F1 Dampers...

[karkai6]

Guys... can anybody plz explain clearly in a simple language how tuning the dampers helps in the handling and balance of the car?

[RH1300S]

I can't explain this in simple terms.........but I'll have a stab:

It's mainly about weight transfer and the management of.....

A car has a static weight distribution (CofG has a position for/aft - side to side and height). When a car is not moving in a steady state, cornering, braking accelerating the tyres "see" the weight as moving. As a car accelerates more load is transfered to the rear tyres etc. etc.

The springs and anti-roll bars affect how much weight is transfered. Which is why the basic cornering balance is set with these things. The dampers on a race car (AFIK) exist mainly to control how fast the weight is transfered. If, for example, you add rear rebound damping you can make a car looser at the rear on the brakes because when the nose goes down and the rear goes up the rear wheels are slower to reach down towards to keep contact with the road.

Also damper tuning helps tune the way a car responds to certain bumps on circuits - this would be mainly about keeping tyres in contact with the road and controlling ride height - comfort is not a consideration.

So, tuning the dampers is a way to create a stable and predictable platform for the driver by adjust the way a car responds to the various forces applied to it (some are driver inputs - some come from track conditions).

To go into much more detail I would probably expose my utter lack of knowledge.

[Jason]

This all I can find in the http://www.sportnetwork.net/ site. If you need a clearer view, http://www.sportnetwork.net/main/s107/st52178.php

[Ciro Pabón]

Dampers and springs main function is to keep the tire in contact with the road. When a spring compresses on a bump, the damper helps to control the movement, and when in rebound it stores some of the energy released by the spring.

Normally, you have two sets of valves or an arrangement of them that allow you to control the low speed damping and the high speed damping. The speed refers to the velocity with wich the "arm" attached to the car moves.

In rainy or low grip conditions, you allow more bleed of the damper (less low speed damping) to allow for delay between the steering wheel movement and the actual loading of the external wheel.

In dry or high grip conditions, you can load faster the wheel and thus you restrict bleeding (more low-speed damping).

If the chassis "is loose" (less low-speed damping) the confidence of the driver on the car diminishes, because he cannot "read" the chassis alignment fast enough. Most drivers prefer more low-speed damping as this gives them a crisp sense of the car.

The problem here is that too much low speed damping will create a car that lacks grip on changes of direction (it is "hard to counter-move" laterally), cannot put power on slow curves because of wheel spin and will generally lack grip after initial turning.

Thus a car suited for a "slider" pilot, with restricted bleed, will probably have traction problems at the exit of curves (I am talking muscle cars here, so please, feel free to correct me if your favorite category does not have hp as the main problem here). A way out is to open a little the flow inside the damper to make easier the weight transfer at the rear on exit.

There are several types of dampers. Dampers work restricting flow oil between two chambers, the compression chamber and the rebound chamber each with a valve stack and a bleed valve.

The bleed valve opens at very low speeds, hence its function to control low-speed rolling. The stacks are rings or donoughts of metal called shims. They flex under the pressure of oil in the chamber to allow for oil to pass. They control high speed movement (high frequency movements or really hard bumps!).

You can vary the thickness or the diameter of the inner hole of these donoughts. If you increase its thickness, they will bend less under stress and high-speed damping will increase. As there are stacks on the compression side (normally on the bottom of the damper) and on the rebound side (on the upper part of the assembly), you can change damping properties accordingly.

There are guides for particular tracks and cars: this example comes from a Penske spec sheet:

Push in middle of corners

1. Decrease rebound LF
2. Increase compression RR
3. Increase rebound RF
4. Decrease compression LF

in that order.

There are tips for "loose" or "push" at entry, middle and exit of corners. Well, that's probably most of what I know...

[karkai6]

Thanks a lot...By the way, U know any website that contains tips for racing on circuits and tuning ur cars for that?

[DaveKillens]

I'd like to add by illustrating what would happen if there were no dampers. The goal at all times is to keep the tire in firm contact with the road, anything else is counterproductive to control and performance.
In a no damper scenario, if a tire comes across a bump, the tire is forced upward by the bump. It continues to travel upwards, since there is no damper to help stop the upward motion. Then the tire is inthe air, and then the springs push the tire down, it comes down with more force than necessary, encounters the road, then is bounced back up again. Bouncy bouncy bouncy. The chassis is being bounced all over the place, the tires are going up and down like tennis balls.
So a damper dampens out the upward movement of the wheel, and also the downwards motion. As well, more sophisitated shocks are variable in force, velocity, and even position. And the upwards stroke (compression) is quite different values than the downward (rebound) stroke.
Addtionally, in Formula One cars, during testing and pre-qualifying, they have adjustable shocks installed, which can alter their behavior by turning soem knobs or screws. Once the car is prepared for the qualifying and race, no more fiddling is allowed by the FIA. So they build a non-adjustable shock with the same performance parameters as the adjustable ones, and fit them tot he car for final qualifying and race. This kind of shock cannot be easily tuned without disassembly, but is simpler, more robust, has less mass and parts than an adjustable shock.

[Ciro Pabón]

Thanks a lot...By the way, U know any website that contains tips for racing on circuits and tuning ur cars for that?

* Maybe you will find Chris's Shock Shop interesting. He wrote the "Shocking Thoughts" you will find here.

He partially disagrees with Dave about the usability of knobs for adjusting dampers. I agree with him: you have to dismantle the dam* thing and change shims or adjust the bleed valve. Then, inspired by engineering muse (that I guess must be Polihymnia), you can do some "knob" adjustments that sometimes the pilot does not even feel. The reason is that for the knob to work you need a super stiff damper (no pun intended!).

Chris is proud dealer of Bill Mitchell's "Racing by the numbers" programs. You could find WinGeo useful, but it will settle you down by U$400. This gave my first opportunity to use my wrenchs and my laptop at the same time: with this (and I am not making this up) you can entertain a paddock full of mechanics for half an hour, during testing! It is like closing Maranello... muahahahaha!

* Penske has a site and I recommend to read there this guide, that includes the "basic setting". There you can take a look to shims, bleed valves and the guts of them. They have the series 7000 for ovals, but it is the same thing, only different.

* You will need a simulation program. I have used LapSim for the glory of our team and the confussion of the opposition (the morons I coach will tell you the opposite). Besides, you can use two laptops! And one is connected to the car! Imagine the possibilities... You will need to buy the basic card, but this will be the single most important tool you will use. Check Bosch site and delve into "Publications and software". You can download it for free. For the interested, this is a nice pdf article on this software, interesting if only by having the most horrible scanning technique I have ever seen.

* With f1perviewyou can get the raf files you will get from LapSim and convert them to nice little circuits that will be the coolest thing ever on the track...

* Finally, you can check my world famous (10 hits a day and counting...) car simulation page, soon to be updated, for other software packages (soon means in the next two years or so).

A word of advice or a point to argue: I believed dampers were the suspension and springs were only for support. Now I got that both work together, but you have to simulate a lot. Also, you could discover that understeer and the such are affected by dampers, but you correct this things with other adjustments. Dampers are to keep the patch on the road when you vary the load (hey! it has a nice ring!), not to correct other problems and even less to correct basic design flaws, the sort that requires welding of the chassis or refitting the engine position.

[RacingManiac]

Tidbits I've heard about the Sachs damper on Ferrari, as told by a Sachs engineer for the F-BMW damper program....the F1 rotary damper on the Ferrari were made to be circuit specific, and not adjustable.....I find that amusing but I guess why not. The aero package were made specific too, why not everything else.....

adds to the cost....

[Ciro Pabón]

... the F1 rotary damper on the Ferrari were made to be circuit specific, and not adjustable.....I find that amusing but I guess why not. The aero package were made specific too, why not everything else.....

I tried to explain: if you make a damper that, through adjustment, is able to shift the weight, then it is too rigid. You have to graduate the internal valves first and then you can do some adjustment, if you really need it. If you have a good simulation package (and I guess Ferrari has one), you arrive with the damper settings presorted.

[Jersey Tom]

Tuning shocks to specific tracks.. wish I knew more about it.

Having linear potentiometers on your shocks, and a data acquisition system (e.g. MoTeC) is great. Let's you log shock position, and from that you can get shock velocity and shock velocity histograms. You want your histogram to be symmetric, which is the easy part. From there, determining if you want to squash or loosen up high or low speed dampening, is the tricky part and is track and weather dependent. As a rule of thumb you'll run less bar and less dampening in the rain compared to dry.

Its just something you gotta play with and find a balance for. Tuning for optimal transient response in dampers is black magic to me.

[Ciro Pabón]

Having linear potentiometers on your shocks, and a data acquisition system (e.g. MoTeC) is great.

We have used laser height sensors instead. They are really cheap, solid state, have excellent frequency, and, if you have simple springs, give you the exact same data (compression is linearly proportional to force). Besides, you get directly the riding height for the aero guys and their diffusers. It is like substituting the quartz of the piezoelectric sensor, or the variable resistance of the potentiometer, for your own spring...

About the black magic: I call it engineering (and I dare to say it is white magic). I like to say that real engineers do the testing, the others do the design. My advice, if it is of any good, is to give them a couple of laps for warming, and then just one lap for each configuration, one step at a time. Look at the tires, they speak to you. And keep your magic wand handy, just in case.

[tf1]

I don't know how simple you want the answer to be. But the basic difference between springs and dampers is what they are reacting to. A spring creates a force based on displacement (how much it actuallymoves). Whereas a damper creates a force based on speed (how fast one end is moving relative to the other). For example, if you have a spring and damper with the same stiffness and the moving end is moved very slowly, the spring will slowly build up force and the damper will provide almost none. If you move it quickly however, the damper will add to the force of the spring.

The best way to study a simplified suspension system is to look at a single damper/spring in parallel connected to a mass. This is sometimes referred to as a kelvin element. If you have only a spring and you move the ground, then the mass above will vibrate forever. But once you add more damping, you will see that the mass stops vibrating more quickly.

The same principles apply in a rotational sense such as on the Ferrari and Toyota cars from last year. A rotational damper is used in conjunction with a torsion spring. The rotational damper is something fairly new. It's main benefit is its size (it can basically become the rocker). It uses a very complicated set of seals that require very precise settings so that it produces the correct loads at the correct rotational speed. Having said that, the number of different dampers used are no different when using linear dampers because the range that is used is quite different on different tracks.

[wazojugs]

There is an article in this weeks autosport about a new damper setup being used by some teams.

several teams have been using a mass damper this season to damp out tyre bouncing frequencies throught corners and keep grip more consistant.

renault and red bull are known to use such system and it is believed that ferrari and williams have fitted it. its a simple mechanical device comprising a weight (9kg) ona spring.

Gary Anderson explains: you see a car bouncing when it hits a kerb, this will be around 8-9 Hz on the tyres. this device will get an equal frequency going in the opposite direction. it similar to a tall building designed to withstand an earthquake where they out a large water tank on the roof, so that when the building sways the water moves in the opposite direction at the same frequency.

in this case as the car is going up the tyre is going down and vice versa. with this the car will still bounce at the same frequency but the amplitude will be damped down. if you take an average tyre load and assume 1000kg you would see a variation of 900-1100kg. but the driver needs feel sure of what he has got as he goes into a corner 900 or 1100kg. witha weight of around 9kg you can get the variation down to 950-1050kg some there is a more consistant load.

its a very good idea and would be easy to setup on ona seven post rig balancing mass against damping. the only downside is that it adds weight on the car quite high up.

[Tom]

I saw that too, but surely this counts under 'movable ballast' which is stricktly forbidden by my recollection?

[jgredline]

Addtionally, in Formula One cars, during testing and pre-qualifying, they have adjustable shocks installed, which can alter their behavior by turning soem knobs or screws. Once the car is prepared for the qualifying and race, no more fiddling is allowed by the FIA. So they build a non-adjustable shock with the same performance parameters as the adjustable ones, and fit them tot he car for final qualifying and race. This kind of shock cannot be easily tuned without disassembly, but is simpler, more robust, has less mass and parts than an adjustable shock.[/quote]

Dave
I really enjoy your insight.
This I never heard of. Good stuff.