OK, I have a 2004 2wd F-150 super crew and recently put on 22" wheels, and all was well still a great ride very smooth. Last night I installed 2" lowering shackles and drove the truck and now it shutters from 15-20 mph! Under accelerating/braking/or just consistant speed. Also since day one it has had throttle lag and a very non-responsive throttle, and I drove a 2005 rental and my friends 2004 and both of them have very responsive throttles. Any suggestions?

 

Sorry, I have no experience with the new bodystyle F150. However, as to the shutters.....

Since it started after the addition of the lowering shackles, you may need pinion shims (On 97-04s you do not need them until a 3 or 4 inch lowering). Look under a stock 05 in the area of the driveshaft and rearend connection, now look at yours. Is there a difference in the angle of the rearend connection to the driveshaft? If so, you need a 3 or 4 degree shim. The pinion shim is a wedge shape piece of metal. It bolts to the bottom of the leafspring pack (will need a longer head centerpin bolt) and re-aligns your driveshaft where it connects to the rearend. If not, you may not have the shackle bolts torqued correctly.

As to your throttle......

Throttle cable could be stretched, and or
throttle linkage may need lubrication, and or
bad gas (common in Winter), and or
your truck has a smaller engine, and or
your rearend gear ratio is different than the others, and or
your truck is a heavier version, and or
larger overall diameter tires will hurt response, and or
vacuum leak (hose disconnected somewhere under the hood)

 

Thank you, I ordered the shimmes and will replace them next week when they come in so hopefully that will fix it. As far as teh throttle in 04 they switched toa fly by wire throttle so I know it's not the cable and the other 04 moddel I drove hat the same size engine and rear end gears, so it cant be that either. Thank you for you response though.

 

DDemel,
Could you please post me when you make your changes. I, too, have the shuddering after a 2" Beltech spring shackle drip on the rear. Love the new stance of the truck
Thank You,
Duggins

 

I GOT THE SHIMMES BUT THEY NEEDED MODIFICATION BECAUSE NO ONE MAKES THE SHIMMES FOR THE 04 F150 YET AND IT SOMEWHAT SUBSIDED THE SHUTTER BUT IT IS STILL NOT ALL GONE. PLUS BY PUTTING THE SHIMMES IN IT ACTUALLY RAISED THE TRUCK BACK UP SOME BECAUSE THE SHIMMES GO ABOVE THE AXLE AND BELOW THE LEAF SPRINGS.

 

On the aftermarket site I was asking about 2" lowering of the 04 4x4 rear end. You comments on shuttering makes me very cautious. When I talked to head FoMoCo delaer mechanic a few weeks ago about lowering, he told me that there would probably be a shudder and maybe even noist. He recommended against this lowering. Now with your experience, I may hold off. Thanks for info.
Re: Dog performance, I too had poor throttle response. I installed a 1714 tuner at but 87 and 91 octanes. I think the 87 setting was the best (in my opinion). Performance was noticably better with the tune.

 

sounds like you hosed up the pinion angle.
need to fix it before it hoses the u joints

 

DDemel, Thanks once again for the post. I'm pulling the 2" drop shackles off my truck to get back the smooth ride.
StylingConcepts (where I bought them) couldn't tell me how much shim to use. The put me in touch with Beltech (the makers). The Beltech technical person wanted to know why I wasn't talking to the people that sold me the kit!!? Finally Beltech told me that there was NO formula even when asked about the same wheelbase truck with the same drop kit. He said 5 out of 10 trucks would be different. He suggested that I buy a series of shims to try, finally recommended going with a middle range of 2 deg. Told me to take it to a SHOP. Wasn't helpful and seems that they have something on their hands with the 04-05's that they aren't ready top deal with. So, I'm pullin' them and putting them on e-bay. High A$$ and all, love me truck.
Duggins
PS. Sure was nice to be able to see over the tailgate...