viperbob

From my persoanl experience, once you hit about 500 HP you are sending too much HP to the front wheels. High speed turns become almost impossible to navigate precisely time after time. You do also do reduce the drive train loss, as long as the power going to the rear wheels can be harnessed with a proper LSD and tires (I needed 12" slicks and could still spin them if not careful in 4th). The car feels 1000% better in turns. Much more precise and able to control with the accelerator pedal. So for me, I gained lots of time going to the 2wd setup. Why do you think the GT3/GT2 and all the Porsche race cars do NOT use AWD?

K24madness

Bob,

Does that same road feel translate the same in street driving?

Rob 97 993c2

Bob - you raise an interesting point, as people do turbo upgrades on our 993tt's , how does the awd adjust to the added power?? Does the car handle less 2-wd when going from stock to 450hp? is there a way to adjust for this so the car handles better?

911/Q45

I think AWD is forbidden in most racing series, otherwise Porsche would use it. Even a stock tt is nowhere near the limit in any reasonable street driving. I'm unclear on the concept of immensely expensive and powerful mods applied to a street car that never sees the track.

viperbob

Don, then why does Porsche in their sport models remove the 4wd system? The Porsche system is not of the most modern and sophisticated. OK for street, but on the track with constant use is not the best. Even so, with a stock car it is OK. Up the power and heat and transfer more power to the front (which can only turn or apply power at the same time) and you do not have an optimal situation....

ruffy

Thanks Bob! you are the man!
If you have a minute, i'd really appreciate if i could consult you on some problems i face at the track.

for the most part, i use my car on Sepang int. circuit... the track conditions are low mu (not the usual high grip track asphalt.. more like the normal road type).
the turns consist of several large straights... main straight makes 240+ kmh. with a good intermediate section which the car seems to do ok. most of the time seems to be made on the hairpins which follow the main straights. big hp is definitely rewarded, only if you can coax the car to turn in neatly without scrubbing wide.

my biggest complaints are that mid corner speeds are really bad... maybe the suspension setup maybe the age of the car chassis is showing?
case in point: when following other cars into turns (m3CSL, 996tt or even evos 8's) i need to make tons of midcorner adjustments just to stay with them! if not the front washing wide, the rear goes wide. since overall weight is similar, i cannot understand why my car breaks away so much earlier. and hence i have to drive twice as hard to stay with the pack. this really is an accident waiting to happen

I'd love to think the 993 chassis could just as competitive (within drivers ability to make up marginal differences )

Does 2wd figure into my equation?

sorry for the lengthy post

viperbob

What kind of suspension do you have on the car now and what sway bars? Also, do you have the Evo uprights on the car?

ruffy

i have the ruf valved bilsteins and the ruf swaybar (i think similar to the rs, with 3 adjustable positions) and as for evo uprights.. i dont know, but i doubt it.

I thought the evo uprights were only applicable for cars with the 2wd applications?

the shocks have seen about 40k kms (mostly b-roads and track)
tires either mspc semi slicks or bridgestones @38psi

does that help?

viperbob

Step 1) Throw away the Bilsteins and get at least PSS9s
Step 2) Get the EVO uprights with the GT2 tie rods. These do work with the 4wd cars.
Step 3) Are the sway bars adjustable front and rear? I have seen a few RUFs with odd combination of sway bars in the past. Get a micrometer and find the size of the front and rears.

If you do this, you will find that your car is planted, neutral, and requires no mid course correcting on the turns. You are experiencing a number of things from your description that can be solved. You will have a LOT more fun and be able to kick those other cars butts...

Jean

If I can just give my opinion on the handling issue..
I would start by making sure that your alignment settings are good, camber (not less than -2deg Front and rear), caster, toe, corner balance..Most importantly, try to find someone who has expertise in kinematic toe adjustment and have them make sure it is well setup.

Definitely you need shocks. After you have done the above, and if the car still handles like that, then you are off to more serious work such as, uniball, RS or ERP toe arms, etc..

Obviously Bob knows what he is talking about, however in my experience and for my ride height, the shop in Germany where I did my suspension said that I did not need the bump steer kit, and in fact the car handles perfectly as is. If I ever feel the slightest unwanted rebound behaviour on the road or track, that will be the first thing I do.

As far as the 2WD setup, it is fantastic but needs caution on heavily modded cars, forget slamming the throttle coming out of a turn, to be honest I still do not have my Guard LSD installed.

Finally I would just like to add that the reason the RS, GT3 and GT2s are not 4WD is not only for weight considerations, but because they are usually built for racing homologation purposes, and therefore they cannot get them homologated to run in races otherwise, as 4WD is not allowed in most series.

ruffy

the sole and only local independant porsche mechanic here in this country and state really isnt up to scratch. and his price tags eclipses the dealers..

neither i can trust for advice on suspension or setup for that matter

talk about being caught between a hard place and a rock... lol

ca993twin

A question for ViperBob on "throwing away the Ruf-valved Bilsteins and getting PSS-9s (at least)":

My Ruf suspension has adjustable Bilsteins and look an awful lot like PSS-9s. I believe that they are revalved and the springs are different as well, but I must say I'm very happy with the way Rufus handles, even better than Waldo with PSS-9s and lighter 18" wheels. The rear has an adjustable rear bar, and I'm not sure if the front has been changed or not. Q45/911 (recent 3.8 Andial conversion) uses this same Ruf suspension, and he has some track time under his belt. I believe he is very pleased with his suspension. Oh sure... its not a true track setup, but I think it feels pretty good. Oh yeah... my question: why should this be thrown away?

viperbob

Steve, most of the RUF shocks on the RUF cars are revalved stockish ones. RUF also sells rebadged PSS9s which would be fine. So if this is what Waldo came with, then you are OK.

ruffy

bob and jean
how do the 12 inch tires work out?

tramlining acceptable?
lap times improvement?
wet weather stability reasonable?

please share

ca993twin

ViperBob,

Thanks for the response. Phew. BTW, it was Waldo that you installed the PSS-9s on... Rufus is the one with the Ruf suspension.

Dang... I wish you were still around here... I have a few more projects for Rufus.