How do I know I bottom out

  • Thread starter Enzo_
  • 10 comments
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Hi,
Based on the various guide i see here, (very interesting btw). I'm trying to tune my car a BMW M3 CSL and I would like to see when I bottom out, i expect to see some spark at the rear of the car. For this I lower the ride height to 63mm F&R and run on Nurburgring and guess what : I see nothing ? (i test only on the first quarter of the track).
what did i miss ? i either try to see by looking backward during the run or during replay.

thanks,
regards
Enzo
 
How does softening the spring rate tell him if the car is bottoming out or not?

It is quite hard to tell in most cars without race-designed diffusers or undertrays, as these are what cause the sparks that some cars produce when they bottom out. Almost all cars will show sparks, but only if they are hitting the ground quite hard - a light knock might not be obvious. It is quite possible that your M3 isn't bottoming out at all, but the best way to tell is to try and interpret the feedback you get from your controller - being a DS2 driver, I never had the easiest time with this, but if you feel short, sharp vibrations coinciding with the car shifting slightly to one side, this is most likely caused by bottoming out.

I suppose one way of learning how to feel it would be to take a very low, very soft race car (one that will easily produce sparks) and watch your rear-view mirror (If sparks show in that, I actually can't remember any more) for sparks. When you see them, remember what the controller was doing at the time, and you should be able to 'read' what the car is doing from your feedback. :)

DE
 
OK, thanks for your advices :)

Actually, in most of the car's setting i've seen here, the ride height is always above the possible minimum except may be for race car. As it is my understanding that ride height should be as low as possible (may be i'm wrong ?) I wanted to understand why the ride height was set quite high as I didn't see any fact of bottoming out at a lower ride height.

regards,
Enzo
 
The ride height on some settings is set higher than minimum to allow for softer suspension. Indeed, a car that is lower, with harder suspension handles best on perfect roads, but on bumpy courses such as the Nurburgring, people apply a softer suspension setting so the car can move around on it's suspension a bit and still stay totally connected to the road. A softer suspension is usually coupled with a higher ride height to prevent bottoming out, as it can cause irregular movements that may lead to loss of control.
 
The ride height on some settings is set higher than minimum to allow for softer suspension. Indeed, a car that is lower, with harder suspension handles best on perfect roads, but on bumpy courses such as the Nurburgring, people apply a softer suspension setting so the car can move around on it's suspension a bit and still stay totally connected to the road. A softer suspension is usually coupled with a higher ride height to prevent bottoming out, as it can cause irregular movements that may lead to loss of control.

ea11r is right i ve bottomed out on the ring one too many times and sheesh it was a wild ride
 
hello enzo... I usually run a seperate set-up for fun stuff like burnouts,drift shots, and de sparks. A soft chassis set-up, including springs,shocks, and ride height should get it done. My M3 CSL is one of my best production racers, and I haven't tried it on mine, but that should do the trick.
If the ring doesn't get it, try running de sarthe at high speed on the straightaway - I get lucky there too sometimes - good luck and hope it helps
 
I tried all of my set-up tricks on my M3 CSL, and couldn't get spark one except off of the rumble strips. I guess the ultimate driving machine was designed too well maybe. good luck.
 

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