F1 2010: Ride height adjustments during pit stops

[speedsense]

[quote="marcushrefer back to my post:



could you please explain why a rocker pushrod assembly could only alter rideheight by changing pushrod length?
to my understanding you make the assumption that the car does not have any droop in it ,something that might be on the front suspension but surely not in the rear?

As soon as you alter the spring preload or coilover assembly length you will of course alter the rideheight(and leverage..) until you hit physical limits of suspension travel.
Of course this is only true if the car sits on the spring platform you make adjustments to ,so with 3rd springs things could catch you ,no question.[/quote]

"...as we now have most of the front suspension with torsion bar arrangements ,one could easily swap the manual screw type adjuster for ride height ,anchoring the end of the torsion bar to the chassis for the hydraulic" piston .


I did assume that you were talking front suspension, as those were your words.
Adding spring preload to a "drooped" suspension and in the rear (unless you are considering have the two main springs "rattle" free between ride height and full droop) Also not a good idea with third springs involved....
I'll tell you what, you drive and I'll do it to your car, then you tell me if it's a good idea, that is when the blood returns to your knuckles and you stop asking me if I was trying to kill you as you tried to rotate the car or cleared that last hill.

[marcush.]

adjusting the anchor point of torsion bar springs for ride height adjustment is surely not my invention and indeed it does not change preload.(given you will not reach phsical stops in the suspension elsewhere.

with a coil spring arrangement ,changing spring preload is not really a good idea ,
i know and I would not do it for changing rideheights.
But changing the length of the coilover unit -why not?-

[Richard]

On a car with pushrod/pullrods and rockers(bell cranks) with the shocks and springs inboard, as with most, if not all of the F1 cars, the only way to change the ride height, is through the length of the push/pull rods. Otherwise all you are doing is compressing the spring and adding "spring preload".

Forgive my ignorance, but how do they adjust the ride height when setting up for a wet track? I'd assumed it was by twiddling with some of the linkages to change the geometry rather than changing the push/pull rods?

If fuel load is changing, you'd also want to change the spring preload and damping settings to compensate for a car that is 25% lighter.

... or perhaps teams will see greater advantage in adjusting the front wing and leaving the rest alone?

They can't change everything in a pit stop, so it will be interesting to see the first pit stops ....

[speedsense]

adjusting the anchor point of torsion bar springs for ride height adjustment is surely not my invention and indeed it does not change preload.(given you will not reach phsical stops in the suspension elsewhere.

with a coil spring arrangement ,changing spring preload is not really a good idea ,
i know and I would not do it for changing rideheights.
But changing the length of the coilover unit -why not?-

Can't speak for a torsion bar sprung car, no experience with it. Though logic would suggest that moving one side torsion would lead to a preload of some sort, though torsion bars are highly progressive in such a case. Moving in or out on the bar, would stiffen or lower the spring rate.

The only problem with the length of the coil over (I presume the spring length), when you have droop involved, is how far into the spring you end up at ride height vs. spring length at full droop.
If you meant dampener length then that puts the rockers into a different location at ride height and depending on the rocker design, if the rockers are progressive,digressive in motion ratio (as they move) in anyway, you may create more problems than you are trying to solve.
Ideally, a true ride height change, should be in length of the pushrod/pullrod. I could see some type of three or four position "selection" on a predetermined height change through some type of telescoping pushrod adjustor.

[speedsense]

On a car with pushrod/pullrods and rockers(bell cranks) with the shocks and springs inboard, as with most, if not all of the F1 cars, the only way to change the ride height, is through the length of the push/pull rods. Otherwise all you are doing is compressing the spring and adding "spring preload".

Forgive my ignorance, but how do they adjust the ride height when setting up for a wet track? I'd assumed it was by twiddling with some of the linkages to change the geometry rather than changing the push/pull rods?

If fuel load is changing, you'd also want to change the spring preload and damping settings to compensate for a car that is 25% lighter.

... or perhaps teams will see greater advantage in adjusting the front wing and leaving the rest alone?

They can't change everything in a pit stop, so it will be interesting to see the first pit stops ....

Depending on the presumed conditions for the whole race, it's a gamble to change ride height, as, if it dries out, your stuck completely with a slow car. Great in the rain, especially heavy, though. Some of fiddling with the rockers could be a) remove a link of the ARB (if it has one), B)remove the slow speed setting on the shocks C) With torsion bars, you could move the arm(s) outboard and soften the spring rate (desired in the rain) D)lastly, changing the pushrod length, would occur (in most cases) at the rocker, it's connected to.

The "key" in the rain, is as much roll and weight transfer as possible, and as quickly as possible to each wheel as needed.

[bill shoe]

I think this discussion is great, the importance of this issue has been underestimated so far.

You need to qualify on light fuel, then start the race on heavy fuel, then run to the end on increasingly light fuel again. You always want the car to run as low as possible to optimize aero performance.

External suspension adjustments during pit stops would roughly correct ride height during the race, but the rules (and clarifications from richard_leeds and scarbs) make it clear that ride height adjustment will not be allowed in parc ferme, i.e. between qualifying and the start of the race. Therefore, pit adjustments will not help you with the biggest weight change that occurs between qualifying and the race.

Larger front-drive cars and SUV's sometimes use a special dampers to keep their rear ride height constant under different loads. This is important because the amount of weight on the rear end of these vehicles can vary a lot from empty to full, but the desired spring rates are typically soft. This means the ride height can change too much from empty to full. Sound familiar?

These rear shocks do not get external power or signals, and they do not change ride height while the car is stationary. Therefore, if you take an empty car and load it with a ton of weight it will droop in the back as long as it's stationary. The shocks have a special damping circuit in series with the regular damping unit. This special circuit uses very stiff and position-proportional damping to raise the rear ride height up to a more normal level. The circuit only changes the ride height when the shocks are being pumped by normal driving motion/energy. Production cars typically take one or two minutes to return to normal ride height once they start driving.

Basically, the special damping circuit preloads the whole suspension to maintain a ride height that is constant over long amounts of time. Normal bumps and body motion are allowed but the shock will always be seeking the same ride height in the long run.

Sorry for long description. These units are well regarded by development engineers at car companies, and the only clear drawback is cost. They are an extra ~$20 per shock compared to normal dampers and this is a lot for mass produced cars. They may be called Sachs "Nivomat" dampers, but I'm not sure.

Anyway, I think this basic concept is the best way for a Formula 1 team to acheive consistent ride height despite large weight variation. And no messing with anything during pit stops. You just have to make sure that one formation lap prior to the race is enough to pump the damper back to it's normal (safe) ride height.

[speedsense]

I think this discussion is great, the importance of this issue has been underestimated so far.

You need to qualify on light fuel, then start the race on heavy fuel, then run to the end on increasingly light fuel again. You always want the car to run as low as possible to optimize aero performance.

External suspension adjustments during pit stops would roughly correct ride height during the race, but the rules (and clarifications from richard_leeds and scarbs) make it clear that ride height adjustment will not be allowed in parc ferme, i.e. between qualifying and the start of the race. Therefore, pit adjustments will not help you with the biggest weight change that occurs between qualifying and the race.

Larger front-drive cars and SUV's sometimes use a special dampers to keep their rear ride height constant under different loads. This is important because the amount of weight on the rear end of these vehicles can vary a lot from empty to full, but the desired spring rates are typically soft. This means the ride height can change too much from empty to full. Sound familiar?

These rear shocks do not get external power or signals, and they do not change ride height while the car is stationary. Therefore, if you take an empty car and load it with a ton of weight it will droop in the back as long as it's stationary. The shocks have a special damping circuit in series with the regular damping unit. This special circuit uses very stiff and position-proportional damping to raise the rear ride height up to a more normal level. The circuit only changes the ride height when the shocks are being pumped by normal driving motion/energy. Production cars typically take one or two minutes to return to normal ride height once they start driving.

Basically, the special damping circuit preloads the whole suspension to maintain a ride height that is constant over long amounts of time. Normal bumps and body motion are allowed but the shock will always be seeking the same ride height in the long run.

They may be called Sachs "Nivomat" dampers, but I'm not sure.

Anyway, I think this basic concept is the best way for a Formula 1 team to acheive consistent ride height despite large weight variation. And no messing with anything during pit stops. You just have to make sure that one formation lap prior to the race is enough to pump the damper back to it's normal (safe) ride height.

Don't believe this would satisfy 10.1.2 of the '10 tech regs which states "The suspension system must be arranged that it's response results only from changes in load to the wheels."
For this to work, as you say, on a car that is sprung from rockers/pushrods system, you would need to replace the spring "load" with the hydrualic "load", which make the car disagree with 10.1.1 "Cars must be fitted with sprung suspension. Hydraulic fluid is not considered a spring. Dampeners which are velocity dependent, are also not considered springs though filled with hydraulic fluid, but respond only to velocity. Having a shock that applies load isn't permissible.
Though this would work fine on a sedan that has coil over struts connected direcly to the a arms, keeping a spring and this circuit (to keep it legal) within a rocker system would present the same problems described with preload and at some point the hydraulic portion has to overcome the spring rate to be effective, thus applying load and no longer a sprung car, breaking both rules.
IMHO
1`0

[Richard]

Depending on the presumed conditions for the whole race, it's a gamble to change ride height, as, if it dries out, your stuck completely with a slow car. Great in the rain, especially heavy, though. Some of fiddling with the rockers could be a) remove a link of the ARB (if it has one), B)remove the slow speed setting on the shocks C) With torsion bars, you could move the arm(s) outboard and soften the spring rate (desired in the rain) D)lastly, changing the pushrod length, would occur (in most cases) at the rocker, it's connected to.

The "key" in the rain, is as much roll and weight transfer as possible, and as quickly as possible to each wheel as needed.

Thanks speedsense. I was wondering if any of the adjustement they use in the garage could be used in the pit stop.

You could imagine with A, B or C that they could have a screw adjustment. For example, rather than remove a link, they have a link that expands or contracts based on a worm screw. I think D is the least likely option.

[bill shoe]

speedsense,

Thanks for your response. It made me think about the concept more carefully and look at the rules you mentioned. I think this concept is legal.

“10.1.2 The suspension system must be so arranged that its response results only from changes in load applied to the wheels.”

We know that normal springs and dampers in a conventional pushrod-rocker system are legal because their responses only result from changes in load to the wheel. A normal spring creates a force as a function of wheel position. A normal damper creates a force as a function of wheel velocity. Therefore we know suspension components are legal if they create forces only in response to wheel position or velocity. A position-proportional damper creates forces as a function of position AND velocity, so it’s legal. I see no direct or implied requirement in the rules that say mechanical objects that create force as a function of position must be separate from mechanical objects that create force as a function of velocity.

“10.1.1 Cars must be fitted with sprung suspension.”

If each wheel had two coil-overs in parallel with an ultra stiff shock on one side that effectively locked out the normal spring/damper on the other side then I think there is a good claim that the wheel is not sprung. However, the concept I described has the special and normal coil-overs connected in series. This means that no matter how stiff the special unit is the car will continue to have normal springing and damping over bumps and during turns, etc. This is due to the compliance from the normal (relatively soft) spring/damper unit.

If a car was in scrutineering or on the track or on a shaker rig, and you pushed against the car you could not tell from the response if it had the additional coil-over in series with the normal coil-over. It would behave normally either way. The only difference with the new concept would be that the car would have a relatively consistent baseline ride height over the course of the race instead of changing by a few precious aero-killing mm.

You point out that the special coil-over unit by itself would have damping forces that would “overcome” its spring. In fact, this unit would not necessarily have a spring at all, but let’s assume a one pound per inch spring. It’s common in production and racing cars for damper forces to be higher than spring forces. Peak forces are usually much higher for dampers than springs. So yes, the hydraulic (damper) force is higher than the spring force and therefore “overcomes” the spring rate in some sense, but this is already normal and not against the rules.

Big picture--

My comments above are a bit hard-ass and “letter of the rules” oriented. What about the spirit of the rules? We all understanding that the underlying intent of these rules is to prevent active suspension and artificial driver aids. The new concept is not an active suspension of any kind, or something that helps the driver control the car. It’s a system that keeps a more consistent baseline ride height in order to optimize the aero performance. This is the same thing conventional suspensions try to do, but the new concept just does it better. This doesn’t make it illegal.

I think this suspension concept is genuinely clever (credit to Sachs or whoever) but it’s not something sneaky that dances around the intent of the Formula 1 rules.

[speedsense]

speedsense,

Thanks for your response. It made me think about the concept more carefully and look at the rules you mentioned. I think this concept is legal.

“10.1.2 The suspension system must be so arranged that its response results only from changes in load applied to the wheels.”

We know that normal springs and dampers in a conventional pushrod-rocker system are legal because their responses only result from changes in load to the wheel. A normal spring creates a force as a function of wheel position. A normal damper creates a force as a function of wheel velocity. Therefore we know suspension components are legal if they create forces only in response to wheel position or velocity. A position-proportional damper creates forces as a function of position AND velocity, so it’s legal. I see no direct or implied requirement in the rules that say mechanical objects that create force as a function of position must be separate from mechanical objects that create force as a function of velocity.

“10.1.1 Cars must be fitted with sprung suspension.”

If each wheel had two coil-overs in parallel with an ultra stiff shock on one side that effectively locked out the normal spring/damper on the other side then I think there is a good claim that the wheel is not sprung. However, the concept I described has the special and normal coil-overs connected in series. This means that no matter how stiff the special unit is the car will continue to have normal springing and damping over bumps and during turns, etc. This is due to the compliance from the normal (relatively soft) spring/damper unit.

If a car was in scrutineering or on the track or on a shaker rig, and you pushed against the car you could not tell from the response if it had the additional coil-over in series with the normal coil-over. It would behave normally either way. The only difference with the new concept would be that the car would have a relatively consistent baseline ride height over the course of the race instead of changing by a few precious aero-killing mm.

You point out that the special coil-over unit by itself would have damping forces that would “overcome” its spring. In fact, this unit would not necessarily have a spring at all, but let’s assume a one pound per inch spring. It’s common in production and racing cars for damper forces to be higher than spring forces. Peak forces are usually much higher for dampers than springs. So yes, the hydraulic (damper) force is higher than the spring force and therefore “overcomes” the spring rate in some sense, but this is already normal and not against the rules.

Big picture--

My comments above are a bit hard-ass and “letter of the rules” oriented. What about the spirit of the rules? We all understanding that the underlying intent of these rules is to prevent active suspension and artificial driver aids. The new concept is not an active suspension of any kind, or something that helps the driver control the car. It’s a system that keeps a more consistent baseline ride height in order to optimize the aero performance. This is the same thing conventional suspensions try to do, but the new concept just does it better. This doesn’t make it illegal.

I think this suspension concept is genuinely clever (credit to Sachs or whoever) but it’s not something sneaky that dances around the intent of the Formula 1 rules.

Is there any information available that can be seen on these shocks? It is a very interesting concept indeed, though making it work as planned within a rocker/push rod assembly seems, at least to me, not a good idea. There are inherit problems with changing rocker location for ride height reasons.
Altering ride height without altering the pushrod length, can be extremely difficult to pull off and still maintain a driveable car. While the rocker/shock/spring assembly isn't a "fixed" length except when stationary, the pushrod/pullrod is always a fixed length. Because of this, any change to the rocker location (specifically to change height) is doing so against the fixed length of the pushrod. When the car is in the air and in the suspension is in droop, changing the rocker location will either (pull the springs away from their perches, or put the spring/shock into a preload condition.
If the car is on the ground, the ground becomes the "droop" limiter, and again your changing ride height against the length of the pushrod. While the springs shouldn't "rattle" away from the perches, at this point, the preload amounts are the issue and rocker location (change in motion ratio depending on rocker design)
Adding to this rebound energy coming from the preloaded spring. The rebound energy can make the car, a rotation mess for the driver and given enough preload, can rotate on it's own without the driver's wishes.

The very reason most setups don't include preload in the rear springs.
IMHO

[bill shoe]

speedsense,

To some extent you are going into, uh, "implementation details" where I have no experience. I will say the rocker position (static ride height) will theoretically not change during the course of the race.

The two coil-overs units in series would probably have the "special" unit mounted on the inboard mount (attached to a clevis on the monocoque or transmission), and the regular unit mounted to the outboard mount (to the rocker). The concept would actually work with either order but I think it's easier to conceptualize this way.

You can think of the special unit as taking the place of the fixed clevis that usually attaches the normal coil-over to the monocoque or transmission. The only difference is that the special unit is not fixed, and instead slowly pulls back from the regular unit over the course of the race as the car gets lighter, therefore the "mounting point" of the regular unit does change, but it changes with the weight change so you can still run zero or near-zero preload on the spring for the entire race. I think the actual preload is determined only by the regular coil-over unit which is still free to expand to full length anytime the car is off the ground. The spring perch on the regular unit does not move relative to the regular unit.

All this is theory and I don't know how difficult it would be to make a special unit like this that would be precise enough for F1. I just know that something like this does work for street cars with relatively soft springs and large travel.

I don't know any specific place to get info on these shocks. Try the web. Hope this helps you understand what I'm saying whether you agree or not.

[speedsense]

speedsense,

To some extent you are going into, uh, "implementation details" where I have no experience. I will say the rocker position (static ride height) will theoretically not change during the course of the race.

The two coil-overs units in series would probably have the "special" unit mounted on the inboard mount (attached to a clevis on the monocoque or transmission), and the regular unit mounted to the outboard mount (to the rocker). The concept would actually work with either order but I think it's easier to conceptualize this way.

You can think of the special unit as taking the place of the fixed clevis that usually attaches the normal coil-over to the monocoque or transmission. The only difference is that the special unit is not fixed, and instead slowly pulls back from the regular unit over the course of the race as the car gets lighter, therefore the "mounting point" of the regular unit does change, but it changes with the weight change so you can still run zero or near-zero preload on the spring for the entire race. I think the actual preload is determined only by the regular coil-over unit which is still free to expand to full length anytime the car is off the ground. The spring perch on the regular unit does not move relative to the regular unit.

All this is theory and I don't know how difficult it would be to make a special unit like this that would be precise enough for F1. I just know that something like this does work for street cars with relatively soft springs and large travel.

I don't know any specific place to get info on these shocks. Try the web. Hope this helps you understand what I'm saying whether you agree or not.

So, if I understand correctly the length of the shock changes to change the ride height. This would be exactly the same as I described above. Adjusting the spring perch against a droop limiter, will effectively push the rocker away, lengthing the shock stroke away from the fixed side of the shock. The two "routes" are identical, from what I understand of your statement.
A few years there was an interesting invention for racing. I forgot who designed it nor have I heard of anyone doing anything with or selling the idea since.
It was a shock that had two stages, of two different and seperate springs with different spring rates. It looked exactly as a normal coil over would look, except, the bottom perch of the spring sat on cylinder, that looked like a narrow "top hat" where the top of the hat was inside the spring and the bottom flare was the bottom perch.
Inside the top hat was another spring of a different spring rate, that sat on a small perch inside of the top hat with a gap below the first flare. The larger spring (in size) had to compress the gap of the smaller (in size) spring, before it could act, and start to compress.
Two different spring rates on the same shock and seemily was a great idea, don't know whatever happened to it....

[lebesset]

talk from australia is that certain teams have a control which allows them to run low in qualifying , then raise it to allow for the weight of the race fuel

is this legal ?

and if it is , is it within the spirit of the regulations ?

[scarbs]

To simply change the ride height with tools and different parts is illegal. To do it with a non mechanical means or within the parc ferme rules is allowed.
I have heard of repressurizing the gas in the nitrogen cylinder in parc ferme (seeJames allens blog).
But I have also heard of temperature adjustment, again using gas inside the damper. I imagine that making it extremely cold would reduce its volume andhence the ride height, allow you to Q on low ride. The unit reaches ambient temperature and expands before the race...

[WhiteBlue]

McLaren suspects adjustable ride-height on Red Bull
ESPNF1 Staff
March 27, 2010

Red Bull could be gaining a controversial advantage in qualifying

McLaren's Martin Whitmarsh has suggested Red Bull's car might be hiding a controversial driver-adjustable ride-height system, after the two RB6s dominated qualifying in Melbourne.

The difference between a car laden with fuel for the start of the race and one running on fumes in qualifying is so great that the weight of the petrol physically alters the height of the car. This means most teams have to run the car relatively high in qualifying, at a disadvantage, in order to compensate for the weight of the full tank needed to start the race. But during qualifying on Saturday, on-board footage from Mark Webber's Red Bull appeared to show the car occasionally bottoming-out.

McLaren boss Whitmarsh told the BBC after the session that, following a similar situation in Bahrain, he wondered why the Red Bulls were not "dragging their arses on full tanks" in the race. He said it is "evidence of ride-height control systems" being in use, "which many people wouldn't have thought were permissible".

In the wake of last year's diffuser row, and the McLaren F-duct saga in Bahrain, F1 could now be set for its next technical controversy. Whitmarsh said McLaren is now "working quite hard" on implementing a Red Bull-like ride-height system, and "hopefully by China we'll have something on the car".

Good morning Macca.