OK, so I am driving on smooth asphalt around town and at about 30 mph I begin to feel a 'wobble' in the car and it gets more pronounced at 35-40 mph. I know convertibles are not as fully braced as sedans/hardtops and some come with an X frame but the 67 GS400 convertible does not have the X bracing and it does not come with rear sway bar. We have checked wheels, tires, front suspension for wear, bent rims, uneven tires (14" tires and rims are brand new) etc. but no problems found. We are now going to look for cracked frame or other issues but anybody out there had similar problems with their convertible? I have had two Chevelle convertibles in the past, a 67 and 69, both Super Sports with 396 engines and 4 speeds and never felt the 'wobble' in them. When driving on smooth asphalt it feels like the front end/wheels are 'loose' and a definite shaking. Appreciate any and all ideas and comments. This has become a research project and I want to find the 'solution'.
Sounds like a classic tire problem. Have you tried switching fronts to back? http://www.v8buick.com/index.php?threads/coker-new-firestone-wide-oval-radial.322261/
We have tried two rims and tires from my 67 hardtop which are OEM rims and new tires on the back of the convertible but no change, still wobbles. I am tempted to try the four new 15" wheels with new tires from the Sportwagon on the convertible and see what happens.
Any chance that you have a bent axel. Might jack up the rear and have someone put it in gear. Then check each tire for wobble.
Has to be aggravating! Another long shot might be real bad toe in/out adjustment. Don't know if camber or caster would cause your symptom.
What is your from end caster set to? The specs call for negative caster, but that was for bias tires. If you are on radicals, set the front caster to at least 3 degrees positive and the steering should be very stable.
Fred we did just that on a lift to see if we had a bent wheel with the car in gear and no wobble on the rear wheels
I did have it aligned at NTS tire store. It helped but not sure I got the correct alignment as those are all young guys and have not worked on 1960's cars. I sold the car but recently I found a local shop that has been aligning cars for 50 years and knows how to align one from the 60's. Had my 69 Riviera done about a month ago and he said it was way out of alignment. Made a difference at 60-70 MPH. I have another GS400 67 convertible that has a slight vibration at 50 MPH so I am going to take it to him to check.
I had a slightly bent driveshaft that would cause a vibration at certain speeds/rpm,s. It would not be there at all at certain speeds and not too bad at others, but there was one speed that was so bad if I had false teeth they would have been on the dash. A friend had this same problem when his driveshaft threw off the weight, and another had the problem when his 2- piece driveshaft spun in the rubber. A bad universal joint can play havoc as well. You might want to check it out. Duane
I had to replace the driveshaft in my '72 GS as the car vibrated. Discovered that when I took to truck shop to check balance. The driveshaft was bent. New driveshaft & several $$ later.
