Bass GT3

RR,

If it's a straight line issue, remove the rear spoiler wedges, if fitted and see how it goes. As NJ-GT says, it might be worth dropping the nose of the car a few millimeters if that does not work. Normally, i would expect the car to fel well planted at these speeds in a straight line.

regards,

Steve

AW

Have you changed the tow settings? My C4S is setup with 0d tow and while it helps in corners, it makes the car unstable in straights. Also, what you describe could be caused by some bump steer issue. Have you lowered the car?

I would definitely take it to a local suspension expert and describe the symptoms.

AW

mds

I agree, my GT3 did the same thing with 0 toe, so check your front toe setting. A small amount of toe in (5 minutes total or 0.05 degrees per side) will help on the straights with no loss of handling in the corners, IMO.

Bob Rouleau

RR - With a pair of GT3's in the family, both driven by instructors, I can report no light front end at speeds up to 235 KPH. Cars have the wing at the neurtal position, sway bars one off full stiff in front, two off full stiff in back. Std ride height and a four wheel track alignment (neg 2.5 deg).

My experience has been that a perceived "light front end" can be caused by incorrect alignment front or rear. Since we have seen that most GT3's arrive with incorrect alignment this may be your problem. A second possibility is a loose or damaged splitter. A friend of mine reported the same symptoms as you. He was at Mosport and saw about 240 on the back straight. The black plastic lip on his car is damaged and at that speed it doesn't take much to upset the balance of the car. He had scraped it an broke off a piece about ten inches wide. Since the darn things scrape easily damage is possible. I had a bit of front end float and it took a black flag to alert me to the fact that the plastic rivets holding the splitter in place had come off causing the lip to flap in the wind. A couple of zip ties fixed it. Let me know if this helps.

Best,

yongster

RR,

It's the spoiler that was on my car when it was at DFC (can buy it from Porsche Motorsport in California for about $115 US). Did Brian put on the 8 degree shims?

Z06

Bob,

On the rear is it not stock 1 from full stiff?.....If you did change it what did you find that you liked better?

cosmos

I am curious with how many holes do you consider "off" I was told that you cant use the last hole? Let me ask you this...how many holes are there in the rear bar, and how many holes from the end holes do you have your bar set at to be "two off from full stiff" rear??

Bob Rouleau

Z06 and Cosmos - Full stiff has the bar closest to the floor pan of the car. Stock setting is one hole down from there front and rear. As I recall there are 5 holes in front and four in back. I softened the rear bar one hole to reduce power-on oversteer on certain turns at the track I use most. It allows me to get on the gas earlier, besides I dislike having to countersteer at over 100 MPH. It has a second benefit in allowing me to trail brake a little more without over-rotating the car.

cosmos

Bob,

Do you get low speed understeer??

geoffucla

The best cure that I've found for low speed understeer is simply to open the wheel up a bit and lift--that gets the car rotated very well with minimal effort. Just be sure to apply the accelerator when it's rotated enough!

Geoff.

Bob Rouleau

Cosmos - Yes, I get low speed understeer - it is a characteristic of the 911 after all. I had it with the stock set-up too. The usual solution is to trail brake to make the car rotate properly. Geoff (above) suggests another method which is appropriate to some turns. His "lift" transfers weight to the front tires although more subtly than trail braking. This works well at corner entry for faster corners.

A 911 understeers in low speed corners so as to be neutral in high speed corners. If you set the car up to be neutral in slow corners (you can do this) you'll have oversteer in the fast ones. Few drivers like a car that oversteers at high speed. My softer rear sway bar means that I have to hold the brakes a touch longer to rotate the car in slow corners -which is no big deal. On the other hand I can apply power sooner in high speed corners and exit going faster which is an advantage at my favorite track. The setup is probably wrong for different circuits but it works for me on Le Circuit Mont Tremblant. It has one further advantage which came from a suggestion on the Racing/DE forum. By introducing a bit more understeer I can trail brake more for medium speed corners which after some practice shaved a couple of tenths off my lap time. The idea was put forth by Chris at Premier Motorsports - a certified "hot shoe" in 911's.

Lastly, and this is probably not your case, a common reason for complaints about low speed understeer is a going into a corner too slowly. The driver then decides to pick up the pace by accelerating before the apex - which causes understeer. Often the solution is to enter going faster and maintain a constant velocity til the apex.

Best,

cosmos

Just so I am clear, you are on hole 3 of four from the ends of the bar. Or one off from full soft.

Bob Rouleau

Cos - It's too dusty to go look under the car right now. If I remember right, the rear sway bar has four mounting holes. The factory config is the rear bar is one hole from the very top. Mine is one hole down from that. Counting holes starting from the one closest to the body of the car, my rear bar is in the 3rd hole down. Does this make sense? My car is in the garage at the office and the floor is way too dusty to crawl under it.

Best,

NJ-GT

We always call the hole closest to the bar (the stiffest one) #1.

Front sway bar comes with 5 holes and rear one with 4 holes.

I run full soft front and full soft rear for autocross (#5 front, #4 rear). We autocross on bumpy lots.

The stock setup is #2 front and rear.

I found the same problem that Bob had in his car at Watkins Glen. When applying power on high speed turns the car was breaking loose on the rear end. Then I tried the 1 from full soft rear (#3) and 1 from full stiff front (#2) and got to enjoy the car better. Finally, I went full stiff front (#1) and 1 from full stiff rear (#2), and the car feels even better. I have been using that setup since August at every track day.

Phokaioglaukos

What setting do you use on the street? The same as for track days?