Straight axle shimmy starting at 62 MPH

It's definitly a balance problem,, But thinking outside the box, don't forget the driveshaft or a bad trans mount, u-joints. Some of these issues will transfer to the steering wheel..

Good luck.

 

Caster ...........................................

 

Tires...Even had this situation on a motorcycle. The tires were new..looked round also. But they sat on the show room for over a year. Changed out the tires and it was smooth as glass.

 

My T had a horrible issue with death wobble. The So Cal stabilizer cured it. And yes we double checked everything else (the basics) before adding it. It is the best $100 you will spend on your car, trust me. Don

 

i agree that its probably a balance issue, if your going to check everything, i would make sure the caster angle is 5 to 8 degrees,no more ,no less. sounds to me you may not have enough caster. hope you find it, please let us know.

 

Find a shop with a road force balancer and get the wheels balanced on that machine. It will show you what is going on. Be sure to get a shop that knows how to use this machine. Make certain that the tech gets the rims centered correctly and runs the diagnostics to verify it! If it is a tire it will show up in the road force. The machine can match the tire high spots to the rim. Takes time but that is what it does. If the road force results are higher than 22 I would probably replace the tires.
Trust me, I used to have all the shops in my area send those real bitch road complaints to our shop to fix the problems. The machine works as long as you got a good tech on it.

 

Update: I took the beads out of the tires and had them re-balanced on a good machine. I thought I solved it. Drove it for a while, and it came back, but nowhere as bad as before. It comes and goes now. I might try the caster deal next week, I've got a buddy who owns a front end center. He had a "on the car" balancer but it shit the bed. I'm pretty sure I've got 6 degrees now, I'll try 7. I also have a steering dampner around somewhere, I'll try it if I can find it. Speaking of the "on the car" balancers, when I was a kid working at my brothers Sunoco station, I used one of those for a few years, you haven't lived until you've had one of those balancing heads blow up on you. Scared the crap out of me. I'll let you guys know how I make out next week. It probably won't be until Friday of next week, got to go to work Mon. through Thursday.

 

Are you talking about the bushings in the hairpins?

 

Any of the above diagnosis might be the cause,I vote for more caster.But with the radials,a belt may be it. Note ,that type steering and radials were not designed for each other.Hope you find it

 

Most all the big guys hot rod builders always include a steering damper on straight axle cars - it cured my Tbucket.

 

Update: I've checked the front end angle with an angle finder and it looks like I have around 2 to 3 degrees caster. I've got an appointment for next Wednesday to have the front end done at my buddy's place. We'll check the caster and add accordingly.

 

http://www.streetrodderweb.com/tech/0902sr_science_of_straight_axles/index.html

 

I had the front end done yesterday. I had only 2-3/4 degrees caster. We increased it to 6 degrees. The car is a lot better, just a slight shake that comes and goes at around 62 MPH, but it's acceptable. We spun the front wheels and noticed that one of my front wheels is a little out. It's not the tire but the wheel, it's a little wobbly. Close enough, I'm satisfied with it, thanks to everyone who wrote in with advice.

 

use the small stabilizer like pete @jakes sell it fiw one for me.

 

Blow the tires up to 28 to 30. 1/8 is a little much for toe in if its a very light car, as little as .030 may be enough. Stand back and look at the car from the front. Draw an imaginary line through the king pins to the ground, and another through the center of the tire. They lines should meet at the ground. If not you may need different front wheels.

 

Double check the caster...it shouldn't be more than 6 degrees Positive.

4TTRUK

 

I had the same problem with my '36. About 60 MPH the front tires would start bouncing, one up and the other one down, then vise versa. Drove thru it once but vib, didn't stop until almost 80. You will never believe what the problem was. One of the BACK tires was way out of balance. It was a 31 X 14 drag slick and all attempts at balancing would not fix the problem. Mounted a new pair and problem disappeared. Obviously, vibration was being transferred thru the suspension.