I have a '76 with power steering and 56k original miles. It wanders when driving down a straight but irregular surfaced road. What is most likely cause? I want to tackle the most probable issue first. Thanks!!!

 

Sounds like a nice car. With 56k mi, it's almost for sure an original 'untouched' steering box. The Corvette steering box, and system, was good, but not particularly long-lived. Basically the Corvette uses a manual steering system with a power (hydraulic) "assist" system. The *good* is that it provides tight manual feel going down the road, that's what Zora wanted. But at slow speeds and around parking lots and a driveway, it produced a very light 'assisted' steering feel, which was key with a big block under the hood. But the downfall is there are more areas that can develop steering play. Here are the most common areas where steering 'slop' could be:

1) Rag Joint (Flexible Coupler) - This is a rubber/fiber disk at the lower end of the steering shaft in the engine compartment, right above the steering box. They wear and can get sloppy. One way they they wear fast is when people try moving a car by 'cranking' on the steering wheel w/o the engine running (way more stress put on the rag joint). Just a little free-play at this point can yield quite a bit of freeplay at the steering wheel. To check it, put a vise grip pliers gently around the steering box shaft (below the flexible coupler) ...and tie the vise grips to the frame or engine, so it doesn't budge ...at ALL. Don't put the pliers very tight, you don't want to put marks on the shaft. Once you have the pliers so it won't move, go inside the car (put the key on 'run' ..but don't start the car), then gently wiggle the steering wheel. If it's pretty tight, it's probably not the flex coupler. If there is some free-play, then the flex coupler or somewhere from the steering box 'up' needs to be replaced. At 56k your flexible coupler could still be good, but it might be dry-rotted and cracked too (from age).

2) Steering box - C2/C3 steering boxes ARE notorious for wearing and causing a lot of steering play. Back in the day, they weren't very long-lived. It could have 'slop' in it, even at 56k mi. The main wear points are the upper bearing by the input shaft (below the rag joint), which is about as big and robust as a child's bicycle crank bearing! The bearing can rust from water getting past the input seal (from washing the engine compartment) ..or get dry from engine heat cooking the grease ...and the bearing oil gets dry ...and the bearings crack and break. When that happens it totally throws off the pre-load and allows the internal main shaft to move up/down a tad. No adjustment of the top screw will tighten the steering (in fact it could cause damage). The second main wear point is the lower output bushing (yeah, bushing, not a bearing). It's a bronze sleeve. Generally they're pretty robust, but it only takes a micro amount of wear at this point to translate into way more free-play at the steering wheel. The actual internal 'hard parts' inside the steering box tend to hold up pretty well. Therefore, fortunately, the steering boxes are pretty easy and inexpensive (relatively speaking) to rebuild if yours comes to that. There are guys on this forum who are experts at rebuilding them.

Because your car is pretty low miles, you could attempt to tighten the top adjustment screw. If that works, it might solve your problems. Put the front end up on jackstands, so the wheels are off the ground. Remove the rag joint and rotate the steering box shaft with a 12pt socket and feel it it rotates smoothly, or if it feels crunchy like bad bearings. If the bearings feel bad, remove the box and replace the top bearing. If the 'action' feels smooth, then tighten the top adjustment screw on the steering box a little and see if that tightens your steering feel. If that doesn't really tighten the steering ....or if the action feels 'rough', remove the steering box, put in a bench vise and replace the top bearing. At your miles, you could probably get away with just replacing the top ball bearing, readjusting the steering box, and reinstall. Your lower bushing is probably still fine. There's a specific way to do the steering box adjustment ...we can get to that when you get to that point.

3) Ball-Stud at the Hydraulic Control Valve - Ok, this is another wear point that can cause steering 'play'. There is a hydraulic 'assist' control valve on the center link behind the driver's side front tire which contains a ball stud that hooks to the steering arm (attached to the steering box). This is a point of wear and free-play. It is designed to have a little movement at slow parking lot speeds ...but there should be enough spring pressure to not be too 'loose'. If the ball stud is worn, or spring is loose.. There is a large screw on the end of the control valve which is adjustable.

4) Idler Arm - These can have up/down play and can cause steering slop.

5) Tie rod ends, ball joints, etc.

More than likely the freeplay is a combination of a worn steering box, flexible coupler. And possibly the ball stud of the hydraulic controller. The most economical way would be to have someone rebuild your car's steering box and put on a new flexible coupler during reassembly.

Sorry for the long reply...

 

My opinion, keep in mind I haven't driven your car. If the steering is overall fairly tight and your only concern is a wonder on less than perfect roads. You could be in need of a front end alignment. Or perhaps a proper 4 wheel alignment.
Taking it in to a good alignment shop if your not a hands on kinda guy. Would be the logical first step. If there are other issues a GOOD shop should be able to pin point these issues for you.
Keeping in mind, the age of this car has far more bearing than the mileage. Rubber bushings on both ends of your car could very well be way past there due date.

 

My 82 has 37K miles and I also had a little wander in the wheel. After studying and inspecting what Mark G mentioned above, I decided to see if adjusting the tension screw just a little would help and test the results.
After only a little less than a quarter turn, the steering got much, much better and drives like a new car. Been doing great for about a year now. Just took it to a Cars and Coffee about thirty miles away including lots of 70mph Interstate driving and it is still doing great. If you decide to try that, a very little twist makes a big difference. I highly, highly recommend you study all the points mentioned above before twisting that AND learn exactly what that screw does before you start twisting on it. Steering is like brakes. You don’t really miss it until it’s not there!!!

 

Post a photo! What wheels and tires do you have?

Most probable: Strut rod bushings and/or trailing arm bushings.

 

Do you have original bias-ply type tires insted of radials? They were notorious for "nibbling" and darting on the road. Lou.

 

Radials a couple years old.

 

Stock rims and Cooper Cobras. Have a couple thousand miles on tires. Had alignment done when tires were installed/

 

Thanks for advice. Tried it. No change.

 

If you click "Quote" instead of "Reply", it helps us to understand which questions are being answered.

You can even quote more than one response.

 

Not an uncommon issue with C3,s. If the items listed by others check out ( would remove the top of the steering box and check the condition of the grease too, it often dries out due the close proximity to the exhaust, ( make sure you measure or count the number of turns taken to remove the adjuster nut though so you can replace it exactly).
When driving on irregular surfaces and you move the steering wheel slightly the ever helpful steering ram will be activated to provide steering assist which is the last thing you wanted when driving straight ahead so naturally you turn the steering wheel the opposite way and the ever obliging ram starts to provide assistance again leading to a see saw kind of steering experience. In my car at least I found the best solution without changing steering boxes or adding a rack and pinion system was to increase the amount of caster to the front wheel alinement to the max I could get which was close to 5 deg achieved by the max No of shims allowed in the caster setting and by slotting the mounting holes for the upper A arms. Check out the amount of caster that a C4 Corvette has compared to the old timey amount used in a C3. This is my experience others seem quite happy with the standard setup when it’s in good condition, I wasn’t because there are a lot of irregular roads where I live.

 

Any ps fluid leaks? The control valve is notorious for needing replacement often in my experience. It would cause a ‘wander” in steering if it’s in its way out.

 

Got it.

 

No leaks.

 

Did the car track ok after the alignment? As other respondents have noted, a small turn on the adjuster on the steering box is the quickest/easiest action to start with. Alignments don’t last forever so a slight change (e.g. hitting a pothole) can make a noticeable difference. Check your toe in - easy to do with two people. Eliminate the obvious first before going down the rabbit hole.

 

You say car was aligned. By whom? to what specs?
a common tire shop alignment to unknown specs could be all that's going on here.
a tad of toe out will cause wonder.

 

With any front steering wandering, the first thing I do is jack up one front tire.
Grab the tire at 6 o clock & Noon. Any play?
Then grab the tire at 9 o clock & 3. Any play?

Back then wheel bearing didn't last 200,000 miles like today.

 

Another vote for front wheel bearings check

 

Mine did this when I got some bad rear tires. Took me forever to find. It's a longshot but might be worth swapping the tires fore and aft to see how it reacts. Wasn't going to share but then I figured that it would have taken me forever to find if I hadn't lucked out and had to change the tires (I forget why? May have punctured it or something?)