Steering Wheel Shake, a Poll

[Bob In Ct]

Over the last couple of years the subject of steering wheel shake (usually between 60 MPH and 75MPH) has come up in conversations and on Club Cobra. The solutions offered include Wheel balance, wheel alignment, drive shaft balance, tune-ups, steering box adjustments and others. None of them work for me and many other owners.

In an effort to get a handle on the problem I'm asking that everyone out there with the problem reply with the brand of Cobra they have, the type of wheel and the brand & type (radial or bias) of tire they use.

I am hoping that in this way maybe a common cause (and solution) to this problem can be determined. Just for the record I have an SPF with Trigos and Goodrich Radial T/As.

Bob

[agro1]

Mine shakes as well. Especially if I take my hands off the wheel, you can see it. But, when I grasp it the shaking stops and becomes more uf a minor vibration...Very typical for this type of car (SPF also) and it's steering geometery.

[Jim Colman]

The Cobra isn't the only car to experience the shimmy. See the following link for possible solutions to your problem.
http://www.miata.net/garage/65_mph.html
FWIW, my Midstates had the same problem until I changed tires.

Cheers
Jim

[jhaynie]

My Unique shakes when slowing down, not so much during acceleration or driving at speed. I haven't attributed it to braking either. I'll figure it out this winter.

[cobrakit66]

thank god i thought it was just my car we have tried everything short of a new rack and pinion

[Pete C]

I had that problem with my ERA and BFG TA radials and tried all the normal stuff but could not seem to make any headway. I then bought a set of Trigos, well 2 sets, one for street and the other for slicks, and the problem went away even though I had the same tires mounted. I've begun to suspect that the old wheels may not have been true. Worth checking. Cheers, Pete C

[Roscoe]

A&C with BF's 245/60 and 295/50 on PS Engineering wheels. Originally had a slight shimmy around 60-65 but alignment and balancing completely removed it all.

Roscoe

[6T5 Cbra]

I have an EM that used to have the shimmy around 65. Changed the front end out to Wilwood spindles/brakes and it seems to have gone away. So far I only have about 500 miles on this new setup so we'll see if it lasts.

Gene

[Zderf]

1998 Can Am Motorcars, Langley B.C.

I've been putting up with my 60 - 80 MPH shimmy for 3 years. As noted by some others, it really rocks when I'm not in my steering dead spot (that's another issue) and my hand is off of the wheel. If I grab it, most of it goes away but the vibration is still there. I decided this summer to attack the problem.

I have had the wheels and tires dynamically balanced. 305/50 rear and 245/50 fronts on Trigo pin drives. They were not much out of balance, but had previously been balanced statically. Had the alignment checked at that time, was within norms (although my left rear needs to be moved aft 0.5", and is not a factor in the shimmy). Boy I was excited.

Test drive... still there.

I also have a slight amount of play in my steering at center, so the shimmy is only noticeable during slight to moderate cornering or working the crown of the road. The steering set up is 1986 Fiero. I suspect I need a rebuilt rack (to remove the play), and the dampener may be worn as well. This could be causing what some are calling a "geometry inherent shimmy" to transmit to the steering wheel.

This winter I plan to install a rebuilt rack, dampener, and sub links.

I will watch this and related posts with great interest. Thanks Bob in CT for bringing this up.

Zderf

[cobrakit66]

Bob how did you do at limerock last weekend

[K.Wilson]

Stearing wheel shimmy can sometimes be difficult to track down as there are many variables.
Assuming that the wheel bearings are adjusted correctly (not too loose) and that the brake rotors are true, it leads you to the tires.
Not all tires are created equal, some have significantly more runout (both lateral and around) than others. A good tire and wheel shop will have a "runout gauge" (a largr dial indicator with a small wheel that will roll against the tire). With the tire and wheel mounted on the car, and the wheel off the ground, the runout can be measured on the side wall and the tread.
If an runout of greater than .200 or .250 inch is measured on the side wall you may want to think about replacing the tire as there may be a ply seperation.
If the tread has a runout of more than .100 inch you may want to true up the tread surface. This is accomplished with equipment that turns the tire and wheel assembly and "grinds" the tread surface to take off any high spots.
If all else fails you can add some additional toe-in, as little as .125 inch will add enough tension (tire scuff) to reduce the shimmy. Tire wear will increase, but the shimmy will be reduced.
Keith

[BLACKJACK]

JIM C - - -

GREAT ARTICLE ON TIRE VIBRATIONS. THE IMBEDED LINKS ARE GOOD ALSO.

IT NEVER CEASES TO AMAZE ME HOW MUCH OF A WEALTH OF INFORMATION IS AVAILABLE ON THIS FORUM - AND THE WILLINGNESS OF EVERYBODY TO SHARE THEIR KNOWLEDGE AND IDEAS.

I'VE BEEN HAVING MODERATE VIBRATIONS IN THE STEERING WHEEL OF THE EXCALIBUR COBRA FOR A LONG TIME. BALANCING DIDN'T HELP AT ALL. WITH ALL THE TESTS AND INSPECTIONS I REALIZED THAT IT WAS NOT SERIOUS BUT, NONE THE LESS, A REAL AGRAVATION. THE ARTICLE AND ASSOCIATED LINKS ANSWERED A LOT OF MY QUESTIONS.

THANKS VERY MUCH FOR ALL YOUR GREAT CONTRIBUTIONS.

Y'ALL HAVE AREALLY GREAT DAY,

BLACKJACK

[ROSS WEAVER]

I have the Goodyear Eagle 1's and the Trigos. Still shakes between 60 and 70 mph, even after realignment and rebalancing.
Puzzled on cause. Could it have anything to do with the spindles?

Ross

[flipper35]

Shell Valley car with the tubular front a-arms. Whatever the rims were that came with the car in '95 and BFG tires. No shimmy between 0 and 140+.

[mikiec]

It took 3 trips to the tire shop for them to get the balance on my tires correct. Now no more shimmy.

Tires BFG TA's 235X60X15

Flaming River 15:1 rack.

Mike

[rdorman]

There steering wheel on my Unique with BFGs shakes a bit. When you let go of it, it shakes more but that car tracks true. I had the same issue on my 300ZX. Balance did not help. It finally took a good tire man carefully balancing the tire on a dynamic balancer to see the problem and correct the balance. Not some kid with ten minutes of introduction to a balancer. He explained the problem and why it happens at that speed but to be honest I forget the explination!

[B. SMITH]

I HAD A SLIGHT SHIVER IN MY EXCAL AND MY UNIQUE AND NORMAL BALANCING WHICH WAS ALMOST PERFECT DID NOT CHANGE THINGS.
I THEN TOOK THEM TO A PLACE,"THE AUTO SPOT" THAT HAD THE "WHEEL ON VEHICLE" SPIN BALANCER. THIS BALANCES THE WHOLE ASSEMBLY INCLUDING ROTORS. YOU CAN FEEL THE IMBALANCE DISAPPEAR WHILE STANDING THERE "HAND ON FENDER".
HOPE THIS HELPS..
B. SMITH

[xlr8or]

B.SMITH,
I was going to suggest that very thing.
I had the problem with an older Z-28 and just couldn't get rid of it by balancing and alignment. I did the balance and alignment myself several times trying to find the problem sometimes it improved other times it was a little worse.. Someone suggested balancing the them while on the car and that worked great by balancing the entire rotating assembly.
Turned out when I replaced the worn rotors a year later I never had the problem again.

Scott

[Jim Colman]

Blackjack took the time to read the link I posted. If some of you other guys would do the same I think you'd find the answer to your questions.

Cheers
Jim

[Back in Black]

A worn steering box...(needs replacement or rebuild) this causes a shake in the steering wheel...but it will be worse when other factors such as out of balance tires come into the picture

This will feel more like a shake than a shimmy