Power steering pump question.

[69427]

I've got a spare GM p/s pump sitting around the garage, vehicle source unknown. It appears to be a bit lighter than the one currently on my '69. If this is off a R&P equipped car then it should work, but it might not be usable if it came off a regular steering box car. How does one figure out by looking (or disassembling the pump) what pressure level these things produce, or how to modify (reduce) the pressure to work with my setup?

Thanks,
Mike

 

[mrvette]

MY only comment is.....15 years ago before knowing anyone smart, I put a serp drive on my '72 stock L48 engine, and ran the stock p/s system with no sweat...using the stock L48/'72 pump valve...screwed in the whole assy and it worked....mainly because I wanted the flare fitting not that AN thing....

It is my understanding the older valve/flow device has reduced pressures/flows....

and with the rack conversion some years later, seems to work just fine for ME with road feel and overall assist feeling....

:shocking:

 

[69427]

MY only comment is.....15 years ago before knowing anyone smart, I put a serp drive on my '72 stock L48 engine, and ran the stock p/s system with no sweat...using the stock L48/'72 pump valve...screwed in the whole assy and it worked....mainly because I wanted the flare fitting not that AN thing....

It is my understanding the older valve/flow device has reduced pressures/flows....

and with the rack conversion some years later, seems to work just fine for ME with road feel and overall assist feeling....

:shocking:

Gene,

You put a low pressure "assist cylinder/rack" pump on a rack application. Of course it will work.
My question is how do I tell if a pump is for a recirculating ball power steering box or for a rack and pinion setup. From everything I've heard the pressure levels are significantly different.

 

[BBShark]

The steering pump relief pressures are set by the flow control valve. I had my modern pump releif pressure set to 1000psi (from 1400-1500) by a local rebuilder. They removed the flow control valve and either added or subtracted washers at the end of the valve.

I have to assume that the only way to do this is with a pressure gauge and trial and error.

 

[Twin_Turbo]

KRC pump -> can swap flow valves in a jiffy. lightweight too

 

[mrvette]

The steering pump relief pressures are set by the flow control valve. I had my modern pump releif pressure set to 1000psi (from 1400-1500) by a local rebuilder. They removed the flow control valve and either added or subtracted washers at the end of the valve.

I have to assume that the only way to do this is with a pressure gauge and trial and error.

Seems reasonable to me, and I did it first with the stock as a stove steering, not knowing anything about flows or pressures....

THEN kept the same '72 stuff in place with the rack conversion, supposedly lower pressure/flow.....worked fine and then maybe 3 years later I put on HBoost....again, no thought about it, still fine today....4? years later on....daily driver....

AND from what Jim Shea has said, from what I remember is the older pressure/flow valve setup has lower numbers then the new stuff....now what the Jeep/Borgeson conversion requires, I dunno...

I know my stuff works ok, so far, for Me....

:beer::search:

 

[69427]

KRC pump -> can swap flow valves in a jiffy. lightweight too

I like the lightweight aftermarket stuff from a technical standpoint, but I'm trying to keep the visible aspects of the car "stock" looking. Despite the fact that I've taken at least 400 pounds out of this car few people at the track or autocross give it a second glance. It still looks like most any stock early BB C3.

 

[TimAT]

I bet Jim Shea can tell you exactly what you need to do to get the pressure exactly where it needs to be.

 

[mrvette]

MY only comment is.....15 years ago before knowing anyone smart, I put a serp drive on my '72 stock L48 engine, and ran the stock p/s system with no sweat...using the stock L48/'72 pump valve...screwed in the whole assy and it worked....mainly because I wanted the flare fitting not that AN thing....

It is my understanding the older valve/flow device has reduced pressures/flows....

and with the rack conversion some years later, seems to work just fine for ME with road feel and overall assist feeling....

:shocking:

Gene,

You put a low pressure "assist cylinder/rack" pump on a rack application. Of course it will work.
My question is how do I tell if a pump is for a recirculating ball power steering box or for a rack and pinion setup. From everything I've heard the pressure levels are significantly different.

I bet Jim Shea can tell you exactly what you need to do to get the pressure exactly where it needs to be.

They designed the rack for say 1500? psi as I recall.....and so I run it at less pressure.....unless I'm not happy with the feel, how can it cause any harm??

now to pump 1500? psi to the old tired stock system....well, that's a bit much....obviously....

but like I said, I just stumbled along....not knowing about all these changes in flow and pressure requirements...never thought of it, honestly, but would have assumed that to steer any given car, no matter the type of system, the force on the wheels needs be X under load....and any left over is Y at the steering wheel....feeling heavy or light, either way....

'need to be' to ME, means enough to take the work out of it in a parking lot, but yet feel decent on the freeway....

and I know that's a touchy feely type judgment call.....

:beer:

 

[JIML82]

The only real problem is if you install a pump with high pressure relief (1200 to 1500 psi) in a Corvette with a production linkage booster type assist system. The special Corvette 1/4 inch ID power steering hoses were designed for only 1000 psi max (I am not sure about the rating for the control valve). So you definately want a low pressure pump (900 to 1000 psi) with the production C2/C3 power assist system.

Now if you install Borgeson intergral power gear or a rack and pinion system, you will be using special 3/8 inch ID power steering hoses that should be rated for higher pressures. From a durability standpoint, it is best to use the lowest pressure relief that still allows you to steer the car with the engine running, the brakes applied, car not moving, on a concrete surface.

With prototype and production GM cars and trucks we used to carefully run tests to determine the lowest flow and the lowest pressure that was needed to steer the car under the worst conditions. Cadillacs used to require 1500(or slightly higher) pressures. Other GM cars were in the 1200 to 1450 range.

With the pampered, low mileage, vintage cars, (but not C2/C3 Corvettes) it is not that big a deal to have somewhat higher pressure systems rather than completely optimized pressure and flows.

However, if you change from a lower flowing pump to a pump with very high flow, the feel of the steering could become lighter and too responsive. I know that this doesn't sound correct (but trust me). It is not the pressure relief of the pump that is dictating the amount of assist, it is the flow from the pump and the action, reaction of the valving to that flow that provides the feel in a power steering system.

BTW, in a comparison study that I did a couple years ago, I did not find that the hydraboost brake option required that the relief pressure of the power steering pump needed to be increased over just a production power steering system. So if your power steering is functioning properly, adding hydraboost brakes should not require higher pressures or flows.

Jim

 

[69427]

The only real problem is if you install a pump with high pressure relief (1200 to 1500 psi) in a Corvette with a production linkage booster type assist system. The special Corvette 1/4 inch ID power steering hoses were designed for only 1000 psi max (I am not sure about the rating for the control valve). So you definately want a low pressure pump (900 to 1000 psi) with the production C2/C3 power assist system.

Now if you install Borgeson intergral power gear or a rack and pinion system, you will be using special 3/8 inch ID power steering hoses that should be rated for higher pressures. From a durability standpoint, it is best to use the lowest pressure relief that still allows you to steer the car with the engine running, the brakes applied, car not moving, on a concrete surface.

With prototype and production GM cars and trucks we used to carefully run tests to determine the lowest flow and the lowest pressure that was needed to steer the car under the worst conditions. Cadillacs used to require 1500(or slightly higher) pressures. Other GM cars were in the 1200 to 1450 range.

With the pampered, low mileage, vintage cars, (but not C2/C3 Corvettes) it is not that big a deal to have somewhat higher pressure systems rather than completely optimized pressure and flows.

However, if you change from a lower flowing pump to a pump with very high flow, the feel of the steering could become lighter and too responsive. I know that this doesn't sound correct (but trust me). It is not the pressure relief of the pump that is dictating the amount of assist, it is the flow from the pump and the action, reaction of the valving to that flow that provides the feel in a power steering system.

BTW, in a comparison study that I did a couple years ago, I did not find that the hydraboost brake option required that the relief pressure of the power steering pump needed to be increased over just a production power steering system. So if your power steering is functioning properly, adding hydraboost brakes should not require higher pressures or flows.

Jim

I've got a C4 suspension (and rack) under the car. The stock C3 pump seems to work very well with this rack, but I'm just in a continuous search for lighter parts. Once I have an idea of whether this pump will work in this application, I can take the stock pump off and compare the weights of the two pumps.

So, I'm trying to figure out/learn some details about these pumps that lets me figure out what the initial application was or how to determine the pressure/flow rating of this pump.

 

[mrvette]

Hire a 100 lbs soaking wet chick to drive it....


:rofl::rofl::drink: set back and relax......:drink:

celebrate the victory over your lard assed buddies.....:drink::drink::rofl:

 

[JIML82]

If you know the year of the C3 pump I can tell you what the flows and pressures should be. That will provide a baseline. The bad news is that I have very limited information on later Saginaw pumps. Pressure relief can be determined by quickly dead heading the pump into a 1500/2000 psi pressure gauge. Although with your rack and pinion system, the normal 1450 psi pressure relief for most Saginaw pumps would be adequate. (As long as you can steer full lock to full lock with your Vette stopped, at idle, service brakes applied, on a concrete or asphalt surface.)

The trick is flow from the pump. Too much flow and your steering will feel light and too responsive. Too little flow and you will find it very difficult to make a slow speed evasive maneuver (i.e. whipping the wheel 180 degrees as if trying to avoid something that suddenly came out on the road in front of you.)

Jim

 

[69427]

If you know the year of the C3 pump I can tell you what the flows and pressures should be. That will provide a baseline. The bad news is that I have very limited information on later Saginaw pumps. Pressure relief can be determined by quickly dead heading the pump into a 1500/2000 psi pressure gauge. Although with your rack and pinion system, the normal 1450 psi pressure relief for most Saginaw pumps would be adequate. (As long as you can steer full lock to full lock with your Vette stopped, at idle, service brakes applied, on a concrete or asphalt surface.) As long as I can steer while the car is moving, I'm happy. I never steer the wheels unless the car is moving. There's just something about turning the wheels at zero speed that grosses me out.The trick is flow from the pump. Too much flow and your steering will feel light and too responsive. Too little flow and you will find it very difficult to make a slow speed evasive maneuver (i.e. whipping the wheel 180 degrees as if trying to avoid something that suddenly came out on the road in front of you.)

Jim

It's looking like building a fixture to spin the pump pulley and plumbing the pump output into a pressure gauge is my only option.

Regarding the present, stock ('69) C3 pump, the steering setup was a complete POS when I got the car. That car was incapable of traversing a chicane quickly as every time I would turn the wheel quickly the steering wheel would lock due to insufficient flow to the assist ram. A friend recommended a swap to a bigger orifice from a different pump, and bingo!, the car was actually fun to drive at autocrosses after that.

 

[mrvette]

If you know the year of the C3 pump I can tell you what the flows and pressures should be. That will provide a baseline. The bad news is that I have very limited information on later Saginaw pumps. Pressure relief can be determined by quickly dead heading the pump into a 1500/2000 psi pressure gauge. Although with your rack and pinion system, the normal 1450 psi pressure relief for most Saginaw pumps would be adequate. (As long as you can steer full lock to full lock with your Vette stopped, at idle, service brakes applied, on a concrete or asphalt surface.) As long as I can steer while the car is moving, I'm happy. I never steer the wheels unless the car is moving. There's just something about turning the wheels at zero speed that grosses me out.The trick is flow from the pump. Too much flow and your steering will feel light and too responsive. Too little flow and you will find it very difficult to make a slow speed evasive maneuver (i.e. whipping the wheel 180 degrees as if trying to avoid something that suddenly came out on the road in front of you.)

Jim

It's looking like building a fixture to spin the pump pulley and plumbing the pump output into a pressure gauge is my only option.

Regarding the present, stock ('69) C3 pump, the steering setup was a complete POS when I got the car. That car was incapable of traversing a chicane quickly as every time I would turn the wheel quickly the steering wheel would lock due to insufficient flow to the assist ram. A friend recommended a swap to a bigger orifice from a different pump, and bingo!, the car was actually fun to drive at autocrosses after that.

THAT and with all the suspension mods, I would like to get someone that does racing to drive it around a bit and see what they think, I have NO experience to say one way or another about the ultimate performance capabilities of this olde tyme roaming war chariot....:gurney:

 

[69427]

If you know the year of the C3 pump I can tell you what the flows and pressures should be. That will provide a baseline. The bad news is that I have very limited information on later Saginaw pumps. Pressure relief can be determined by quickly dead heading the pump into a 1500/2000 psi pressure gauge. Although with your rack and pinion system, the normal 1450 psi pressure relief for most Saginaw pumps would be adequate. (As long as you can steer full lock to full lock with your Vette stopped, at idle, service brakes applied, on a concrete or asphalt surface.) As long as I can steer while the car is moving, I'm happy. I never steer the wheels unless the car is moving. There's just something about turning the wheels at zero speed that grosses me out.The trick is flow from the pump. Too much flow and your steering will feel light and too responsive. Too little flow and you will find it very difficult to make a slow speed evasive maneuver (i.e. whipping the wheel 180 degrees as if trying to avoid something that suddenly came out on the road in front of you.)

Jim

It's looking like building a fixture to spin the pump pulley and plumbing the pump output into a pressure gauge is my only option.

Regarding the present, stock ('69) C3 pump, the steering setup was a complete POS when I got the car. That car was incapable of traversing a chicane quickly as every time I would turn the wheel quickly the steering wheel would lock due to insufficient flow to the assist ram. A friend recommended a swap to a bigger orifice from a different pump, and bingo!, the car was actually fun to drive at autocrosses after that.

THAT and with all the suspension mods, I would like to get someone that does racing to drive it around a bit and see what they think, I have NO experience to say one way or another about the ultimate performance capabilities of this olde tyme roaming war chariot....:gurney:

What????..

 

[mrvette]

If you know the year of the C3 pump I can tell you what the flows and pressures should be. That will provide a baseline. The bad news is that I have very limited information on later Saginaw pumps. Pressure relief can be determined by quickly dead heading the pump into a 1500/2000 psi pressure gauge. Although with your rack and pinion system, the normal 1450 psi pressure relief for most Saginaw pumps would be adequate. (As long as you can steer full lock to full lock with your Vette stopped, at idle, service brakes applied, on a concrete or asphalt surface.) As long as I can steer while the car is moving, I'm happy. I never steer the wheels unless the car is moving. There's just something about turning the wheels at zero speed that grosses me out.The trick is flow from the pump. Too much flow and your steering will feel light and too responsive. Too little flow and you will find it very difficult to make a slow speed evasive maneuver (i.e. whipping the wheel 180 degrees as if trying to avoid something that suddenly came out on the road in front of you.)

Jim

It's looking like building a fixture to spin the pump pulley and plumbing the pump output into a pressure gauge is my only option.

Regarding the present, stock ('69) C3 pump, the steering setup was a complete POS when I got the car. That car was incapable of traversing a chicane quickly as every time I would turn the wheel quickly the steering wheel would lock due to insufficient flow to the assist ram. A friend recommended a swap to a bigger orifice from a different pump, and bingo!, the car was actually fun to drive at autocrosses after that.

THAT and with all the suspension mods, I would like to get someone that does racing to drive it around a bit and see what they think, I have NO experience to say one way or another about the ultimate performance capabilities of this olde tyme roaming war chariot....:gurney:

What????..

What I was saying is that will all these mods over the years, in the chassis/suspension dept, I have NO standard of comparison....nothing to really GO on to factually critique my own car....no instruments, nothing but the seat of my pants...

and by NO means do I consider myself a well educated driver....just maybe slightly better than average found on the streets every day...

 

[69427]

If you know the year of the C3 pump I can tell you what the flows and pressures should be. That will provide a baseline. The bad news is that I have very limited information on later Saginaw pumps. Pressure relief can be determined by quickly dead heading the pump into a 1500/2000 psi pressure gauge. Although with your rack and pinion system, the normal 1450 psi pressure relief for most Saginaw pumps would be adequate. (As long as you can steer full lock to full lock with your Vette stopped, at idle, service brakes applied, on a concrete or asphalt surface.) As long as I can steer while the car is moving, I'm happy. I never steer the wheels unless the car is moving. There's just something about turning the wheels at zero speed that grosses me out.The trick is flow from the pump. Too much flow and your steering will feel light and too responsive. Too little flow and you will find it very difficult to make a slow speed evasive maneuver (i.e. whipping the wheel 180 degrees as if trying to avoid something that suddenly came out on the road in front of you.)

Jim

It's looking like building a fixture to spin the pump pulley and plumbing the pump output into a pressure gauge is my only option.

Regarding the present, stock ('69) C3 pump, the steering setup was a complete POS when I got the car. That car was incapable of traversing a chicane quickly as every time I would turn the wheel quickly the steering wheel would lock due to insufficient flow to the assist ram. A friend recommended a swap to a bigger orifice from a different pump, and bingo!, the car was actually fun to drive at autocrosses after that.

THAT and with all the suspension mods, I would like to get someone that does racing to drive it around a bit and see what they think, I have NO experience to say one way or another about the ultimate performance capabilities of this olde tyme roaming war chariot....:gurney:

What????..

What I was saying is that will all these mods over the years, in the chassis/suspension dept, I have NO standard of comparison....nothing to really GO on to factually critique my own car....no instruments, nothing but the seat of my pants...

and by NO means do I consider myself a well educated driver....just maybe slightly better than average found on the streets every day...

Gene, what does this have to do with the subject of this thread????

 

[mrvette]

It's looking like building a fixture to spin the pump pulley and plumbing the pump output into a pressure gauge is my only option.

Regarding the present, stock ('69) C3 pump, the steering setup was a complete POS when I got the car. That car was incapable of traversing a chicane quickly as every time I would turn the wheel quickly the steering wheel would lock due to insufficient flow to the assist ram. A friend recommended a swap to a bigger orifice from a different pump, and bingo!, the car was actually fun to drive at autocrosses after that.

THAT and with all the suspension mods, I would like to get someone that does racing to drive it around a bit and see what they think, I have NO experience to say one way or another about the ultimate performance capabilities of this olde tyme roaming war chariot....:gurney:

What????..

What I was saying is that will all these mods over the years, in the chassis/suspension dept, I have NO standard of comparison....nothing to really GO on to factually critique my own car....no instruments, nothing but the seat of my pants...

and by NO means do I consider myself a well educated driver....just maybe slightly better than average found on the streets every day...

Gene, what does this have to do with the subject of this thread????

Well we talking about reduced pressures, and feel for various combos of flow etc....and racks vs stock vs Jeep boxes, and my comment is reflecting on my wish for someone good to drive my car to give me honest feedback about it, that's all......seems ok to me, but that don't mean it's GOOD......

:gurney:

 

[69427]

I was perusing a local junkyard today looking at p/s pumps, and saw one in an old Grand Am. It has a plastic reservoir, and a single (lightweight) vee-belt pulley (compared to my stock heavy dual pulley). I think I'll stop back at the junkyard tomorrow and pick up the pump and compare the weight to my present C3 pump. I can use the time I was going to spend making a fixture to test the pressure of the other pump to test fit this one into the Corvette (assuming the weight difference makes the effort worthwhile.)