29 Model A Street Rod Pogos

[Road Journey]

Have 1929 Model A street rod with a Chevy small block engine. Front end will seriously pogo if I hit a chuck hole or railroad track too hard. Only way to stop pogo is to stop car & start out again.

Only info I have from former owner on front end build is:

(1) “Long-arm suspension ties into single transverse leaf in front
(2) Steering mechanism original style setup”

Front wheels spoked, front tires are B.F. Goodrich Silvertown 5.50 x 17. I run about 30 PSI.

Any ideas on possible cause of problem, pogoing? Two photos below.

Thank you.

Ernie Wickersham
Avon, Indiana

 

[nkaminar]

You may have better luck getting an answer in the Hod Rods and Customs forum.

It sounds like you need better shocks or that the shocks are worn out. Try jumping up and down on the front end to see if the car bounces. You should not be able to get it to bounce. If it does then consider an upgrade to the tube shocks.

It could also be that you need to rebuild the spring.

The suspension is a complicated combination of springs and shocks all designed to work with the weight of the car and the weight of the axles, wheels, etc. (unsprung weight). It is like tuning the carburetor for the best performance. You may need to tune the front suspension for the best performance.

I did not see any transverse link to keep the front axle from moving side to side. If the car does not have that you may want to add one.

 

[Synchro909]

Sounds to me you have what we call "Death Wobble". I suggest you search that.

 

[johnneilson]

I notice something that may be causing the "death wobble".
If you do not have a panhard bar, a bar that centers the axle to the frame, your problem is more than likely the spring is too long.
The shackles that connect the spring to the front axle should be angled, not vertical nor horizontal. They should be approx 45 degrees and the spring ends should be shortest dimension. This will help center the axle to the frame and stop unwanted movement of axle.
What you have is creating a parallelogram allowing the axle to move side to side.

J

 

[nkaminar]

John, Thanks for naming the transverse bar that I mentioned in my post. I now know it is called a panhard bar. I visited a friend today that has a nice rod. The axle is centered with a pin on the axle that slides up and down in a vertical slot on the frame. The pin has a roller. He had similar problems with his front end and solved it by rebuilding the spring. He put Delrin pads between the leaves.