Horrible Shimmy! HELP!!

tabascom16 · #1 (**permalink**) 11-01-2009, 04:55 PM

This is driving me nuts. I have a 79F250 and just put all new spring bushings and add a leafs in and a D60 in front. Truck use to drive smooth as can be before the axle swap with the 38.5 super swampers.

Now I have a horible shimmy where the whole truck just starts shaking out of control. I adjusted the front end alignment and runs a whole lot better now but right around 35mph the truck gets in a huge death shake. Now if I can get through that to 40 and above it runs smooth as can be again.

Any thoughts?? I am starting to think maybe a huge tire weight fell off cause it is at such a set speed. I need to swap the front tires to the back maybe and see if that helps any. Any other input?? Could worn out king pins be a culprit...but with that you would think the faster you went the worse it would be.

ranger429 · #2 (**permalink**) 11-01-2009, 05:08 PM

It is called death wobble, search it and you'll find a bunch of threads.

Is this the first for the Swampers or were they on it before?

tabascom16 · #3 (**permalink**) 11-01-2009, 05:53 PM

The death wobble is on the f150's with a track bar. The 250's have leaf fronts so no track bar. And same exact tires were on it before I made all the mods. I would be total random luck to lose a wheel weight at the same time and could that really even cause such sever wobble...just seems odd that it is at a very precise speed so you would think it has to be something about a wheel.

ranger429 · #4 (**permalink**) 11-01-2009, 05:59 PM

Well thanks for schooling me on the difference between a 1/2 and 3/4 ton. I have had plenty of 3/4 ton trucks that have also had death wobble. I would go over all of your bushing and make sure everything is tight. Death wobble is when your front end shakes violently, doesn't matter what it's on.

compman25 · #5 (**permalink**) 11-01-2009, 08:17 PM

What's the history of the D60 you just put in? Sure it's not bent?

78_f800crewcab4x4 · #6 (**permalink**) 11-01-2009, 08:46 PM

maybe excessive play in the tie-rod ends?

montana_highboy · #7 (**permalink**) 11-01-2009, 10:57 PM

Were the super swampers put back on the same side they were originally on? they may have some irregular directional wear pattern that's creating a bad vibration at a specific speed.