tquattro

questions from a novice autox'er!

I recently changed my non-sport (12mm) rear sway bar to a stock sport (15mm) bar. It's made a noticable difference both on the street and at autox events.

I know that if I upgrade the front to a sport bar that it will reduce roll and but may result in a little more understeer that my current setup.

What I was wondering is the effect that a stiffer front sway has on grip at autox events. Will the stiffer bar help any with grip and turn in or will it simply result in more understeer? I read somewhere (can't find link) that up to a point reducing roll can increase the tire's effective grip. Is that true?

Also can anyone direct me to a decent web site/book on suspension setup?

Thanks

Paul

squidix9

Stiffening the front will give you oversteer, cause the rear to get happier more quickly.

You can do that yourself choosing a lower gear, but ultimately you want the higher gear with a bit of oversteer "available" if you need it.

tquattro

19mm neuspeed rear bar on stiff = oversteer

From what I've read a stronger front bar equals understeer

General concensus is that the stock sport front bar is large enough. I've still got the non-sport front bar (29mm hollow) and am trying to decide if it's worth changing for autox...<ul><li><a href="http://www.se-r.net/car_info/suspension_tuning.html">linky</a></li></ul>

squidix9

Understeer = where the car pushes through the corner, usually accompanied by a lot of body lean.

Oversteer = the rear end is happy through the corner wanting to beat you to the exit, indicative of a very stiff suspension.

Adding sway bars front or rear, or changing spring rates/shocks will affect cornering.

You can achieve oversteer by doing a number of things; stiff rear bar/heavier front springs

In the attached link, I don't necessarily like how he dfines understeer. Once you lose grip the terminology essentially fails. It also depends on whether you are focusing on chassis dynamics or ultimately handling. A front bar will cause the front end to be flat around a corner, if you lose grip you will have understeer, however if the car is balanced you will actually gain oversteer. A lot depends too on taking the car a whole or talking about fornt and rear separately.<ul><li><a href="http://www.se-r.net/car_info/suspension_tuning.html#Understanding%20Vehicle%20D ynamics">Lookee here</a></li></ul>

tquattro

I'm using the non-sport front bar on by A4. The setup I have (RollControl springs, NeuBils and sport rear bar) is great for the street, but because the springs are still relatively soft, the car exhibits a lot of roll when cornering hard. You can just about see this on my crappy sig!

Based on what you are saying, if I was to upgrade the front bar, my run times may benefit from better balance due to less weight transfer / roll. Of course if I mess up and go in to a corner too-fast the end result is understeer

Thanks for the input. I'm relatively new to all this and unfortunately there are no experienced Audi drivers at the events I go to... I'm trying to change only one thing at a time so that as my driving improves I also can understand the effects of the changes I make.

squidix9

the most common mistake people make on cars is doing things piece by piece.

Adding one performance piece can actually do more harm than good unless you take care of the entire related system.

One of the most common is adding extra heavy duty sport type sruts to OEM springs. The stock springs are generally to soft for the stiffer struts and then people wnoder why they don't get what they xpected.

Your best bet is to go for a package, either from a supplier, or a complete setup that someone else has run and tested. This way you get struts/springs/bars that work together.

Check out the performance and marque forums, and do a search on springs or struts or bar

tquattro

I'm happy with my street setup. I did a lot of research to find a street setup. I guess that I'm looking more for a balance between a track and street car.

Unfortunately there seems to be a lot of information available on making a car go faster from an engine standpoint, but a lot less about tuning the overall handling of a vehicle.

RSTPerformanceRacing

On our road racing cars we have taken the front sway bar completely out... what we found is that with a front sway bar it will actuall lift the inside wheel (in a turn) thus that wheel has less grip (To keep the car from "rolling" it actually has to "lift" the inside wheel). When you try to accelerate it will spin due to the decreased grip.

A key thing to note is that this is in a FRONT WHEEL DRIVE Audi Coupe, and it is on a ROAD COURSE...

just wanted to give you all something to think about!!!

Raymond "Trying to keep both wheels on the ground" Blethen<ul><li><a href="http://www.rstperformance.com">RST Performance Racing</a></li></ul>

John/TSR

Always have removed (and thrown away) front bars in my FWD race cars. I've used front bars to 'balance' out a rear suspension in RWD race cars, but currently tend to run them really soft. In my current rear engined/RWD race car, I've got the front bar links dangling off the far ends, in 'stoopid soft' mode.

Bigger front bars just make the front end push, and screw up turn-in.