Track Wheel Setup - Square vs Staggered

[zvovchik]

Originally Posted by thstone

Boxster's are designed with inherent understeer. Most owners increase the front tire width from the stock 205 to 225 to reduce understeer. 235 is even better.

However, if you go the next step and install 255's up front, the car typically goes from natural understeer to natural oversteer (because now the front has a lot more grip). This won't be an issue while driving around town at normal speeds, but crank it into a freeway on-ramp with a set of RA-1's or take it to an autocross and at the limit the rear end is going to be loose.

Thus, most owners who go square install adjustable coilovers, adj drop links, and adj sway bars so the handling can be adjusted back to neutral (or however the owner likes it best).

If you wanted to try going square on the stock suspension, then yes, disconnect the rear sway bar and set front tire pressure slightly lower than the rear tire pressure. The car should still exhibit quite a bit of oversteer so be prepared to react accordingly.

Adjustable coilovers(pss9 2k $),
adjustable drop links (front/rear Tarret 1k $)
, and adjustable sway bars (gt3 front/Tarret tear 1k$)
And we havent got to lower controll arms and other bits.
Plus my time installing the stuff, sounds like about 4k of dollars and that much closer SPB build. 4k can buy a lot of tires of going staggered for $4k. Oversteers that bad huh if just doing square and no mods.. I do notice that bit of understeer a bit when pushing the car, its not that bad though.
Hmmm you made me think. Seeing that photo of Boxster on three wheels got me waay exited.
Hmm it sounds like ALL IN or nothing hehe

[zvovchik]

Forgot to ask, what tire pressures are we talking about if going squared? Maybe i try put my existing 255 AS/3 up front and install new RA1 in the back for starters. Existing as/3 are fairly new and i live in portland OR, so im trying to have wet weather capability..back to pressures....What would be reccomeded?
Im thinking as/3 fronts would offset the grip with RA1 in the back. Am i tottaly wrong here?
Thanks

[Topless]

Originally Posted by zvovchik

Forgot to ask, what tire pressures are we talking about if going squared? Maybe i try put my existing 255 AS/3 up front and install new RA1 in the back for starters. Existing as/3 are fairly new and i live in portland OR, so im trying to have wet weather capability..back to pressures....What would be reccomeded?
Im thinking as/3 fronts would offset the grip with RA1 in the back. Am i tottaly wrong here?
Thanks

Completely incompatible tires. Your car would push like a pig all day.

Maybe choose some middle ground and mount RE71R on all 4 corners. This is a fast tire that works street or track. Almost as fast as RA-1 but works better on stock suspension. You will still toast the outer shoulders but a better fit than RA-1 tires.

[zvovchik]

What is the easiest way to adjust camber? Are gt3 arms required or is there a cheaper way while running stock suspentions? Maybe ill be better off just running staggered and get better tires? Hmm but still a camber adjustment is a requirement i understand, if i am to track it at all right?

[Topless]

Originally Posted by zvovchik

What is the easiest way to adjust camber? Are gt3 arms required or is there a cheaper way while running stock suspentions? Maybe ill be better off just running staggered and get better tires? Hmm but still a camber adjustment is a requirement i understand, if i am to track it at all right?

Lots of guys do lots of things to get camber in the car. Slotted strut mounts, camber plates, coil overs, lowering springs etc. All can work to some degree and there are a dozen threads here pontificating the merits of each. The top Porsche setup shops all over the country pretty much agree: "Just get GT3 adjustable arms." They make the setup and alignment process very straightforward and they will transform your car into a track worthy machine.

[zvovchik]

Youre advice and recomendations much welcome. Thank you!:dance:

[thstone]

Originally Posted by zvovchik

Im thinking as/3 fronts would offset the grip with RA1 in the back. Am i tottaly wrong here?

Trying to balance the handling with different front and rear tire compounds is the wrong way to go about it. Well, that is unless you have a large selection of tires to choose from and have time to do a lot of testing (which I am assuming you don't).

Here is the standard process to set up a car with one set of tires: Install the same tires on the front and the rear, THEN use the suspension to adjust the handling, THEN use tire pressures to fine tune the handling. And don't forget, the driver may need to adjust their driving technique to get the most out of any given setup.

In this case, the problem is that the stock suspension has no adjustability. The Porsche factory gets around this by doing tons of testing to find the right mix of tires (type and sizes), suspension, and tire pressures that result in the handling that they want. Without adjustable suspension and with only one type/size of tire, you don't have anything left to use for adjustment (except pressure which is not going to move the needle very far).

I've done lots of laps on RA-1's; shaved vs full-tread, heat-cycled vs non-heat cycled, in the dry and in the wet, but I've never mixed them with an all-season street tire.

Best of luck.

[thstone]

Originally Posted by zvovchik

Seeing that photo of Boxster on three wheels got me waay exited.

I think that you mean like this? The photo earlier in this thread shows a Boxster on TWO wheels (most likely after hitting the curbing and bouncing both inside wheels into the air).

It takes the full Spec suspension to get the car to handle like this. And look at the right front, the tire is nice and flat to the track while the wheel is at roughly zero camber (when fully loaded). It needed -3.7 deg camber (static) to be able to achieve that and the only way to get that kind of camber is adj lower control arms.