Death wobble

I know this is going to sound stupid, but heres what happened to "Poppy", the old lifted 69. I lifted it and it did the same thing. so we changed everything on the front-end. it did the same thing still! Turned out the tires had seperated on the inside with less than 1000 miles on them! change the front tires with the rear and see what happens. I betthat your rear does the boucing. also check your hubs tto see if they are disengageing when in the free position.

 

I'm pretty sure it's not alignment. I've tried numerous positions. 1/16" toe-in to zero, which is in the range of where I want my tires, causes death wobble. Massive toe-out does not eliminate it, but masks it enough to make it driveable. I think putting a damper on it wouldn't be a bad idea once I get the tie rods flipped.

I swapped the tires front to rear this morning. It did nothing. Tires and balance are fine.

The more I shake the frame, the more I suspect those soft rubber shackle bushings are allowing slop. If I shake it hard enough, I can see the bolts squashing the rubber out of the gap.

EDIT - Hubs spin freely both sides when disengaged.

 

I would say solve the dw first, then put the steering damper on there. I don't think it's a great idea to try and mask the dw with a damper.

Just thinking on the toe-out, that probably masks the dw by acting as a damper - forcing the tires apart.

My uncle told me that they used to have to jerk the steering wheel hard to stop dw in an old truck. I didn't have any luck with that method, I had to come to a complete stop to make it quit.

 

something else I thought of is, Hows the Drag link springs? That can cause problems like this since if the springs are weak they can start springing off of each other. Napa sells a rebuild kit for them for 6.00.

 

Say again? :?

 

If your drag link has weak cup springs, you know, the springs behind the "Jesus" nuts and cotter pins on the draglink, are weak, when you hit a bump or slight imperfection in the road surface can cause one spring to compress in while the other does the same. when the "load is released " it will spring back. the springing multiplies till you feel it in the wheel and stop the truck.

 

Are you talking tie rod ends (TREs)? They're almost new.

 

These are the parts they are talking about:

They go in the ends of this part:

 

Ahhh... I didn't even know that had springs in it. Well, those aren't new, but like I say, pretty much zero slop. I will definitely check it out, though. Not sure if my Ross box is the Holy Grail of all Ross boxes or something, I know a lot of people complain about them, but prior to me changing this bracketry around, my steering was golden. I guess it's possible I broke something when I jacked the frame.

 

Do you have ball joints or king pin bearings? In my expeience, which is not much, wobble is caused by either tires, or bad caster angles, it could also be caused by bad brakes, but it appears you do not have that problem. The wobble occurs because the caster is changing from positive to negative or the caster is not the same on each side. Positive is with the lower ball joint or bearing more forward. Think about how the front forks are on a bike. How close to neutral are you? Positive caster helps keep the wheels in a straight line. Toe will not change your DB only mask it as stated before. Caster could be changing because of a loose bushing also, not sure of the reversal set up you have. Looking form the side, you could draw an imaginary line though the center of the ball joints or king pin bearing and determine where your caster is set, if it is close to 0, any looseness will change caster. Does it occur when applying the brakes, going over a bump, just a 30 mph, or other conditions? I have seen where an upper ball joint has been worn and caused a similar condition. Make sure everything is tight and not worn, spring U bolts, bearings, hubs, bushings, etc.

Just went to look at your photos (DSC00222), it looks like the shim under the spring pad is the wrong way. The angle it is at would decrease caster, but line up the driveshaft yolks better. May want to try turing the angled shim around 180 degrees.

Maybe your physics class can help you determine the harmonics of the vibration

 

I FIXED IT!!

It was the soft rubber bushings that I got from Krage's. If you are considering them, I highly recommend trying the poly bushings instead, or making your own out of a metal sleeve and washers. I did the latter.

I turned down some extra poly body mounts I had laying around from another project vehicle for use on the inside of the hangers. Very hard stuff. I cut them flush so that there is no "lip" sticking out. I think that is where the majority of my problem lay. (The soft lip was allowing the shackle to flex laterally.) I used fender washers on the inside of the shackle inbetween it and the hanger to replace the lip, and thick washers and lock nuts on the outside, all grade 8. Very tight now. I set my alignment back to a slight toe-in, and it ran pretty good. I'm off a little since I did it in the dark, but I could not reproduce DW, even when aiming directly for the bumps.

I might spring for a thrust angle alignment tomorrow after I look at it in the daylight, then head off to Kansas Rocks on Sat. (Unless my knuckles get done at the machine shop, which of course means I will be up until ~5:30 Sat morning changing out the front end.:twisted I think I'm going to take her up to the pub now and have a Bully Wheat to celebrate.

 

a lot of good input on your problem from the forum members. It's more than likely the trunion bearings (kingpins to some ).they get railroad track grooves in them after a while and the shaking starts.i just replaced mine a couple months ago and about 8 years before that.the correct align. is important ,but you will NEVER get it to drive right with bad bearings.thats not my opinion ,just the facts mike s.

 

I'd still do the draglink rebuild though. That way it's all good and you can rule that out on other notorious pop up bug that happen when you change what god deemed to be perfection.R) I don't knock people that lift and modify thier Jeep, but for me I have come to realize that when you mess with Gods most perfect design, sometimes the Jeep God's throw little curves at you for it!R)

 

Speaking of a draglink rebuild... For the inexperienced who's had possession of his 67 Jeepster (Ross steering) for about two months now... Is there a trick to it? I've replaced the TRE and now going after the bell crank and draglink. I've got to get the play out of the steering. Only then will she be about perfect. Pics to follow. Go USA

 

Good to hear you got her fixed.

 

When you guys say "bellcrank", do you mean the Pitman arm? A bellcrank is a part of the clutch mechanism. The short bent arm off of the steering box to the drag link is called the Pitman arm. Just trying to keep it all straight and avoid confusion (which is a daily travail).