steering wheel vibration

[Werner R.]

this has everyone stumped. happens only between 60 and 70. same if i am coasting in neutral. same if i gently press the brake. i do not think this is wheel balancing becase it was the same before the new tires; the wheels have been balanced twice including looking for high spots and runout; the vibration is periodic i.e. it vibrates for a second then pauses for a second and so on between 60 and 70. 8" fronts, 10" rears. new front bearings, springs and shocks.
new u-joints on drive shaft and one half shaft. there is no steering system shock absorber on this car, but i am concerned about the periodicity of vibration. what could be doing this. it shakes badly when i let the wheel go, and if it were a constant shake, i would swear the wheels need balancing, but it comes and goes, even at a constant speed. someone suggested the idler arm, but i have had a reputable front end shop check the steering and they say everything is tight.
any help will be appreciated.
werner

[Joe DeAngelis]

Re: steering wheel vibration

Werner,

What is the year of the car and specific modifications from stock?

Joe

[Werner R.]

Re: steering wheel vibration

joe, the car is a 1964 roadster with a BB and headers. it has 8" front and 10 " rear wheels, but i am aware of no other mods, specifically, no mods to the steering or suspension [although there is no steering shock absorber installed at present]. i know the ball joints are NOT original [they are bolt on], but as for the rest, who knows. i am probably the umptheenth owner.
werner
i should add that the front cross member has been notched, to accept the longer harmonic balancer, when the BB was installed. beyond that it is pretty stock.
i do have the 550 pound [HD] springs up front because of the heavier engine. i thought the stock 64 spring was about 480 pounds, but i am not sure.

[Joe DeAngelis]

Re: steering wheel vibration

Werner,

Mid year Corvettes are notorious for picking up strange vibrations. I own a 66 roadster that I took through several steps to eliminate a few vibrations it had. The easiest place to start may be with the addition of a steering dampener. I assume your suspension shop checked for the obvious, ie, ball joints, bushings, tie rods, worn or loose shocks, etc. I would also check the balance of the drive shaft and the half shafts, especially with new u-joints. (Also, make sure the u-joints were installed properly and are operating correctly with no binding or play).

If the vibration increases or becomes more apparant under acceleration, it could be something different. In that case, I would look at the motor mounts, flywheel balance or even the engine specs (timing, dwell, etc.).

Hope some of this helps.

Joe

[Werner R.]

Re: steering wheel vibration

joe thanks for the info and i will look into the things you mentioned.
however, remember that my vibration is not engine speed senitive, nor is it a constant vibration at 65 mph. picture a big string that vibrates for one second and is then still for a second and then vibrates, very regularly, no matter what.
now if a u-joint were bad, would that not always vibrate at 65, or would it be a rapid on/off type of thing, which is what i have? is the same true for drive shaft vibration?? i called a drive shaft shop and they felt that if the shaft were out of balance that the vibration would be always there, but would get worse with increasing car speed. they did not feel it ould rapidly come and go, over and over.
i can try the steering wheel damper, but i am concerened about the underlying vibration. i DO NOT KNOW how well my front end shop checked control arms or ball joints. i think they focused on steering. i am willing to replace the ball joints, because it is cheap and easy. however, i do not want to do the control arms unless it is probable that they are the culprits.
is there any test i can do to see if the control arms are bad etc??
again, any thoughts are appreciated.
werner

[Roy Braatz]

Re: steering wheel vibration

If the back lash or pre-load in the steering box is to loose and or the TOP steering shaft bearing is worn you could be geting a high speed vibration FEED back ,harmonic or what ever they call it.????????????? That is were a steering shock would mask it.

[Mike McKown]

Re: steering wheel vibration

I read over three times what you said about tire and wheel balance. It sounds like a dynamic wheel balance problem. Sometimes, balance shops will put wheel weights on one side of the wheel only or in the center inside of the rim due to wheel configuration for appearance issues. I would change the front wheels and tires with a known good set and see if the vibration is still there. Even with a loose or worn out front end, you should not necessarily get a vibration. Another thing you might try is find a shop that still has the balancer that spins the wheel on the car. Raise the car on the A-frames and spin it up and see what is moving.

Mike

[Werner R.]

Re: steering wheel vibration

thanks to one and all. most people that respond think it is a balancing problem in the wheels and that i need to find a shop that will balance them on the car. i do have this and i will try it. i will post the results. some people also are concerned about the wide 8" front wheels and think i should try some kind of offset spindle system. the best i can do here is to look into it, but i am not too excited about spending megabuckx if i can avoid it.
finally, i am definately going to install the steering damper as soon as possible. thanks again.
werner