Fast bumps slow bumps

[Petr Kantor]

Hello dear setup wizards,

I have another installment of questions regarding setups. This time about springs, and bumps.

After reading the RD setup guide and stuff, I'm confused in the terminology again.

For Springs, stiffer means more NM in the spring. Is it true that generally you want to run the springs as soft as possible, with increase only to keep car in ballance through various corners.

How can one judge a good spring settings?

Bumps Fast/slow, are in Race07 represented in just numbers. What means to stiffen bumps, does the number go up, or down, and by how much generally?

And how are the bumps connected with springs and perhaps anti roll bar in making the setup good?

Can you please elaborate from your perspective, what do you do when setting up a new setup, and what are the high/low settings you use for what kind of tracks?

Also, I'd like to know how to tell that I'm heading in the right direction with my setups, and perhaps what to do if I have a qualify setup and want to make a long race lasting one, what changes would I do ( i feel this applies almost generically on all qualify - race setups transitions).

I know I'm asking a lot, but one won't learn without asking will he?

Cheers, regards

Petr

 

[Marco Bijl]

i will leave this one for one of the setup guys to answer.

Do have to point out the Friendly Development series which is coming up. I am pretty sure it will be discussed there
Thread is still closed for entry, so keep an eye out for it to open.
Link here.

Did move the thread to the setup section though.

 

[Marian Zelenka]

Stiffer springs for high speed and less bumpy tracks with less corners. But Race07 is just a game and anything can work. Even though I've read lots of articles and explanations, it's still a trial and error for me.

Higher number = stiffer.

I never use a setup for qualification. I'm not that fast so I don't care. I gain places in races instead.

 

[Ariciuc Razvan]

Softer springs = more grip but also more skid = a bit slower. Stiffer springs should make you faster but only if you drive on the limit, if not they'll just make you loose control easier.

Bump/Rebound:
Slow (bump/rebound)= your steering input. Low value means that it takes more time for the spring to absorb or rebund giving you more grip or a more stable car over bumps (really depends on track and driving style).
Fast(Bump/rebound) = feedback from the track, level changes, bumps,curves, same ideea here as above.
This is what i understand but spring/bump/rebound are one of the hardest thing to set up properly cuz the changes are very small and they generaly show up in better times not feel (that's if you don't change them by more than 2 clicks). If you maxx them out (high/low) tha car will react very diferently.

"Dampers counteract the springs' natural compressing and decompressing by resisting those forces. Dampers do this via hydraulic fluids being pushed through small valves inside the damper while the damper is in motion. A higher damper value equates to greater resistance.

A wheel's maximum grip level will be achieved when the spring is fully compressed. This is when that wheel has maximum weight being transfered through the suspension, tire, and to the track. In a generic sense that weight equals grip. How quickly or slowly that spring is allowed to fully compress is the job of the damper. Springs may dictate HOW MUCH weight is transferred, dampers dictate HOW and WHEN that weight is transferred.

The easiest way to begin to understand dampers is in a straight line, under braking or acceleration:

Under braking, much of the car's weight will shift from the rear of the car to the front. The front springs will compress while the rear springs will decompress (or rebound). The dampers do the same and will compress (front) and decompress (rear). The faster the front springs are allowed to achieve their most-compressed state, the faster the front tires will have maximum grip for that all important braking. A softer compression setting will give the least amount of resistance to the spring compressing, allowing weight to transfer very quickly once the brakes are applied. The rear damper compression setting will have no effect on what happens here, but the rebound will. A greater rebound setting will resist against the rear springs decompressing. If the spring is not allowed to rebound quickly, the rear tires will be somewhat lifted off the ground (exaggerated of course). Softer rebound settings in the rear will allow the rear tires to stay connected with the road and offer more rear-grip during that weight transfer to the front.

Under straight-line acceleration the complete opposite is happening, with the rear dampers compressing and the front dampers decompressing. Surely you will want maximum grip on the rear tires under acceleration, but the front tires may need grip adjustments to prevent understeer oversteer. You can adjust this condition by adjusting how the rear suspension compresses or how the front suspension rebounds.

The same philosophy can be applied laterally (side to side) as well. Long sweeping corners that do not involve large braking or accelerating will shift weight to the left and right of the car. How fast you allow that weight to transfer is up to you and can be adjusted via the left and right dampers, but keep in mind how that will also effect your front to rear damping.

If your car is equipped with fast-damping adjustments, everything above still applies but only when the suspension is in "fast motion". An example of your suspension moving in fast-motion is when you are hopping over curbing, something I like to call "curb smacking". This is when you are shocking the suspension into movement in a very short time frame. Hitting a curb at speed (like you might at Monza, or the final chicane at Magny-Cours) is forcing your suspension to compress or rebound in a much shorter time frame than normal weight transitions. This is where fast-damping comes into the mix.", From setup developer by Tim McArthur.

P.S. like Marian said this is the theory, in practice god know what's best. The response i get to what's best is always this one : "What ever makes you feel comfortable"

 

[Rupe Wilson]

 

[Kirk Heath]

I have a similar question, Having watched BTCC and the Porsche support classes at Donington, I downloaded the True 2 Life Porsche Cup, and 2011 Donington Mod. Now when braking from 100m approaching the final chicane, and then turning in to hit the first curb, the car bounces uncontrollably and skips over the track or spins. Probably due to no weight over the front wheels, would anyone be kind to assist in a better set up for these?

 

[Alberto Casado]

I... True 2 Life Porsche Cup, and 2011 Donington Mod. Now when braking from 100m approaching the final chicane, and then turning in to hit the first curb, the car bounces uncontrollably

I think the bold part defines very accurately the feeling of those porsches, I am afraid you cannot do much to cure that.

 

[Kirk Heath]

Not sure Alberto, watching the real ones, they get through fine, even if I slow right down they spin out. I am using the default set up though.
I will have to try with WTCC cars, if you have these add ons, would you mind seeing what results you get as well?

 

[UMC 22]

Now when braking from 100m approaching the final chicane, and then turning in to hit the first curb, the car bounces uncontrollably and skips over the track or spins.

All cars 'bounce' a lot at that point of the Donington 2011 mod. Brake earlier and take the chicane slower and you'll be fine. Avoid hitting the curbs as they almost always cause a spin, even in FWD cars.

 

[Hiroshi Awazu]

I have a similar question, Having watched BTCC and the Porsche support classes at Donington, I downloaded the True 2 Life Porsche Cup, and 2011 Donington Mod. Now when braking from 100m approaching the final chicane, and then turning in to hit the first curb, the car bounces uncontrollably and skips over the track or spins. Probably due to no weight over the front wheels, would anyone be kind to assist in a better set up for these?

I was having the same problem at Istanbul while following Dennis Phelan around one night. He suggested to me to set brake bias to 63/37, that took care of the spinning part, as for the bouncing i'm very poor at car setup so i can't suggest anything there.

 

[Kennett Ylitalo]

There's basically four kinds of "bouncing".

One is where the damper are set too soft so that the springs start to oscillate.
The second is where the springrate is set too low and the car starts to bottom out either hitting the ground or hitting the limits of suspension travel.
The third bounce is where the springs and dampers are set too tight and the car start to hover over bumbs.
Fourth is when the car is transferring so much weight on front tires that the other tires start to lose their grip. This phenomenon is accentuated if the bounce happens only in the initial turning phase just before the apex when the load on the outside front tire is greatest. Inside wheels start to loose grip because of unloading, all the weight and need for grip is transferred to the outside wheel, the laws of physics steps in and the outside tire starts to slip; it looses grip, weight is transferred back to inside wheels, they loose grip and so on, the car starts twitching and skipping. Too low/high antiroll bar is the case combined with poor suspension settings. Rarest of them all since it needs a lot of variables combined for it to happen. It also feels mostly like twitching and sliding not bouncing.

Also any combination of too tight springs on the rear/too soft on front combined with too tight rebound on rear/too soft bound on front, ie any kind extreme unbalance causes unpredictable behavior.

Finding out what is the cause is not always easy... Experimentation and experience is the only key. Telemetry analyze with MoTec can help if you're able to read the info correctly. Bottoming is easiest to find, if you start to tighten the springs one click at a time the problem should go away. Oscillation can be found on the straights, if the car bounces a lot after it hits the bumb, tighten dampers. Hovering feels mostly like lo-grip conditions.

EDIT: Oh yeah, one tip i got from a real life racer: if the car spins from the curbs, lower rebound settings, both fast and slow. From my experience, start with the rear fast rebound.

 

[Ray Lilley]

This site has some great articles in it's archives http://www.autospeed.com. Use the search feature to find other setup factors.

As for springs try this 'More Than Just Bounce' piece... http://www.autospeed.com/cms/A_112686/article.html
..Springs And Natural Frequencies ..http://www.autospeed.com/cms/A_112279/article.html and so much more.
Make note of the piece that tells you how the spring rate determines how much travel you will get between Bump & Rebound. ie. the higher the car sits the less shaft left in Rebound. Something I never considered.

I have read many and they make good sense. I just have to understand what the car is doing before I can make use of this information. Many more hundreds of miles to do before that will happen :-(