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.

what do you have for sway bars?

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

+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

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...

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?

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

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.

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...

when I was getting tons of oversteer( old NT01 tires), I removed the rear sway bar and it brought the back end in check.

Hmmmm I may try that during our warm up session...

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.

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!

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

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.

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...

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.

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

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.

Sway bar: the only thing i can say is interesting point of view.

What do you mean with racing? A race track with top speeds above 160 mph/h or a typical US race court on a parking lot?

Sorry, but there might be different approaches what racing might mean. I don't mean that in a bad way. But if i'm on the Nürburgring i would never had the idea to disconnect the rear sway bar, because that will lead me into massive trouble, because the inner wheel won't be controlled.

Regards, Markus

Steve said he was at Roebling which is a real race track with a long history of club sports car racing. It also has a very long front straight where most cars run completely out of Hp trying to push air out of the way. I have run this track many times in a Lola S2000 car as well as my 986 S but I can't say what speed, as I don't look down much heading into turn 1 there.

I will avoid a useless internet debate over the application of sway bars.

Steve: if you send me data on your spring rates, and corner weights if you have the data (if not, I can use mine), I have some computer models that calculate natural frequency and ideal damping rates based on our cars geometry that I can send you.

I'm not sure about the ride height data that you gave, but I am guessing that it was measured from the ground to the top of the wheel arch. If so, the tire OD has a direct influence on the measurement, so that makes it hard to compare data, but I'm guessing that your ride heights are too low. One problem with running the ride heights too low on these cars is that the low control arm goes over horizontal, at which point you start to loose camber with increasing suspension compression. It is best not to go much below the OEM ride height on these cars.

What tires are you running? -3.2 is allot of - Chamber for on street tires. Your stance is pretty low from your picture. Are you bottoming out your struts?

I'm running same struts at the max setting and -2.5 in the front on tight tracks -1.5 front on fast tracks -2 rear 0 toe. 15 mm wheel spacers front 7 mm wheel spacer rear. 4" clearance from the body weld behind the front tire to the ground. 4.25" to the rear braces to the ground at the front edge of the inner rear wheel well. GT3 arm front and rear no spacers front, 6mm spacer rear. 235 40 18 front 275 35 18 rear

On RS3 tires I get push front. I can improve a little by adjusting rear toe link out 1 to 2 flats. (Negative rear toe) On Z214 the car is pretty neutral. On NT01 the car is a little loose in the rear if I accelerate to hard in the middle, and I have to play with the pedal until past the apex.

I'm home safely, there is a lot of good info here and i will reply more tomorrow. I think I just made too big of a change, and need to dial the change back down.

I figured they were too low but they looked so good :)

I'm not sure what you mean by the inner rear wheel not being controlled. A sway bar links the two sides of the suspension together, increasing roll stiffness, which ultimately reduces grip on that end of the car.

I don't want to argue with you, I'm just giving my experience. By racing, I meant wheel-to-wheel sports car racing on closed circuits. It's irrelevant to this discussion, but I've been up to 154 mph, which is just short of 250 kph on a straightaway.

Steve, I think LAP1DOUG is right, now that you posted a picture of your car, it does look like the ride height is very low. You should take him up on his offer to check the data on your spring rates and see what he says. It sounds as if he has a ton of experience, it'd be smart to take advantage of that.

I've found that a good way to keep track of ride height is to measure from the wheel hub center to the top of the wheel arch, that way different tire heights don't affect your measurements.

A few thoughts:

You have made a lot of changes to your suspension but never had a pro look over your setup and make final tuning and corner balance adjustments? Maybe it is time. :)

I ride right seat in a lot of different cars with a lot of different drivers at the race track. The best handling cars always have a pro setup even if it is a mild build. The worst setups by far are DIY by enthusiastic drivers with little or no suspension experience. Several have been damn dangerous and ended their day early before backing into a wall or armco at 150mph.

There are just way too many variables and unknown unknowns to solve this issue on a car forum. Math and measurement is required. I suggest you find the best Porsche setup guy in your area and drop off your car for assessment and recommendations. The result will be quick and certain to get the numbers right. It will cost you some $$ but a lot less than a car write off I am sure.

Good luck with your car development.

PS: Markus, disconnecting the rear sway is a common tactic for racing in the rain to regain an element of control through standing water. It has resulted in many class wins along with proper rain tires under nearly un-driveable wet conditions. It will not cause any loss of rear wheel control so I suspect you are simply confused by the terminology. If you must disconnect it on a perfectly dry day to gain control of the car, you have a serious setup issue that must be addressed.

Hello Topless,

thanks for clarification. Might work in wet on lower speeds and with a non aggressive driving style.

But i have some major worries on high speed corners (above 160 mph) in combination with load alternation, bumps on dry tar with slicks and a rear wheel driven car. I can only say that there are situations where it can be dangerous to not have a linkage between wheels, because you will loose the rear axle within milliseconds and don't have a chance to get the car back.

So if you're an experienced race driver or race mechanic with long experience on your car and you know what you are doing and your overall suspension setup is OK, that might work for specific situations. But i wouldn't give such tips without a warning, because in that case the impact will be hard.

Hello Racer Boy,

sorry, i don't wanted to be rude or argue with somebody. I would recommend to go in detail about suspension physics. I don't won't to do it on an internet forum, because it's really complex and because it can be misleading. There are really many parameters and aspects to go into. That won't be a post, that would be a book to write. ;)

Hello steved0x,

it's nice to have a good looking car. But good looking doesn't always mean that it's also fast. ;)

I would go with Toplees. Look for a shop that has experience in race suspension setups. And if they are experienced in Porsches and the K-Sports suspension too this will be a big plus. I know that such a setup costs a lot of money. But i think itÄs worth it and also you have the chance to a lot of questions.

Also i would recommend to read some good books about suspension setups or race cars technology in general. A good one, which is easy to understand if you have some math and physics knowledge might be M. Trzesniowski, Rennwagentechnik. It gives an overall view on race cars. Don't know if it's avaiiable in english language. But i'm pretty shure there are other good ones out there in english language.

Always take care, always safety first. ;)

Regards, Markus

For me at RRR my top speed on the front straight is 121-123 MPH, most of the back side of the course is 60-95. I don't look either, but I see it on my videos after when I watch them.

Heights were measured just as you said, from the arch of the fender down to the ground passing through the wheel center cap. I'll send you the tire sizes, corner weights, and spring rates. Thank you!!!

I am on RS-3, I agree that is a lot of camber. The way I had installed everything that is the minimum I could get :) I definitely have more adjustments to make :) Thank you for sharing your setup.

Yes I did, too many! I agree. I had different shops do the corner balance and alignment, but nobody to give me recommendations about what I "should" do or say things like "you're too low dude!!!"

Part of the problem was a time crunch, due to various things, mostly my hobby level skills, which left me in a rush at the end, but I have to be honest and say that even with more time I probably would have left it too low in the front, because of looks, and the other lowered track boxsters I have seen that looked really low :)

I believe it! The car was terrible. Last time at RRR (totally OEM stock and original M030 sport suspension with ~120,000 miles, max camber in front (-1'ish, -1.7 in back, no toe front, a little toe in in the back) I was running 1:30 with 2 flyers at 1:29. This weekend my best was 1:38 and it was terrifying!






I will check them out. I got suckered by looks, I admit it :)

I've got the corner weights, they are biased toward the rear, but I don't have them handy. I can say that braking felt less "powerful", maybe because of all the camber? I was getting into ABS going into turn 1 almost every time, where before I almost never got into ABS. The +30 mm ride height increase in the rear was just happenstance, when I finished the installation and put the wheels on, that is what it ended up with :) More thought is required for next time :)



There is a shop here in Jax that does a lot of Race Caymans, does anyone know of a good Boxster race shop in FL or south GA, preferably within a 1-2 hour radius of where I-10 and I-75 intersect in Lake City, FL?

A big thank you to everyone that contributed to this thread. I will admit that on the drive home yesterday I had visions of returning the car to stock and selling it, and quitting from it for a while (that's how bad it was). This morning I am more encouraged and have the start of a plan to get things better :)
Steve