bad shimmy - Diesel Forum

jcconstruction · 02-12-2009, 05:42 PM

i have a 06 f 350 dually super duty 4x4 auto diesel 34,000 miles
and it has a bad vibration in it when it hits bigger bumps in road the whole front end shakes violently steering wheel turns from side to side can hardly control it to get it off to the side of road and must almost stop the truck to get the shaking to stop everything seems tight under the front any thoughts would be helpful

OT · 02-12-2009, 06:56 PM

jc..did u just get your 6L or did vibration/shaking just start? IIRC..sometime ago a TSB was issued about what your saying. Maybe long shot, but try setting F/R tires to correct psi. Good luck!

soflasmoker · 02-12-2009, 07:20 PM

Could be alot of things or a combination of things, trac bar, really bad tie rod ends, ball joints, pitman arm (the nut sometimes backs off and makes play) or it could be as simple as OT said and your tires could have diff psi's in them and cause it.

jcconstruction · 02-12-2009, 09:37 PM

thanks will check pressure was driving it to store just now and seems to have very slight constant vib init friend laid money on ball joints seems early for those

**andrewbalser** · 02-12-2009, 10:47 PM

Don't count out the ball joints so quickly. I had my first one go at 30k, so I got the OEM replacement under warranty. At around 50, the other one went, and the replacement one from before was starting to get play in it. Since warranty was up and I was paying the bill, I had all new MOOG, greasable ball joints put in. Now I'm at 90,000 and not a tick from the ball joints yet.

storage_man · 02-13-2009, 02:43 PM

I've got a 06 F250 that does the same thing. I bought the truck new and this just started about 6 months ago. I don't think its ball joints because both trucks (jcconstruction's) are 4x4's.

I've jacked the truck up and checked for loose tie rod, etc. There was no play at all. Tire pressure has always been even. But what I think it maybe is bad shocks. What do you guys think ? The truck rides good no different than the day I bought it.

firemansdiesel · 02-13-2009, 05:38 PM

Sounds like you experienced the death wobble. Check your trac bar (bushing/play & tightness). Then work your way to the front (tie rod ends, ball joints, alignment /caster*, tire tread wear, etc..).

roofwalker · 02-15-2009, 03:36 PM

it'll drive along just fine, but when I am making the slightest turn to the left or hit a bump, this thing will shake your fillings loose.
It ate up a pair of 325/60/20 bfg AT @ 500 ea.
when i put the new ones on, 95% of the problem went away.
I looked underneath and noticed my boots were sucked in. there is no way to grease the ball joints. but when the truck was in the air, i tried but could not find any slop or play anywhere.
Has anyone solved this yet? I'm not looking to give FMC any more of my money.

jcconstruction · 02-16-2009, 04:59 PM

dealer looked at truck today and said it is a steering damper gone bad and everything else is good and tight as for the front tires wearing out on outside edge they said it had nothing to do with the steering or suspention but was from hauling heavy loads causing it to "ride a wheely" and toe in creating wear on outside of tire strange thing is truck rated for 23500 at most ive hauled 2 ton on trailer nothing requireing wheely bars

jcconstruction · 03-10-2009, 09:58 PM

well we installed the new steering stabilizer, helped but still shimmys ,dealersaid needs front tires to get rid of the rest off the problem,put on new tires still shimmys when it goes over overpasses but not as bad now. had truck checked by another independant machanic a good honest one and he could not find any thing wrong in the front just as the dealer has concluded twice and as as i have checked it several times finding noting loose. this thing has just a small shake in steering wheel back and forth even on a good smooth road any thoughts ?

RatherBNtheWoods · 03-10-2009, 10:05 PM

Sounds like the "death wobble" mine had.
There is at least two TSB's out on the matter.
The first TSB changes the caster angle and replaces certain steering wheels.
The second, latter and possibly last TSB replaces the stabilizer mounting bracket with a stronger/new design and IIRC a new(but maybe not different) stabilizer.
This latter fix resolved my problem. I no longer drive with white knuckles when towing.

jcconstruction · 03-10-2009, 10:13 PM

where are you reading the tsbs at would like to check them out

jcconstruction · 03-10-2009, 10:39 PM

found them worth a try thanks

**andrewbalser** · 03-11-2009, 11:30 PM

Ok, whomever gave you that bit about the hauling/towing heavy, and weight being taken off of your front axle sounds like he was guessing, and it's not a very good guess. The reason why I say that is that the whole theory of what he's pitching you would only be remotely possible if the F350 dually that you have had independant front suspension. Now, I know starting in 05 that they switched to a coil suspension system, but the Super Duty is still equipped with a straight front axle. On this particular axle type, the camber of your front wheels is negligibly affected by the amount of load that it bears. So.. IMO your load towing/hauling has NOTHING to do with it. The TOE-in part, on the other hand, could be the whole culprit. TOE in will cause the outside of the tire to wear prematurely, and with extreme toe-in you will see that wear in a cycling pattern around the tire. We had a 99 F53 motorhome chassis that had the "death wobble", and it was eventually corrected with an alignment job. We were told that the toe-in was the cause. This thing would start shaking so bad, you'd have to just about come to a complete stop to recover from it.

RatherBNtheWoods · 03-11-2009, 11:40 PM

Quote:

Originally Posted by andrewbalser

Ok, whomever gave you that bit about the hauling/towing heavy, and weight being taken off of your front axle sounds like he was guessing, and it's not a very good guess. The reason why I say that is that the whole theory of what he's pitching you would only be remotely possible if the F350 dually that you have had independant front suspension. Now, I know starting in 05 that they switched to a coil suspension system, but the Super Duty is still equipped with a straight front axle. On this particular axle type, the camber of your front wheels is negligibly affected by the amount of load that it bears. So.. IMO your load towing/hauling has NOTHING to do with it. The TOE-in part, on the other hand, could be the whole culprit. TOE in will cause the outside of the tire to wear prematurely, and with extreme toe-in you will see that wear in a cycling pattern around the tire. We had a 99 F53 motorhome chassis that had the "death wobble", and it was eventually corrected with an alignment job. We were told that the toe-in was the cause. This thing would start shaking so bad, you'd have to just about come to a complete stop to recover from it.

Well I can't figure out who or which post your responding to, but towing certainly made my truck's death wobble worse. Towing was a factor because it changed the caster angle(not the camber angle) as the rear of the truck squatted under a load. I believe that's why the first TSB had the tech's remove some caster. Wasn't the root evil cause of the problem, but a factor and it did help some.