Understanding dampers and springs???
Discussion
Can anyone explain how a damper makes a car feel?!? I know what they do but how would you know if u increased a spring say from 225lb to 400lb - how would u know if the damper was up to it or needed to be firmer? And visa-versa?
I have track car an there is so much info on which spring rates to go for and which are the best dampers. I already have coilovers and can obviously feel the increased stiffness over OE springs and dampers, but I just want to know if there are any tests or rules of thumb or anything so I can differentiate between the feeling and performance from the springs (and torsion bars in my case) and the dampers!
Sorry for long winded post but it's hard to explain.
Another way to summarise it is, somebody asked me how the dampers were performing (in my new coilovers) - no idea was my answer!
I have track car an there is so much info on which spring rates to go for and which are the best dampers. I already have coilovers and can obviously feel the increased stiffness over OE springs and dampers, but I just want to know if there are any tests or rules of thumb or anything so I can differentiate between the feeling and performance from the springs (and torsion bars in my case) and the dampers!
Sorry for long winded post but it's hard to explain.
Another way to summarise it is, somebody asked me how the dampers were performing (in my new coilovers) - no idea was my answer!
no simple answer.
there are formulas for calculating the ride frequency is a given car/spring setup, and from this you can then calculate the required critical damper curves, HOWEVER!
this is only gong to be a start point for a track car, it's really down to having a driver that can identify what's going on (as in test driver).
there are formulas for calculating the ride frequency is a given car/spring setup, and from this you can then calculate the required critical damper curves, HOWEVER!
this is only gong to be a start point for a track car, it's really down to having a driver that can identify what's going on (as in test driver).
If it's underdamped it'll feel bouncy and floaty, if overdamped it'll feel skittery because the wheel will be slow to return to the neutral position and will skip over bumps instead of remaining in contact with the road surface. Might be tricky to tell if your suspension is rock hard, though.
The answer's in what you already know through common sense really. The springs will give the car initial resistance in response to impulse and load, such as bumps in the road, dive and squat under braking and acceleration, and cornering loads. The dampers will control the way the springs bounce up and down. Simple as that really. A stiffly sprung car will jiggle over bumps and not roll much through corners, and a softly sprung car will do the opposite. A softly damped car will bounce around after an initial load to the springs, for instance from a bump or from cornering.
There's a lot more to it than that of course...
I would really love to know more about setting cars up and the various effects. Does anyone know of a course you can go on, trying different settings on a car perhaps and learning about them? When I'm testing if I want to change something on the car I'm not always that confident what I need to change and what effect it'll have. Springs, ARBs, dampers, tyre pressures, toe and rake mainly.
There's a lot more to it than that of course...
I would really love to know more about setting cars up and the various effects. Does anyone know of a course you can go on, trying different settings on a car perhaps and learning about them? When I'm testing if I want to change something on the car I'm not always that confident what I need to change and what effect it'll have. Springs, ARBs, dampers, tyre pressures, toe and rake mainly.
Scuffers said:
no simple answer.
there are formulas for calculating the ride frequency is a given car/spring setup, and from this you can then calculate the required critical damper curves,
I used these calculations to analyse the suspension on my Civic trying to find why it was so bad on bumpy roads despite relatively soft springs. Turned out the spring rates were way too soft for the damper valving, so I was overdamped. Stiffer springs fitted and the ride actually got better!there are formulas for calculating the ride frequency is a given car/spring setup, and from this you can then calculate the required critical damper curves,
I can plot out the ideal damper force curves with relation to weight, spring rate, motion ratios etc. I can also do, with a bit more info, calulated load transfer and so give an idea of handling balance with any particular setup. Email me if you want a hand, I can have a go at figuring out what an ideal setup would be.
Scuffers said:
HOWEVER!
this is only gong to be a start point for a track car, it's really down to having a driver that can identify what's going on (as in test driver).
I agree with this though, any calculated 'ideal' is only ever a baseline.this is only gong to be a start point for a track car, it's really down to having a driver that can identify what's going on (as in test driver).
Edited by Kozy on Wednesday 2nd February 11:53
If you buy a set of coilovers the damper should be mstched to the springs so they can control them. Way to set one ways I was told was set of with max damping, which would give a really crashy ride and back them off on the surface you will be driving on until the crashyness goes, this should then be optimal. Don't go starting with too little damping as the piston could strike the end of it's travel causing damage.
Herman Toothrot said:
If you buy a set of coilovers the damper should be mstched to the springs so they can control them. Way to set one ways I was told was set of with max damping, which would give a really crashy ride and back them off on the surface you will be driving on until the crashyness goes, this should then be optimal. Don't go starting with too little damping as the piston could strike the end of it's travel causing damage.
That's completey the opposite to what I would do!It would have to be a very bad damper that allows you to do damage reaching the limits of travel (bump rubbers anyone?) And also to get to the limits of damper travel would imply incorrect lengths for the application.
RobM77 said:
I would really love to know more about setting cars up and the various effects. Does anyone know of a course you can go on, trying different settings on a car perhaps and learning about them? When I'm testing if I want to change something on the car I'm not always that confident what I need to change and what effect it'll have. Springs, ARBs, dampers, tyre pressures, toe and rake mainly.
Give this guy a call, I used to work with him at Prodrive, he certainly knows his stuff, and i'm sure could sort you out some track & w/shop time to play with things in a controlled environment.http://pcadynamics.com/
Max_Torque said:
RobM77 said:
I would really love to know more about setting cars up and the various effects. Does anyone know of a course you can go on, trying different settings on a car perhaps and learning about them? When I'm testing if I want to change something on the car I'm not always that confident what I need to change and what effect it'll have. Springs, ARBs, dampers, tyre pressures, toe and rake mainly.
Give this guy a call, I used to work with him at Prodrive, he certainly knows his stuff, and i'm sure could sort you out some track & w/shop time to play with things in a controlled environment.http://pcadynamics.com/
I still think it would be a good idea for someone such as that guy to do a course on setup for club racers or trackday enthusiasts with classroom sessions and practical sessions. It could be run over a weekend for example. I create training myself actually and would be happy to help plan such a thing, so if you ever chat to him you could mention the idea. I'm a typical club racer in that I know a bit of the theory of setup, but really am stabbing in the dark on test days!
Scuffers said:
That's completey the opposite to what I would do!
It would have to be a very bad damper that allows you to do damage reaching the limits of travel (bump rubbers anyone?) And also to get to the limits of damper travel would imply incorrect lengths for the application.
Recommened to me by an F1 mechanic to do it the way I described. It would have to be a very bad damper that allows you to do damage reaching the limits of travel (bump rubbers anyone?) And also to get to the limits of damper travel would imply incorrect lengths for the application.
The bit about damaging shocks came from GAZ as someone killed a pair of new GAZ shocks on an MX5 by starting at full soft. The GAZ man (Derek?) posted on the forum in reply saying it should be done hard to soft as full soft would have allowed the shock to bottom out killing it (Piston to internal bit, forget what he called it) - in that case I believe they replaced the shocks as a good will gesture. I suppose you could reply "need I say more" to that one though
Edited by Herman Toothrot on Wednesday 2nd February 15:08
Herman Toothrot said:
The bit about damaging shocks came from GAZ as someone killed a pair of new GAZ shocks on an MX5 by starting at full soft. The GAZ man (Derek?) posted on the forum in reply saying it should be done hard to soft as full soft would have allowed the shock to bottom out killing it (Piston to internal bit, forget what he called it) - in that case I believe they replaced the shocks as a good will gesture. I suppose you could reply "need I say more" to that one though
To me that would suggest that the spring rate isn't sufficient (or the spring is too short) for the application.The damper isn't there to support the car or to absorb impact energy directly, it's to control the spring and prevent oscillation. The spring absorbs the energy of a bump, the damper stops the spring simply kicking all that energy back out in an uncontrolled manner as soon as the load is removed.
WeirdNeville said:
To me that would suggest that the spring rate isn't sufficient (or the spring is too short) for the application.
The damper isn't there to support the car or to absorb impact energy directly, it's to control the spring and prevent oscillation. The spring absorbs the energy of a bump, the damper stops the spring simply kicking all that energy back out in an uncontrolled manner as soon as the load is removed.
Sorry, damper is there to take the shocks, the springs just hold the car up.The damper isn't there to support the car or to absorb impact energy directly, it's to control the spring and prevent oscillation. The spring absorbs the energy of a bump, the damper stops the spring simply kicking all that energy back out in an uncontrolled manner as soon as the load is removed.
Scuffers said:
WeirdNeville said:
To me that would suggest that the spring rate isn't sufficient (or the spring is too short) for the application.
The damper isn't there to support the car or to absorb impact energy directly, it's to control the spring and prevent oscillation. The spring absorbs the energy of a bump, the damper stops the spring simply kicking all that energy back out in an uncontrolled manner as soon as the load is removed.
Sorry, damper is there to take the shocks, the springs just hold the car up.The damper isn't there to support the car or to absorb impact energy directly, it's to control the spring and prevent oscillation. The spring absorbs the energy of a bump, the damper stops the spring simply kicking all that energy back out in an uncontrolled manner as soon as the load is removed.
I'm not an engineer, but that's the physics answer. I think!
Herman Toothrot said:
Recommened to me by an F1 mechanic to do it the way I described.
The bit about damaging shocks came from GAZ as someone killed a pair of new GAZ shocks on an MX5 by starting at full soft. The GAZ man (Derek?) posted on the forum in reply saying it should be done hard to soft as full soft would have allowed the shock to bottom out killing it (Piston to internal bit, forget what he called it) - in that case I believe they replaced the shocks as a good will gesture. I suppose you could reply "need I say more" to that one though
That's a very very VERY badly designed damper if that's really the case. The expert advise to stop the damper bottoming out defies belief.The bit about damaging shocks came from GAZ as someone killed a pair of new GAZ shocks on an MX5 by starting at full soft. The GAZ man (Derek?) posted on the forum in reply saying it should be done hard to soft as full soft would have allowed the shock to bottom out killing it (Piston to internal bit, forget what he called it) - in that case I believe they replaced the shocks as a good will gesture. I suppose you could reply "need I say more" to that one though
Edited by Herman Toothrot on Wednesday 2nd February 15:08
Argument went along the lines of different users so different spring rates, so damper needs wide range of adjustment needed so a supplied spring may allow the damper to go through it's travel too easily if say hitting a speed bump if the damper is at the far end of the range. As you can imagine plenty of comments came back at least it was suggested a warning leaflet in the kit that running at extremes will damage the damper......
RobM77 said:
Umm, doesn't the spring take the initial impulse/shock of a bump in the road or a sudden loading from the chassis? The springs are technically the "shock absorbers" in that sense. The damper then controls the spring thereafter.
I'm not an engineer, but that's the physics answer. I think!
nope, a spring just provides a force, how much depends on where it is in it's 'travel' (as in how much it's compressed)I'm not an engineer, but that's the physics answer. I think!
the damper is there to control the speed of the movement, both in bump and re-bound.
Herman Toothrot said:
Argument went along the lines of different users so different spring rates, so damper needs wide range of adjustment needed so a supplied spring may allow the damper to go through it's travel too easily if say hitting a speed bump if the damper is at the far end of the range. As you can imagine plenty of comments came back at least it was suggested a warning leaflet in the kit that running at extremes will damage the damper......
anybody that designs a damper that can't deal with hitting the ends of travel needs help.end of the day, it's the dampers job to ultimately define the limit's of travel of the suspension system.
now, in some setups, what's done is to ensure that the spring setup is such that the spring will go coil-bound before the damper bottoms out, but that's not the conventional way to limit travel.
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