Pics of body roll?
07-04-2002, 04:35 PM
#1
Nordschleife Master
Thread Starter
Pics of body roll?
Curious to see pics of body roll of 951's with different suspension setups...and stock suspensions...
Here's one of mine
<a href="http://members.rennlist.com/adrial/almost%20wheel%20lift.jpg" target="_blank">http://members.rennlist.com/adrial/almost%20wheel%20lift.jpg</a>
and another:
<a href="http://www.metronypca.org/autocross/Autocross2K2/Events2002/Nassau6-30-02/yarihkirchen.html" target="_blank">http://www.metronypca.org/autocross/Autocross2K2/Events2002/Nassau6-30-02/yarihkirc hen.html</a>
Here's one under heavy braking:
<a href="http://www.eden.rutgers.edu/~yarin/Picts/944%20nose%20dive.jpg" target="_blank">http://www.eden.rutgers.edu/~yarin/Picts/944%20nose%20dive.jpg</a>
I've noticed that it really depends on where you are in the corner...so multiple pics would help us get an idea.
Mods listed below...
Here's one of mine
<a href="http://members.rennlist.com/adrial/almost%20wheel%20lift.jpg" target="_blank">http://members.rennlist.com/adrial/almost%20wheel%20lift.jpg</a>
and another:
<a href="http://www.metronypca.org/autocross/Autocross2K2/Events2002/Nassau6-30-02/yarihkirchen.html" target="_blank">http://www.metronypca.org/autocross/Autocross2K2/Events2002/Nassau6-30-02/yarihkirc hen.html</a>
Here's one under heavy braking:
<a href="http://www.eden.rutgers.edu/~yarin/Picts/944%20nose%20dive.jpg" target="_blank">http://www.eden.rutgers.edu/~yarin/Picts/944%20nose%20dive.jpg</a>
I've noticed that it really depends on where you are in the corner...so multiple pics would help us get an idea.
Mods listed below...
07-04-2002, 06:36 PM
#4
Two at almost the same place. Once me, then my racing mechanic, about 20 mph faster. The car has stock Turbo Cup suspension, and is STIFF. Speed is about 60 Mph at this place, and the curve is pretty tight, on to the main straight.
[IMG]<a href="http://boards.rennlist.com/upload/DSC00489-8X6.JPG" target="_blank">http://boards.rennlist.com/upload/DSC00489-8X6.JPG</a>[/IMG]
[IMG]<a href="http://boards.rennlist.com/upload/DSC00492-8X6.JPG" target="_blank">http://boards.rennlist.com/upload/DSC00492-8X6.JPG</a>[/IMG]
GeorgeK
[IMG]<a href="http://boards.rennlist.com/upload/DSC00489-8X6.JPG" target="_blank">http://boards.rennlist.com/upload/DSC00489-8X6.JPG</a>[/IMG]
[IMG]<a href="http://boards.rennlist.com/upload/DSC00492-8X6.JPG" target="_blank">http://boards.rennlist.com/upload/DSC00492-8X6.JPG</a>[/IMG]
GeorgeK
07-04-2002, 10:48 PM
#5
Race Director
Here's one of a stock TurboS, which supposedly has a stiffer suspension than the standard Turbo:
I recall the magazine testers mentioning that the car would rub its rocker-panels on the ground. Another article comparing the 944/944S/951 said that the Turbo would rub its tires on the fenders under cornering.
Here's my car with the following configuration:
- 200lb/in front springs
- stock 23.5mm torsion-bars
- stock shocks
- 968 M030 swaybars (rear set to full soft)
As you can see, the body rolls is much, much less than the stock TurboS:
And the final incarnation of suspension upgrades:
- even stiffer 350lb/in front springs
- 25.5mm torsion-bars
- Bilstein shocks
- Weltmeister swaybars (front full-stiff, rear medium-stiff)
The body-roll has been eliminated completely as can be seen through this sequence showing entry, mid-corner and exit:
I've lined up the photos so the same points of the track coincide vertically. Compared to the last BMW M3, my car leans a lot less. As you can see from the entry and mid-corner phtos, the BMW does that stink-bug tail in the air dive on the corner-entry with lots of body lean in mid-corner.
However, that didn't help me keep up with that BMW, which was 10-seconds /lap faster! Ok, I can take off about 3-seconds for the passenger and another 4-seconds for race-tires. But you can't really match a double-wishbone, 5-link rising-rate suspension set-up like in the BMW with McPherson struts and trailing-arms. The BMW rides smooooothly too!
Remember, that reducing body-lean does nothing for weight-transfer; which is only based upon the car's center-of-gravity height, track-width, and cornering-G. If you weld the suspension solid so that there's no body-lean at all, you'll still have the same amount of weight-transfer to the outside wheels (there's only a minor contribution from C.O.G. shift).
What you are accomplishing by stiffening up the supension is reducing detrimental camber change. As the body rolls, it dials in positive camber on the outside wheels. Sure, there's some negative camber resulting from the suspension compression, but it doesn't make for anywhere near enough to compensate for the positive camber from the body-lean. By stiffening up the body-roll (through springs and/or swaybars), you'll keep the outisde tires more vertical to the road and get more grip. But then you'll lose grip in the bumpy corners because you'll be bouncing off them... So it's a compromise with our cars.
If you had a double-wishbone or multi-link suspension like the BMW on the other hand, you can customize the camber-change curve under body-roll such that the tire will always remain vertical regardless of how much body-roll you have (well, most of the time). In which case, you can maximize cornering-grip with ride-comfort as well.
I recall the magazine testers mentioning that the car would rub its rocker-panels on the ground. Another article comparing the 944/944S/951 said that the Turbo would rub its tires on the fenders under cornering.
Here's my car with the following configuration:
- 200lb/in front springs
- stock 23.5mm torsion-bars
- stock shocks
- 968 M030 swaybars (rear set to full soft)
As you can see, the body rolls is much, much less than the stock TurboS:
And the final incarnation of suspension upgrades:
- even stiffer 350lb/in front springs
- 25.5mm torsion-bars
- Bilstein shocks
- Weltmeister swaybars (front full-stiff, rear medium-stiff)
The body-roll has been eliminated completely as can be seen through this sequence showing entry, mid-corner and exit:
I've lined up the photos so the same points of the track coincide vertically. Compared to the last BMW M3, my car leans a lot less. As you can see from the entry and mid-corner phtos, the BMW does that stink-bug tail in the air dive on the corner-entry with lots of body lean in mid-corner.
However, that didn't help me keep up with that BMW, which was 10-seconds /lap faster! Ok, I can take off about 3-seconds for the passenger and another 4-seconds for race-tires. But you can't really match a double-wishbone, 5-link rising-rate suspension set-up like in the BMW with McPherson struts and trailing-arms. The BMW rides smooooothly too!
Remember, that reducing body-lean does nothing for weight-transfer; which is only based upon the car's center-of-gravity height, track-width, and cornering-G. If you weld the suspension solid so that there's no body-lean at all, you'll still have the same amount of weight-transfer to the outside wheels (there's only a minor contribution from C.O.G. shift).
What you are accomplishing by stiffening up the supension is reducing detrimental camber change. As the body rolls, it dials in positive camber on the outside wheels. Sure, there's some negative camber resulting from the suspension compression, but it doesn't make for anywhere near enough to compensate for the positive camber from the body-lean. By stiffening up the body-roll (through springs and/or swaybars), you'll keep the outisde tires more vertical to the road and get more grip. But then you'll lose grip in the bumpy corners because you'll be bouncing off them... So it's a compromise with our cars.
If you had a double-wishbone or multi-link suspension like the BMW on the other hand, you can customize the camber-change curve under body-roll such that the tire will always remain vertical regardless of how much body-roll you have (well, most of the time). In which case, you can maximize cornering-grip with ride-comfort as well.