modular

I installed DJM rear shackles at the 1.5" drop position with zero drive line shudder about a month ago. Last week I had Belltech drop struts (1" drop position) & Belltech rear Street Perf. drop shocks installed and the shackles moved to the 2" drop position. The tech drove the truck after his work and thought he noticed some slight shudder at low speeds off and on so he installed 2 degree shims I had with the shocks. Here is where it gets interesting and my question.....after picking up the truck I noticed no low speed shudder but I now have a vibration between 75 and 80 mph that was NOT there before the install. If the pinion shims where not needed would they cause a vibration at higher speeds?? Conversely, do I need to install larger 2.5 or 3 degree shims? Any help is greatly appreciated.

modular

I seem to be getting conflicting information. When you lower a truck using shackles the pinion shim is installed with the fat end facing the rear of the truck, correct?

modular

Looks like even with the 2* shims the pinion angle is still of a little less than 2* so 3* shims are in order. This was double checked with a pinion angle finder.

Woo Sah

Lol. You seem to be answering your questions as you go. The good thing is it sounds like you got a good shop working with you and I get to follow your progress.

I have the Belltech drop shackles lower to the 2" hole and didn't have any problems with shudder or bumping. I did use belltech shim kit #4974. However I did fold the creases also. I added airbags for towing and bottom out with 5psi or less but that is a bag mounting bracket problem. Still coming up with a plan to correct it.

Im gonna follow you along to see how you do. I have the drop struts on standby as I am putting on some 305/50-20 Terras when i decide on my model rim. If I can get get a little more drop after the install ill use the adjustable struts. If I can use the adjustables I was going to get some feed back on the performance rear shocks before I purchase them. And off course if I can't drop the front with the tire choice I may just get a matching set of performance shocks/struts.

Good luck, I'll be lurking.

02reaper

iTrader: (2)

The fat end of the shims should go towards the front of the vehicle. This points the pumpkin down. The lowering shackles make your pumpkin point up more.

modular

That conflicts with 90% of what I have read or been told nor does that make sense. Placing the thick end facing the front of the truck will raise the front of the pumpkin. The link is just one of many articles I have read......

http://www.fordmuscle.com/archives/2.../F150Lowering/

papa tiger

Is your drive shaft free to flex. You should line it up as straight as practical. Spounds like it is way off. Thick part of shim in back would point the pumpkin up. Turn em around and see what happens. He should have done that. Some jobs don't go as planned.

modular

You are the second person to mention reversing the shims. I have a 2 piece drive shaft. We are going to try 3* shims in place of the 2* shims Saturday morning. If that does not work I guess the next step would be reversing them to see how that works out.

papa tiger

You'll probably see a 1/2 mpg gain when you have it finished. Low and very quick, smoooooth. LOL. Sway bars ? Did they have to go? If not I bet stability is fun, and sooooo low. Do the front tires angle out now? You can also lower your front air dam by an inch on its studs with washers. Just watch dips as it will rub on some coming out of parking lots. Seems to drive even better lowered.

modular

Humor...I recognize that...

The front is only down 1.25" and the rear 2". This is VERY mild. Alignment is 100% good as it was done after the front struts we're installed. Heck, I am even going to add the Hellwig rear bar come spring.