Turn, darn it, turn.

dps214 said:

Olemiss540 said:

Personally I think that amount of tire stagger wouldn't suit a 50/50 weight distributed car

Good thing that's not what's being discussed here. More like 45/55.

Yeah...more front tire would be nice. But until he's ready to chop the fenders off he's not getting more than maybe 255s on the front.

Apologies as I did a quick Google search before posting and this was the top of the search bar:

"The weight distribution of the Boxster is close to fifty-fifty, with a bit more weight on the rear axle (Boxster 2.5 manual 47% front/53% rear, Boxster 2.5 Tiptronic 45/55)."

Gasp. Didn't realize an entire 53% of the weight was on only the rear axle. Definately needs 60mm more rear tire with that much weight hanging in the back to manage all of that oversteer the OP is having.

Now that I know what's being discussed here, we can have a civil discussion without the snippy snappy.

Olemiss540 said:

dps214 said:

Olemiss540 said:

Personally I think that amount of tire stagger wouldn't suit a 50/50 weight distributed car

Good thing that's not what's being discussed here. More like 45/55.

Yeah...more front tire would be nice. But until he's ready to chop the fenders off he's not getting more than maybe 255s on the front.

Apologies as I did a quick Google search before posting and this was the top of the search bar:

"The weight distribution of the Boxster is close to fifty-fifty, with a bit more weight on the rear axle (Boxster 2.5 manual 47% front/53% rear, Boxster 2.5 Tiptronic 45/55)."

Gasp. Didn't realize an entire 53% of the weight was on only the rear axle. Definately needs 60mm more rear tire with that much weight hanging in the back to manage all of that oversteer the OP is having.

Now that I know what's being discussed here, we can have a civil discussion without the snippy snappy.

Before you say something you might regret, those figures are also base model 986. The 986 S and 987 6-speeds shift even more weight to the rear, and are 45/55 to 43/57 from the factory. Considering that the tools, spare, and other stuff you take out to autocross are also in the frunk, along with the gas tank, it can easily tip to 40/60 on an otherwise stock Boxster.

There's a reason why the factory recommends significantly higher pressure in the back. 

I would start with the settings Javelin recommends.  I found out the same thing when I had a Boxster S.  The local tire shop with great reputation set the tires at 35 all around and then to insult me more they recorded my 2000 Boxster mileage on their computer for my 2000 996.  That error cost me at least $5000 on bringatrailer when selling my 996.

Adjustable swaybars are an easy way to tune the understeer/oversteer balance while leaving the street manners pretty much unchanged since swaybars do not change bump stiffness. If a few psi of tire pressure plus or minus can fix an understeer problem, i dont think you had an actual understeer problem.

Yeah, it has an abundance of rear grip, no front weight and high front pressures. 

Lower the front pressures to 30-32 rear pressures 37-39, alignment is maxed out but maybe try to add a hair more toe out in the front, try the front bar disconnect trick to see if it helps (personally I would look at a softer front bar and a bigger rear) 

Good luck.

I appreciate all of the feedback. I will use the next event to play with air pressures and hopefully collect tire temp data as well.  

My historical approach has been to add more rear sway bar to reduce under steer. 

2007 Ford Fusion had severe under steer as you might expect and a big ol' Eibach rear bar made the car very neutral with the right adjustment hole (yes, I tracked a manual Ford Fusion  ).

2005 Mustang GT had moderate under steer. Whiteline rear sway took it to slightly loose which felt very good on that car.

2013 Ford Fiesta had severe under steer. Added two different elements to the rear torsion beam axle and it was then very neutral.

The Boxster has less under steer then the three above so maybe air pressure will get me close. I will likely try adding more rear bar if I can't get it out with other adjustments. I am hesitant to remove or reduce the front bar as the stock springs allow plenty of roll as it is the and camber curve isn't favorable. 

What I really should be asking is how to make it not look like a 4x4 (drop it an inch) without changing the ride quality 

I have a 2007 base Cayman and had the exact same problem as you. From stock, after installing the Tarett rear 19.1mm adjustable anti-roll bar and Tarett/GT3 five-point front bar, my car still understeered with fronts in the middle and rears at second softest. I adjusted the fronts to second softest and ended up with the rear at the stiffest anti-roll bar settings, and turn in was perfect, yet there was still steady state understeer. I didn't want to go full soft up front on the bars because I didn't need anymore turn-in sharpness/oversteer. Then it was Ohlins R&T with camber plates for about -2.0 front and -1.8 rear, which helped when running 235 front and 265 rear RE-71R tires, but still the same steady-state understeer, just not as bad. I tried different tire pressures and shock settings and it didn't help much. Without going to adjustable control arms or cutting holes, there was one thing left to do: square the tires. I was able to fit 265/35-18 tires on 987.1 Cayman S rear wheels up front (had a set of 265s I wasn't using and figured why not). So I decided to go 255/40-18 (255/35-18 too expensive) A052 at all four corners to be in STR. I'd recommend 255/35 because I had to replace and shave down a radiator support bolt that's behind the front of the front fender liner to ensure it didn't rub too much at full lock. In the end, I bought two more 18x9 987.1 Cayman S rear wheels, mounted the Yokohamas. I run 15mm spacers at the rear with this setup. Extremely neutral with no understeer unless I enter a corner too fast, or in extremely tight corners. In steady state corners, no more waiting forever to power out, and I can get on or off-power rotation. This is the way to go if you don't want to go the destructive (cutting holes) and/or expensive routes of finding more camber. Unless squaring the wheels/tires is a bit much for your non-autocross car. Here's a recent run that shows the car's handling characteristics: https://youtu.be/SlM1GqIDjpU 

In reply to Dlowney19 :

Great feedback and thank you for the detailed process that you went through. Of course it would cost some additional money so I will play with other options first but it looks like additional investment may be required. 

How is the ride quality with the Ohlins R&T? 

I have to ask...are you able to run in STR with SCCA or a different organization? 

Left foot brake?

In reply to porschenut :

For steady state understeer? Not sure I follow but I am open to try anything.

In reply to fusion66 :

I paid about $600 for two ebay Cayman S wheels, so not super cheap...

Last year 987.1 base Caymans were able to run in STR. This year, they're STU, so I'm no longer STR. However, after this year's first autocross with WDCR, I discovered that my lighweight flywheel put me out of STR last year, so I ran the wrong class for 2022 and the start of 2023. (Yes, I notified our local chapter...) I love the Ohlins, perfect coil-over for the car. More compliant than non-PASM stock suspension by a hair.

In reply to Dlowney19 :

Thank you for the feedback on the Ohlins...maybe a 2024 upgrade :)

In reply to fusion66 :

No prob! What I meant by steady state understeer is understeer that crops up in longer, sweeping corners where maintenance throttle is required. For some reason I call it steady state because I have to keep the car steady with no additional throttle until the car's ready to power out. I should probably find a new term...

Edit*: Or just use "steady state cornering" like you do :)

fusion66 said:

I appreciate all of the feedback. I will use the next event to play with air pressures and hopefully collect tire temp data as well.  

My historical approach has been to add more rear sway bar to reduce under steer. 

2007 Ford Fusion had severe under steer as you might expect and a big ol' Eibach rear bar made the car very neutral with the right adjustment hole (yes, I tracked a manual Ford Fusion  ).

2005 Mustang GT had moderate under steer. Whiteline rear sway took it to slightly loose which felt very good on that car.

2013 Ford Fiesta had severe under steer. Added two different elements to the rear torsion beam axle and it was then very neutral.

The Boxster has less under steer then the three above so maybe air pressure will get me close. I will likely try adding more rear bar if I can't get it out with other adjustments. I am hesitant to remove or reduce the front bar as the stock springs allow plenty of roll as it is the and camber curve isn't favorable. 

Definitely don't disconnect the front swaybar. And with limited camber you're right that going softer probably won't help. It could actually be a situation where a stiffer bar would help by better maintaining the tire contact patch.

Start with tire pressure. If a few extra psi fixes it, then you're done. If it moves in the right direction but doesn't fix it (or causes other issues) then it's rear swaybar time.

Dlowney19 said:

Without going to adjustable control arms or cutting holes, there was one thing left to do: square the tires. 

Gasp! You must leave in your tools in the frunk. 

In reply to Olemiss540 :

Of course, that's my other secret.

dps214 said:

Definitely don't disconnect the front swaybar. And with limited camber you're right that going softer probably won't help. It could actually be a situation where a stiffer bar would help by better maintaining the tire contact patch.

Start with tire pressure. If a few extra psi fixes it, then you're done. If it moves in the right direction but doesn't fix it (or causes other issues) then it's rear swaybar time.

What he said ^

NASA Speed News: Camber Matters – Optimizing Track Performance for Strut Suspension Cars

Honestly, get the presures right before you start playing with anything else. Use a tire pyrometer after every session. Read this article:

NASA Speed News: Tuning Tires – Tracking tire temperatures and tuning your setup accordingly can pay dividends on the racetrack

Then plug your tire temperatures into the spreadsheet on that last page to decipher what your temps are telling you:

Tire temperature spreadsheet