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Power Steering Pump Output Pressure at Idle

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Old Mar 27, 2019 | 06:14 PM
  #1  
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From: Centennial, CO
Car: 1987 Trans Am
Engine: 355 Edel Int, SLP, Edel heders 8PSI
Transmission: T5
Axle/Gears: 3.45 Borg Warner
Power Steering Pump Output Pressure at Idle

Hello TGO friends! I looked around on here and not one post i found shows any info on the Saginaw power steering pump output at idle. I may be using the wrong keywords. OR if anyone knows of a TGO link to some previously discussed info. Upgraded to the type 2 pump and the steering is stiff and tries to turn itself. I have the Borgeson pressure reducing kit and cant figure if i need to reduce it to 1,000, 850, or 700 psi.
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Old Mar 28, 2019 | 08:47 AM
  #2  
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Re: Power Steering Pump Output Pressure at Idle

I'd give Turn One Steering a call and ask for Junior.

They balance all of our boxes and pumps for the UMI Performance test cars. Been very happy with their service and technical knowledge.

ramey
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Old Mar 28, 2019 | 09:05 AM
  #3  
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From: Centennial, CO
Car: 1987 Trans Am
Engine: 355 Edel Int, SLP, Edel heders 8PSI
Transmission: T5
Axle/Gears: 3.45 Borg Warner
Re: Power Steering Pump Output Pressure at Idle

Thank you Ramey for the info! Called him and the old Saginaw P pumps put out 1,100 PSI. The Type 2 pump puts out about 1,200-1,300 PSI. Junior believes i have a valving issue in my brand new steering box which i wouldn't doubt. But i hope these specs help someone for years to come.
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Old Mar 28, 2019 | 08:13 PM
  #4  
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From: Centennial, CO
Car: 1987 Trans Am
Engine: 355 Edel Int, SLP, Edel heders 8PSI
Transmission: T5
Axle/Gears: 3.45 Borg Warner
Re: Power Steering Pump Output Pressure at Idle


I am going to try 2 shims then ill report back
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Old Mar 30, 2019 | 04:44 PM
  #5  
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Re: Power Steering Pump Output Pressure at Idle

That pressure reading only occurs when the steering system is trying to turn the wheels against a totally immobile obstruction; i.e., at full lock.

The PS system is constant-volume. The pump circulates the same amount of fluid at all times. When sitting still and not trying to move the wheels, the fluid just circulates freely from the pump to the gear and back, and there's for all practical purposes ZERO pressure in it anywhere. Then as you turn the wheel and the system encounters resistance, the pressure rises, to the extent that there's resistance to turning the wheels to match the steering wheel. When you turn the steering wheel and the wheels haven't turned as far as you've told them to, there's a valve (spool valve) that its position changes, such that the pressure is raised on the side of the piston in the gear that it needs to push on to make the wheels match the steering wheel. The pressure only goes high enough to provide the necessary force on the piston.

Changing that regulator spring ONLY affects the MAXIMUM effort that the system will exert. It has NO EFFECT WHATSOEVER on the normal operation of the system.

GM systems aren't real picky about that. Most GM vehicles have anywhere from 1200 to 1400 psi at full lock. (full lock: steering wheel cranked all the way to one side as far as it will go and then the wheel held hard against the stop, to where the system makes that whistling kinda sound and slows the engine down and maybe even makes the belt slip a bit) At ALL OTHER times, it's irrelevant.

The pump is just a pump... a dumb blind illiterate thing that moves fluid and if the fluid encounters resistance, makes pressure. Kinda like, if you had a well for your house's water system with a pump that feeds it, the brand or whatever else of your pump, isn't gonna make a damn bit of difference to what comes out of your faucet, except if its limits are exceeded. And the brand or "rating" of the faucet similarly won't make a difference either. Your steering is a hydraulic system, the same as any other in those respects.

Because of how it works, the pressure in the assist system is near zero at idle and when no effort is required from it to move the wheels. I doubt changing that spring is going to fix your problem.

Last edited by sofakingdom; Mar 30, 2019 at 04:54 PM.
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Old Apr 28, 2019 | 11:27 PM
  #6  
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From: Centennial, CO
Car: 1987 Trans Am
Engine: 355 Edel Int, SLP, Edel heders 8PSI
Transmission: T5
Axle/Gears: 3.45 Borg Warner
Re: Power Steering Pump Output Pressure at Idle

Thank you for all the replies! It was a defective steering gear.
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