Run a smaller Power Steering pulley?

[Elliott]

If I drop from a 5 3/4" pulley on power steering to 4 1/2" am I likely to have any problems with my power steering or should this run fine and just require a different belt?
I'm working up some custom mounting for a high flow HB pump and this pulley fits some other dimensions I'd need.

[brent]

Originally Posted by Elliott

If I drop from a 5 3/4" pulley on power steering to 4 1/2" am I likely to have any problems with my power steering or should this run fine and just require a different belt?
I'm working up some custom mounting for a high flow HB pump and this pulley fits some other dimensions I'd need.

Basically it's like "will more revolutions create too much pressure in ps pump as well as return/pressure lines and box itself creating a situation where parts might wear out faster, etc?" Hope I got what you were saying.
Good question. I dont have a a clue, but hope you get some better answers ...
Call me retahded but the first thing that came to mind a few minutes after reading it is this: 50/50....I know the box and hi-pressure line could take it, but return line and pump sounds iffy...
...am always willing to be took to school on this site-- Brent

[Elliott]

Yeah, I figure it's gonna run faster, but in a basically lower rpm rig (for the most part) I'm hoping that will be ok. It's off a bad asp early Mustang that ran a saginaw pump so I'm kinda thinking the wear issue is going to be ok. I've got in a AGR pump, gonna have a quart size cooler/reservoir and the pump will be serving the HB, and a 2" steering assist ram.
This thing has the backspacing I need to run a modified low mount pump that I'm scratching together with a Cummins BT4 front GM pump bracket.
I'm kinda thinking there should be more torque on the pump with the smaller pulley, so I guess like you suggested I was basically wondering if there are going to be any wear issues or if the pump might aireate too much... do we really need a 5 3/4" pulley, and could this 4 1/2" pulley possibly be an advantage?

[brent]

Originally Posted by Elliott

Yeah, I figure it's gonna run faster, but in a basically lower rpm rig (for the most part) I'm hoping that will be ok. It's off a bad asp early Mustang that ran a saginaw pump so I'm kinda thinking the wear issue is going to be ok. I've got in a AGR pump, gonna have a quart size cooler/reservoir and the pump will be serving the HB, and a 2" steering assist ram.
This thing has the backspacing I need to run a modified low mount pump that I'm scratching together with a Cummins BT4 front GM pump bracket.
I'm kinda thinking there should be more torque on the pump with the smaller pulley, so I guess like you suggested I was basically wondering if there are going to be any wear issues or if the pump might aireate too much... do we really need a 5 3/4" pulley, and could this 4 1/2" pulley possibly be an advantage?

Nothing's changed, you need better answers than me...I stick by my conjectures for now...almost thinkin now if yr changing ps pump to larger (?) capacity that the aeration and wear could be negated due to volume of fluid divided by time...like breaking even or back to where you were.
OK, Im steppin out out of this now, I know there are scientific geniuses on this site..--Brent

[Serious Johnson]

More conjecture: I don't recall hearing of anyone having issues with these pumps on Chebbys spinning 7 grand.

S.J.

[jeepsr4ever]

Thats spinning about 25% faster. We have made lots of pullies at 5 1/4 for rockcrawlers. I havent seen anyone use such a small pulley on a driver but heck the pump spins that fast at a low rpm anyways. I say go for it.

[Rogue]

looks like your the crash test dummy on this one

IMHO slower is better

[Lindel]

It shouldn't hurt anything at all. The pump will spin faster at lower RPM's, and will give you a little boost in output.

[Rogue]

strictly theoretical i would say even though you've increased your capacity for fluid the inner diameter of the supply line would be your limiting factor as the pressure would be controlled by the pressure control valve. aeration would be my biggest concern not wear and tear of parts as you'd be pumping it out faster than it can come in. however at 25% as jeeps said i don't think you have nuthing to worry.

[475thFG]

I've never heard of it harming a PS pump to overspin it a little. I saw a tightwad-type guy in Bakersfield using a factory pump on a small block chebbie that turned 9 grand down the strip routinely. His words were "If it breaks, I'll fix it. Not like I need power steering going down a 1/4 mile drag strip, right? It ain't what I'd call catastrophic".

[drlocke]

I'd say put on the smaller pulley and relax and enjoy! Life's too short to fret over the small stuff! If it makes you more comfortable in your quest to protect a power-steering pump then lower the "redline" needle on your tach.....

Actually, after I've shot my mouth off here and made an [rectum] of myself: How much $$$ is a PS pump....?

[475thFG]

Originally Posted by drlocke

I'd say put on the smaller pulley and relax and enjoy! Life's too short to fret over the small stuff! If it makes you more comfortable in your quest to protect a power-steering pump then lower the "redline" needle on your tach.....

Actually, after I've shot my mouth off here and made an [rectum] of myself: How much $$$ is a PS pump....?

Not sure how much new, but you can buy 'em from a salvage yard all day for $20 or less. They're very rugged and almost never go bad. Never had one break that I can recall, though I've had them leak a few times.

[Elliott]

Thanks for the input guys... in the mean time I found a different front bracket that will provide me with more room for using a OEM single groove pulley... but if I find I want to ramp up my pump at low rpm in the future I may just swap one of these in. The 2" assist cylinder may actually need help at low rpm.

[brent]

So did you go from 5.75 to 4.5? Or whats the OEM single size? And how did you find the room despite new hb?
Brent---sucker for happy endings lately

[Elliott]

I was going to go from the OEM 5.75 to the 4.5, but I found a different front bracket that should allow me enough backspacing over the Cummings 4BT bracket that I have to let me run an OEM single groove. If I decide I need more low rpm umpf from the pump I may pick up a smaller pulley later.