Hi all, I have read and experienced (as I actually own one) the lightness of the 355 steering system. I have had the alignment reset not too long ago to more agressive specs, and though there was an improvement, the steering is still quite light. It doesn't really bother me as much as others, but the lightness is marked especially compared to a non-power steered car that I jump into and drive from time to time. The tech that did the alignment made a suggestion, and I thought I'd throw it into this forum. Has anybody tried changing the pulley size of the power steering pump on a 355? He mentions, and it made sense to me, that he has seen it done on other cars with the desired results. So, if we increased the pulley size of the pump to slow it down, do you think it will decrease the boost and result in heavier steering? Other than possible needing a longer belt, can this be done without having to take the engine out? Has anybody tried this? If this works, it seems like a relatively easy mod, as the new pulley can easily be fabricated and installed once the appropriate diameter is determined. Or is it possible perhaps to even disconnect the power steering pump without affecting other systems? Thanks for any input. Regards, Alex
Power steering systems all have a pressure regulator built in to keep the pressure more or less constant over the pumps anticipated operating RPM. If you change the pulley size it will make slow RPM effort higher but high RPM will remain the same, which if anything is the opposite to what you want. The Challenge cars had a different pump which differed in one way only. The pressure regulator was built for a different (lower) pressure. The entire pump was expensive but I would be looking towards a way to making a valve adjustment. That is a method used by Detroit all the time. Cads, Firebird Trans Am's and Corvette's all used the same pumps with a different regulator set up.
In the Hot Rod community there's alot of steering swapping going on with different manufactures pumps being used with different manufactures steering assembly. As a resulut, some steering has way to much pressure causing waaaay to light steering. A company called Heidts has designed a valve to bypass some of that pressure so the systems are no longer overboosted and brings the effort back to a normal feel. It also compensates for engine speed. Perhaps this same valve can be used to help increase the effort? After all it's a simple bypass valve and works in line with the hoses and is adjustable and fail safe. It's cheap (about $80) and very easy to install. Here's their web page: http://www.heidts.com/heip27.htm#power Article on using: http://www.heidts.com/images/art2.pdf Article on installing. http://www.heidts.com/images/art1.pdf JD
Thanks, Brian, Jeff. Interesting stuff. Sounds like someone who has a knack for experimentation can try this valve to see if it works on our cars. I am thinking that it should, the principle is the same with all power steering systems. It should also be easily reversible if the desired effect wasn't achieved. Looks like a perfect job for you, Jeff. The coil-on-plug conversion you did is quite a bit more complex than this. <G> Regards, Alex
You can also increase caster angle to maximum using the front ball joint shims, and further to this, you can fit a Challenge quick rack.
In reply to your last question, yes, it should be possible to disconnect your power steering. These systems pretty much have to be designed so that if they fail that you still have manual steering (which on the F355 should be markedly similar to normal 348 driving). I'd think that a 10 minute job to remove the power steering belt would let you try a safe parking lot drive experiment to verify the above. I'd think that taking off the power steering pulley from a 355 or Mondial would give you the 348's manual steering.
Not entirely 100% sure here,but non power steering cars usually have a different steering rack/box ratio. You will find on normal cars,if you remove the powersteering belt,the steering will be alot heavier than a non-powersteering car of the same model. As i said,im not sure if ferrari do the same with their racks?
yeah great...that changes it from 3.75 turns lock to lock to 3.5. I couldn't even tell the difference, quite frankly.
doesn't the assistance vary with rpm/speed? i thought i remembered reading that somewhere. certainly feels heavier to me on the track at constant high revs and speed...or it could be my imagination.
Thats where the powersteering pressure switch helps PP. At high speed,in most cars with a pressure switch fitted,the switch reduces flow/fluid into the steering rack,giving the steering a heavier feel at higher road speeds/rpm. Powersteering pumps are constant flow pumps,and flow always increases with rpm. Flow needs to be reduced because it can be dangerous at higher road speeds when the steering becomes too "light". Apparently?
well...that explains that, then! i actually quite like the light steering at low speeds, and have always found good feel at high speed. Maybe I'm just used to it. I have a 2:1 steering quickener...I must fit that one day. I think it would be terrific.
I thought there was a factory delete option on the 355 power steering. My manual has different caster settings for the alignment depending on whether there is power steering or not. There is no mention of different equipment. I wonder if it is just that simple? I am a complete novice, but I thought I understood that increased caster would improve your steering feel and stability but would increase steering effort. So you can run more with power steering and (in theory) get better feel and stability while having a lighter overall feel. Having reduced the boost on my Audi (can be done with one of 3 plug-in relays) I am not convinced that it has any effect on the actual steering feedback or "feel". I think it may just be easier to modulate input with a little more resistance. I like it better, but I am not sure it is really any more communicative, just heavier (Audi's are known for uncommunicative steering).
