63 roadster Slight shimmy on front end

[Bob A.]

I have been experiencing a "slight" shimmy/steering wheel vibration in the front end and cannot figure it out. The steering wheel is smooth as silk leading up to cruising speed, shimmers at 70-75 mph then smooths out at 75+. Both sets of tires and rims have been speed balanced, ball joints are solid as are tie rods. Steering box was restored as was the complete drive train in 2021. The shimmer happens with the both the original rims & repro tires as well as with the new repro rims and new radials. Any guidance on where to look next is much appreciated.

Bob Aquilino #32465
919-619-1339

[Harry S.]

Re: 63 roadster Slight shimmy on front end

Bob, I fought the same problem for about 15 years. My car was not abused, it was neglected, so lots of small problems needed to fixed to get rid of the shimmy. I received many suggestions from members and should have used their priority list and not mine. The problem had nothing to do with wheels, tires and balancing. In 2020 I put in a new clutch. While doing so I realized someone in the past cut off 1/2 inch of the transmission yoke that was attached to the driveshaft. Probably to make it easier to remove and install it. Anyway, I found an NOS 16 spline yoke and driveshaft. Had them rebalanced as a unit. I believe the new clutch, yoke, driveshaft and U-joints fixed the problem.

Suggestion, pull the driveshaft and have it balanced as a unit. Mark everything with a crayon as you need to take it apart to reinstall it.

Good Luck

[Richard M.]

Re: 63 roadster Slight shimmy on front end

Bob, Harry's input is definitely a possibility, but just a few other questions...

How much does the steering wheel move side to side when the shimmy occurs at that speed?

Also, Have you checked front wheel bearing free play?

When you had the tires speed balanced, was it a "Road Force" balance?
I had a similar issue on a car with a wheel shimmy, this after speed balancing all 4, and the Road Force balance corrected it.

What is the engine and HP? Is it a Base 250 or 300 HP? Does it have a Steering Damper installed?
It has always been confusing that base/300 engine equipped cars had a Steering Damper, but some SHP cars did not(oil pan clearance). Wondering if there is some unique effect happening.

Rich