nomis3613
Premium
- 831
Hi,
Here's some food for thought about dampers:
1) Are damper settings backwards for (understeer and oversteer), like the springs are?
No dampers are not “backwards” in either how they react to bumps, or how they affect weight transfer.
(anyway I prefer to set springs according to the car's weight distribution and not using them to tune general under/oversteer, so to me it doesn't matter whether the springs are backwards in their balance effect or not)
2) How does damper setting affect the car's behavior over bumps?
The dampers affect how much grip is lost by the "impact" of striking the rough surface. If the dampers are tuned correctly, there will be no grip lost from the impact (however often the "bump" is part of a lower grip surface (eg a kerb) so the car will have less grip because driving over a kerb has less grip than the road).
3) What's the difference between bound and rebound for bumps?
Bound affects how much grip is lost in the initial impact, and rebound is how long it takes for the car to get back to full grip afterwards.
If the bound is too stiff, the bump will cause the whole car to be lifted upwards- an ideal bound setting causes just the suspension to lift and the body remains level.
If the rebound is too stiff, the wheel will “hang in the air” instead of returning to the road, causing a loss of grip. (the more technical explanation is that the suspension needs to extend after the crest of the bump, to maintain the contact patch).
4) If the above bad effects only occur when the damper settings are too stiff, does this mean you should you use the minimum damper settings for bumpy tracks?
No. Real life theory says that for a given spring rate, there is a damper stiffness required to best control the wheel movement, resulting in the least loss of grip. I believe GT4 models this correctly. However, if you are running stiff springs, it is most likely that even without the damper, the springs are too stiff to follow the bumps of the road. Try softening the springs first.
As for the benefits of stiffer dampers, see question 7. Also, stiffer dampers give a quicker repsonse to inputs (such as steering), so the car feels tighter and more responsive.
5) Should rebound be 3-4 times bound, like the scrolling text says?
I have found that even if the rebound setting is slightly higher than the bound (and the bound is set correctly), the wheel will not hang in the air after a bump. I do not believe the difference is 3-4 times, though, more like 2-3 clicks.
6) Should the dampers be tuned based on the spring stiffness (like real life)?
Hmmm... tricky question. I prefer to set the ratio of front to rear spring rate purely based on the car's static weight distribution, therefore I do not tweak the spring stiffness to match the dampers or vice versa. My preference is to set the overall spring stiffness (eg 2.5/2.0 vs 10/8) based on a compromise between body movement (braking dive and roll stiffness) and harshness over bumps. Then I use the dampers to fine tune the bump response and weight transfer. The short answer is no, if I double the spring stiffness, I will not automatically double the dampers- however I will check how the dampers behave with the new spring setting.
7) Soooo... I've heard dampers have other effects, like weight transfer during cornering/braking/accelerating?
Yep, there are 2 ways dampers effect handling, and sometimes they have the opposite effect. The effects are caused by 1) forward/backward weight transfer and 2) roll stiffness (where the dampers act like stabilisers). Also, the dampers only effect while the car suspension is moving (eg while the weight is moving forward as start to brake). Once the weight transfer is complete (eg later in the braking, once the noise is pointing downward at a constant angle), then the dampers have no effect.
Front Bound: increase this to reduce entry understeer, increasing also increases understeer in general (yes, it's self-contradictory- so if you have entry understeer you'd need to increase the front bound, then use some other setting to reduce the understeer in general)
Front Rebound: increase this to reduce exit oversteer, increasing also reduces oversteer in general
Rear Bound: increase this to reduce exit understeer, increasing also reduces understeer in general
Rear Rebound: increase this to reduce enty understeer, increasing also reduces understeer in general.
8) General tuning strategy
In my opinion, the most important function of the dampers is to hold the tyres on the road over bumps. If bumps are an issue, I'd be tuning the dampers solely to cope with the bumps best, and then use stabilisers etc to fix the handling balance. However if the track is smooth, then the dampers can be used for the weight transfer.
9) Disclaimer
I've based the bump response stuff from testing the Caterham (so you can easily see the suspension travel) at Nurburgring. The weight transfer testing was done using the Vantage at High Speed Ring, same as Sukerkin's method here. Sorry, I don't have lap times to campre, I think the feel of the car and comparing the lines with the ghost car gives better the results than lap times (which are highly influenced by inconsistent driving between runs).
Yes, at this stage the theory is based on 2 FR cars only at this stage.
Here's my original OP below (so the first few replies can be read in context)
---
1) Are damper settings backwards for (understeer and oversteer), like the springs are?
No dampers are not backwards. But the effect of dampers on overall balance is so minimal that it doesn't matter much anyway. Spring rates and stabilisers are far more effective at fixing balance problems.
2) How does damper setting affect the car's behavior over bumps?
The dampers affect how much grip is lost by the "impact" of striking the rough surface. If the dampers are tuned correctly, there will be no grip lost from the impact (however often the "bump" is part of a lower grip surface (eg a kerb) so the car will have less grip because driving over a kerb has less grip than the road).
3) What's the difference between bound and rebound?
My current theory is that bound affects how much grip is lost in the initial impact, and rebound is how long it takes for the car to get back to full grip afterwards (but whatever the effect is, it is very subtle so I'm still doubtful about this one)
4) Should rebound be 3-4 times bound, like the scrolling text says?
Again, the effect is so small, that it is hard to tell. On bumpy tracks, I found that softer suspension (both bound and rebound) gave the best results. For smooth tracks, again I found no benefit in using the 3-4 times rule. So I think the text is either wrong, or the effect is negligable. Or maybe this is true for the physical strength (eg damping force divided by shaft velocity), but the game already compensates for this in the values given in the slider. Maybe, maybe not.
5) Should the dampers be tuned based on the spring stiffness (like real life)?
No. In every case, I found that the softest dampers produced the smallest loss of grip over bumps. In technical jargon, this means that there is no such thing as an underdamped spring in GT4. Also, softer dampers mean the car turns better when the brakes are released (compared with stiffer dampers) at the start of a hairpin etc.
6) So the dampers should always be set to the minimum then?
Mostly. The biggest effect of dampers I found was the speed of the forward weight transfer for MR and RR cars (lift-off oversteer- how these cars want to spin out when you lift off the accelerator while turning). The important thing is that the dampers don't affect how strong the lift-off oversteer is, but how quickly it all happens. Softer dampers cause it to happen more slowly (which on one hand can give you time to correct the slide, but on the other hand by the time you notice it then it's too late). Stiffer dampers cause a more immediate loss of rear grip (so the sliding rear won't creep up on you, but maybe it will happen too quickly anyway).
The actual amount of lift-off oversteer can be reduced with stiffer rear springs (yes it sounds strange, but ask any 911 owner), the dampers only affect how quickly it all happens.
For cars without weight transfer problems (most FR and FF cars) then yeah I can't see any benefit in stiffer dampers. Softer dampers mean more turn-in and you'll be less disturbed by any bumps/kerbs you happen to meet.
Here's some food for thought about dampers:
1) Are damper settings backwards for (understeer and oversteer), like the springs are?
No dampers are not “backwards” in either how they react to bumps, or how they affect weight transfer.
(anyway I prefer to set springs according to the car's weight distribution and not using them to tune general under/oversteer, so to me it doesn't matter whether the springs are backwards in their balance effect or not)
2) How does damper setting affect the car's behavior over bumps?
The dampers affect how much grip is lost by the "impact" of striking the rough surface. If the dampers are tuned correctly, there will be no grip lost from the impact (however often the "bump" is part of a lower grip surface (eg a kerb) so the car will have less grip because driving over a kerb has less grip than the road).
3) What's the difference between bound and rebound for bumps?
Bound affects how much grip is lost in the initial impact, and rebound is how long it takes for the car to get back to full grip afterwards.
If the bound is too stiff, the bump will cause the whole car to be lifted upwards- an ideal bound setting causes just the suspension to lift and the body remains level.
If the rebound is too stiff, the wheel will “hang in the air” instead of returning to the road, causing a loss of grip. (the more technical explanation is that the suspension needs to extend after the crest of the bump, to maintain the contact patch).
4) If the above bad effects only occur when the damper settings are too stiff, does this mean you should you use the minimum damper settings for bumpy tracks?
No. Real life theory says that for a given spring rate, there is a damper stiffness required to best control the wheel movement, resulting in the least loss of grip. I believe GT4 models this correctly. However, if you are running stiff springs, it is most likely that even without the damper, the springs are too stiff to follow the bumps of the road. Try softening the springs first.
As for the benefits of stiffer dampers, see question 7. Also, stiffer dampers give a quicker repsonse to inputs (such as steering), so the car feels tighter and more responsive.
5) Should rebound be 3-4 times bound, like the scrolling text says?
I have found that even if the rebound setting is slightly higher than the bound (and the bound is set correctly), the wheel will not hang in the air after a bump. I do not believe the difference is 3-4 times, though, more like 2-3 clicks.
6) Should the dampers be tuned based on the spring stiffness (like real life)?
Hmmm... tricky question. I prefer to set the ratio of front to rear spring rate purely based on the car's static weight distribution, therefore I do not tweak the spring stiffness to match the dampers or vice versa. My preference is to set the overall spring stiffness (eg 2.5/2.0 vs 10/8) based on a compromise between body movement (braking dive and roll stiffness) and harshness over bumps. Then I use the dampers to fine tune the bump response and weight transfer. The short answer is no, if I double the spring stiffness, I will not automatically double the dampers- however I will check how the dampers behave with the new spring setting.
7) Soooo... I've heard dampers have other effects, like weight transfer during cornering/braking/accelerating?
Yep, there are 2 ways dampers effect handling, and sometimes they have the opposite effect. The effects are caused by 1) forward/backward weight transfer and 2) roll stiffness (where the dampers act like stabilisers). Also, the dampers only effect while the car suspension is moving (eg while the weight is moving forward as start to brake). Once the weight transfer is complete (eg later in the braking, once the noise is pointing downward at a constant angle), then the dampers have no effect.
Front Bound: increase this to reduce entry understeer, increasing also increases understeer in general (yes, it's self-contradictory- so if you have entry understeer you'd need to increase the front bound, then use some other setting to reduce the understeer in general)
Front Rebound: increase this to reduce exit oversteer, increasing also reduces oversteer in general
Rear Bound: increase this to reduce exit understeer, increasing also reduces understeer in general
Rear Rebound: increase this to reduce enty understeer, increasing also reduces understeer in general.
8) General tuning strategy
In my opinion, the most important function of the dampers is to hold the tyres on the road over bumps. If bumps are an issue, I'd be tuning the dampers solely to cope with the bumps best, and then use stabilisers etc to fix the handling balance. However if the track is smooth, then the dampers can be used for the weight transfer.
9) Disclaimer
I've based the bump response stuff from testing the Caterham (so you can easily see the suspension travel) at Nurburgring. The weight transfer testing was done using the Vantage at High Speed Ring, same as Sukerkin's method here. Sorry, I don't have lap times to campre, I think the feel of the car and comparing the lines with the ghost car gives better the results than lap times (which are highly influenced by inconsistent driving between runs).
Yes, at this stage the theory is based on 2 FR cars only at this stage.
Here's my original OP below (so the first few replies can be read in context)
---
1) Are damper settings backwards for (understeer and oversteer), like the springs are?
No dampers are not backwards. But the effect of dampers on overall balance is so minimal that it doesn't matter much anyway. Spring rates and stabilisers are far more effective at fixing balance problems.
2) How does damper setting affect the car's behavior over bumps?
The dampers affect how much grip is lost by the "impact" of striking the rough surface. If the dampers are tuned correctly, there will be no grip lost from the impact (however often the "bump" is part of a lower grip surface (eg a kerb) so the car will have less grip because driving over a kerb has less grip than the road).
3) What's the difference between bound and rebound?
My current theory is that bound affects how much grip is lost in the initial impact, and rebound is how long it takes for the car to get back to full grip afterwards (but whatever the effect is, it is very subtle so I'm still doubtful about this one)
4) Should rebound be 3-4 times bound, like the scrolling text says?
Again, the effect is so small, that it is hard to tell. On bumpy tracks, I found that softer suspension (both bound and rebound) gave the best results. For smooth tracks, again I found no benefit in using the 3-4 times rule. So I think the text is either wrong, or the effect is negligable. Or maybe this is true for the physical strength (eg damping force divided by shaft velocity), but the game already compensates for this in the values given in the slider. Maybe, maybe not.
5) Should the dampers be tuned based on the spring stiffness (like real life)?
No. In every case, I found that the softest dampers produced the smallest loss of grip over bumps. In technical jargon, this means that there is no such thing as an underdamped spring in GT4. Also, softer dampers mean the car turns better when the brakes are released (compared with stiffer dampers) at the start of a hairpin etc.
6) So the dampers should always be set to the minimum then?
Mostly. The biggest effect of dampers I found was the speed of the forward weight transfer for MR and RR cars (lift-off oversteer- how these cars want to spin out when you lift off the accelerator while turning). The important thing is that the dampers don't affect how strong the lift-off oversteer is, but how quickly it all happens. Softer dampers cause it to happen more slowly (which on one hand can give you time to correct the slide, but on the other hand by the time you notice it then it's too late). Stiffer dampers cause a more immediate loss of rear grip (so the sliding rear won't creep up on you, but maybe it will happen too quickly anyway).
The actual amount of lift-off oversteer can be reduced with stiffer rear springs (yes it sounds strange, but ask any 911 owner), the dampers only affect how quickly it all happens.
For cars without weight transfer problems (most FR and FF cars) then yeah I can't see any benefit in stiffer dampers. Softer dampers mean more turn-in and you'll be less disturbed by any bumps/kerbs you happen to meet.
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