Zulu Alpha

I know I posted this video in the in the Track video thread but I have a question for whoever can help. As you will see in the vid, as soon as there is slip angle in the car, it judders and bogs. Is this a GT3 thing? I don't remember my C2S doing it on track. What is the cure? Is it a setup thing? Will the car ever be able to slide without this judder?

The Setup:

MPSC2
Front: 29 PSI HOT
Rear: 32 PSI HOT

It has a factory specs on the alignment except for some very slightly added camber in the front.

PLEASE HELP!

P.S. Last month I tried a clean lap and I was slower with a 2:18.10. The more I pushed the car the faster it got, but as soon as it goes, it does without warning. It just goes. The car judders and bogs, there is no flow to it. It's very frustrating.

orthojoe

That is stability control kicking in. You can turn it off

kfmcmahon

PSM

kfmcmahon

http://www.porsche.com/international...anagement-psm/

Zulu Alpha

It's off, ESC + TC is off

aamersa

It's in the nature of the Gt3 to do that. By contrast my 458 is a more majestic slider. When the gt3 rear end breaks loose it's not too pretty, that has been my observation from the very beginning of my gt3 ownership.

My 2 cents is that the rear engine weight bias is the culprit.

MileHigh911

Could be a software thing, where you have the ESC+TC off (light is on), yet it isn't off. With all of the sliding around Chris Harris and the others have shown in their videos, not once was there a complaint. With todays electronic controls, I assume thats the issue.

Jpacione

I tend to believe it's a malfunction of some kind. I don't have a problem with slip angles when I want them.

orthojoe

That is weird....

Zulu Alpha

Appreciate the input guys. I think it's a combo of tire pressure and set up as a friend tells me. I'm looking for a different perspective and other possibilities. In some of my other videos you will see that once this judder happens, and I foresake the corner, I give it a boot full and ride out a slide. I know that's not the point, but the point I'm trying to make is that stability control and traction control have nothing to do with it, so it's not ESC + TC cuz I know that is completely disabled and it never intervenes.

I'm still leaning toward setup like my buddy says, add camber... Any other perspectives?

Zulu Alpha

Maybe it's the MPSC2 tires it's self, maybe it doesn't like any slip angle? I'm lost.. I don't know anymore. Unfortunately, due to warranty reasons, we can't change to another tire (I.e Trofeo R) due to the warranty and it will void.

Going back to the vid just now, you will notice that the judder only happens when the rear steps out... Rear camber could be a factor. Maybe I'll increase it a bit and see how it goes.

Leigh2

I'd monkey around with the tire pressure they look a little low to me for cups...

Zulu Alpha

Also, possibility. I'll do that as well. I mean I set the pressures to 29/32 after its baking hot. It will not go a degree over.

Leigh2

Well, generally speaking when the car feels chunky when slipping it's usually due to low pressures.....electronic influences eliminated. I haven't run cups for a while but when I did (18") I ran R34 hot and F32 hot. I found them horrible at low pressures I had to start them high and bleed them off as they heated up.
FYI I now prefer Trofeo R's they are easier to deal with....

Zulu Alpha

Sorry, what do you mean by "Chunky when slipping?" I didn't quite get the reference.

I remember trying a set of pressures and bleeding it down to 29/32, and found that this is the best grip. But I could try the pressures you just recommended next time. Btw, coming to think about it the front end doesn't judder at all now. It's only the rear. So might look into changing to a more aggressive camber.