BBX

Is it possible to get less effort steering by replacing the steering pump pulley with one of a different size?
I was just curious. I like light steering.

Mrmerlin

there might be a different size but you would need to go smaller to get a faster turn at idle and the pump pulley is already small.
\ Now if you were a machinist you might be able to fab up a bigger pulley for the crank

BBX

So speeding up the pump will result in less effort at the wheel?

GlenL

I don't think so. The pressure is set by a relief valve.

Consider that you want the lightest steering in a parking lot when the car is idling and the least at highway speeds. And that you don't want the assist level to change when the car shifts. If the boost was driven by just the speed of the pump it'd be all wrong.

Mrmerlin

if you add some throttle see what happens to your steering wheel effort

BBX

Oh oh oh... makes perfect sense!

BBX

/so there is also an assist level valve?

karl ruiter

I'll be interested to follow this. I also feel steering at low speeds could be a little lighter. My 944S2 is so much nicer in this regard, with the same size tires (I think). I had a p.s. rack apart years ago and I don't recall a pressure relief valve, but it was a long time ago. Could be in the pump, I suppose.

danglerb

I recall threads where people do something, swap some part, to make the steering effort higher or lower.

Make sure its working right before getting too far down the update path.

Tom in Austin

There are several things involved, including flow restrictors in the PS lines. I know the 91 and newer cars have a different PS pump that helps lower effort, but not sure anyone's make a definitive statement about the rack being different. I corresponded for a while with the Griffith (of Griffith's, a rack rebuilder) trying to get a clear statement about whether there's a 91-and-up rack and he said no.

Ralph Newman

The newer pumps, '91+, put out 100 bar of pressure which is higher. Griffith claims a 25% ease of streering. I just put one on and it does seem to streer easier. However, I increased my front tire width at the same time so it is a little hard to tell. Also, I am pretty sure that the pump pressure is controlled by an internal bypass valved so speed should make no difference unless it was turning very slowly.

mcholdfast

Installing a 91+ Porsche rack in my 89 GT made a huge difference in the required steering effort. I had also purchased the HO pump but decided not to install it because I was happy with the feel with just the rack swap. I think if you get an aftermarket rack for a 91+ car, you're going to get the same rack as the earlier models. You have to get the 91+ Porsche rack to make the difference. There's a difference in price too but if you plan to keep the car and drive it, it's worth it.

Tom in Austin

That's right Mike, the 91+ rack is hard to find, people mostly don't differentiate from prior MYs, even Griffith wouldn't say he could promise a given rack was 91+ or earlier.

BBX

Is there a casting in the rack to date it? How can you identify a 91+ rack?

BBX

And what made it different? internal gear ratio?