plane_pal

I'm new to the forum and could use some advice.

Two years ago I bought my first corvette, a 1964 365hp convertable which I dearly love. But there seems to be a problem that I can't work out. From speeds of 45-65 there is an incredible shimmey or wobble in the front end. It doesn't happen at slower, city speeds - only when I'm getting upto highway speeds.

I have had the front end alignment checked and the tires re-balanced, and the shimmey is still there. The steering is a little loose, but I wouldn't think that would make a difference. One other thing, there are times when the shimmey isn't there!! I would say that the shimmey doesn't occur about 20% of the time. This makes me even more nervous.....

I searched the archives and couldn't find any other threads dealing with this topic, hence my post.

One last piece of information - the tires. There are low profile modern tires on the beast. I wonder if that could have some effect?

To describe the shimmey is tough, but suffice to say that with both hands on the steering wheel, my entire upper body is shaking.

Any help or ideas would be greatly appreciated.

thanks,

-dave.



[Modified by plane_pal, 10:45 PM 12/10/2001]

Curtis

I will be interested to hear what other people will say, but I will tell you that one time I had a little water in my tire and it would shimmy on the car, but it didn't show up on a tire balancer. The water was put there by a air hose that had condensation in the line.

The only problem I see with my theory is you say 20% of the time it doesn't shimmy. That being the case I don't know what to say other than see what other people can come up with. I did want to mention my theory, in case it can help in some way.

Good luck,
Curt

67435animal

I had this problem as well and it turned out to be defective tires. The sidewall was collapsing. After a few 1000 miles, you could see where the sidewall had a bubble in it where it was weak.

Don't overlook your tires.

magicv8

If your "front end is a little loose" it can be the problem. Check the idler arm. If it is loose, replace it. Do you have power or manual steering? Are your shocks good? If you have radial tires, did you use 1976 Corvette alignment specs to set it up for radial tires? 1964 specs will produce "bump steer" or "hunting" with radial tires.

pittsaj

Dave is right about the alignment spec...
I had my 65 realigned and it is now a different car..

You don't mention how and when this occurs, and
You don't mention shocks..
Sometimes when you hit a bump in the road with bad shocks you can start an osilation that can feel like shimmy.. It will usually calm down a bit after the hit, but I have seen it when it will only calm down with a reduction in speed or a turn.
Also check the front end out real closely,,,
Looking for loose control rods and bolts..
Raise the front off the ground and have a friend push the tires around while you are looking for loose parts..
Don't overlook upper and lower control arm's, ball joints and wheel bearings..

Good luck

Chuck Gongloff

I fought a shimmy in the front of my 69. Turned out to be a slightly bent rallye wheel. Check the normal stuff...tie rods, ball joints, idler, etc. Also upper and lower control arm bushings. Also, check the steering box and pitman arm. Could also be a flat spotted tire, or a tire with a "shifted" belt. Agree with the alignment tip. So true about the correct spec if using radial tires on a midyear. Chuck

stngry63

I've had the same problem at 60 to 70 mph. Sometimes it shimmies and some times it doesn't. Sometimes, hitting a bump seems to set it off. It seems to be worse on hot days. The side walls of my tires are a little wavy. I don't know if this is normal or not. Also, I'm running repro knockoffs. The spinner and adapter seem to be a lot of unbalanced weight. I'm considering low-profile tires, but I'm a little wary about the handling. I have a picture of my car from an autocross and the inside front tire on the turn has some severe camber change. I don't know if a low profile tire will lift and lose contact. I'm considering 225/55-17 and 225/60-16 tires. Has anybody done this who throws their car around? Alignment/Balance problems?

StrayDog

SUGGEST..replacing upper & lower sterring colum bushings it may help somewhat see " Zip restration "..the tires on my 66 are 205 X 65 r15" I had allinged with specs from Corvette Brake Suggest talking to there tech people......will be putting 205 X 60 R 15 on rear as need more traction. my shocks are Monroe radial tuned type , 1 " front sway bar , & 330 lb mono rear composite spring................will be redoing front suspension as winter project as my front springs are tired & will redo with new front end rebuild kit... Vette Brakes has quality stuff

[Modified by StrayDog, 8:44 AM 12/11/2001] :)


[Modified by StrayDog, 8:47 AM 12/11/2001]

simard

One of the failure modes on a tire is perpetual imbalance.

wernerreis

i had a very similar problem on my '64. i took it to a good front end shop-no problem. i took it to a tire shop and they used tape weights to balance the hell out of it. did NOT cure things. took it to a truck tire specialist [10 " rear rims] and he put some powder in the tires to balance things. says it works for trucks and SUV's. did NOT cure the problem. took it to small neighborhood tire dealre, where a young kid with greasy long hair [he looked like a burgler and drug dealer] showed me the defects in the tires [belt failure]. they were all bad. i had them all replaced with goodrich comp t/a's. that DID cure the problem. my advice: keep going to good tire shops. :cheers:

396 RAT

If your idler arm is in good cond, and everything seems tight on the front end
have the front wheels spin ballanced on the car.
I had a similar problem (Shimmy when braking from speed) yrs ago and the spin ballancing was the cure.
Could not be seen on a regular ballancer. Installed new rotors for no reason. :nonod:
(but it sounds like it could be the front end?)
Good luck! :cheers:

kellsdad

One quick way to check your tires is to rotate them and see if the shimmey changes.
Tom