My 69 coupe is really unstable in freeway turns (particularly to the right). The car seems to have a mind of it's own. It won't hold an consistent radius and has to be aggressively driven through the curve. It seems to want to follow every irregularity in the road surface. This car had the front suspension professionally rebuilt by the previous owner. Not sure about the steering box. The car only has 70K miles on it, so I would be surprised if the steering box were worn out. It's mounting 235/60R15's on stock rally wheels. The car is actually a little scary to drive. Any suggestions as to the possible causes?

 

How are your shocks?

 

Yes, check if steering box need to be repaired or adjusted. Also check if you need wheel alignment and balance.

 

There are several things that could be causing your problem; and more than one could be at fault. The rag joint, loose steering box, steering control valve, ball joints, idler arm, shocks, front and rear wheel bearings, loose rear suspension. Just because they said it was professionally rebuilt doesn't mean that the mechanic understands the pecularity of the C3 Vette. You do need to find the problem before you drive it regularly for safety reasons.
Bernie

 

Jack it up and grab each tire at 12 and 6 o'clock and see if it tilts, wiggles, or squeeks...basically anything other than rotate. Don't be shy. Really shake them around. Do the same with hands at 3 and 9.

 

Power steering control valve adjustment.

 

Could be as simple as a massive toe-in or toe-out alignment problem. Makes 'em feel very squirly and requires a lot of steering input.

 

have you checked your rear wheel bearings and alignment?

 

Toe-out can make the vehicle dangerous.

 

I don't disagree that toe out can make a car "squirrely", but I just had a MASSIVE toe out problem corrected (Posted about here) and the car cornered really well and tracked straight. It was only uncomfortable on roads with bad ruts and even then it would just climb the rut, ride the high section, and be happy. Overall, I would say the steering was just extremely sensitive. If I turned the wheel, it WENT! It may help that the rest of the car was just redone and healthy. My on-center adjustment is very tight. I have no play whatsoever. If I had had the bad luck to combine my toe out with a worn steering gear or bad bearing/bushings, it would have been downright scary.

I think the severe unpredictablility comes from worn components going whichever way they feel like.

 

You have to get the car in the air and go through it. I've rebuilt boxes with 40k miles that has worn gears so don't let the miles fool you. You need to check the front and rear suspension and rear end yokes all can be part of the problem.
Good luck

 

How old are your tires?

After I bought my Vette I had a issue with tramlining and the car seemed to "float" over rough pavement. My tires looked like they still had plenty of tread so I thought it was something else.

I finally took the Vette to a tire dealer. They were able to tell me that the age of the tires were over 8 years old.

A new set of rubber all the way around fixed all my handling issues.

An article on tramlining: http://www.tirerack.com/tires/tirete....jsp?techid=47

Good luck!

 

Mine had a similar experience when the control arm bushings went bye-bye. I agree that jacking up the front end and grabbing a wheel and shaking could show where the problem is. God bless, Sensei

 

The suspension has been all rebuilt, change too some modern tires.

 

I understand your pain. I have the same problem. From 1970 to 1975, I owned a C3 small block with the F41 suspension. I originally had the original F70/15 bias tires on it. When I needed new treads, a BFG guy convinced me to go G60/15 radial. As I recall, the car drove like a dream. Neutral steering or a touch of understeer that could be neutralized with a little accelerator. Fast forward to 2000, I bought a 1973 small block with F41 suspension with F70/15 BFG radial tires. My steering appears to have a mind of its own. I have rebuilt front and rear suspension, steering column and rag joint (not the gear and not the power assist) and paid a little extra to the Goodyear dealer to give me that "perfect" alignment front and rear. I got some incredible computer printouts of that alignment and trust that Goodyear did a fine job. My experience is that the car is a little slow to react and after the turn is established attempts to "tighten" the turn at high speed. I thought that it was just my experience. Based on what I have learned on the CF site, I am convinced that the problem is in the power assist. Here is a possible scenario: Start turn, understeer weight shift body roll etc. causes the nose to lag slightly behind the steering angle. The g's are established and the car is turning now but the power assist is still pumping fluid and forces the draglink a bit more in that direction. This is probably a mechanical problem that can be corrected however I have not seen anyone describe the fix. Most of the guys who are interested in serious cornering performance have opted for either the more modern Cherokee power assist (I understand it was built by the same folks that built the Corvette recirc-ball unit, Saginaw Steering Gear div of GM now Delphi so you don't need to worry about a MoPar part on your vette) or the TransAm (I believe) rack and pinion with power assist that comes as a C3 bolt-on package from Steeroids or CC. There are lots of discussion about which way to go. I think both camps have some convincing pros and cons. It would be nice if one units clearly dominated. As I did, you may wish to listen to and even question the reasons for some folks choosing a particular unit. I'm still undecided. I would like the cleaner looking installation of the Cherokee box and avoid the possibility of problems with sigmoid u-joint binding of Steeroids but I view the Cherokee box as just moving the power assist from the draglink to the box. If this would fix my power assist problems completely, I would consider it. I know that if the sigmoid u-joint is installed correctly, owners rave about the Steeroid. I'm still gathering data and flipping the coin. Good luck.

 

The cars tendency to "tighten" the turn in corners is more likely due to toe steer (some call it bump steer) in the rear suspension as it "jacks" up. The stock Corvette rear suspension has a bad problem with "jacking" in hard turns. This is where the rear suspension geometry actually raises the back of the car inducing toe steer. The car literally steers like a forklift.

If the power steering is causing the erratic handling the control valve needs to be rebuilt and or adjusted properly.

BigBlockk

Later.....

 

At 70,000 miles my side yokes were worn so bad that when driven on any road with a rut it would through the car sideways. The worn yokes on my car allowed for at least 1/2 inch in camber change on each wheel.

garson