Hey yall,

A little background info, I just finished a lift on my 01 f150 4x4 supercab 5.4L, with a fabtech 6", single steering stabilizer, 2" torsion crank, and 2.5" aal. Its running on 37x14x16 Super Swamper IROK's wrapped around **** Cepek dc-2's.
I finished 'er up on friday, andc have driven 20 miles since, and unfortunately found out that my truck has contracted the death wobble disease. It first occured comming home from the shop, went over a bridge at about 40-45 and on the downslope the wheel started to shake a little bit and within a second or two it was so violent I had change flying out of the cupholder and my drink was splashing all over the place. After comming to a stop and changing my shorts I limped it home. The next day I took a 14 mile trip and noticed the wobble won't occur until I am over 40mph and hit a bump of some sort, however it hasn't been violent since the first time. just a small side to side shake in the wheel. I havn't gone over 55mph yet. I noticed whenever I go over concrete (such as a bridge) instead of asphault, it gets worse, especially if there's expansion joints.
Now, I have thoroughly inspected the entire steering rack and the idler, pitman, and ends are all tight and have no play. Ball joints are only 20k miles old and are all tight, all lift bolts are tight, can death wobble be caused purely by alignment? my next action is to bring it to a offroad alignment shop, have them do it, and go throught the entire thing and torque it all down.

Is there anything I can do to inspect further? are there any key points known to cause this problem on this truck? Can it be caused solely by bad alignment?
Thanks in advance for any help guys, I've been searching for fixes for a long time and cant narrow down anything, any help at all is much appreciated.

 

I'd start at the alignment shop, especially if you have just installed the lift, and have yet to get it aligned. If the toe-in is wacky, crazy things can happen.

And you should post some pics for us all to see....

 

Thats what i figured. Reading about how some people have had a demon in the truck that alignment doesnt fix didnt sit well with me and I wanted to get a jump on any fixes i should look for.
Its redneck aligned for the time being, toe in a 1/4" measured tire to tire, but who knows if one is sticking out more than the other. plus the steering wheel is 90* counter clockwise when driving straight (i was in a rush). Itll be in the shop on monday

Pics are in the pic thread in the 97-03 forum, I probably posted about 12, hahahah.

 

I'd say its probably your alignment. I've yet to experience any death wobble in over 50k miles of driving my truck with the lift. What AAL did you go with, and did it eliminate the need for the fabtech block in the rear? I'm debating on either a AAL and (hopefully) just the stock block) or a complete new spring pack for the rear to eliminate all of the blocks.

 

Even just having the alignment off a little with tires like that it's sure to make the vibrations worse. And post some pics! We love lifted 97-03's around here!

 

Pics in the 97-03 pic thread, don't wanna repost all over the place! Haha, and yeah I figured so. The aal was 2.5" of lift, and a 4" block. Over christmas im going to reward my self with 6"shocks leaf packs to elimanate any axel wrap. Or atleast minimize it.

 

Alright guys, big problems. Alignment shop called me today and said that he drove it and its still shaking. I asked if it was wobbling and he said yeah all that. Now if its shaking I know that's just the aggresive tires but he also made it sound like its still wobbleing at 35 and up...
any ideas y'all? He also said he thinks its a bad tire. I mean, keep in mind these are 37x14 BIAS iroks. granted they're rough tires but I don't think this should cause death wobble. Ill be picking it up tomorow and testing it out, but I know I need to rotate them to find the bad one.
ANY ideas at all? I need to make a 450mi round trip next weekend to put the gears in.... I checked the rack but it seemed tight. Next up is rotating the tires and seeing if that's the issue. But im in a time crunch here.

 

It could be the a tire, bias tires are a little more finicky when used for daily driving use. They flat spot and have more sidewall flex which attributes to their ride quality especially at higher speeds. Is there a reason you went with bias over radials?

 

Alright guys, big problems. Alignment shop called me today and said that he drove it and its still shaking. I asked if it was wobbling and he said yeah all that. Now if its shaking I know that's just the aggresive tires but he also made it sound like its still wobbleing at 35 and up...
any ideas y'all? He also said he thinks its a bad tire. I mean, keep in mind these are 37x14 BIAS iroks. granted they're rough tires but I don't think this should cause death wobble. Ill be picking it up tomorow and testing it out, but I know I need to rotate them to find the bad one.
ANY ideas at all? I need to make a 450mi round trip next weekend to put the gears in.... I checked the rack but it seemed tight. Next up is rotating the tires and seeing if that's the issue. But im in a time crunch here.

 

After i put my lift on the truck would randomly jerk violently to the right. I couldnt drive over 30mph. I was somewhat surprised i made it home, 12 miles, without wrecking. An alignment fixed it and i have been fine since. I hope you find the problem.

 

Those 37x14x16 tires are a lot of weight in rubber slung way out from a 16" wheel rim where the wheel weights are. You are trying to balance a 37" diameter circle which is a good foot wide with weights on a 16" circle. 37-16=21 and 21/2 is 10.5 inches from rim to tread. The imbalance can be anywhere in the rubber / carcass ... inside, outside, center, etc.

Add that you likely have much more outwards offset which changes the tire's center line to ball joint steering axis relationship. A little imbalance on center is different than having that same imbalance in a huge tire moved away from the steering axis.

You may never cure it with that setup, and if you don't .... it's your steering and suspension that's taking a beating. You can only align to a point, it is not a magic fix. All it takes is a slight imbalance on such a heavy tire/wheel setup and a bump to start a oscillating wobble that overpowers the steering components by sheer weight. That's why you have to stop to stop it once started.

Back in the old days, when I first bought my '77 F150 ..... guys with the huge 38-40-44" tires on 15" wheels often had racks of several steering stabilizers (like a shock absorber laid on it's side) to help control the tires, but those extra stabilizers and huge tires still add great stresses to steering boxes and linkage and I've seen frames cracked and boxes worn slam out.

You might try swapping the big tires front to rear / vicy-versa ?

Might slip the stock wheels and tires back on to "try" out .... for that trip anyway?

 

Oops, sorry phone double posted...
I figured so and one is severly unbalance...need to figure out if that one is on the front. I went with bias because at the time a aggressive 37 radial was wayyy above my budget, and bias are much better offroad in my opinion. I know they should scrub around corners but tires alone causing DW?

 

@tbear
excellent info. This all makes sense, its not the setup that I would love but its what I can afford. Its only got a single stabilizer at the moment as that's all that's offered...besides skyjacker exclusive setup. Im going to weld the second one on.
im definately going to see if I can determine if its one bad tire this weekend, and if it is ill get a replacement. But also the stock wheels are a good idea since they havnt sold yet. As a bandaid for the trip they wont work...31" tires with 488's for 500 miles is a wallet killer.

 

You might want to try having them road force balanced or maybe even trued. I've heard of problems with interco's bias tires not being perfectly round before.

 

Road force balance? What about beads?