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

[David M.]

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

The parts came from Corvette Central 2017. We went through 3 valves. All three did the same thing...hydraulically locked the steering wheel in full CCW position.

With the car on the lift, engine on, front wheels off, the system stays centered without wanting to wander left or right while under pump pressure. The balance is good.

What about having the fluid lines crossed??? Does anyone have a hydraulic schematic? I know I put the new lines on in exactly the same position as the old lines were affixed ....but was that right, to begin with?
Again we didn't notice the problem until after the rebuild.

Joe, The part number on the part we just received from ZIP is 3928651 GM2

Old vs new:

[Joseph S.]

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

Dave, Are you sure that the steering box is centered when the wheels are at 100% straight? Could the box be allowing more travel to one side than to the other side?

Also, I can't tell from the photos, but is the pitman arm correct for Power steering?

[Joe L.]

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

The parts came from Corvette Central 2017. We went through 3 valves. All three did the same thing...hydraulically locked the steering wheel in full CCW position.

With the car on the lift, engine on, front wheels off, the system stays centered without wanting to wander left or right while under pump pressure. The balance is good.

What about having the fluid lines crossed??? Does anyone have a hydraulic schematic? I know I put the new lines on in exactly the same position as the old lines were affixed ....but was that right, to begin with?
Again we didn't notice the problem until after the rebuild.

Joe, The part number on the part we just received from ZIP is 3928651 GM2

Old vs new:

David------

Forging number sounds correct but I can't confirm until I get home in two weeks.

One of the two hoses from the control valve to the cylinder is incorrect although this should have no bearing on your problem. One hose should have short radius but both in your photo have the long radius. However, this might contribute to getting the hoses installed wrong.

[Leif A.]

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

Dave,
The hoses need to be connected in a criss-cross fashion at the control valve. The lower hose from the cylinder goes to the top left hole on the valve and then the top hose from the cylinder crosses over the lower hose and connects to the lower hole on the valve. See picture below. The cross-over is critical to proper operation.
Great article on the correct installation. https://www.motortrend.com/how-to/17...-82-corvettes/

[Joe L.]

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

Dave,
The hoses need to be connected in a criss-cross fashion at the control valve. The lower hose from the cylinder goes to the top left hole on the valve and then the top hose from the cylinder crosses over the lower hose and connects to the lower hole on the valve. See picture below. The cross-over is critical to proper operation.

Leif------


In this case, I think the "crossover" has occurred at the rubber portion of the hoses. So, even though the installation is incorrect, I think it should be at least functionally correct.

[David M.]

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

Dave, Are you sure that the steering box is centered when the wheels are at 100% straight? Could the box be allowing more travel to one side than to the other side?

Also, I can't tell from the photos, but is the pitman arm correct for Power steering?

Joe,
I don't know but good info to add to the root cause analysis. Taking ownership 30 years post production anything is possible.
Will check and verify.
Good data coming in guys, keep it coming. Ill follow through on the thread and conclude for archives...once Root Cause is verified.

Thanks all.

[David M.]

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

Here is the best shot I have of the pitman.

[Joe L.]

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

Here is the best shot I have of the pitman.

Dave------

There will be a forging number on the pitman arm that will identify whether it's the standard steering pitman arm or the power steering arm. It will be a 7 digit part number. As I recall, if it's the standard steering arm the part number will begin with "38"; if it's the power steering arm it will begin with "37".

However, it has been reported that the standard steering arm will actually work OK with power steering. Many times folks converting from standard to power will not change the pitman arm and I've never heard of any resulting problems (although that does not mean that none ever occurred).

[Gary R.]

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

Hi Joe,
I look at the last 3 digits for a quick ID, #383 = PS, #451 is manual.

Visual comparison as I'm sure you know is the PS arm is more offset than the manual arm to allow the Ram rod to clear. A PS arm should work on a manual setup but the manual arm may have interference if used in a PS setup.

[Mike T.]

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

I recently added Power Steering to my 65 and 66 Roadsters and have a pic showing the difference in offset between the PS and non-PS Pitman arms, PS on the left.Pitman Arm Differences PS versus Manual.jpg

[Gary R.]

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

Good picture Mike. I was going to pull one from my file but you beat me to it. What is that grease on the spline? Looks like an original single lip lower seal.

[Mike T.]

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

Hey Gary - This was the box from my 66 L72 Roadster, the one I used the kit from you to go through. That car had a body-off done way back in the early 90's and is the cleanest car I've ever bought but...there were a number of things that needed attention and the steering box was one of them. I remember looking at the top of the steering box and wondering what they used for the lash bolt/screw and you looked at it and said..."they reinstalled it Upside Down"IMG_9690.jpgIMG_9731.jpgIMG_9732.jpg.
There had to be literally 3/8 inch of up-down play in the sector shaft. Check out the pics attached. One shows the upside down lash screw, the others show the sector up tight into the box and the last one hanging down...tons of play. The lower seal was a two-lip variety but with the sector just sliding up and down, the grease had an easy way out.

[Gary R.]

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

Ah yes I do remember that. Clearly someone had no clue what they were doing, also the amount of yellow paint is ridiculous. I don't think Geronimo had that much war paint on. I have to admit that is the first time I ever saw the lash screw installed outside of the cover. You never know what you're going to find. Hope you're well and you're not affected a lot by the drought out your way.

[Mike T.]

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

Gary - I've done a number of steering boxes over the years, typically with your parts and guidance, and there I was looking at that 'odd screw' and the light just didn't go on...until you pronounced it 'upside down'.
And yes, they got carried away with the 'paint blotches'. Kinda looks like they used a 'roller'.
Very true, years of drought out our way but on a good note, our Monsoon Season, usually from mid June to mid September, was very wet this year, the 5th wettest Monsoon on record. Just hope the drought doesn't return.

[David M.]

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.