Death wobble.....really low speeds

I had the exact same thing, 5-10 mph, like it's going to jerk the wheel out of your hand. Long story short, too much caster. had almost 9 degrees, took out about 3 degrees, havn't had a problem since. Also make sure your early style tie rod end is adjusted right. Tighten it until it bottoms out, then back off to the cotter pin hole. If there's any springy in it, it compounds the problem.

 

Start By putting front axel on jack stands . Rotate the rims one at a time,
Look for bent rims. look for in and out wobble not out of round. Out of round is up and down. I would use a dial indicator.
Next grab top and bottom of tire and try moveing the top and bottom in and out.Push the top in and pull the bottom out. also look at the drum and see if the wheel beerings are snug. Next grab the front and rear of the tire and try moving the wheels side to side have some one hold the steering wheel.
This also checks the tierod ends the steering box .I am gonna bet this shoul find the problem.
What caster are you running?? How much toein. Are the wishbones split?

 

Have you "zeroed in" your steering box?.....that and the aforementioned steering dampener should cure your steering ills. I had the same quandary with my 26 T roadster;......and then an old-timer overheard me talking about it at a show, and explained how to remedy the problem. my 2 cents only.

 

Lots of good information....thanks a lot fellas.

I'll let you know if any of this fixes the problem.

 

where can you get this dampner? anyone got pics? place to buy?

 

Ive never seen one for 10 bucks.. I ran the socal one on my 32 coupe and I put it on when i built it and i never drove with out one. I dont have one on my roadster and its toed in 1/8 and the caster is about 7 degrees and it drives fine.. I had issues years ago with a model a and the wheel bearings were too loose cause the cheap castle nuts in the brake kit allowed too much slop when backed off to the first notch. I actually shim em now and ive never had a problem since..
Dave

 

You have some give in the system somewhere. Something that is allowing enough slack to let the wheels swing back and forth. It could be king pins, tie rod ends, loose steering box mounting, bent tie rod, or binding spring shackles. Go over it with a fine tooth comb.

 

There is no slack.

I don't think you understand what is happening. It's not like a little wobble...it's a 30 degree sweep back and forth. It goes from the wheels to the tie rod and up through the steering wheel.

Why would the spring shackles have anything at all to do with this? The king pins are brand new and good. The tie rod ends are brand new and good. The tie rod is straight as an arrow. The steering box is tight. I did not build a piece of ****.

 

This problem is very common on Model Ts, and several instances have been posted on the Model T forum, that frozen spring shackles have resulted in shimmy. I can't explain why, but it does it. I am ***uming that you have a transverse leaf spring---?

 

I solved a nasty death wobble with a panhard bar. The whole front suspension would move in a rapid oscillation that was very scary to feel but cool to watch.

 

Fidgiter, this is from the Total Performance website.:


<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD width=9 bgColor=white></TD><TD width="100%" bgColor=white><TABLE cellSpacing=0 cellPadding=0 width="98%" border=0><TBODY><TR><TD>
"What Factors Cause Front End Shimmy?



</TD></TR><TR><TD>
Frontend shimmy is caused by a number of things.
The combination of worn out components and or frontend alignment will cause serious problems.
First and foremost, the components that make up the steering ***embly must be in good condition. These components are:

Tierod ends​

Heim Joints​

King Pins and bushings​

Steering links​

Drag link​

Radius rods​

Pittman arm​

Steering box bushings​

Hub bearings​

Shackle bushings​

All of these components must be in good condition. Replace any part which shows wear, or movement beyond design specifications. If in doubt, replace it.
***uming all of your components are OK, the next step is to align the frontend. If your T Bucket has bias ply tires then you should have a maximum of 1/8" toe in. Radials should be "0" to 1/8" toe out maximum.
The final step, (and VERY important) is to balance the complete rotating ***embly! Attempt to balance your tires mounted on the hubs if possible. If this option is not available to you, then balance the components separately. Your drums or rotors and tires must be accurately balanced!
Tire inflation has been a subject of controversy for a very long time. But there is a basic starting point. For spoked wheels, (motorcycle type) start at MAXIMUM inflation. Generally 45/50 lbs. For all other tires, start at 28/32 lbs. Test your T on several road surfaces especially rough roads. Inflate or deflate your tires to minimize bouncing. You will always get some bouncing, but less is better. Make sure that both front tires have EXACTLY the same air pressure.
There is a big difference between shimmy and bounce! You need to avoid shimmy at all costs! This is a self induced harmonic which will destroy your whole frontend and possibly cause a serious accident. Shimmy starts when the rotating m*** (tires, wheels, hubs, and rotors or drums) harmonics go into oscillation with the steering components(links, bushings, rods, and tie rods). They "push" against each other causing a violent back & fourth motion (Shimmy). Because this motion is self induced, it progresses until something breaks, or over come by an external force (IE: hit the brakes and slow down). It is imperative that your frontend be in absolutely perfect working order.
Have you ever rolled a tire around your garage, or down a street before? If you have, then you may recall how the surface governed the direction the tire rolled. This same condition exists on your T Bucket. To overcome this, a frontend alignment is setup to create an equal force on both front wheels. This effect is called "toe in" or "toe out". This equal force tends to overcome most road surfaces, making the frontend responsive to the drivers command. However, too much of either can create a new set of problems. Tire scuffing will be the first on the list. Then there is the problem of shimmy. Toe in tends to cause shimmy more than toe out. Zero toe in/toe out will virtually eliminate shimmy however your frontend will feel "loose". In other words, your car will walk back and forth while cruising. This effect is usually manageable, but annoying. Regardless which "toe" effect you need, limit the adjustment to a maximum of 1/8" The next adjustment available to you is "CASTER". This is the tilting of your king pin bosses. This caster effect tends to make your front wheels follow the centerline of the front axle. Caster is good for helping your T track straight. You always want the caster effect to "follow" your axle. You adjust your caster by adjusting the length of the UPPER clevises on your radius rods. Typically, about 5 degrees of caster is plenty, and in some cases 2 or 3 degrees is all thats required. Have you ever pushed a shopping cart around a grocery store, and noticed sometimes the front wheels shimmy? Thats way too much caster! So go easy on your caster adjustment. Finally, there is camber... you can't change it easily because it's built into the king pin bosses. However, as your king pin bushings wear out, you induce more camber. So check your king pins & bushings occasionally for wear."


</TD></TR></TBODY></TABLE>I hope they don't mind my stealing it.

I think straight axle+skinny bias ply tire=shimmy. unless your lucky.
I'm not, a pothole on the left front between 20 and 30 mph will make my t roadster shake and wobble, but quickly accelerating will get out of it better than trying to slow down to stop it.

It's about creating a force on the tire thread that's greater than the force that's inducing the wobble.

Mine was REALLY bad. Doing the items on their list, getting everything tight and right helped a lot. Now I don't have to fear every bump in the road, just certain ones

I'm running 1/16 toe in right now, 6 degrees caster(haven't changed that yet), 20 lbs air in 5.00 16's on 35 wires. And also squared up the front and rear axles to the frame. everything has helped a little.

Get it as good as you can, than put a damper on if you have to.

Frank



</TD></TR></TBODY></TABLE>

 

The king pins are new, is the axle?

 

Yup...the only pieces on the front end that are not new are the spindles, backing plates, and of course the wishbones....and wheels.

 

lol


i did and mine drives like a dream!

 

it didn't change with more air in the tires?

 

Eric I know what it is. That car does not like you, and is trying like hell to get to my house. Just take the hent and let it go, you know it will be in good hands.

 

IMO I would try a panhard bar. The panhard bar on the front of my dodge truck went bad and it would nearly break your arms trying to hold the wheel. If your bones are split you have lost some of the control they were desighned to have.

 

1300 views and 46 posts, but no definate positive answer that would cure every car?

I do agree that adding a damper seems like a band-aid, BUT, if you remove the stock factory damper from a vw bug, you WILL get an instant death wobble. Not a shimmy, but the exact same violent wobble as these old hotrods.

A friend is trying to fix his 33 for 2 weeks now and everything tried so far almost seems worse; caster changes, toe, etc.

2 new tierods ends going on today, plus centering the box throw precisely, Pitman precisely at vertical, precise toe adjustment with real tools, etc. If that does not work, I think we will go with a vw damper tomorrow. I am 100% sure a damper will fix it, but we hoped to find out what causes this problem in the first place.

 

I vote for steering dampner. My 27 did the same thing last year. I tried everything suggested here and the only thing that worked was the dampner. I almost missed Roundup over it cause it was drive it there or leave it @ home. I used a $20 one from a 93 Ford Ranger that I bought @ O'Reilys.

 

IMO, you are probably right about the wishbone being cut and they now don't brace the entire front end. My friends 33 started this wobble after splitting his bones.


But I did have a parallel leaf rod 35 years ago that had a severe death wobble, and it originally started when I took off stock steelies and used deeper dish front mag wheels. After nearly wrecking the car in 2 weeks of use, I put the stock wheels/tires back on, IT STILL did it

 

I just re centered the box on my 32 roadster this weekend and only cause it had play in it going straight down the road cause it wasnt centered. That really doesnt cause a wobble but it compounds the problem if your trying to fix it. Go thru that T/P list and check and recheck. Id still add the dampener cause they work in this situation. Mine is fine but i had a problem years ago on a t bucket and a 30 a c-dan and the dampeners cured em both..
Dave

 

Dumb question, but do you have shocks installed?
Good ones?
Some time back a HAMBr was chasing a similar problem and eventually it came to light the car had no shocks.

Have you tried a different set of tires & wheels on the front?
That would take any potential tire/balance probs out of the picture.

Inflation pressure seems light to me, but perhaps 20# is enough for that style tire.

I run big & little radials (24" and 30" tall respectively) on my 2400# 32 roadster and they carry 30# in front and 20# in back.
Seems like similar cars with bias-ply run about the same pressures.

I'm curious if the car is cross-steer (Vega box etc.) or has a fore & aft draglink?
Not saying to change a fore & aft draglink to a Vega cross-steer, but few cross-steer cars have a death wobble problem.
I think that may be due to they usually have a panhard bar.

How are you measuring caster?
It should be measured against a level floor.
Measured against a level area of the frame can work, but if theres a lot of dago (rake) you'll need to take that into account.

Sort of a self-answering question cuz most of us use a bubble level protractor or swinging arm model.

Where you measure makes a difference.
Usually you can get the device onto the flat machined area of the axle kingpin boss.
If the floor is not level, measure caster, swap the car end for end and measure again.
True caster will be an average of both readings.
(Most garage floors have a one degree tilt so water etc. will drain out the front door.)

If you have a cross-steer setup and no panhard what may be happening is centrifugal force swings the ch***is to one side via the spring shackles, you straighten out and roll on a little throttle and the wobble starts when the front end weight starts hunting for center on the swinging shackles.

 

I've built 100s of straight axle ch***is with Vega steering and no customer complaints. I build my new deuce roadster with Schroeder steering and it dam near shakes you out of the car! 7 inch pitman vertical, draglink parallel, 7 degrees caster with 1/8 toe in with 550/16 Excelsor tires, New 48 Ford lever shocks, new king pins. I'm scratching my head so I call Ken at Rolling Bones and he says they have had some shake in the past and that they have tryed the dampner with modest success. He also said that Varni didn't want one and his car drives fine. I have installed a dampner but have not been on a test run yet. I'm sure there is one of you guys willing to tell me what is wrong and how to fix it!

 

That happen to me. Turned out to be the front tires were bad. I bought a set of used wheels and tires for the car as I was building. Planned to put new rubber on it but never did. I could not figure out what I did wrong so I asked the local front end shop. They wanted to bend my axle. I called super bell the told me to change my tires.
They were right.

 

I had this happen with a 71 dodge truck with a worn out steering box. It was ok except for alot of play going forward but when I had to back up on the road it would wobble really bad, dangerous. I could not hold it in the road without going very slow. I put a new steering box on it and it was fine. Water had got in my box and it had a slurry of rust, mud, oil and water in it when i drained it. it was like grinding compound.

 

C9...thanks for those tips. All measurement so far has been by eye. I hope to find time this week to get it done right.

I do have shocks, P&J short shocks. Upper mounts from the frame, lowers bolted underneath the wishbones. I made sure they weren't binding as well.

It is side steer, F-100 box, speedway loop style steering arm, home made draglink w/ standard Ford tie rod in the front, model A style tie rod at the box.

 

Check your shackles, they should be at 45. Also you may want to get your tires shaved, there is a guy in LB that does it for B ville cars. Runs about 500 to do all 4.

 

Here's what you want.

Available at Sears.


$10.


$16.

I've had the black one for a long time and it works fine.


Great for shooting tailshaft and pinion shaft angles as well.

 

please at least try a new set of front tires!
The suspense is killing me over here!!
TP

 

That is the absolute last thing I will do! ****ers are expensive and I just got these.