Cornering Issues at Recent DE

tcampbell · 07-06-2001, 12:05 PM

Just got back from a three day DE at Summit Point! Quick question for you suspension/tire experts out there. The car seems to be able to hold its own if not better in very sharp, quick turns or S-curves. However, it was very difficult to keep up with most of the other cars in the long sweeping turns. What gives? Car is 1984 Carrera coupe; torsion bars = 24 front & 31 rear; Mille Miglia 7.5 & 9.0 Cup 2 17" wheels with Bridgestone RE730 205 & 255 tires. Any thoughts? I'm thinking that because of my stiff suspesion set-up and lack of body roll, this may be a tire issue. Thanks in advance. By the way, if it is strictly a tire problem does anyone out there have a recommendation as to hybrid street/DE tire (I drive to all events) that's a little more affordable than the SO-2's?

campbellcj · 07-06-2001, 01:52 PM

What exactly was the problem you felt with the car? Was it understeering, oversteering, or just neutral drifting i.e. just plain out of grip at a lower speed relative to the other cars?

You could certainly switch to a DOT-R tire such as the Kumho V700, which would add a tremendous amount of additional grip but obviously wouldn't counteract any tuning issues in the suspension itself...in fact stickier tires will just work the suspension even harder, so if there is anything non-optimal in the car's setup, it will become even more conspicuous!

Chris C.

Jandrews · 07-06-2001, 02:04 PM

Funny, I have just the opposite problem. My car is an '73 RSR look (wide body), running 225's and 275's on 8 and 9 inch wheels. Tires are the RE730's as well.

My car wants to carry the front tire about 6 inches off the ground through all hard turns, due to some nasty body roll. I hate to admit that I do not have a rear sway bar attached at the moment, and I know that is the source of most of my problem. I guess I would state that I have had no problem with the RE730's whatsoever, other than a little oversteer under hard power coming out of tight turns (throttle steer). I think slicks would be the only thing that would help there.

------------------
John
70/73 RS Spec Coupe

Jack Olsen · 07-06-2001, 02:16 PM

The 24mm size choice for the front seems a little odd. But like Chris says, you're going to need to be more specific about the handling problem you're talking about. Are we talking about drift, understeer, oversteer? What are the other cars. C4s simetimes kick my car's butt in some long sweepers, and anything with PMS or traction control can also make up for a lot of driver skill issues, especially in the wet.

------------------
Jack Olsen
My Rennlist home page • My Pelican Gallery page • My Porsche Owners Gallery page

89911 · 07-06-2001, 03:11 PM

Your torsion bars are about as stiff as I have ever seen. What shocks are you using? When you say you are losing ground on sweeping turns, It may simply be an acceleration issue unless you are being pulled off by lack of traction. Can't say that road adhesion has ever been a problem, and we have similar cars. I have run A032R's and G-Force R1's and the R1's are much grippier.

------------------
8 9 9 1 1, The last of the line.

tcampbell · 07-06-2001, 04:28 PM

Sorry guys, I was a bit mistaken on the torsion bar size. Here's the exact suspension set-up:

Front: 22mm Sander T-Bars; Bilstein HD front inserts; -0.7 degree camber

Rear: 29mm Sander T-Bars; Bilstein sport rear inserts; -1.0 degree camber

Other: Weltmeister strut brace; Weltmeister turbo tie rods; aligned and corner balanced

The experience is very neutral drift, like I just don't have enough traction in general. I haven't been experiencing significant understeer/oversteer issues. Yaw seems easy to control via throttle input. I can say that body roll is nearly nonexistent, which leads me to believe this might be tire-related.

orbmedia · 07-06-2001, 05:57 PM

I hate to be the one to say it, but if you're slow in the sweepers you need more balls.

rstoll · 07-06-2001, 06:02 PM

Did he say Balls?????

------------------
Robert Stoll
83 SC
83 944

tcampbell · 07-06-2001, 07:54 PM

Not very scientific, but it's worth a try. I'll see if I can work on that between now and Pocono DE.

campbellcj · 07-06-2001, 08:18 PM

Another thought -- which is definitely a personal preference -- is to let a highly experienced instructor/racer take your car out for a couple of laps, with you riding shotgun.

If it's a big group then there's probably somebody else there with a similar car to yours whom you could trust to drive your baby and subsequently give you an honest account of anything noteworthy.

Chris

scca_ita · 07-06-2001, 09:09 PM

Keep off the curbs, turn in later and use the whole exit. You may have too much front suspension and not enough tire. The shoot takes balls. Just keep in it and let the car drift out to the exit, straighten your wheels then brake hard. The entry to 5 is not important just stay on the concrete. Turn 9 should be flat out in 3rd gear. Use the whole exit. Try turn 10 in 4th gear with a little tap on the brakes before tuning in, but turn in later.

So in general it sounds like your turning in too early. Dont turn in until you see the apex.

I raced summit for 8 years in the late 80s early 90s. Consistain 1:29s - 1:31s in an ITA golf 16v.

scca_ita · 07-06-2001, 09:09 PM

Keep off the curbs, turn in later and use the whole exit. You may have too much front suspension and not enough tire. The shoot takes balls. Just keep in it and let the car drift out to the exit, straighten your wheels then brake hard. The entry to 5 is not important just stay on the concrete. Turn 9 should be flat out in 3rd gear. Use the whole exit. Try turn 10 in 4th gear with a little tap on the brakes before tuning in, but turn in later.

So in general it sounds like your turning in too early. Dont turn in until you see the apex.

I raced summit for 8 years in the late 80s early 90s. Consistain 1:29s - 1:31s in an ITA golf 16v.

89911 · 07-07-2001, 12:50 AM

Hey, the guy is concerned about tires and your questioning his manhood.

I do understand where your coming from. Watkins Glen has esses on the start of the backstretch that initially you swear you can't get out of 3rd on. After a while you can stay in 4th and gently acclerate. After that you can be in 4th and keep the gas ALL the way down and not lift at all. The last stage take, Hmm, intestinal fortitude but it is where most of the ground is made up on that track. There is just little room for error and two concrete walls on either side. Sweeping turns can be intimidating because of the speeds and some tracks are worse then others because of the speeds. You have to be full of testosterone to turn good times at the "Glen".

------------------
8 9 9 1 1, The last of the line.

[This message has been edited by 89911 (edited 07-07-2001).]

patalive · 07-07-2001, 09:17 AM

tcampbell - -
-
Curious to know what DE you were running with - a Porsche club or other? If the PCA, which run group? Did you notice what which cars were leaving you behind in the sweepers. (I assume you are referring to turns 3, 4, 9 and 10.)
-
Are you saying that you were actually losing traction and drifting in these corners? Curious to know your technique for turn 4 and your exit speed on turn 10?
-
Turn 4 is probably the fastest and scarest turn at Summit - downhill, right hander - cars take this corner at anywhere from 90 to over 100. As soon as the car is settled, you must brake hard for T-5, a 30 mph throw away turn. To keep up with traffic, you must keep your foot in it thru turn 4, settle the car, and then brake. If your speed is up, you must keep on the gas, otherwise the the car feels very unsettled thru 4. Knowing that you must brake hard and slow WAAAAAAY down for 5, you might be lifting thru 4.????
-
Chuck
83SC

tcampbell · 07-07-2001, 07:36 PM

The event was PCA. First two days at Jefferson Circuit, the last at Summit Point Raceway. Based on the replies here and further discussions with some of the more experienced drivers in my PCA region (I currently run in blue--local region uses green, blue, white, red/black), it appears that I just need more seat time. In response to your questions, other cars overtaking me were 911's, not so much in turns 3 and 4 at Summit Point, but 6 and 7. Turns 4 and 5 at Jefferson Circuit also presented the same dilemma. The only thing I can really think of at this point is that I may have been approaching with slower entry speeds and accelerating through versus hotter entry. Orbmedia may have a valid point after all

patalive · 07-08-2001, 03:41 AM

Ah - the Summit Point Carousel, i.e., turns 5, 6, 7, 8 - tight corners. I suspect it is technique at play here. One challenge of the carousel is to come out on the proper line for turn 9, a high speed turn leading to a second longest straight. If you screw up 6, it's difficult to get back on line, with speed, thru 7 and 8 to get a good shot at 9. I really enjoy going from 6 to 7 - in second gear I am throttle steering, especially at turn in to 7 - - a hot day and good sticky track tires help here, particuarly if you are able to dial in sufficient negative camber for them.
-
I suspect that more "seat time" in these corners will lead to faster times.
-
chuck

Randy W · Randy W's Garage

Good suggestions regarding seat time. From what you have said, the mechanical side would likely be most improved with 225/245 R tires, but the limits are higher and the warnings more subtle. Sway bars will be more influential than shocks in steady state sweepers.

Randy Wells