I don't like electric assist stearing.

Yes. The car understeers. But your complaint was the electric assist. Know how I know this to be true? Read the subject line (above) that you entered.

My rear engined '65 Corvair could be set up to oversteer by changing the stock 15F, 27R tire pressures to about 30F, 30R. Of course, a 10 mph side wind would then blow the car off the road at any speed over 35 mph, but when you're young and adventurous...

You're right - Grinder needs to get out more. Just about every Road & Track BMW test indicates "mild" as opposed to "moderate" or "heavy" understeer and usually describes BMW steering as excellent.

Tom K.

You're right - I was wrong. Unfortunately unlike many members in this group I recognized a flaw in the Z4's handling and attributed it to the electrical assist steering. I should have attributed to the design of the suspension.

In any case. The understeer is still present regardless of the source.

You're right. I was wrong to attribute it to electrical assist steering.

That should make you feel better.

Unfortunately the understeer is still there regardless of the source.

It's a matter of degree. I have not found any articles referring to understeer in Boxsters or the Toyota 2000 but have countless on the topic for Z4s.

And you are wrong. I have looked for Articles on this. Truth of the matter is you are grouping "most cars" when the topic at hand is a handful of sports cars.

The problem is you are looking at ALL BMWs. I am concentrating on the Z4. It's unfortunate Homers are unable to recognize understeer much less too afraid to put a car into that type of situation.

Try google - 18000 hits on Z4 and understeer.

Took me less than 2 minutes to find (by the way, nobody referred to as the understeer as an excellent attribute).

"This sensory satellite delay does little to bring you in phase with the Z4's responses, and combined with the numb electrically-assisted (a first for a BMW), non-linear steering and the chassis' tendency towards steady-state understeer, it's no wonder things can feel slightly out of kilter when you're pressing on."

"Sadly, when we pitched it against the Porsche Cayman S (097), it revealed a propensity for understeer and a confidence-denting sense of disunity between the front and rear ends. "

"Out on the fabulous Jerez circuit, the dull steering doesn't really dent your progress, but the Z4 M's quite pronounced understeer does. "

"Basically, it is tuned to be an inherent understeerer. Always understeer, understeer and understeer. Whenever you push it harder and faster, understeer will get into the picture. The harder it corners, the more understeer it shows. Now we don't know why BMW needs rear-wheel-drive and an engine locating behind the front axle to create an understeerer. "

"grinder" wrote

I may have been confusing rec.autos.driving postings with postings here - I've certainly seen many postings on this matter.

However, you are wrong if you think that a Boxster (my wife has one) does not understeer - at least for initial and middling responses. My NSX understeered. Modern Porsche 911's are tuned for understeer - although if you go to the limit it oversteers. My statement stands that all cars (including BMWs) understeer.

FloydR

OK, sorry to be redundant.

So... now we get to the crux of the matter. The car exhibits more understeer than you'd like.

How to reduce understeer (or induce oversteer if taken far enough):

Increase front tire pressure Decrease Rear tire pressure Shave Front tires (decrease tread depth) Wider Front Tires Narrower Rear Tires Make Front Camber more Negative Make Front Caster more Positive Reduce Front Toe-in Softer front swap bar Stiffer rear sway Bar Soften front springs Stiffen rear springs Softer front shocks Stiffer rear shocks

So you see... you aren't exactly stuck with the handling you have right now.

Many BMWs come with staggered tires. Get rid of that as a first step. Put the same size tire and wheel on both axles and you may find things are much more "balanced" right there. Of course it won't look like a dragster anymore... C'est la vie.

Modern ones yes - and rightly so for safety in extremis. But it's not so long ago the semi trailing arm equipped ones like the E28 etc could oversteer pretty easily and bite the unwary.

The very first BMW I drove was a 525 auto - the one before the E28 - and lost it at a pretty low speed on a wet roundabout. No harm was done and I caught it before it spun, but it surprised me - my car was a considerably more powerful auto and would have taken the same treatment easily. But then it had a De Dion rear axle.

Indeed. I had an E12 530i and it was that way. We also had an E21 320i that we lost in a ditch spinning just like that.

FloydR

Well that's peculiar. My Google search for "boxster understeer" turned up 14,800 articles. Many mention how *all* cars these days are set up to understeer. For Z4 understeer, the most common fix I've seen is adding an extra degree of negative camber, iirc. I think there's a DIY for this on

Seems like grinder now justs want to complain. As someone else wrote you're not stuck with the set-up you have - you can change it. Contrary to popular opinion BMW do NOT always produce car with everything being at the best it can be. What's best for BMW isn't always what's best for the driver. I can a bit tired when people say "BMW know what they're doing leave things alone".

What annoys me is when 'they' take a car on a track and criticise the outright handling. The design of a track car has little to do with a road one - especially if that road one is more of a fast tourer than out and out sports car.

I can't do anything better than that. Mine turned up over 18,000.

Many mention how *all* cars these days are

That is like saying all tires provide traction. Your statement is true but there is a matter of degree. "It is common practice among automobile manufacturers to configure production cars deliberately to have a slight linear range understeer by default. If a car understeers slightly, it tends to be more stable (within the realms of a driver of average ability) if a violent change of direction occurs, improving safety."

I own a Mini S and a Z4. There are situations where the Mini is glued where the Z4 slips.

How much a car understeers can be measured in the number of degrees more the steering wheel have to be turned per G of lateral acceleration. Here are the measured linear range values for some cars. The higher the number the more the car understeers.

Nissan 350Z 19 Mazda MX-5 21 Nissan 350Z Roadster 21 Ford Mustang GT 22 Renault Megane Sport 22 Maserati Gran Sport 23 Mini Cooper S 23 BMW 330i 25 Alfa Romeo 147 GTA 27 Corvette C6 27 Corvette Z06 28 Lotus Elise 111R 28 Porsche 997 Carrera S 28 Saab 9-3 Aero combi 28 Å koda Octavia RS 28 Porsche 997 Carrera 29 Porsche Cayman S 29 VW Golf GTI 29 Porsche 987 Boxter S 31 BMW M6 32 Range Rover Sport Supertech 32 Ford Focus ST 33 Mitsubishi Lancer EVO8 34 Porsche 968CS 34 Audi RS4 35 BMW M5 35 BMW Z4 Roadster M 35 BMW M3 Comp Package 36 Opel Astra OPC 36 BMW Z4 3.0i 37 Subaru Impreza WRX STi 37 Subaru Legacy 3.0 aut 38 Volvo V70 T5 39 Audi A4 2.0 T Q 41 Mercedes E55 AMG 42 Audi A4 V6 3.2 Q Avant 43 Porsche Cayenne Turbo 45 Smart ForFour Brabus 45 Mercedes SLK 350 47 TVR Tuscan 49 Alfa Romeo 159 2.2 JTS 51 Morgan Roadster V6 71

I experienced serious understeer on an off ramp from 280 merging on 92 in Half Moon Bay. It was not on a track.

Actually my first step will be to change tires away from run flats. The softer sidewall will provide better traction. The second choice will be to put a STIFFER roll bar (25mm) on the front AND a softer (22mm) on the rear.

I'd love to hear how this works out for you. Please post again once you've done this. epbrown

It will be a while. I will change tires first to see how that works. If the understeer is still more pronounced than I would like, I will put on the roll bars. BTW, I will purchase the M5 mobility kit and stick it into the trunk after the tires are changed.

I spoke with the DINAN engineers and the wanted to upgrade to the Stage 2 suspension which I cannot afford right now. Their second choice was to add roll bars which "adds larger and adjustable front and rear anti-roll bars to reduce body roll for superior handling. The adjustable anti-roll bars provide the ability to fine-tune the system for closer to neutral balance reducing understeer. "

CLOSER to neutral balance is what I want. The tire changes should also improve traction.

If you do, it will increase the understeer.