aaw ****, i've got the death wobble...

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hillbilly4008

Well-known member
Joined
Nov 7, 2008
Messages
598
Location
Upstate NY
over the past couple weeks ive had my truck to the point where i could drive it a little. I put maybe 3 miles on it so far. Over that 3 miles the hairpins werent tightened down all the way(i know, i got ansy). This morning i tightened everything up, then took it down the road about a 1/4 mile and got a severe shimmy in my wheels. Looking through my windshield i could see the tire whipping back and forth. The steering wheel was going bonkers too. This happened at roughly 25-30mph, and it happened at the exact same spot going both directions.

Now i've done some searches on "death wobble" and turns out that its pretty common.

I know i have a bent spoke on my 19" model A rim(MOST LIKELY THE CAUSE). Can that be straightened? Whats the best way? None of the local shops can balance a 19" wire wheel. Think a motorcycle shop could?

I didnt have the front shocks hooked up. This im sure is adding to the problem. But how do some people get away without running front shocks?

Im gonna go through and recheck my caster and toe-in tommorrow.

Is tire pressure an issue? Im running the 550-19s @ 35psi. I've read that hot rods dont need as much pressure because of the weight, 19psi reccommended. Any truth to that? Also im running a 700lb 454. What do y'all reccommend i do?

What did you guys to do cure your wobble?
 
mine did this , it was toe in
but theres to many thing that it could be, and i didnt run shocks, when i set the toe in it went away
 
This is one of those subjects where you can ask 10 people and get 10 different opinions, and there can be more than one thing contributing to the problem. Here are some things I think can cause it:

1) I think suicide front ends are more prone to doing it than a spring over axle configuration. I never really had an issue with it until I started running suicide front ends. Maybe something to do with the axle being way out in front with less dampening action by the spring. (I know springs don't dampen, but they do control bounce to some degree. If you doubt that statement, run a weak spring vs a stiff spring and see how much more control the strong one has over each wheel.)

2) Shocks are a biggie in my opinion. If the shock isn't keeping bouncing up and down to a minimum, the wheels will start hopping, progressively getting more out of control as speed increases, or if you encounter washboard road surfaces.

3) Toe in and toe out are also key. Some cars actually handle better with a little toe out. All the books tell us 1/16 to 1/8 toe in, but that isn't always the case. You have to play with your particular settings to find one that your car likes the best. I ran my 27 with 1/8 inch toe out to cure a slight death wobble that developed after driving it for a few years.

4) Tires are a major contributor. We think we buy new tires and they are perfectly round. In the case of bias plies, that might not be as true as for radials. I don't know if bias plies are worse today than in the past, but we are seeing thread after thread here and on other forums about death wobble. Some people have said they had to have their tires shaved (ground perfectly round) to true them up. One guy said one of his tires was 5/8 of an inch out of round!

5) Rims. Wheels can be bent or out of round too. We sometimes use 60 and 70 year old wheels on our cars, and some of them can be very much out of round or bent. Even new rims can be bad. After getting my Son Don's T running I was following him one day and the rear of his car was hopping up and down a little. We did some checking and found one brand new steel rim was bent badly. Coker replaced it at no charge, but we had to paint it to match the others and have the tire remounted. New wheel cleared up the problem.

6) Wheel balance. It may not be enough to balance the wheel and tire only. Sometimes the brake drum can be out of balance. I had a Toyota that even brand new tires would not fix for a wheel hop problem. Finally the dealer put the car up on a spin balancer that spun the entire rotating assembly, rebalanced it, and the hop went away. Some truck shops still carry those balancers that roll under the tire and spin the whole assembly.......you have to look around to find them nowadays though.

7) Caster. Here is another area where you get all kinds of opinions. Too much caster can cause problems as can too little. We originally screwed up and had my Sons at 11 degrees, and when we reset it to 6 degrees it made a huge difference.

8) Having a square chassis. To track right a car has to have both axles square to the frame. If you have ever seen a car that was wrecked and going down the road slightly sideways, you know what I mean. There are lots of ways to do this, but I like to square up the rear axle first by measuring from the exact center of the front crossmember to the same spot on each side of the rear axle. Then I make the wheelbase exactly the same on both sides. That is just one way, but it works.

9) Steering dampener. Some people call the dampeners that go between the tie rod and axle, or tie rod and wishbone, a bandaid. However, they do work great. No car leaves SoCal Speed Shop without one installed, they believe in them that much.

10) Tire pressure. Too little or too much can cause problems. I recently bought a $ 12 digital pressure gauge and found my tires were inflated all over the place. Since I redid them with the accuracy of the digital gauge the car handles much better.

11) Worn parts. On a straight axle car these can be kingpins, tie rod ends, wheel bearings, and steering box. Even wheel bearings that are too loose can cause it.

So, there can be tons of reasons for handling problems in a hot rod. You simply have to do process of elimination, make sure all parts are in balance and tight, and then make one change at a time until you get it to stop bouncing. Death wobble got it's name because it can kill you if it happens at the wrong time. Any of us who have had it happen at speed know how scary it is, and how it makes us not want to drive our cars, especially on the interstate at high speeds.

Hope some of these areas help anyone experiencing the problem.

Don

Oh, one more that I just thought about.............slop in the steering box. The steering box has to control the front wheels, and if there is play in the box it can't do that effectively. We found even the brand new Flaming River boxes in our two T's were too loose. We tightened up the adjusting nut and it helped a lot. Steering felt better too.
 
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Don

You are such a sage, great tips... I too, am afraid to drive my car until I correct this Death Wobble... Since I got it running, everything was great for 2 weeks, then BAM... it started this uncontrolable wobble... It seems to be getting progressively worse... I tried switching from swap meet shocks to original shocks (likely worn also), no better... Next I'm going to put on new shocks, thicker tie rod bar (current is 7/8) thinking going with 1 to 1 1/4 inch, steering dampner, adjust caster and toe, and maybe replacing wheel bearings... Also will try to reinstall 2 leafs that were taken out of front suicide spring setup... All thru a process of elimination... Someone mentioned that with a cross steering setup, you dont have this problem...
 
I would try the shocks first. When I put my T together I used a set I bought off of Ebay on the front. They were used, but the chrome was nice and they seemed ok. When I had the problem I took them off and tried to extend and compress them by hand..........I could move them in and out with almost no resistance. Bought a new set from Speedway, much stiffer when tested by hand, and the problem went away.

Death wobble always seems to originate in the passenger side front tire and then it sets up a reaction in the drivers side tire. Don't know why, but I think it has something to do with the passenger side having more linkage and the ability to move easier side to side because of that.

It's a real bummer though when it happens. I saw a dragster at the Nostalgia Drags get DW about mid track, he had to get out of it real quick! :eek:

Don
 
I have had 4x4s do it when everything was tight and right, added a shimmy shock and the problem went away. Most 4x4s come with one now.

Coming from a Jeep background, this issue is very very common umoung lifted vehicles. Most of that though can be attributed to bad caster angles after installing a lift kit, bad driveshaft angles on the front axle, in need of an alignment after a lift kit install and even just large tires being difficult to balance.

Donsrod has probably put up one of the most comprehensive lists of what to look for to fix death wobble that I have seen, (posted above).
 
I agree with everything Donsrods says, but its my opinion this problem lies primarily in the caster and toe. I have never liked the feel of a car that runs toe-in I think you should be toed-out 1/8 or so. It seems you start getting into DW area when you're less than 5 degrees or more than 8 degrees of caster. Its also my opinion if you correct it with the other things mentioned you're just putting a band-aid on it.
 
The wheel needs to be "trued" not "balanced", any Harley shop can do it. I did a bunch of these when I was a Harley mechanic just be sure and take a hub with you.

However I would bet that it is a caster or toe problem.
 
well i popped the bent wheel off today. Built me a tool to attach to my slide hammer to straighten the spokes. Works great! As i was pulling the bent spokes i realized that the wheel is not flush with the drum! Took a closer look and the friggin weights on the brake drum werent letting the wheel seat where it should. I swear, its always something simple that you'de never think about.

So i have 3 big factory weights on my drum that i either need to grind down or take off. Im assuming the drum needs those weights. Question is can i have a brakeshop move the weights to another location so i can get my rim on? perhaps on the outside of the drum? I dunno, maybe it would be easier to just grind an 1/8" off the weights.
 
I've never done this but someone else may have, you could remove the weights and go to the other side and grind an equal amount off the lip to rebalance.
 
well i ground down the weights, and i still am having problems. Now there more predictable, anywhere between 25-30mph. You can either stomp on the breaks and come to almost a dead stop, or stomp on the throttle and drive out of it. If you drive out of it, this shakes come right back when you let off.

I ordered a VW Beetle stabilizer today, $38 from local foreign parts store(that just sounds weird) should come in tommorrow by lunch. Did you know that the VW Beetle has been around since 1947!

I went out and bought an angle finder, found out that my axle is 5degrees caster.
 
Sounds like you have a multitude of problems...

Make SURE the wheels are seating properly and install a support ring behind them. They are specifically made for mounting early Ford wire wheels to later Ford hydraulic drums. They are available from Speedway for about $20. Your life is worth that much, not to mention others sharing the road...

If you are straightening spokes was the wheel bent before? Did you check for runout? Also, a 19" Model A wheel can be balanced on just about any average tire balancing machine. I know because I have had several of them done at a local garage, and they use the same computer balancing machine used for every other wheel and tire they do - nothing special. You just have to convince the idiot behind the counter to work instead of just saying "no". So, check your wheels for runout and have them balanced.

Not enough caster is at least part of this problem. On a vehicle like this you should be running a minimum of 7 degrees, and I like to keep it around 9 or 10. That with 1/16-1/8" toe-in keeps it tracking nice and straight.

Once you are SURE your wheels are straight and balanced, air up your front tires close to max cold pressure. This helps eliminate wheel "hop" at speed.

I know you wanna drive, but until you get it ironed out be safe!!!
 

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