Hei out there.
Is there anyone that can explaine what the different things inside do.A see throuh picture would bee nice too.What makes the flow control and pressure control.I need too make the steeringeffort a bit easier and faster.I have a steerbox from Z28 perf susp and old style pump.These cars dont growe on trees here.
Nice sunny day here.
Take care out there.

The following link has a pump blowup that might be of help. Although the websight is for C3 Corvettes, the pump information is correct for GM cars and trucks that use the Saginaw big P-pump.

http://www.corvettefaq.com/c3/P-PumpBlowUp.doc

The blowup pic shows all the components of a 1975 (and later) power steering pump. The difference is that the driveshaft (1) is completely smooth and is designed for a interference fit pulley. All pumps before 1975 had a driveshaft with a keyway and a threaded end for a nut.

The parts that dictate how much oil is moved for each revolution of the pump shaft are (11), (13), and (14). They are the rotor, vanes, and cam ring. The thickness of the ring and the rise of the cam dictate the pump displacement. Most pumps displace 1.32 gallons (5 liters) per minute at some low speed (like 700 rpms). Pumps with thicker cam rings and larger cam rise can flow more oil at that same 700 rpm.

(7) is the control valve. Inside the valve (behind the nut with the screen) is a spring and ball check. Shims behind the nut control the spring load and dictate the pressure relief setting for the pump. Later control valves retain the nut with loctite rather than shims. The control valve was set at the factory for a specific relief setting.

(24) is the discharge fitting. The throat diameter and the size of a very tiny hole that reaches into the throat diameter dictate at what point the pump goes into "flow control". In otherwords, the pump is a positive displacement device. The faster it turns the more fluid is displaced. After about 1500 pump rpms the pump will quickly start flowing way too much fluid. So the pump flow control system is designed to recirculate fluid internally inside the pump after it reaches a specified flow. Most pumps are set to flow from 2 to 3 gallons (7 to 11 liters) per minute at 1200 to 1500 pump rpms.

There are several scans of the Saginaw pump from the Chevrolet service manual. They are also posted on the www.corvettefaq.com websight in the Steering section. They may also be helpful.

Now that you know how the pump works, I have bad news for you. The amount of steering effort and feel is about 90% controlled by the valving in the steering gear. The gear has a rotary valve that has a torsion bar inside. The thickness of that bar (and the porting in the valve) dictates your steering effort and feel. The valve is assembled at the factory with a very precise machine that flows a controlled amount of fluid as the valve is balanced and pinned.

It is true that flowing large quatities of oil will make your steering gear valve more responsive but that is not the correct way to go when you want to change steering effort and feel. Large quantities of oil flowing through your steering circuit will generate high back pressures and consequent high steering fluid temperatures.

JIML82

I'd like to add to JIML82's excellent info that the usual problem encountered with using an older model pump on a newer box is the old pump MAY lack enough pressure and flow to properly run the new box.
The good news is, the problem is in the pump pressure/flow valve not the new box.

Mods to the pump can help if:
1 you run out of boost when turning the wheel car stopped, engine at idle, like when parking the car. problem is low pressure.
2. When you turn the wheel quickly, and the box momentarily runs out of boost but recovers quickly. The problem is lack of flow.

3. if the steering is jerky at idle or low speed, the belt is slipping.

4. if you hear groaning noise, the fluid has air in it or is overheating.

If you want the steering to be stiffer or softer, the valve in the steering box controls that, not the pump.

The pressure and flow can be increased on an old model pump but you don't want to change those settings unless you really need to. The danger is too much flow and overheating.

Fantastic respons.
What shell I do.I have bought a new cardone steerbox Z28-89 and i would like too keep my old style pump.For the time beeing i cant open any article in the corvette forum but i will try again.I dont want the old feeling back but a little bit easier. I will keep working on the problem.
Thanks again Guys.

Johan, I run the Cardone third gen steering box and the old style pump, steering effort is perfect. You should not need a different pump, just hook it up and see if it works for you. I also run a slightly smaller Grant 714 Mahogany Steering wheel which is 14" in diameter that helps with the less assisted feel as well.

I agree, try your pump and see how it works first.
If you have any of the problems I listed above there is a restricton you can drill out for more flow, and a shim can be removed from the pressure valve. BUT you don't want to change these unless you really have to.
David

Along these lines, will a pump from an lt1 fit a 3rd gen pump (Cardone 276550) without the fitting adapters? I was hoping they would all just be metric and I could save the money on the fittings and just use the lt1 lines.

You could go that way but what hoses would fit?
I think using a first gen pump with adapters would be better because you could use first gen hoses.

Hei guys.
I think I have the problems 1 and 2 i David`s replay.As I understand the old pump delivers 900psi and a pump on Z28-89 is about 1400psi,correct?I have drilled the hole in the fitting assa connector from 2,75 to 3,0 mm.Made it a lite better.what should I try now?
Again thanks for the info so far.

Only trying my settings.

for more pressure, remove a shim from the pressure control valve. Remove the spool shaped valve, remove the nut with the screen in it's center. Be very careful to not damage the outer surface of the valve. I pad my vise with aluminum, then insert a drill bit into the hole in the side of the valve, letting it hit the side of the vise jaws, then turn the nut. The nut is in VERY TIGHT.

More pressure only helps when turning the wheel when stopped, engine at low speed or idle, make sure the belt is not slipping first.

flow can be increased by drilling out the restriction in the outlet fitting. The hole size should be around 3.5mm. The larger you go, the more jerky the steering get's and there is more fluid flow and heat.

Since you have allready drilled your outlet, I would try increasing the pressure next, then drill more if you lack boost momentarily when turning the steering quickly at higher engine speeds.

Hallo David.
I will try that and see.Keep You posted.
Thanks again,Guys.

I just want to respond to all of the wonderful information that was posted regarding the power steering pump. I have never been so impressed with all the information posted on this site. Thanks to everyone for the help. Keep up the good work!!

Robert

Hei Guys.
Short uppdate.Drilled the hole too 3,75mm and removed the small shim on to valve assy control.Not much better.The steering is fine when driving but heavy when parking in low or idle.I have picked apart a pump from a blazer-79 with monster mudders and it was 3.75 and the measures is like mine.Dont know what too do.The belt is not slipping.Have not tryed a smaller pump wheeel.

Johan,
One trick is to slightly raise idle speed.
Is the steering heavy or is it running out of power assist?
A pickup truck pressure valve is supposed to have the highest pressure setting, around 1400 psi.

Are there any more shims left on the valve? Some valves have two shims, often a thick and a thine one, I have read in articles you can remove all the shims if more pressure is needed, but I have no idea what the pressure would be.

The belt can slip and make no noise, double check that it is not slipping. You can put a chalk stripe on the pulley and it will help you see if it stops or slows down.

I found I really had to pay attention to the PS belt, I had a lot of trouble with it slipping but I had the stock narrow pulley system on my 67. 70 and later have wider "Deep Groove" pulleys and only first gen Z/28's and big blocks used them.

If you have all shims removed and the belt is not slipping, then I would suspect the pump is not in good shape and you may need to rebuild it or get a rebuilt pump.

If you are testing your steering by turning the steering wheel while your front brakes are on, that puts a lot of extra load on the steering system. The brakes prevent the tires from rotating while the steering wheel is turned, the tires have to be scrubbed on the pavement and that takes a lot of power. It all depends on how hard you step on the brakes.

Hallo David.
There is no shims left.I will double check the belt and try steering with my brakes on.It sems fine when driving but in slow corners it is much heavier close too idle.
Uppdate is on the way.

If you have a lot of positive wheel offset, that put's more load on the steering too.
Is your engine drive pulley and pump pulley the same diameter?
What is the maximum RPM for your engine?
David

Hallo David.
Have not tried anything jet but the answers too your quastion is the wheels is 7" backspace 4,5.The pulleys is engine 170mm pump 145mm and i wount pull it past rpm 6000.Its okey once you drive it you can turn with the palm of yuor hand.Trouble is when parking and so on.I will try some thing in the morning if the weather is better.

I am starting to think your pump may not be in very good conditon. With all the things you have done, it should be working better by now.
The only other thing I can suggest is to try the GM clear power steering fluid. What fluid do you have in the pump now?
David

The same as the tranny Dextron 3.I will try too borrow the pump from the blazer with monster mudders and try.
Thanks again David.
ps.Fantastic that we are so far apart on the globe.ds.

Most power steering pumps run at 1.25 times engine speed. This gets the flow up so that parking and low speed power assist is consistant. I am quite sure that this probably isn't the problem but what is your idle speed? Very low idle speed can affect steering performance as well.

Back when I was working for GM (Saginaw Steering Gear Division), the powertrain people at GM were always trying to reduce engine idle speed to improve EPA fuel economy numbers. This would cause the power steering pump to spin at too slow a speed to generate sufficient flow for parking assist.

JIML82

The GM clear PS fluid is supposed to be the best. Transmission fluids are made with clutch engagement in mind, and not optimum for pumps but will work, maybe not the best though.

I agree with David. With everything that you have done you should have better results.

In dealing with this issue several years ago, I found that most all rebuilders use a common pump cam. When I questioned the rebuilder about the volume differences for different pump cams he thought I was crazy. Lesson learned? Don't trust a rebuilt part for a high-performance application.

The GM fluid is outstanding. After recently upgrading to the new 600 Saginaw box it took very little time to bleed the system. Plus, its on-track and temperature capabilities have been good.

Symptomatically, when I put in the new 600 box I used GM fluid based on comments here. The bleeding process was so trivial as to be boring - which I'll take!

Uppdate.
I have taken 2 pumps apart.Mine and another 1.What to look for if broken,cant see anything that is not as it should bee.One thing that comes too mind,I dont have any sqeeking sound when hitting the end either left or right.idle about 750-800 rpm.
Keep trying.

Hei Guys.
Short uppdate.I will send My thanks too all of You out there that helpt me.Everything seems too go a little bit better now.I am getting used too the heavier feel.Still searching for a different pump but cruising on for the summer.

The stiffer box does take some getting used to. :thumbsup: