I don't like electric assist stearing.

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grinder wrote:


No, I'm sorry you are just wrong. Regardless of how you "select" them, if you increase the stiffness of the front sway bar you will increase the amount of understeer. If you decrease the stiffness of the rear sway bar you will increase the understeer. If you do both you will *really* increase the understeer.
You have it exactly backwards to what you want to do. For what you want (decrease understeer or introduce oversteer) you need to stiffen the rear and/or soften the front.
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-Fred W

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Whatever. I will turn it over to the engineers/technicians and tell them what I want to do.
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You'd be best to tell them what you *want* rather than what to do otherwise you'll end up with even more understeer and a ride like a truck.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

Not to worry. I will tell them "I know Dave!!!!" and my problems will be solved (or they will be bored to death). ;>)
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Maybe, but won't change the handling *balance*

Both of which will increase understeer. ;-)
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

I wasn't talking about balance. The added traction of soft sidewall tires will help reduce slip.

Only correct if incorrect sized roll bars are selected.
http://www.turnfast.com/tech_handling/handling_antiroll.shtml As we mentioned, the anti-roll bar helps increase the mechanical downforce of the outside tire during cornering. This increases the traction of that tire, and that end of the car (front or rear). An increase in traction at that end, may leave the opposite end with too little traction. An imbalance of traction occurs, and one end of the car will lose traction before the other end. If the front tires lose traction before the rear tires, the car will understeer. If the rear tires lose traction before the front tires, the car will oversteer. Changing the anti-roll bar stiffness can adjust this out.
According to Dinan engineering:
"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. "
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grinder wrote: <snip>

Yes. Stiffer front *and* rear bars will increase lateral transfer and reduce body roll. The adjustability can be used to change the balance of the car by making the front bar *relatively* less stiff than the rear one to decrease understeer.
JRE
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JRE wrote:

I do not think that last statement is correct. An adjustable bar allows you to tweak the tension from side to side on the same axle. It does not allow you to change the tension from front to rear because a) the bars are not tied together and b) nor are they fixed in position like a torsion bar (spring). The sway bar pivots in its bushings if the 2 wheels on that axle travel up and down together. It only applies cross force when one wheel moves up or down compared to the other wheel on that axle.
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Fred W wrote:

Think about the end effect. If you reduce the roll stiffness at the front through either replacement or adjustment of the front bar, you will decrease understeer. If you increase the roll stiffness at the rear you will also decrease understeer. But if you increase or decrease them both in proportion it will not change the balance of the car. It's the proportioning between the front and rear roll stiffness you're trying to manage, right? So if one installs stiffer bars front and rear and wants to decrease understeer, one must stiffen the rear one more than the front one...in other words the front has to be relatively softer than the rear at the end of the change.
JRE
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JRE wrote:

I agree with you 100%. You simply restated my case. None of which has anything to do with "adjustable roll bars". You cannot increase (or decrease) an adjustable bar's stiffness. You can only adjust how much gets applied left to right.
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At both ends. Resulting in the same understeer. It might improve the steering response, though.

I'm only commenting on what you've written. Increasing roll stiffness at the front increases understeer. As does reducing it at the back.

It's not for me you need to quote this. You need to read and try and understand it. ;-)

Actually just adding larger anti-roll bars is a bodge which will spoil the ride. Camber changes are a better way to set about it.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Sat, 17 Mar 2007 01:02:36 +0000 (GMT), "Dave Plowman (News)"

Maybe, but it depends on the car. The OEM tyre sidewalls for the NSX are stiff to the point of being damned near solid, but they have a soft compound tread rubber set in a bias pattern. With non-OEM tires (ObUS) on this car, there is a 'slingshot' delay effect in the handling which is really nasty. It's completely absent with the correct tyres. Obscure trivia, but I'm in an obscure mood tonight.
--
Dan.

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Could be. Most of the reports I've read when changing from OEM run flats to 'conventional' suggest comfort is the main gain.
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wrote:

Read the post from E Brown. Also when I went to conventional over ride flats on my Mini S the handling improved dramatically AND the noise difference was huge. It was like going from a go-cart to a limo.
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So the handling went from excellent to dreadful?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

I will make this as simple as I possibly can:
1. I replaced ride flat tires with conventional tires on my Mini S. 2. The handling improved dramatically. This includes a smoother ride that handled rough stretches better and cornering. 3. There was a huge reduction in noise. The noise reduction was comparable to going from a go-cart to a limo.
Hope this clears everything up for you and hopefully you can figure it out without pictures.
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London SW

Read the post from E Brown.
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Reread what Fred wrote because he's absolutely correct. *Your* proposed antiroll bar changes on the car will simply aggravate your problem. Hopefully, the sheer number of those of us pointing this out will convince you.
If, OTOH, you are a sworn Disciple of the Denizens of Dinan, give them the list of suggested changes above and ask them about it. I've met (actually, 'had dinner with') Steve and he's not an idiot. Although he'd love for you to buy a whole suspension package from him, I don't think he'd lie to you about the effect of those simple changes on understeer/oversteer. If you want a more tailored approach, you might contact my old pal, T.C. Kline, since he's done a lot with the Z4 in the past few years. You can tell him I sent you. -- C.R. Krieger (Knows they all understeer)
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Next time you have dinner with Steve ask him to clear up his web site which states: "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. "
You may also ask him to tell his engineers not to suggest roll bars to help reduce understeer.
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grinder wrote:

Dinan's website is doubtless correct. It's your interpretation that's wrong. Relatively stiffer front bars will increase understeer. Relatively less stiff front bars will decrease it.
Since nothing comes for free, decreasing the stiffness of the front bar by itself will also increase body roll.
JRE
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