Planet 9

I have a 2007 Cayman S with 18" wheels and Pilot Sports. Recently bought a 2000 Boxster S (first year for the S) also with 18" wheels but with near new P-Zeros. In the Cayman I run 32 pounds front and 36 rear - cold. Hnadling is great. The Boxster with these same pressures seems front heavy: more difficult turn in, more steering input needed, no "return" in the steering wheel after completeing a turn, etc.

Maybe the camber settings were changed between the two models, or maybe weight distribution is different? Feels like perhaps more neg camber is needed in the Boxster.

Anyone with comments/ideas?

the "return" you mention has nothing to do with tyre pressure. It's governed by the Castor angle, which (I believe) in the 987 is not adjustable. I'd be amazed if it was adjustable in the 986.

Unless you're really pressing-on, turn-in won't show improvement with Camber. It absolutely will if you're going fast, but if it's reluctant even at low speeds, it's not the Camber at fault.

Seeing as your car is now 8 years old I'd get its alignment checked. More than likely it's off-kilter. An 18" wheel can easily be curbed with no damage to the rim, and that could shoot the alignment totally off. I make it a point to do a laser-alignment every time I get a car on my hands, even if it's box-fresh from factory.

I'd say perhaps your front tyres are near the end of their life, or they're not the same kind as the rears, but you did say new P-zeros. Weight distribution is absolutely not the issue; Not unless you have a 200lb sandbag in the front trunk.

The P Zeros have about 4k miles on them. Car itself only 20k so it hasn't been driven much and the original owner was in his 70's so not hard miles either. No sandbag in the front (;>); could be the dead body though.
I'll check the alignment as you suggest, but if the caster is not adjustable and the camber not likely to make a difference, that leaves toe I guess.
Thanks for the tips.

slight toe out in the front helps turn-in alot

__________________
996 GT3 lower control arms at all corners
997 GT3 front sway bar
Quaife TBD
DMC harness bar/G-force harness
Hawk HP Plus pads

I had a 2000 986s and recently bought a 987s and I'd have to say the 987s is a bit tighter and more nimble feeling around turns. the 986s was highly competent but the turn in didn't feel as tightly wound -more relaxed I guess. I'm sure though you can set up the 986 to give you less push and more bite if you wanted.

Enjoy. Both the 986 and 987 are great cars

Perhaps the steering rack isn't as tight, and you simply feel like it's understeering, while it's just a case of the (different diameter?) wheel has to turn more?

My experience exactly. The 987 Cayman never feels nose or butt heavy always neutral. My 986 feels like a front wheel drive car at slow speeds with a fair amt of push.
I'll see if the toe is not up to spec or go slightly negative as suggested in another post.

I'll check steering wheel diameter. The cars are 3000 miles apart, but we're en route to the Cayman this wk end.

Castor is definitely not adjustable on either of these cars. I find that more negative camber on the front definitely helps turn in. Unless you bought the Pirellis, they may be old - even though they're low mileage. Not unsafe - just not as grippy as fresh. Have fun!

Good point about tire age. Thanks.

Further information on the subject:

The shop manual for the 986 Boxsters shows that the US spec for front camber is plus one half degree, but for the "rest of the world" it's minus 1.3-1.5 degrees. All other alignment specs are the same.

Not sure why the difference, but I wonder if Cayman specs are also different for US vs ROW.

(OT)
I wouldn't draw that conclusion from age alone. I know several hard core track junkies in their 60s and 70s who regularly eat "youngsters" for lunch.

__________________
Dan

Speculation: In the US, if you over steer and go off the road backwards, a lawyer will sue Porsche for not intentionally dialing in under steer. It is generally better/safer to see whatever you are about to plow into before it kills you. LOL.

Purely a guess.

__________________

2007 Speed Yellow Cayman GT 2.7 (retired)
2008 Guards Red Cayman GT 3.4
"Carpe Cayman"

I doubt they mean positive camber. There's practically no car on the market with positive camber, it's rather quite dangerous and feels unsettling at straight-ahead driving. I suspect it's a miss-interpretation, or description error. Some call it "one degree negative camber", some call it "minus one degree camber". There's even more space for error (as I recently discovered) because some use degrees and minutes, and others degrees in decimals.

Meaning one and a half degree can be written as both 1.5deg and 1.30'deg. Where 1.30' is absolutely not the same as 1.30. I spent half an hour on the phone not understanding why my mechanic suggested 0.7 was "less than" 0.15, when what he meant was 0.7' is less than 0.15'.

Madness. Anyway, back to your post, I suspect the 05 boxster meant half a degree negative camber, not half positive camber. They may have changed the language in the mean time.

Read quickly - didn't notice.... but, doesn't the 987 have a wider front track too? I thought they actually widened the connection points that resulted in about an inch wider track.


kj

Pint:

These are the values from the manual. You're correct that some values are in degrees and others in what appear to be minutes.
Maybe you can decipher what they mean in ordinary language ie. degrees positive/negative as we generally use.

Front Toe-In Total: ROW +5' +/-5'
USA Same

Front Camber Standard: ROW -10' +/- 30'
USA +5' +/- 30'

Front Camber Sport: ROW -15' +/- 30'
USA same as above

Rear Toe: ROW -1 degree 50'
USA -2 degrees 20'