I work as a tech at a ford dealership, and I wanted to level my 2wd screw, but know all about the vibration problems, so heres what i've figured out so far.

2" drop, terrible vibration, almost undrivable.

2" drop and 2deg shims, can't feel the vib. as much, but still annoying at around 60-65mph.

2" drop and 3deg shims, best so far, barely noticable boom noise, not really a vibration, at around 60-65.

went back to stock, then i noticed a booming/slight vib. around 60 that i must not have been in tune with until now???

1" drop, (the second set of holes in the shackles), pretty noticeable vib and booming at around 60 still.

tommorrow i'm going to put the 2 deg shims in with the 1" drop and try that.

The only problem with the 2" drop and 3 deg shims, is that the u bolts are really too short for the thickness of the shims, so im only going to shim it 2 deg and hope that it works with the 1" drop.


more later......

 

Wow, talk about hands-on research!
Great info, keep us posted on your results!

 

I had the Bell Tech shackles installed several months ago and have never noticed any vibration and I am very particular. The dealer did not install shims, he said with a 2" drop they weren't necessary. My only complaint is the 2" did not level the stance. There is still a slight rake. I believe another 1" would do it but can't find away to drop it 3", just 2" (shackles) or 4" (shackles and hangars). I've thought about doing the 4" with shims and adding an airlift kit to make it level. Any comments?

 

I too developed the harmonic drone after dropping the rear of my SCrew with shackles.

But within a week the hum / drone went away
I figured I just wore in the u-joint at a new angle then it was used to.

It's just not there anymore.

 

ok, update:

today i tried the following 2 combinations that both worked very well. I also removed the "factory shim" thats bolted in the leaf spring by the centering bolt. I realized the factory shim was actually working a little to the disadvantage (it angled the pinion to the ground a little) and it added about 1/4 to 3/8 of a inch of u-bolt thread that is needed with the aftermarket shims. Heres what worked for me:

1" drop on shackles with factory shim removed and 2deg shim.

2" drop on shackles with factory shim removed and 3 deg shim.

both of these combos had less noticable vibration and boom than the factory setup! Like i said before, i never tuned in to the vibration that my truck had from the factory until i tried the shackles alone, and then went back to stock. But that doesnt suprise me because ive seen quite a few screws come in with vibrations with the stock setup even. Ive just never paid much attention to them because our front end guy usually works on all that stuff, and i mostly do electrical/driveability.

Anyway, if anyone is experiencing problems with 2" shackles, i think that removing the factory spacer/shim and using a 3deg wedge shim to angle the pinion back upwards (large end of the shim towards the rear )

 

LariatScrew,

I don't know where you live in eastern NC, but on my next trip out to Cape Hatteras I owe you lunch.

I've all but ordered my 2" shackles and I was wondering if anyone had done any comparisons of various drops and shims. I didn't want to have to do it twice, since I really don't have access to a good place to do the work.

Looks like I need to go ahead and get the 3" shims with my kit.

Thanks, dude.

 

I live in Kinston, work at Evans Ford here in town. If you are ever near, stop by, my name is Jeff

 

LariatScrew,
Been reading your threads on vibration.
I have the 2" lowering shackles on and I get a vibration in the steering wheel at 20, 40, and 50 mph and this at 1400-1500 rpm.
I also have a exhaust drone over 60 mph. I have the factory Harley Davidson exhaust system on.
On some highways I don't have the vibration.
Would the 3 deg shim with the factory shim out fix the vibrayion?
My ford dealer installed the shackles and all the other stuff.
Thanks for any help.
My web site is:
http://www.***-internet.com/jimwalker/newpickup.htm
My e-mail:
jimw@***-internet.com

 

hey, this is me, one of my old id's

i think that it will be the best it can be with the factory shim removed and a 3deg shim. As to whether it totally fixes it, i think every truck is a little different. Weve had factory screws with vibrations that were never totally fixed, so its hard to say.

 

I originally had the Belltech 2" shackles installed to even out the truck and it did the job. Just recently had 2" hangers and 2" coils with Belltech nitro shocks installed for a total 4-2 drop..what a difference WOW...no vibration at all with any of the installs.
https://www.f150online.com/galleries...y.cfm?gnum=338

 

 

Back in May I posted some threads regarding the 2" drop, vibration and the need for shims. At that time I got responses from "experts" that thought I was crazy.

After installing the 2 degree shim, the vibration is all but gone. Still a little at 60-65 mph. After reading the posts here, I'm going turn the factory shim around to gain a little more angle.

It's nice to know I'm NOT crazy after all. Well....maybe a little!

 

Here's a pic of my Screw after the 2" drop. Still a slight rake. Back end has settled a little since this picture.

 

Dan,
We've got the same exact truck.....down to the taillights. Thanks for posting the side-shot pic of your's. I now know what mine will look like after the drop. Which kit/parts did you use and the vendor(s).
Thanks,
Kevin

 

Same truck as me too! I also have the black Stull Billet and love it. I want to lower mine as well. I just haven't had the time.