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Permalink Reply by Jack Diehl on April 20, 2008 at 3:56pm

Thanks for your comment about keeping it below 4000 rpms during break-in. I've been feeling a little bad about the amount of highway miles I've put in already.....1000 miles total in less than 2 weeks....many of them highway. But most of those were around 70 mph.....3000 - 3400 rpms. I varied it a little, but not a lot. Runs great though. Hope it's breaking in ok. At 1000 miles, I'm thinking about changing the oil. hmmm. Maybe this afternoon. + Jack (new picture.....instead of me with the fish, my yellow smart with the black spokes)

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Permalink Reply by SATO on April 21, 2008 at 2:43pm

did not recognice you... nice rims by the way, did you clear coat them?

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Permalink Reply by SmartPassion on April 20, 2008 at 4:39pm

Pretty convinced it may be a tire tread design issue. This due to the way the tread slots into some freeways rain grooves.

Since the car is still under warranty, I suppose we can all go back to Penske and complain. :-P

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Permalink Reply by geosynch on April 20, 2008 at 6:50pm

I am sorry to be the bearer of bad news, but the squirminess you feel isn’t tires and it won’t be fixed by any vortex thingy.

The very thing that make the smart car so maneuverable makes it squirmy at speeds – the short wheelbase. Any smart owners out there who bought this car to do serious highway miles have two choices. Get used to it or sell the car. The smart was designed as a city car. That’s not to say you can’t take it on the highway, but you’ll never get the smart to be stable at high speeds until you lengthen the wheelbase.

Blame it on Isaac Newton.

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Permalink Reply by SATO on April 21, 2008 at 2:58pm

could any % be mitigated by less toe in?

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Permalink Reply by geosynch on April 21, 2008 at 3:25pm

Perhaps, but I couldn’t say with any certainty as vehicle stability is outside my area of expertise. If it does help you are treating the symptom and not the root cause. By lengthening and shortening the wheelbase you are trading off maneuverability for stability (in this context stability simply means the ability to track a straight line). This applies to everything from bicycles to buses; a unicycle is a lot more maneuverable than a tandem, but it is easier track a straight line on a tandem.

For disclosure, I’m a mechanical engineer by training, but I’ve made my career in spacecraft stability. Ask me anything you want about how to point a satellite and I can help you. I’m comfortable talking about basic vehicle dynamics, but a specific question like how much will toe-in affect tracking a straight line is simply out of my league.


Best,

Geosynch

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Permalink Reply by SATO on April 21, 2008 at 6:08pm

can then ANY satellite that you know of help in the Smarts tracking a straight line?? Sorry could not hel it. I know the wheel base issue and its obvios it cant be FIXED.. well not by us with a couple of spaners "wrenches". I wonder how racing go-karts differ in this. they share our principle of short wheel base too.

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Permalink Reply by geosynch on April 21, 2008 at 8:27pm

Hi SATO,

The go-kart analogy is a good one. Racing go-karts are capable of 100+ MPH quite easily. They will certainly be susceptible to the same problems.

Once you are tracking a straight line, you are going to keep tracking that line until something perturbs your motion. That’s Newton’s first law.

I’ve never experienced cross winds in my smart, but then again, out of 600 miles, only about 30 of them have been at speeds above 45 or so MPH. But cross winds are going to be one of the forces that will “perturb” your straight line. A brief overview of this thread confirms that has been the community’s experience.

Another thing that will perturb your straight line is the road surface. On my way from the smart dealer in San Jose, I found the expansion joints on the stretch of 280 between San Jose and Los Altos to have a downright nerve-wracking result on my smart at around 70 MPH. But other stretches of highway I’ve been on have been fine.

Back to the go-kart analogy, the surface they are racing on is supposedly smoother than the average interstate. And with such a low profile, the cross winds would probably have to be gale-force to have a detrimental affect. So while a go-kart is susceptible to the same problems, my guess is that in most cases, the average racer doesn’t experience what we’ve all experienced in the smart.

The bottom line is I love my smart and it is my daily driver. But I also bought it knowing I’d never drive the smart further than about a 50 mile radius from my house. I have other cars to use if I need to go further.

Best,

Geosynch

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Permalink Reply by Jack Diehl on April 21, 2008 at 10:35pm

I drove across Florida last week with a beastly cross wind, at speeds between 65 and 75 mph. I felt some wind 'buffeting', but never felt unnerved by it. In fact, in the past 2 weeks I've driven over 1000 miles and the majority of that has been 65-75 mph on the highway. Nice solid little ride....very German. No problem.

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Permalink Reply by smartster on April 21, 2008 at 9:07pm

ok, i think we solved the squirmyness issue...

I just installed our new brake kit, racing pads, driller rotors, ss brake lines and high grade fluid, while those probably didn't help we also installed our racing tires, which are ContiPreminumContact 2's and I went out to wear the tires in a little.

First off wow the new brake kit, damn stopping isn't an issue anymore, but on to the good stuff. After I had driven the tires in a little I went out on the test track which is a wide open area on top of a hill and gets a lot of crosswind. I've done this track several times and always the smart gets squirmy with the wind.

Today for the first time even while running at 100mph there was NO squirmyness, none, it was almost like a normal car and I was very impressed. The new brakes really couldn't have helped, but the new high grade tires with the right pressure did the trick.

Now the tires are wider then stock, 175/55 R15 on the front and 195/50 R15 on the rear, we didn't go up in wheel size as with the upgraded suspension and already stiff ride we wanted the tires to absorb as much as possible, plus I just love the 6 spoke wheel.

Previous to these tires we where using high performance winter tires, which obviously where too soft and the sidewalls a little too much give that resulted in that squirmyness even with wider tires. Sadly this isn't something you can do without buying a new set of wheels and tires, also might help to lower the car like I did as gives a lower balance and less flow of air under the car. I opted not to put the BRABUS front/sides on but maybe those will help as it will deflect the air up over and around the car better, so ya it should help, but I opted not to install them as prefer to keep the soft black rubber to protect against the evitable cross country track adventure.

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