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Old 04-30-2016, 11:41 AM   #1
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Any tricks to reduce oversteer with limited adjustments at tbe track?

I've got new ksports installed and also have gt3 lca in front, and adjustable toe in back. I made guesses on my front camber plate, and In the front I have -3.2 camber (and no toe) and I can't take any more camber out. I have -2.2 in the back (and tiny amount of toe in) and can't get any more neg camber. I ran put of time and had to go with this setup. The back is very loose... I need to get them back even by adjusting the tops of the struts but I have to drop the struts to do it. Any tips on how to dial out oversteer through the limited changes I can do here at the track?

Then when I get home, what settings should I go for? Right now it is very loose and I don't have any confidence to push it.

I am at the center camber plate setting in back, and a little off center in front (toward the neg camber direction).

Ride heights are:
FR 616mm
FL 616.5 mm
RR 643
RL 644

So I can go.up or down with my camber settings if needed, or add height, but probably can't lower much more.

Last edited by steved0x; 04-30-2016 at 11:43 AM.
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Old 04-30-2016, 11:44 AM   #2
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Old 04-30-2016, 12:05 PM   #3
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what do you have for sway bars?
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Old 04-30-2016, 12:07 PM   #4
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At the track you can lower the tire pressures a little in the rear and add a little to the fronts.

If you have adjustable sways, try a little softer in the rear, then if that doesn't fix it, stiffen the fronts.

if you did not have the car corner balanced after the struts were installed you need to do this to get the car at least close to balanced before any other adjustments
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Old 04-30-2016, 12:21 PM   #5
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+1 Deadeye

If you change ride height and damper pressure states (i really don't know the correct technical english term. In german it's Druckstufe and Zugstufe - which describes the dampening factor when pushing or pulling the damper) you always have to adjust the sway bars to get a good result on the track.

Regards, Markus
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Old 04-30-2016, 01:25 PM   #6
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I have M030 swaybars, non adjustable but I do have adjustable drop links, no preload on the bars.

I got corner balanced so all should be good there.

I'll try adding some pressure to the fronts and take a little out in the back.

One issue, there are a *lot * of cars here, 44 signed up in my group although maybe some are 1 day only, but feels like 35+ on track, at Roebling (2.02 miles) that is a lot!

Maybe adjustable sways is my next step...

I guess there is a lot to do when you step away from a factory tuned setup...
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Old 04-30-2016, 01:26 PM   #7
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I have all 4 of my dampers in the middle position, 18 clicks from full hard. Anything to be done there? Or is that more for ride comfort?
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Old 04-30-2016, 01:26 PM   #8
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If loose in the rear I would start with more rear toe in . I also would only want to see about 1/2 deg less camber on the rear vs front
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Old 04-30-2016, 02:19 PM   #9
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I wonder if it is my mojo? Last time I was here at RRR I had the stock suspension and I was running 1:30 and high 1:29, now I am running 1:38 and feeling terrified I also tore up my front tires running the weekend I ran those times so I def needed more camber... My tires look really good, even wear, and I'm going to try and get tire pyrometer readings tomorrow.

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Old 04-30-2016, 02:20 PM   #10
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Quote:
Originally Posted by johnsjmc View Post
If loose in the rear I would start with more rear toe in . I also would only want to see about 1/2 deg less camber on the rear vs front
Yeah, I'm going to adjust my struts when I get home and fix that. Maybe it is a mental thing? With a 1 degree difference it is messing with my mind... But I am sliding around a lot too...
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Old 04-30-2016, 03:23 PM   #11
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when I was getting tons of oversteer( old NT01 tires), I removed the rear sway bar and it brought the back end in check.
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Old 04-30-2016, 04:33 PM   #12
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Hmmmm I may try that during our warm up session...
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Old 04-30-2016, 04:43 PM   #13
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Somebody below mentioned changing the tire pressures. Agreed. My Box is very sensitive to tire pressure. So much so that you might be able to change oversteer to understeer with pressure changes alone.
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Old 04-30-2016, 10:44 PM   #14
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Quote:
Originally Posted by steved0x View Post
I have all 4 of my dampers in the middle position, 18 clicks from full hard. Anything to be done there? Or is that more for ride comfort?
Absolutely - if you have adjustable dampening rates (especially adjustable rebound will be effective), soften the end that you need more traction at, and stiffen the other end.

So in other words, if you have too much oversteer, soften the rear, and stiffen the front.

This is a better solution than changing to sub-optimal tire pressures, because you lose overall traction by doing that. Remember, when testing and tuning, only change one thing at a time - if you change many things at once, you won't have any idea what's causing what!

Good luck, and have fun!
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Old 04-30-2016, 11:24 PM   #15
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Hi,

my question would be: is the rear loose in general or only in some situations.

Is the rear loose if you
break hard on a straight line?
break hard on a straight line in combination with bumps?
break in corners (which isn't recommended but we are racing)?
you are cornering and go off the throttle?
you are cornering and go on the throttle?
you are cornering without load cycle?

Also i like to ask why you've chosen a +30 mm ride height in the rear?

Did you check the weight at every wheel? I suspect you will ave a little more weight in the rear of your Box.

In general: if you combinate more weight with a higher ride in the rear, you will always get a more loose rear.

Regards, Markus

Last edited by Smallblock454; 05-01-2016 at 06:48 AM.
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Old 05-01-2016, 03:36 AM   #16
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Do you have adjustable rear toe arms installed? If a Boxster is lowered too much from stock I think the rear tends to toe out? If toed out it alone would explain the rear loose behavior/feel.
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Old 05-01-2016, 07:33 AM   #17
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I have aftermarket toe arms that provide extra adjustment range.

The back steps out during steady state cornering with maintenance throttle. Very scary.

Braking is good, turn in is excellent, I just have no confidence in the back and it is affecting me mentally.

The heights I ended up with were just what I came up with using the ksport starting points. It looked ok by the fender heights the back is 30'ish mm higher which is more than an inch, I didn't realize that they were that far apart.

I softened the back 6 clicks and hardened the front by 6 clicks so the fronts are 12 clicks from full hard, and fronts 12 clicks from full soft, with 12 clicks between them. Seemed to help but by this time my confidence was shot, so I called it a day and we are heading home...
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Old 05-01-2016, 08:37 AM   #18
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Too late now I guess, but as j.fro suggested, I would disconnect the rear bar for a quick fix.

These cars are fairly sensitive to wheel rates front to rear.

Good luck getting it sorted.
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Old 05-01-2016, 09:21 AM   #19
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Whooo. If you disconnect the rear sway bar this car will be undriveable. That is a dangerous idea. Don't do that, especially when racing and you have other people around you that can get hurt. Always safety first.

@steved0x

I think your overall setup is much to aggressive. Maybe this will work on a cart track but not on a race track. And only little steering and throttle movements will affect much. Which can be indeed very scary in a mid engine car.

You're question what you can do on the track for a quick fix. The quick fix would be to soften the rear dampers, because you don't have adjustable sway bars. Maybe harden the front dampers, but because your car front is very low, that will have the side effect that the front starts to bounce and you loose grip on little bumps.

But my recommendation would be to start with a much less aggressive and driveable setup and go from there with testing and time tracking. Always only adjust one parameter when testing.

As a general setup i would level the car. Bring the car up in the front 20-25 mm and lower the rear maybe 5-10 mm. And start from there.

Camber setup is also very aggressive. Please consider that changing the ride height also in general affects camber and trailing. The guys on the Nordschleife i know don't drive with more than -2.5 degrees on their 996. OK, 996 and 986 is different, but i think -3.2 is only for close courses at mid high speeds.

There are some good books about setting up suspension on cars out there. I think t's a good idea to educate oneself in theory of suspension and chassis setup, because what i sometimes read on the internet frightens me. And it helps to understand what the car is doing. Just my 2 cents.

Regards, Markus
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Old 05-01-2016, 11:16 AM   #20
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Disconnecting the rear sway bar will not be dangerous, at worst it will cause the car to understeer (push) a lot, which is very safe. Not fast, but at least you won't spin. I've raced cars that when it rained, we disconnected the rear sway so I could have nice, safe, predictable understeer in the wet.

Steve, you said the rear stepped out under constant throttle, does it snap out, or progressively come around? Will it keep going further and further out and then you'll have a big moment, or does it just step a few degrees and then take a set? If the new cornering attitude is predictable and won't bite you, then the adjustment may be in your driving.

It does take a bit of getting used to going from a car that pushes, to one that corners tail-out. You made some very big changes to the set-up on your car, and it probably will want to be driven differently now to go quick on the track.

Each step in getting quicker (both the car and you the driver) can be difficult, as you will have to move out of your comfort zone each time.
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