How to get AC in my Smart!!!!

[brian r]

Originally Posted by redbluff

Not an engineer but go drive a Pure and you will certainly see the difference. I was so shocked that I called the dealer and asked. Maybe someone better than me can explain it but you dont feel the hard hits and bumps. I am not exaggerating. It is so much better that I drive the Pure and not the Passion.

Two reasons.

When road imperfections are hit by a wheel, the road does not move and transfers the energy of the impact to the tire and wheel. This energy is then transfered to the suspension, which is absorbed by the spring and shock combination. Any remaining energy is transfered to the chassis. Energy is transfered here as momentum (p), which is created by the mass of the wheel (m) moving at a given velocity (v). This is Newton's Second Law: p = m x v


The steel wheel is heavier, so it creates a higher momentum than the ally one would in any given suspension cycle. Since the energy applied to the suspension is greater with a steel wheel, the suspension moves deeper into it's range of travel, and is able to absorb more energy, so in theory less is transfered to the frame of the car. This is perceived as a smoother ride.

The other difference is in the absorption characteristics of the wheel itself. The alloy wheel is stiffer than the steel wheel (it has a higher shear coefficient). This makes it a lot more resistant to bending when you hit a pothole, but it also results in a more instantaneous transfer of energy through the wheel. When the steel wheel hits a bump, some of the energy transfered by the tire is absorbed by the wheel flexing. If you hit a big enough bump, the steel wheel will bend before the alloy one will, because it's softer and absorbs more energy.

Since the mass of the wheel is independent (in simple equations) from its shear coefficient, these two events are independent, but contribute to a better ride.

[Westfield 11]

Actually many times the steel wheel is lighter than the alloy wheel. Has anyone ever weighed the two smart wheels and gotten actual facts for this discussion?

Racing only, ie. Non-DOT approved wheels are lighter than stock steel wheels in many cases, but then they have no safety margin for potholes and other road hazards not found on the track. Factory alloy wheels have a definate styling advantage over the usual steelie on offer as standard equipment, but a performance advantage? I doubt it unless there is a size/width difference in which case the comparison is not valid.

Also I question the premise that an aluminum wheel is stiffer and better resists bending than a steel wheel. This directly contradicts my experience with wheels and potholes over the last 30 years. I have worked with various aluminum alloys in my aviation career as well as teaching aluminum sheetmetal structures to aircraft techincians for 5 years. The shear strength of aluminum is below that of steel in every case I have seen or studied, have I missed something? Even the hardest and most brittle of the alloys, the 7000 series has a lower shear strength than even mild steel.

[astuto]

Originally Posted by wrumbarger

I work at the Tyson's VA dealer,

We had an orphan pure that came without AC.

We wanted to add it (cause no one wanted to buiy it without?)

Our mechanics wouldn't touch it.
They said they would literally have to strip the car down and rebuild with the AC. Too much time and trouble and the labor would cost more than the parts.

I was probably one of the people who turned it down. Did you ever sell it? I have a son who lives in New Hampshire who needs a new car and it doesn't have to have a/c. Make me a deal

[Westfield 11]

Originally Posted by brian r

If you hit a big enough bump, the steel wheel will bend before the alloy one will, because it's softer and absorbs more energy.

I am sorry Brian, but IMHO that is just plain wrong: for an equal cross sectional area the alloy wheel is lighter and softer.

[Smartdavis]

How did this thread go from AC to wheels? Surely the AC units are modular and can be installed later? That's what a Smart tech told me once.

[mdfortwoguy]

Originally Posted by Springlering

And yes, I know, it would only have been a few bucks to get a new motor, but it was the whole principle of the dang thing burning out the day after the warranty expired!!! I never replaced it just for the simple fact it made me so mad every time I thought about it.

Did you take it to the dealer and attempt to get them to goodwill the repair, since it was 1 day out of warranty? Sometimes, they'll split the cost with you or take care of it all...

[mdfortwoguy]

Originally Posted by Smartdavis

Surely the AC units are modular and can be installed later? That's what a Smart tech told me once.

Different HVAC head units, probably different HVAC blend units (no A/C means no recirculate function), adding the condenser up front as well as running the lines for refrigerant. Perhaps a different fan for A/C versus non-A/C models, install the compressor, which most likely involves dropping the subframe, add in refrigerant costs, the labor (I'd love to see the book rate on this), who knows how complete the wiring is... etc. Then, it's covered by 12/12,000 warranty only, and your car has been torn apart, God knows what else broken, who knows what rattles will start and when... etc.

It's not a plug-and-play system in the least...