Another power steering problem....
Thread Starter
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
Another power steering problem....
I've been chasing down a problem with the power steering on my 68, and think I may have found it. Need the Forum's opinion before I buy the wrong part.
So far, I've replaced the pump, steering box, control valve, and ram, and the car is STILL hard to steer. I removed the control valve and took it to a local Vette place. There it was bench tested, and showed to be holding 1050 PSI in both directions when the ball stud was moved over. The valve was then re-centered on the bench. I installed the control valve and bled the system....same problem
So I started thinking, maybe I should re-center the valve on the car with the ram disconnected. I noticed it didn't take much turning in either direction to get the ram moving, but I did get the valve centered. Now for the interesting part....
With the car still running and on stands, I could turn the wheels by hand to get the ram moving, and noticed that with the ram moving out, I can still push it in with one hand. I can also pull the ram out when it's supposed to moving in. This doesn't seem right to me.... or is this normal? Would an internal leak in the ram cause this?
Would like to hear any suggestions
So far, I've replaced the pump, steering box, control valve, and ram, and the car is STILL hard to steer. I removed the control valve and took it to a local Vette place. There it was bench tested, and showed to be holding 1050 PSI in both directions when the ball stud was moved over. The valve was then re-centered on the bench. I installed the control valve and bled the system....same problem
So I started thinking, maybe I should re-center the valve on the car with the ram disconnected. I noticed it didn't take much turning in either direction to get the ram moving, but I did get the valve centered. Now for the interesting part....
With the car still running and on stands, I could turn the wheels by hand to get the ram moving, and noticed that with the ram moving out, I can still push it in with one hand. I can also pull the ram out when it's supposed to moving in. This doesn't seem right to me.... or is this normal? Would an internal leak in the ram cause this?
Would like to hear any suggestions
Thread Starter
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
That's understandable, but I'm referring to when I turn the wheels with the ram didconnected. At that point the control valve is supplying pressure to the ram. I can push the rod in when it should be moving out, and pull it out when it should be moving in
Burning Brakes
Joined: Feb 2002
Posts: 752
Likes: 31
From: Melbourne Australia
I think the behavior would be very different if the wheels were on the ground. On stands there is nothing for the ball stud in the control valve to react against, unless you try to stop the steering wheel from turning while you turn the wheels by hand.
I think that if the car was on the ground with the ram disconnected from the frame, you would not be able to move the ram by hand if a helper tried to turn the steering wheel. The ram would move quickly to its stop and you won't be able to budge it by hand.
Jim Shea might chime in on this thread, he's very knowledgeable on C3 steering systems.
Joe
I think that if the car was on the ground with the ram disconnected from the frame, you would not be able to move the ram by hand if a helper tried to turn the steering wheel. The ram would move quickly to its stop and you won't be able to budge it by hand.
Jim Shea might chime in on this thread, he's very knowledgeable on C3 steering systems.
Joe
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Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 113
From: Saginaw Michigan
I think that you are correct that without a reacting force (i.e. the tires being on the ground) the ram will not extend or retract with any appreciable pressure.
The amount of effort to steer the car is controlled by the springs inside the control valve.
Another factor that could cause heavy effort would be still having trapped air in the system. When you replace all of the major components in the system (control valve, ram, pump, hoses, etc) there are many places that can trap air and it might take considerable time to get it out. So even if you don't do a very good job of getting the air out before starting the engine, the air will work its way out of the system over several days as long as you drive and steer the system full lock to full lock a few times during that time.
Jim
The amount of effort to steer the car is controlled by the springs inside the control valve.
Another factor that could cause heavy effort would be still having trapped air in the system. When you replace all of the major components in the system (control valve, ram, pump, hoses, etc) there are many places that can trap air and it might take considerable time to get it out. So even if you don't do a very good job of getting the air out before starting the engine, the air will work its way out of the system over several days as long as you drive and steer the system full lock to full lock a few times during that time.
Jim
Thread Starter
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
Thanks for the info guys
I'll check it out again tonight when I get home.
Jim, I see you're from Saginaw. My dad lives in Clio, and my family has a long history working for GM in the Flint area. I try to go back there every few years when I get the chance
I'll check it out again tonight when I get home.Jim, I see you're from Saginaw. My dad lives in Clio, and my family has a long history working for GM in the Flint area. I try to go back there every few years when I get the chance
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 113
From: Saginaw Michigan
I've been pretty much a Saginaw boy all of my 64 years. I started on co-op with Saginaw Steering Gear Division, GMC right out of high school in 1961. When I graduated from the University of Detroit in 1966I hired into the Product Engineering Department at Saginaw. I worked pretty much in steering systems my entire career until I retired in 2001.
I was the supervisor of the flexible coupling, power steering hose, and hydraulic seal group from 1969 through 1985. (Beginning at the early part of the C3 era through the early years of the C4 program.) So I do have quite a bit of first hand engineering knowledge of the Saginaw parts.
I purchased brand new 1976 and 1980 Corvettes and began saving engineering information on the C3 models because of that fact. The information has become invaluable over the years!
Jim
I was the supervisor of the flexible coupling, power steering hose, and hydraulic seal group from 1969 through 1985. (Beginning at the early part of the C3 era through the early years of the C4 program.) So I do have quite a bit of first hand engineering knowledge of the Saginaw parts.
I purchased brand new 1976 and 1980 Corvettes and began saving engineering information on the C3 models because of that fact. The information has become invaluable over the years!
Jim
Thread Starter
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
Thread Starter
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
OK, I replaced the pump with an AGR unit from Summit, and it made a big difference still a little on the stiff side, it will likely get easier as the rest of the air works it's way out
I've noticed it doesn't take much adjustment of the control valve to get the ram moving. I only have to make about a 1/8 turn of the nut on the end either way to move the ram. Does that sound right, or is there a damaged seal(or something else) inside the valve?
still a little on the stiff side, it will likely get easier as the rest of the air works it's way outI've noticed it doesn't take much adjustment of the control valve to get the ram moving. I only have to make about a 1/8 turn of the nut on the end either way to move the ram. Does that sound right, or is there a damaged seal(or something else) inside the valve?
Burning Brakes
Joined: Feb 2002
Posts: 752
Likes: 31
From: Melbourne Australia
When it is centered correctly it doens't take much adjustment...yours sounds about right. The nut should be adjust halfway between the point where the ram moves in and where it moves out.
Joe
Joe
Thread Starter
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
What a coincidence, I get a reply from Australia as my daughter is watching the Wiggles
The adjusting nut is real sensitive, and it is centered, so if that's right, I'll leave it alone
Thanks Joe
The adjusting nut is real sensitive, and it is centered, so if that's right, I'll leave it alone
Thanks Joe