Pinion Angle Shims

[LekRap]

Hey,

So I've been on a mission lately to get the best ride possible while having the stance that I like. Got the Gieser Bros progressive coils and really like them. Then the other day, got Deavers on the rear, really like them too...

But...I'm still feeling some "hoppy"/bumpy/vibration in the ride, seems like mostly at slow speeds and when I am coasting/off the throttle.

Got the Deavers installed at Deavers in Santa Ana since I'm pretty local. They warned me at the end of the install that my 1.5" drop shackles may need shims. They said to try it out a few days and then they could make some shims for me if needed.

I called them after driving it a few hours and asked if they could make up those shims for me. My question is what degree shim do I need? I know the Ford Racing drop shackles lower around 1.5" and provide shim (I think it's 2 degrees). Since my front is mid perch height (around 1.5-2" up in front), would that require another 2 degrees? I guess I'm just doubting that just a 2 degree shim would make any real difference???

Does anyone have any experience with shims? Does anyone know an easy way to measure the pinion angle?

 

[Towerhog]

These are the 2.5 degree shims for the Ford F150. Ive used them to rid myself of a driveline vibration. They go between the leaf spring and leaf pad on the axle.

Specialty Products Company | SPC Alignment | The Automotive Alignment Leaders

If you google pinion angle, youll get all sorts of explanations. But the bottom line is you want the rear axle pinion to be on the same plane as the transmission output shaft. Something like this.



You can use the shim in either direction (thick end front or back) which ever corrects the angle.

This is the angle gauge I use. But there are others.

 

[J DAMAGE]

First link is the protractor/tool to use to measure your pinion, can be found at most hardwear store or performance shops, 2nd is a write up.

Empire Polycast Magnetic Protractor-36 at The Home Depot

Measure Pinion Angle | ClassicBroncos.com Tech Articles

 

[LekRap]

Thanks @Towerhog and @J DAMAGE...I appreciate the help! I have been googling it and my head is kinda spinning, so thanks for helping narrow it down.

Towerhog, did the 2.5 shims make a drastic difference for you?

Is it common to have these issues? I feel like the 1.5" I went up in from and the 1.5" I went down in back shouldn't change that much, but hopefully I am wrong and I'm hoping it solves the choppiness I feel at some speeds.

 

[MTF]

I wish Jeff at Deavers would have mention something to me about the shims when they made my custom +2's.
The stock bump stop horn has a angle to it also, how much I'm not sure. I did see it somewhere years ago on this forum.
I still have them in my garage next to the stock springs.
I'm not getting any unusual feedback from my Deavers, might be because I did the Axle Exchange driveshaft too.

I'm very interested how it works out for you.
I may just do it because it does make since to have a straight line of sight. I'll have to give Deavers a call come Monday.
I just hope that if I do this it won't push my driveshaft to much closer to the tranny. I just got done shortening the driveshaft Wednesday.

 

[Towerhog]

Im running Deavers +2 right now. Ive had to use the shims since I swapped out the stock leafs for a set of RPG/Nationals. Even when I went to the Deavers I had to carryover the shims because of driveline vibrations.

When I first measured the angles with the RPG's the transmission was 6 degrees and the pinion was at 2.5. Do the math and I came up 1 degree short using the 2.5 degree shims. But that was ok. It brought the angle into tolerance and took care of any driveline vibrations. If you look at FORD's spec's for the F150, they are close to a 3 degree spread. So anyway, no vibrations.

 

[MTF]

Are you guys using the stock driveshaft?
I have to say, I've never felt any driveline vibrations even the few times I've at 140mph
with the stock driveshaft and/or stock springs, Nationals now with the Deavers or any combination.

 

[Bulletnjm]

140 in a Raptor

 

[MTF]

Yeah, that's why I stated a few times. It's a little scary.
I don't do much over 130 to 135 from now on. Did that last week going home from KHC on the 95
Had to test out the springs and driveshaft. LOL

 

[Bulletnjm]

Thats awesome lol