This is a spinoff from my 'Saying Hi' thread since we got into a chassis set-up discussion.
Porsches in general come with virtually 0 front negative camber. This is because lawyers have too much to do with cars these days! This is designed to get more understeer in the car especially important in a mid-engined car with a novice driver. They generally also us a lot of toe in. This helps the car go straight, but hurts turn in response. On older Boxsters you hardly had any camber adjustment capability. From reading the press book (thanks K-man) I see that there is a camber adjustment range of up to -1 degree. I would like to see a little more, maybe up to -1.5 to -2. It just gives you so much more to work with especially with the higher cornering forces generated by race rubber. Toe is no problem.
If you don't adjust front camber you will eat your tires alive on a track day if you drive the car agressively. the drawback is that if you use your Cayman as a daily driver with mostly straight zero corner load miles, you will eat up the inside edge of your tire. Also, too much front negative camber with reduce the front contact patch under straightline braking. So you need to find the balance. Luckily with a rearward weight bias the rear brakes on the Cayman will do a lot bigger portion of the work compared to a front engined car.
Does anyone have some good information of '05 Boxster chassis set-up because this should be a good starting point for the Cayman.
Another quick note: the semi dry sump oiling system is fine for DOT R rubber, but it's not sufficient for the higher lateral loads that would be generated by a full slick racing tire. Too bad it wasn't a true dry sump like the GT1 based motors in the Turbo and GT3.
With regard to dry sump, I am not aware of any problems with the newly modified system in 05' going forward on race tires. Of course it could take some time for these things to show up, but the 05 system is supposed to be an improvement to address past concerns.
As for alignment, yeah I ate up my stock tires driving aggressively on the track so I concur, needs more negative camber. I was able to get -2 degrees on my old 986 ROW M030 suspension, not sure if Porsche will release an equivalent for the 987/Cayman generation or not. I haven't looked into what the adjustment range is either.
The press guide you just posted shows a max of -1 degree.
I saw that, but I'm suspecting that is with the stock suspension and not with a sport suspension, and actually 1 degree is a lot on a Boxster, you'll have to stick some track tires on and try it for yourself I'm afraid.
Hopefully I can just pick up a second set of the stock 18' cheap from a member here upgrading to aftermarket. That way I can use them for track wheels. I used to be able to fit all 4 track wheels/tires inside my 350Z with the passenger seat out (then you had to know how to reset the airbag light), but I am wondering if it will be possible in the Cayman?
inflated or not inflated? African or European swallow? /fckeditor/editor/images/smiley/MWPX/tounge_smile.gif
IMHO, and not knowing anything about the 987 chassis...
Front camber is certainly important, no doubt. However, it truly depends on the specific tires used, overall camber curve of the suspension geometry and few other items. For example, the RX-8's and C5/C6camber curves are superb. They do not need a lot of camber as the geometry allows to gain negative camber under load; hence they are able to run quite efficiently with under -2 degrees in most conditions at the track events and autocrosses.
In terms of tires, Hoosiers and Toyo's do like quite a bit of camber; whereas Kumho's V700 and V710s don't seem to need that much. Also, there are several new R tires that I have not used from Pirelli, Yokohama, Dunlop, etc.
I do not know if how Cayman's chassis will be, but we might not have to be concerned about it. And, there is nothing that a camber plate and bolts can't accomplish /fckeditor/editor/images/smiley/MWPX/regular_smile.gif
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IMHO, and not knowing anything about the 987 chassis...
Front camber is certainly important, no doubt. However, it truly depends on the specific tires used, overall camber curve of the suspension geometry and few other items. For example, the RX-8's and C5/C6camber curves are superb. They do not need a lot of camber as the geometry allows to gain negative camber under load; hence they are able to run quite efficiently with under -2 degrees in most conditions at the track events and autocrosses.
In terms of tires, Hoosiers and Toyo's do like quite a bit of camber; whereas Kumho's V700 and V710s don't seem to need that much. Also, there are several new R tires that I have not used from Pirelli, Yokohama, Dunlop, etc.
I do not know if how Cayman's chassis will be, but we might not have to be concerned about it. And, there is nothing that a camber plate and bolts can't accomplish /fckeditor/editor/images/smiley/MWPX/regular_smile.gif
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That's because the cars you mention use a double wishbone setup which does a much better job of gaining camber under load. The McPherson strut type suspension doesn't do that nearly as well. That is why roll stiffness is also more important in a McPherson strut type suspension.
Edited by - raceboy on 09/23/2005 2:39:44 PM
Certainly valid and that is point as well. Even though Cayman uses McPherson arrangement, I do not know how else they are supporting it in the details. Gotta have the car, lift and look, and test /fckeditor/editor/images/smiley/MWPX/wink_smile.gif
