NJ-GT Please explain this.
Thread Starter
Rennlist Member
Joined: Jul 2006
Posts: 4,296
Likes: 477
From: SE Mass
NJ-GT Please explain this.
And thank you. Just a little air under the right front. Got grip? I haz some.
Photo in by Dan Mull, BMW club pro photo. Takes pics at many autocross events and track events around here.
Photo in by Dan Mull, BMW club pro photo. Takes pics at many autocross events and track events around here.
Three Wheelin'
Joined: Oct 2003
Posts: 1,489
Likes: 17
Trending Topics
Rennlist Member
Joined: Sep 2006
Posts: 1,968
Likes: 0
From: Vancouver, BC, Canada
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Every Era of 911 Owner Explained in One Sentence
Verdad Gallardo
Thinking of Buying a Porsche? Do These 10 Things First
Joe Kucinski
Pixar Pals Turned Into 1-of-1 Porsches!
Michael S. Palmer
Theon Goes Full Carbon Fiber With Stunning New Build
Verdad Gallardo
Genius Porsche-Themed Gifts That'll Make Any Dad or Grad Smile
Joe Kucinski
10 Used Porsches Are Selling for Way Too Cheap
Joe Kucinski
Tuner Is Converting Porsche 911s Into Shooting Brakes
Verdad Gallardo
This Coachbuilt Creation Is A Modern Take on the Legendary Porsche 917
Verdad Gallardo
Is This Convertible Cayenne A Steal, Or A Returnless Investment?
Verdad Gallardo
Rennlist Member
Joined: Sep 2006
Posts: 1,968
Likes: 0
From: Vancouver, BC, Canada
Three Wheelin'
Joined: Oct 2003
Posts: 1,489
Likes: 17
At a bumpy site, if the course designer isn't careful, someone can get 4-wheel air.
I lost one event (came in second) because I got air and one boost hose came off
on landing, 2 corners from the end and the car went into limp mode.
I lost one event (came in second) because I got air and one boost hose came off
on landing, 2 corners from the end and the car went into limp mode.
Rennlist Member
Joined: Sep 2006
Posts: 1,968
Likes: 0
From: Vancouver, BC, Canada
Think Knight Rider turbo boost. 
...ok...maybe not.
Yes, it was a bit bumpy in places. This was a case of the local PCA chapter holding a weekend retreat in the interior of BC. The mall was kind enough to let us use their parking lot and it was bumpy, sloped, irregularly shaped and covered in grit. Definitely far from ideal. However, the course designer did a fantastic job with these challenges and made the most fun course I've ever driven.
I had worn Kumho V710 on the car and the grip was dicey most times on the slick surface. Add on bumps and the car was dancing on the edge of spinning most of the run. I was "in the zone" that day and had a blast. Parts were like this:
Heading into the stop box was a right and then left into the box. Doing the right turn at high speeds meant the rear of my car broke loose and started to slide. I had to drive in a way to get traction back and reel it in to make the left turn into the box without smacking a cone by going in sideways. It felt great to accomplish that.
Another time where the bumps showed up was when our guest speaker, Ross Bentley (Speed Secrets author), drove a 997 Cup car and that car was so stiffly sprung on the bumpy course it was hopping all over the place, even as much as a full car width sideways in the air. Ross really knows how to drive and kept it under control.
I gave Ross a ride on my last run and then tossed him the keys to my car. He promptly beat me by 0.5 seconds.
Cheers,
...ok...maybe not.
Yes, it was a bit bumpy in places. This was a case of the local PCA chapter holding a weekend retreat in the interior of BC. The mall was kind enough to let us use their parking lot and it was bumpy, sloped, irregularly shaped and covered in grit. Definitely far from ideal. However, the course designer did a fantastic job with these challenges and made the most fun course I've ever driven.I had worn Kumho V710 on the car and the grip was dicey most times on the slick surface. Add on bumps and the car was dancing on the edge of spinning most of the run. I was "in the zone" that day and had a blast. Parts were like this:
Heading into the stop box was a right and then left into the box. Doing the right turn at high speeds meant the rear of my car broke loose and started to slide. I had to drive in a way to get traction back and reel it in to make the left turn into the box without smacking a cone by going in sideways. It felt great to accomplish that.
Another time where the bumps showed up was when our guest speaker, Ross Bentley (Speed Secrets author), drove a 997 Cup car and that car was so stiffly sprung on the bumpy course it was hopping all over the place, even as much as a full car width sideways in the air. Ross really knows how to drive and kept it under control.
I gave Ross a ride on my last run and then tossed him the keys to my car. He promptly beat me by 0.5 seconds.
Cheers,
Addict
Rennlist Member
Rennlist Member
Joined: Jan 2003
Posts: 6,583
Likes: 12
From: Los Everglades
Some more air (my old GT3 on some sticky tires). My much better balanced Fiat lifts an inside front or an inside rear on transitions. Even the GT3 Cup running spring rates over 1500# lifts the front tires. I have seen this even in Formula 1 cars, and that's the top of suspension development of any racing, period.
You can minimize front wheel lift by increasing rear spring rates, but then you need to balance the front with stiffer rates as well, and eventually the car would be too stiff for road or autoX use.
You can minimize front wheel lift by increasing rear spring rates, but then you need to balance the front with stiffer rates as well, and eventually the car would be too stiff for road or autoX use.
Last edited by NJ-GT; Aug 13, 2013 at 10:18 AM.