Power steering

[lessismore]

Has anyone test driven a SMART without power steering? I don't think I've ever driven a car without, so I don't know what it is like or if it makes much of a difference in such a small car.

[SmartBob]

Probably most of us. It drives real easy. Many plan to buy without it.

[robotbill]

I configured 26 Nov and decided not to get power steering I have no problem driving my'81 Alfa Spyder even when doing slow speed maneuvers. This car the Smart is smaller so I don't see a problem.

[CruisingAZ]

I am going to go to the dealer after the first of the year and drive one with and one without if they have them. With my higher number I should not have to confirm prior to January 1st.

[kmeinhold]

I drove the car without power steering, it takes very little effort. However the non-power steering smart takes more turns, lock-to-lock. IE - so when you go around the corner or park, you will have to turn the wheel a bit more.

I ordered the power steering - for an everyday commuter car, the least effort and closest to zen I could get was my goal. For fun I will take out the TR6 or the MGA

[Gortok]

Originally Posted by kmeinhold

However the non-power steering smart takes more turns, lock-to-lock.

Not true, according to some of the people who work on them...

[Old smart]

Originally Posted by Gortok

Not true, according to some of the people who work on them...

The ratio with non-P/S is 22:1, and with P/S, 21:1. So what does that mean? It isn't that they put 1/21th more teeth on the rack, or that the pinnion circumference is changed by 1/21th, to make steering easier - that is a stupid thought! But it does argue that there is some difference in the rack end-stops between non-P/S and P/S (probably more robust or cushioned on the P/S to accomodate the additional pinnion torque against them). And as a result, the turning circle of a P/S car will be 1/21th greater than a non-P/S (about 16").

[Gortok]

I'll see if I can find the link....

[Gortok]

http://www.clubsmartcar.ca/forums/vi...ght=pas#171126


BUT...I misunderstood what he had said...sorry.

Bob in Europe:

We made the PinPAS gear in the 450. I understand that Delphi makes the gears in the 451.

The best reason for having PAS is in parking assist; far as I know (but am not absolutely sure), the ratio is the same for both manual and power variants.

By the way, if you want to see if your 450 has the PinPAS gear, look in the driver's side front wheel arch along the front side of the axle and if you see something that looks like a silver soup can, then you have the feature... from inside the car, just try to turn the wheel, with one finger, from lock to lock when at a standstill... if one of your knuckles doesn't come out of joint, then you probably have the PAS option... finally, at least here in Europe, the ECU for the PinPAS is located on the dash panel forward of the battery sump and should have a label saying "MB Lenkung" or "Presta Steertec" on it...

Cheers, Bob


So...Maybe they are NOT the same.

[MicroNut]

Originally Posted by fishrdnc

The ratio with non-P/S is 22:1, and with P/S, 21:1. So what does that mean? It isn't that they put 1/21th more teeth on the rack, or that the pinnion circumference is changed by 1/21th, to make steering easier - that is a stupid thought! But it does argue that there is some difference in the rack end-stops between non-P/S and P/S (probably more robust or cushioned on the P/S to accomodate the additional pinnion torque against them). And as a result, the turning circle of a P/S car will be 1/21th greater than a non-P/S (about 16").

I hate to disagree, but, um, I disagree.

Steering ratio is defined as the ratio between turn of the steering wheel and resulting turn of the road wheel (actually the average turn of the left and right road wheels since the inside wheel typically turns more than the outside). A 21:1 ratio translates to 17.1 degrees of turn at the road wheel for one full turn of the steering wheel. A 22:1 ratio translates to 16.4 degrees. This means that for a given amount of steering wheel lock, a smart with EPS will transcribe a tighter circle than one without (i.e. the EPS steering is "quicker", if only a little).

Quicker steering can only be achieved by some difference in the steering gear. Changes to the end stops can affect the turning circle, but not the steering ratio. A difference in ratio can be achieve by means other than the number of teeth on the steering pinion (e.g. shorter steering arms would achieve the same result).

None of this explains why one would bother to engineer such a minor difference into the two systems. That part makes no sense to me...