Haven't been here for awhile, got the 73 back together after 5 years and have put about 500 miles on it so far.

All the steering components were changed. The alignment has been done twice now. The issue is a slight pull when you are going down a straight smooth road, pulls left. Not sudden, just a gradual left drift when you let go of the wheel. It is enough pull for the car to climb the crest of the road and continue left.


The brakes seem to all be the same temp, have switched tires from side to side, The car drives well same effort turning right as left. The wheel doesn't take off on its own like when a control valve isn't balanced.

Is it possible that the control valve is out of adjustment or something? I am getting ready to go and find a nice quiet straight stretch of road, get up to speed and carefully turn the car off to stop to PS from working, but before I do that I would appreciate any input you might have.

Thanks
Mark Potter

 

Two possible issues:

1. The steering control valve on your P/S might need to be "centered". There is an easy procedure for that. If not centered, you will get a slight drift in one direction. (Ask if you need the procedure.)

2. Tie-rod adjustment error can also cause what you are getting. Some alignment mechanics dial-in some compensation for 'crowned' roads so that you don't have to steer a bit to the left, just to keep the car going straight; others set the car for a flat road. You might ask how your car was adjusted.

The alignment may have been done "by the book", but may not have been done as these smaller cars (with big wide tires) require for proper tracking. Front tires need to have 3/32" to 5/32" TOE-IN so that the tires will not "hunt". This isn't the symptom you described, but if you have more work done by the alignment shop, you should ask if they set the toe-in needed by these cars.

 

Did the shop give you a printout of their settings? Differences in caster can give the behavior you are seeing. Also you don't think it is the control valve but aren't sure. Putting the car up on a jack stand and turning the motor on will tell you for sure if it is balanced.

If you eliminate the control valve and are willing to play with the shims a bit, you may be able to solve this that way. Note I wrote in my shop manual years ago says if it pulls left, transfer a 1/32" shim from front to rear on the left side. It's been a while and somebody may call me on this but that was my note at the time.

It's easy to get back to where you were by moving the shim back with no harm done to the shop's settings.

 

If you could post that balancing procedure or give me a link I would like to take a look at it.
Thanks
Mark

 

As ignatz wrote in prior post, raise front wheels off floor; remove the left front wheel; remove the end cap off the control valve. Start engine, then center steering wheel and release it. If it drifts off to one side, the control valve needs to be adjusted.

Adjustment procedure: [use 1/4" or 3/8" drive ratchet or breaker bar with socket to fit adjustment nut on control valve]
1. Turn nut so that the front wheels do not drift in either direction;
2. Now, turn the nut CW so that there is slight drift, then turn it in opposite direction until wheel drift is stopped. Mark the orientation of the breaker bar. (Do not reverse direction of your wrench during this step.)
3. Turn the nut CCW so that there is slight drift, then turn it in opposite direction until wheel drift is stopped. Mark the orientation of the breaker bar again.
4. Find the mid-point between the two orientation marks you made in steps #2 & #3, and turn the nut to that position with your wrench.

This should be the "sweet spot" in the control valve where there is no bias causing the wheels to drift in either direction.

5. Turn off ignition, reinstall control valve end cap, install wheel, and lower car to floor.

That's it.

 

Go to about the 5:50 mark of this instruction video.

 

Hey guys, let me ask what might be a obvious thing. If a PS control valve is only "slightly" off center or out of adjustment could it cause only a slight pull to one side?

This might sound dumb but the only experience I have had in the past was with the sudden almost violent movement of the wheel to one side.

Thanks
Mark

 

Intuitively, it has to overcome the centering force of the toe-in, so I would tend to say a small offset is unlikely to do that. However little things add up and it might all be a combination of slight differences here and there, all of them in the same direction. It sounds like you are trying to think your way through this. Just get the car up in the air and see what happens.

Or ... complain to your alignment shop. They shouldn't give you a car that wants to run to the left.

 

YES. Mine was like that.

 

If you have ever done this adjustment, then you would know that a slight drift is VERY possible. The closer the adjustment nut is to the correct centering position, the less the drift. With front end in the air and wheel off (no load on the tires), a little shift will make the steering actuate very slowly in one direction. If the wheels were put back on in that state, the car would tend to drift in that direction, if it were on flat pavement.

You would only get a sudden lurch-type action if the adjustment were WAY off...or if there was air in the system...or if the hydraulic hoses got reversed...or if the guts of the control valve were damaged or mis-assembled.

 

This was a great thread.
Thank you for sharing this and I hope you fix your issue soon.
Best regards,
David

 

My steering only worked after replacing the rear strut rods and an alignment by a chevy old school tech. This is after bliestien shocks, new front end (ball joints, tie rods ends, idler arm, and control arm bushings ). Oh a Borgeson unit. 30K miles, two trips to san diego later and I'm looking for a 1000 mile trip for this summer. Now my 78SA is a joy to drive. Lars rebuilt carb helps.