DS Autocross Mods

[Golin]

Alright,

So I did a T&T this past weekend, and finished second in the Tire class. Beat everything excpet an FSP Honda Civic.

Anyway, I'm looking ot do some mods that will help improve the little things in the MS3 without bumping the car into the Street Tuner classes.

I was looking at just doing the front bar, as I believe that's allowed by the SCCA rules, but wasn't sure how much that would net me overall for the cost.

So throw your ideas out there. I know the stock classes are fairly tightly drawn, but still looking for an edge.

 

[Moonpie.Express]

You talking the front swaybar?
COBB, Hotchkiss, Autoexe...just to name a few.

 

[Kosh]

This list I believe is current for stock classes

Appearance, comfort and convenience options, e. g. gauges, alarms, turbo timers, shift knobs.
Removal of spare tire, tools and jack.
Harness (seat belts cannot be removed), must be DOT approved.
Any DOT approved tires (see rules for restrictions), including R-compounds, of any size (no modification of fender well, no rolling fenders, removing liners, tires cant rub a hole into the liner either).
Wheels (stock size only, offset within 0.25"/6mm of stock).
Wheel spacers (resulting offset within 0.25"/6mm of stock).
Lug nuts.
Brake pads, speed bleeders.
Shocks that maintain stock ride height, can be adjustable. See rule book for details!
Front sway bar.
Different alignment using factory adjustments (no camber bolts).
Spark plugs.
Air filter element can be removed or replaced.
Cat-back exhaust.

 

[Golin]

Right,

I know that there are some bars available, and I'm aware of what the permissible modifications are.

I was more curious as to whether anyone had tried any, and if they have, if they're worth anything.

I.E., is it worthwhile to do just a front bar for AX, or is it not worth it.

Basically I'm looking for suggestions on what has worked within the confines of which modifications are allowed for DS.

 

[Kosh]

Front bar in FWD = more understeer and wheel spin under acceleration but more lateral grip when corner-entry oversteering

 

[Breezy]

Why not try softening the front bar, either thru softer mounts if possible, or loosening the end links. Less wheelspin, more grip, but less responsive. These cars are almost too responsive out of the box anyways.

 

[Golin]

Kosh,

What is this corner entry over steer you're talking about? I grew up driving VW Beetles (the old ones) so I'm used to oversteer, but not from FWD. Do you set up oversteer with tire pressures or is it just a different driving technique I need to learn.

 

[Kosh]

When you brake and go into a turn you are transfering weight from the back of the car to the front of the car. Less weight in the back and the car has less holding it to the ground. This causes the back end of the car to rotate and can even lift the inside rear wheel off the ground. When the back end rotates it is also called lift-throttle oversteer or snap oversteer.

If you have a stiffer front swaybar when your rear inside wheel tries to lift off the ground the front end doesn't flex as much. It makes the front springs compress more and also compress more evenly.

 

[TurboWagon]

When you brake and go into a turn you are transfering weight from the back of the car to the front of the car. Less weight in the back and the car has less holding it to the ground. This causes the back end of the car to rotate and can even lift the inside rear wheel off the ground. When the back end rotates it is also called lift-throttle oversteer or snap oversteer.

see MkI&II Rabbits/GTI's, and Sentra SE-R in the dictionary.

But seriously, that pretty much sums up entry oversteer. It is possible with pretty much any FWD car however but easier for those with shorter wheelbases. I have yet to take the MS3 out yet but my MkIII GTI would definitely get up on 3 wheels around the track (im sure the front-heavy VR6 helped a bit too...)

Great definition btw.

 

[sleeper3]

when I was racing, you had to leave the spare tire in. weird.

 

[tsunami]

moved to suspension subforum for further discussion

 

[Golin]

Is there a particular way to initiate the oversteer with technique? Like I said before, I've really only driven RWD at speed, and most were rear engined as well. I'm curious to see what kind of modifications to technique I need to get the back end around, other than taking as much weightout of the back as possible.

 

[sleeper3]

taking weight out of the back won't necessarily create oversteer situations. it's more about weight transfer. I'm not 100% sure how to do it in a front wheel drive car, but in my 350z, I'd break, steer, and nail the gas while turning the wheel back in the other direction. the rear end would come so far out it was scary. and awesome. but scary.


















but really awesome and fun.

 

[major error]

+1

I've only been able to get the rear end loose once, and it wasn't the greatest feeling in the world...
I was more concerned with not spinning out, but I'm fairly certain it was off-throttle, snap oversteer (in the middle of a slalom on a slight grade.)

The biggest bang-for-the-buck improvement you can make is tires. After that, you need to tune the loose nut behind the wheel.

 

[Kosh]

Is there a particular way to initiate the oversteer with technique? Like I said before, I've really only driven RWD at speed, and most were rear engined as well. I'm curious to see what kind of modifications to technique I need to get the back end around, other than taking as much weightout of the back as possible.

There is a fancy term for what you do but I can't remember what it is called now. Lets say you are going into a left turn hairpin. Before you turn the wheel to the left you turn it to the right then back to the left. It sets the weight off balance and will cause you to rotate the back end more than if you just turned left after the straight.

 

[major error]

I heard that referred to as "The Swedish Flick" (from the days of watching WRC on Speed...)

 

[Golin]

Ah, so that technique is much like what the World of Outlaws guys do, except the opposite directions. Right first then left as opposed to left first, then right.

 

[jp4130]

Why not try softening the front bar, either thru softer mounts if possible, or loosening the end links. Less wheelspin, more grip, but less responsive. These cars are almost too responsive out of the box anyways.

"Too responsive." lol.

Kosh,

What is this corner entry over steer you're talking about? I grew up driving VW Beetles (the old ones) so I'm used to oversteer, but not from FWD. Do you set up oversteer with tire pressures or is it just a different driving technique I need to learn.

You can change the balanace of your car dramaticly with tire pressure. Try putting 38 front 31 rear. The front tire will have a stiffer sidewall to support the contact patch, while the back tire will flex under load distorting it's contact patch, this will help to get rid of understeer. Try these settings, as starting point. then adjust one end a a time to get the balance you want. The amount you can change things with tire pressure alone is amazing. Post up your results if you try this.

(drive2)

 

[Kosh]

"Too responsive." lol.



You can change the balanace of your car dramaticly with tire pressure. Try putting 38 front 31 rear. The front tire will have a stiffer sidewall to support the contact patch, while the back tire will flex under load distorting it's contact patch, this will help to get rid of understeer. Try these settings, as starting point. then adjust one end a a time to get the balance you want. The amount you can change things with tire pressure alone is amazing. Post up your results if you try this.

(drive2)

Nice tire pressure info! I'll use that this Sunday (drive2)

 

[major error]

pressures are dependent on tire too.

I was using 42F/32R at one point on the stock RSAs, and the push was still pretty bad.

YMMV