avddrift

2011 I had a good year on the track, in my first full year of club motorsport, in my 964 C2 Track enhanced car. In 2012, I took some weight out, upped the power a bit with chip, intake and fabspeed exhaust. The biggest change was going from 17" turbo twist track wheels, to 18" o.z. alleggerita hlt with Yokahama A050 R.Spec tyres. Now I am up a class (based on power to weight). I had a suspension expert get more aggressive with the camber, ride height and suspension.

Trouble is, the car is faster, but more on the edge, and especially on fast sweepers, the tail keeps stepping out. Heart in the mouth stuff. My mechanic suggested I soften the rear sway bar, but that was no better. The suspension expert said firm the rear sway bar, a little better, but still no where near comfortable. A local hot shoe drove my car, and said he felt the problem may be the amount of toe on the rear.

I was searching for answers on the Rennlist and pelican forums, and discovered a few posts describing the Weissach Effect. Could this be what I am experiencing? Now that the car is more aggressive on the setup, does that accentuate this change of toe?


Now part two, do the following items on the wish list to improve the handling, especially trying to educe the amount of mid corner rear slip? Please offer advice, or even a quick yes or no on the following items on whether they improve, or a high cost waste of time and money.

Control Arm Bushing Set,
Rennline Sealed Monoballs,
Adjustable Control Arms,
either Tarett Engineering Rear Toe Control Arm Set,
or Rennline Adjustable Control Arms,
Elephant Racing Monoball Kits
Sway Bar Bushings & Brackets
Tarett Engineering Adjustable Drop Links
Urethane 964/993 Front Control Arm Bushing Kit by Chris Walrod
964 Rear Spring Plate Set (pr) (935 Style)

Thanks in advance! appreciate that this may have been discussed previously in a variety of threads, but i'm not sure if it describes what I "feel".

Kind Regards,

Antony van der Drift

RSAErick

Out of curiosity, what are your front and rear alignment settings (camber, caster, toe)?

KaiB

In addition to the alignment settings, let's hear about spring rates, dampers and tire pressures.

Do you have transitional issues, i.e.: understeer at turn it, waggle under braking or throttle on oversteer at exit.

Are you running a LSD? If so, what?

Best
(you wouldn't be picking your foot up mid corner to correct understeer, would you?)

avddrift

Here is the setup numbers from my suspension guy, as well as the current setup position of sway bars etc. I am running hot tyre pressures of target 28psi fronts and 30psi rears. The Yokohama's are brand new as of last weekend, and running soft compound all around. I am finding very little understeer, and the car feels really good apart from the tail happiness on high speed turns. Slow turns are quite good, and I can balance the car with power on/off rotation through the slower turns, with good response from the inputs.

I don't have any transitional issues, in fact the car is really quite communicative. Sure there may be the odd "waggle", but i'm not leaving anything behind, i'm going quite hard. KaiB, i'm not mid corner lifting. If I need to at all, it is prior to the turn, and powering through. And I am not finding any understeer issues. It is during the powering through that the car is really sitting back on it's haunches, then all of a sudden, the *** kicks out a bit, then hooks up again. I know my car has an LSD, but I don't know what. How much effect can this have on the high speed issues?

My suspicion is either the geometry is changing mid corner due to either the Weissach action, or the bushes and rubbers joints are worn, and not up to the kind of stresses I am exerting on the car during sprint events.

I am in Australia, and have just woken to read your replies. Apologies in advance if my response is slow.

Many Thanks and Kind Regards,

AvdDrift

KaiB

I really like your shopping list.

Contact Steve Weiner about perhaps using ERP, as well as points where less might be spent.

Is this occuring in both directions? Is your current suspension free to travel?

I read this now as a transitional issue, not steady state as it is occuring as the throttle goes in - correct?

Bill Verburg

If monoballs are available for joint #2 & #3 I'd use them, the Cup cars only used 2 x3mm shims in joint #3

Porsche's early rear steer experiments may have been fine for street use when all the parts were new but for track use, especially w/ aged components a change is certainly called for

avddrift

Hello KaiB,

Yes, the slip is occurring in both directions.
The shopping list is a copy/paste from the standard online places, but I don't want to waste money on unnecessary shiny bits. I wasn't sure who Steve Weiner was, but google cleared that up. I am at work now, so can't follow up until later, but I will contact RS, to discuss my issues. Thanks for the tip. I think I have just found my holy grail. I see there is a nice article on "Claudia" as well. Congratulations on a beautifully prepped car.

Regards,
Antony van der Drift

fizzledorf

I think the problem is that your last name is Drift...

Babalouie

My C2 is the same, it's veeeery taily.


Then I had a wheel alignment done, and it turns out I had 5mm of front toe out, and only 3mm of rear toe in. According to the guy, this would explain why it's so taily, as the rear end gains toe out as the body rolls, so you need to start off with an excess of toe in to counteract this. He recommended 6mm of rear toe in as a start (and the GT3 race cars they set up in that shop run up to 9mm).

Maybe try dialling in more rear toe as a start?

Steve Weiner-Rennsport Systems

Hi Tony,

I just looked at your alignment and setup sheets and have a question about your shocks and what they are. I've printed these out for reference, if you call.

Please e-mail me with this info and I'll try to help in any way I can. I know I can offer some suggestions about your list of components that will be an improvement,...

avddrift

Hi Bill,
Interesting comments. I "felt" the results of these experiments before realising there was rear end steer. I can understand the reasoning, as in the late 80's, unless a way could be found to stop young bucks going through the shrubs backwards on liftoff, Porsche would be facing continuing criticism.

I will be researching monoballs and upgrades etc. I can only assume that the wear and tear, on top of stickier tyres is going to exacerbate the problem.

avddrift

Haha,
Easier than saying my car is Fizzledorfing all over the place.

I had my name long before the sideways boys got a hold of it.

avddrift

This is how I feel as a lonely 964 owner finding this forum.

ChaseN

Can't see that video in the US...copyright issues

But welcome to Rennlist! I'm sure these guys will get your problem figured out.

Steve Weiner-Rennsport Systems

Well done!!

I think it will not be difficult to alleviate your case of "fizzledorfing" so the car is more predictable & controllable.