I have always wondered about people slowing down the pump speed to "desensitize" their steering as that would suggest that the pump pressure is speed sensitive and if that were the case, then wouldn't the car be nearly impossible to steer at an idle?

 

What is over boost?

It's another one of the myths that has been repeated so many times everybody thinks it must be true.
Drive a wooden stake in it's heart and kill it.

 

I used the 80's F150 pulley 5Z-A1A to make my power steering less one finger to turn and it worked great!

 

Okay, I'll bite... over-boosted to me is when it's TOO easy to steer the vehicle. My Acura TL and Suburban do not have this feel. There's just the right amount of 'road feel' and resistance as you turn the wheel. Now, when I drive my in-laws 10 year old Navigator, the steering is too easy and feels loose. You can quite literally turn the wheel at any speed with your pinky finger! I don't like driving it and I don't feel the road at all.

My car is still under construction, but I did pick up one of those larger pulley's that NailBender references just above. Many here on the forum are using this. When I sent all my PS stuff to Chock, I also sent him the new pulley and asked him to put it on, which he did. Thank you @CHOCK !

Bottom line: People here talk about the stock PS system feeling over-boosted. So I'm hoping that on my first drive, that new pulley makes my car feel more like my Acura and not like my in-law's Navigator

 

My 67 steering with standard pump & pulley became heavier after increasing the castor to about 5.5°. Or the increased return-to-centre made it feel heavier? Anyway, it feels better than the previous 0° caster setting.

 

I went out to see if I could change my power steering pulley to make it steer easier........ Hmmmmmm.

 

As Al would say "I don't think so Tim"

 

I dropped a '66 Mustang 289 complete with the stock p/s into a '40 Ford Sedan and used a power rack and pinion from a T-Bird fabbing hoses to connect them together. The steering was crazy fast in the sense that it only took about 3 full turns lock to lock! It was like driving a go cart when cornering- 2/3 a turn of the wheel and you were going around the corner already. Not really over-boosted per say, but a gearing issue that could be misconstrued as such...

 

i thought pumps had some sort of relief valve where it bleeds off any over pressure

 

In line restrictors in the pressure hose end

 

Mismatched pressure supply to the rack or box could certainly cause an "0verboosted" problem, but the subject here is the pulley size directly changing the pump pressure. If that were so, then at hi rpms the car would be uncontrollable and at idle you would have no assist. Clearly that is not the case.
And why would trucks use a bigger pulley, to control hi rpm pressure? More likely to have more pulley surface area and less chance of slippage due to trucks having more stress against the system would be my guess.

 

Good point. The differences go way back to the 6 cylinder cars with 4" plulley (Low reving engne) to the small block cars with 4 1/2", to the 351 cars with 4 5/8" cars etc, to the high revving Hi Po Cars with much larger pulley shat slowed the pump rpm. The Diameter was not for pressure regulation, Pulley diameter was to not over drive the internals of the pump, destroy the cam pack, throw out the slippers.

 

I'm sensing some serious big pulley negativity. The big pulley worked great in my car but the Ford pump couldn't handle 6400 rpm and would lock up and kill the belt. I found a solution. 6" pulley BTW.

 

I'm sensing some serious big pulley negativity. The big pulley worked great in my car but the Ford pump couldn't handle 6400 rpm and would lock up and kill the belt. I found a solution. 6" pulley BTW.
View attachment 902198

I think that is the point exactly, you didn't change it to desensitize the steering but rather to slow down the pump rpm to keep it from "throwin' a rod"...

 

I’m not an engineer…whew😜…this is what I have determined.

I have factory power steering and have 235/40/18 with Arning/Shelby relocation.

Previously had 235/60/14 at stock control arm location.

Both have been responsive to steering input, as it should with the hydraulic assist. The whole point of the system.

If steering is twitchy, alignment needs to be “modernized”. I have used performance settings that were commonly found in catalogs and magazines back in the 90’s.

The only correct way to reduce this “over boost” is to have the maximum system pressure limited to a lower value.

A larger pulley is slightly increasing the RPM at which the pump will relieve itself…”bypass.”

A lower tension spring or “shims” would allow the normal operating pressure to be lesser…”less boost.”

I looked at this on my foxbody power steering pump used with my factory power steering.

The factory foxbody pump has a screen/spring/check ball/plunger assembly that must be pressed together to predetermine system pressure.

Don’t know if I am correct about the part.

 

I am guilty of using the over-boost moniker when in reality it was the one finger steer I did not like. The 6.25 inch pulley replacement did help to get closer to a one hand steer.

 

My issues with the steering being too easy were partly my fault. I put a roller bearing idler arm kit on my car some time back and then I removed it and went back to the OEM bushing. Two things helped matters...polyurethane PS ram bushings and more caster. Indirectly. larger tires helped too. Less negative camber probably helped also...more tire contact. It feels better now and I like to get some resistance when I turn especially at high speeds.

 

Before I went to manual steering on my 70 coupe, I was going to install this heidts pressure adjuster into the system. I didn't like the 1-finger feeling of the steering system. It allows pressure to bypass into the return side reducing the pressure reaching the valve/ram thus "de-sensitizing" the power assist. Its fully adjustable, I really like the concept. Never did try it though, I like the manual steering.

ADJUSTABLE POWER STEERING VALVE (PS-101) - HEIDTS

Tune your power steering with our Adjustable Power Steering Valve. It allows you to set or tune the feel of your power steering with just the turn of a knob. WARNING: This product can expose you to chemicals including nickel and urethane, which are known to the State of California to cause...

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