Power Steering Cont Valve, wheel jerks to the left???

[Joe L.]

Re: Power Steering Cont Valve, wheel jerks to the left???

Ordered this LH knuckle from Corvette Central. The darker one.
There is significantly more meat on the stop feature.

The Corvette shop will install it and give it a good 4-wheel alignment. They also need to straighten the steering wheel as its not clocked at exactly 12oclick. We just installed an Ididit Tilt column. This has nothing to do with the problem.

New dark-colored part is top pic.
Middle pic is of the drivers side or LH side. You can see how much material is missing. The tire rubs on the frame on this side.
Last pic is the passenger or RH side.

David------

I do not see a significant difference between the stops on the new steering arm and those on the other arms.

By the way, what is the forging number on the new arm?

[David M.]

Re: Power Steering Cont Valve, wheel jerks to the left???

SOLVED IT! I can finally conclude this thread! Game Score = Me 1 car 0! 5 years later...

Review:
After a full front end rebuild in 2017, with many referbed and new parts including new upper/lower control arms (UCA/LCA) etc. The steering wheel would lock from hydraulic pressure in the full CCW position. You had to shut the engine off to release the power steering pump pressure on the ram. Very unnerving and probably not safe.

Dual root causes (RC):

RC1: The LH (drivers) steering knuckle was altered at some point in its life where it mates with the hard stop pad on the lower control arm(LCA). See above pics in thread #45. The dark knuckle is the new one from C.Central.
Looks like someone ground off material on the original part(lighter one)?

RC2: The receiving pad on the new replacement LCA was not welded in the right location and was missing material. It was off just enough to not mate with the knuckle.

The two parts were not engaging as designed, thus preventing the hard mechanical stop. The tire hitting the frame was the new stop!


The Repair:

Step one: It took ordering 2 reconditioned knuckles and some phone time with ZIP and CCentral to find one with the most meat. They are all a little different. Ahhh 68 quality control.

Step two: Cut and repositioned the C shaped outer end in the receiving pad on the LCA.

4 wheel Dick Gulstrand "touring" alignment = a pleasure to drive now.

Before & after shots.

[Gary R.]

Re: Power Steering Cont Valve, wheel jerks to the left???

I am glad you found it and posted the answer. I never have seen that one before. I would think the inside of the tire had rub marks on it, correct?

[David M.]

Re: Power Steering Cont Valve, wheel jerks to the left???

Not so much. The frame exhibited a faint rub at the two rivets.
The only time there was an indication of a problem was in tight maneuvering situations. Otherwise one would never(hopefully) have the wheel to the full CCW lock position while driving at any speed. Maybe young n dumb doing doughnuts?

[Timothy B.]

Re: Power Steering Cont Valve, wheel jerks to the left???

David, what caused the hydraulic issue you posted about with the slave cylinder going full lock in one direction?

[David M.]

Re: Power Steering Cont Valve, wheel jerks to the left???

Timothy,

The pressure was not turning the wheel for you. That would be a bad balance adjustment on the control valve.

To induce the problem the driver needed to turn the steering wheel full CCW say in a parking lot maneuver, not going down the road. At the very end of spinning the steering wheel CCW, the ram would rather violently jerk the steering wheel out of your hands, spin about it about 1/8-1/4 of a turn more and hold or lock the wheel hard CCW left. Had to shut off the engine to get it to release.

The mechanical stop provided by the tie rod knuckle & lower control are were misaligned allowing the steering linkage to move beyond the intended/designed travel, only in the full CCW position.
The passenger knuckle & LCA stops were aligned beautifully. The problem didn't exist full CW, or hard right.

This over travel allowed hydraulic pressure into both the feed & return lines hydraulically dead heading or locking the the ram. Probably opening up both left & right signal ports in the control valve at the same time. At least this is my theory.

Restoring/limiting the linkage travel to factory spec 100% resolved the problem.