter brackets, the C-notches, the saddles, bump stops, and a butt load of hardware. Well written instructions5 with templates to boot.

I'll just make my own the next go 'round now that I have these as models from which to get dimensions.

 

I must've said it 100 times, measure your pinion angle before making any suspension mods.
I did an axle flip on my short bed w/flexo. Moving the axle to the top of the spring pack did not change the pinion angle. Mine is just about at 5 degrees, upward on the pinion angle.

 

Right... the issue is with doing the front spring hanger flip which results in a severe nose-up pinion angle that's waaay out to lunch. The before and after difference is a whopping 10 degrees which is way beyond what I would consider doable with just shims.

Respectfully, the discussion has nothing to do with an axle flip (spring-over) except to note it as a (my) solution.

 

I'm in the middle of the same dilemma. I put the DJM lowering kit front and rear. I ended up with a 5 degree difference in my pinion angle. I put two (2) 2.5 degree shims between the springs and rear-end to get it back. I also removed the pins from the centre of the leaf pack. I replaced the pin with a grade 8 bolt that was about 3/4" longer than the pin. The shims I got have a hole in the centre to fit over the pin/bolt. With the longer bolt in place, it goes through the spring pack, both shims, and into the spring pad on the rear-end. It worked well.............for awhile. After a few hard launches, everything seems to have shifted. Now the truck dog tracks and I get a month out of a u-joint. My point is, if you can do it with out shims, that would seem to be the best way.

 

I'm betting it's the bolt. You might consider welding the shims to the housing and going to a local spring shop and getting new pins with the correct size heads.

 

Or, if you have access to a machine shop, have someone make you a one-piece steel shim to your specific angle requirements.

 

The shims I've got are aluminum so I can't weld them. I thought about getting a one-piece 5 degree shim made.....maybe I'll make some inquiries around town to see about getting a couple made.