Tuning shock absorbers

I've been frustrated for ages by these setup guides which simplify damper tuning to "increase front bump for more oversteer" etc. only to find that this isn't really the case, or the truth of the matter is more complicated than that. So it's been a breath of fresh air to find this article, which despite being more vague, probably shines more light on this black art than anything else I've ever found.

http://f1elites.com/4d/?p=46

Could someone who's more familiar with chassis tuning post their thoughts? Would you back up what this guy's saying, or has he got the wrong end of the stick?
 
Yes, the hdc files specify the dampers in detail. However, in real racing these are not always precisely known either, which is why there are shock dynos.

I don't think the game devs meant to support race engineering much. Basic information like suspension geometry is left out. We're also in the dark on engine torque curves, tire temps & pressures, brakes, i.e. information that manufacturers can provide. Some of these things are to be determined during "development & testing" like real teams do (e.g. there are procedures that give you the location of a vehicle's center of gravity). But, we're really on the ground floor here.
 
We are. The game doesn't give us the tools/means to measure many of these things. We can't just measure the chassis with a tape measure, as they haven't programmed a tape measure in.

It's disappointed me a lot to see how many racing simulators don't include the means to test and measure different parts of the car. We can't observe characteristics of a chassis like bump steer, camber gain, etc. we can't measure the weight distribution, we can't measure the effect of aerofoils (to balance the downforce)... I'd love to know these things, or at least have a good, reliable way to check them myself.
 
I suspect that Simbin among other Sim creators has decided that giving too much information would make the game too difficult for the average player to understand or want to deal with. I would like to know at least what the weight balance is and would also like to be able to adjust things like turbo pressure in order to make the car a little more real, but these things are likely to be left unused by the masses or things that they would prefer others create setups for so they don't have to worry about. Unfortunately the sims have to be made to allow for the maximum number of people to enjoy which means leaving some features out.
 
If you can access the car parameter files (.hdc .sp .tyr etc.) then you have the information you need to calculate motion ratios, damper ratios, roll stiffness, anti-dive, anti-squat, weight distribution, aerodynamics etc. It takes a lot of time but it's possible to get everything imported into an excel spreadsheet and set it up to calculate everything as you import setup files and then have that go into MoTeC so you can develop some pretty advanced maths channels. The thing is that a lot of it doesn't matter as you discover how limiting the setup ranges we are given really are making it obvious that some aspects (not all) of the cars are probably not realistic. http://www.racesimcentral.com/forum...or-HDV-file-and-it-s-role-in-defining-the-car http://www.racesimcentral.com/forum...tor-PM-file-and-it-s-role-in-defining-the-car http://www.racesimcentral.com/forum...or-TBC-file-and-it-s-role-in-defining-the-car these post are absolutely essential to understanding what's going on in these files and from that understanding you may be able to create better setups but it's hard to do because I don't think the development community is on the same page. Also Kangaloosh car factory has some powerful analysis tools you can use for bump steer, camber gain etc.
 
Yes, the car files have it all. Except, a) I don't think we were meant to see them in Race (why are the built-in cars encrypted? the mods are not.) b) they give away too much and c) there's quite a bit of fudging going on (if I remember correctly -- not a modmaker myself) and probably a few bugs here and there (I've seen bizarre ride heights such as 30 cm for one wheel and 10 cm for the rest in Motec for a car at rest) so I don't know if I can count on everything that I see.
 
That's why I said "if you can access" :) and I think there's a way to break the encryption but I'm pretty much going off of what I see in GTR2 and mods where there is no encryption. I'm sure there is a lot of fudging as not all information is freely available to just everyone or in a format that's easily imported to the parameter files, so this would explain any and all guesswork by modders who can't do wind tunnel tests, CFD or laboratory tire analysis. I've seen the same strange ride heights (formula BMW comes to mind right away) and I'm almost positive that this doesn't relate to the actual ride height but just where the ride height is measured from which seems to be from the undertray coordinates specified in the .hdc but I haven't proved this. I think there's a way to develop the physics so that all setup ranges can stay within a window that allows for different driving styles without there being much laptime disparity between opposite ends of the spectrum (for example I don't think a damping ratio below 0.3 or extremely low spring rates are ever desirable). As things are now there are good setups and bad setups. If things were made so that you couldn't really go wrong then the racing would become more and more about driving skill rather than setup skill. I don't think there's anyone in the sim racing community who wouldn't want that.
 
Well Brendan, there are drivers and there are tuners, some times they are one and the same person, most times they are not. I don't mind tinkering with the setups, and I have a real good understanding of what "should" happen when you change this item in this direction, so my setups tend to be decent. I am no math wiz, nor am I an engineer, so I leave all that to the professors, I just race and adjust :)
 
Interesting way of describing transitional information for spring dampers. In some aspects the OP is correct but you are right he is very vague and a couple of the things he mentions to do will get you into trouble and will make setting up the car a lot more difficult.

First remember that before anyone even attempts to make changes to the setup of the car, they should be very proficient and comfortable with car and track. I would suggest that being able to do 5+ laps with laptimes around .5 to .8 apart is where you want to be before you attempt a change. The reason for this is because you need to be that good to see the differences from what you are changing. I don't mean to imply that some of you can't see the differences, but some of the changes might not be seen if your laps times are what you are going by. Also remember that the spring dampers are usually the last thing you adjust to try and get the car balanced as the rest of the suspension is more suited for the rougher tuning required first.

Spring dampers are designed to control the weight transfer to and from any given wheel at any given time. They make it to where the weight either hits hard onto the tires or soft depending on settings. Controlling the weight transfer allows for better grip where we want it and will help reduce lap times a little because of it. Car weight control is usually described as balanced when you can enter, negotiate and exit a turn without a ton of thought and control input to keep the car from losing control. If you need to make constant changes in your steering input, throttle input and brake input to be able to make a corner, then your car is not in balance.

Keep in mind that any change that is made to spring dampers will most definitely have effects on areas besides what we are trying to get straightened out. As most of the suspension tuning we do is for road courses and not ovals, the beginning tuner should always keep the settings to where they adjust symmetrically, or where you adjust one side and the other side automatically adjusts for you.

A couple of small notes to remember. For the most part anytime you adjust bump on one end of the car, you should adjust rebound in the opposite direction on the other end of the car, there are exceptions, but the beginner need not worry about that just yet. Also note that testing your adjustments on a straight line are not going to give you much information on the changes. For RWD cars, pretty much the quicker you get the weight on the back tires the faster you can accelerate, and the faster you get it on the front tires, the harder you can brake, but only in a straight line. For negotiating turns, sudden weight changes put the car out of balance and can cause you to lose control very quickly.

There are charts all over the internet on how to adjust your spring dampers for different conditions that you are experiencing. Keep in mind that most of that information out there refers to stiffening or softening the damper. To stiffen, you would raise the numeric value for the bump or rebound which ever you are adjusting. To soften it would be the opposite. For instance if the car won't turn and wants to keep going straight with no brake input then it is likely that the weight isn't on the front wheels enough to allow them to work. To fix this you would adjust the front bump to make it stiffer and make the rear rebound lighter in order to let the weight move onto the front tires. For acceleration, RWD cars want the weight on the back, but FWD cars want to keep the weight on the front as long as possible. To keep the weight on the front, you would stiffen the front rebound and soften the rear bump.

I would suggest that anyone attempting to make changes to a setup that is just learning, talk to someone who is experienced in it so that they can help explain what each setting does and when you would change it. I would also suggest that unless you are an alien and can feel the differences immediately, run several laps to find out if your change made a difference. A general rule of thumb though is change gears first, change springs next, then anti-sway bars and then dampers. Once you have done this, go back and start at the beginning and do it all again until your car is not improving with your changes.

Now i know what i was doing wrong. Thanks for info Jim
 
If you stiffen the rear bump on a front drive car, the rear wheels will take the weight quicker as there is resistance to the suspension being compressed. Softening the rear bump allows the suspension to move more in the compression making it take longer for the weight to settle in on the rear tires. This allows the front wheels to keep the weight longer, thus keeping traction.

Like I mentioned in the earlier post, the front and rear work together to make up the whole and is why for the most part you adjust both the front and the rear at the same time. Stiffer front rebound keeps the weight from moving up and back as quickly which means that there is less force being transferred to the rear. The softer bump on the rear means that what force does get moved up and to the rear will take longer before it takes away the weight from the front.
 
If you stiffen the rear bump on a front drive car, the rear wheels will take the weight quicker as there is resistance to the suspension being compressed. Softening the rear bump allows the suspension to move more in the compression making it take longer for the weight to settle in on the rear tires. This allows the front wheels to keep the weight longer, thus keeping traction.

Like I mentioned in the earlier post, the front and rear work together to make up the whole and is why for the most part you adjust both the front and the rear at the same time. Stiffer front rebound keeps the weight from moving up and back as quickly which means that there is less force being transferred to the rear. The softer bump on the rear means that what force does get moved up and to the rear will take longer before it takes away the weight from the front.

Then this guide is wrong: http://www.racedepartment.com/race-setups/3511-racedepartment-setup-guide.html#post460181
It says, if you have understeer on corner exit then + rear bump.
 

This isn't very useful for the cars with encrypted .hdc, .sp files etc. But especially for mods where the files aren't encrypted allowing you to get the relevant data to make the calculations this is extremely useful, at least that has been my experience.
 
Agreed, it has proven to be very useful. And I've used it to help with setups in stock content in Race 07 too, as I found a way to decrypt the game files and get the information I need. Problem is, some of the cars have shocks which are always too stiff, no matter what you do. The default setup on the DBR9 for example has slow rebound ratios of 2.65 at the front and 2.9 at the back. WAY higher than the suggested figures in your videos, more than 300%. From there, they only go down to a minimum of 2.32 and 2.49. I don't get why they made the cars like this... Ah well.
 
I have run into the same problems not being able to get the shocks tuned to an acceptable ratio, either too soft with the saleen S7 in GTR2 or too stiff with MMG F1 (at least in rebound). So I just do the best I can and it has always led towards the right direction at least. However ratios over 2 would have me questioning if I messed up the calculation, still if the other cars look better than some that are way off from where you expect than mistakes are probably unlikely if you've done it dozens of times. It's quite obvious that at least most of the time the physics for stock content and mods alike are done by feel rather than rigorous measurement of an actual example of the car in question, that said they're good at what they do.
 
Then this guide is wrong: http://www.racedepartment.com/race-setups/3511-racedepartment-setup-guide.html#post460181
It says, if you have understeer on corner exit then + rear bump.

Since this thread has been resurrected I figured I would respond to your statement. Keith's guide has setup information for rear wheel drive cars. Most settings are ok for front drive cars as well, but corner exit is the opposite for front drive. Rear drive you want the weight on the rear to give you better traction, but you don't want to take the weight away from the front till you are going straight. Front drive cars need the weight to stay on the front as long as possible to keep the traction on corner exit.
 
(...)Rear drive you want the weight on the rear to give you better traction, but you don't want to take the weight away from the front till you are going straight. Front drive cars need the weight to stay on the front as long as possible to keep the traction on corner exit.
But even in a RWD car you don't want the weight to transfer away from the front too quickly when accelerating out of the corner as this could induce understeer. An indication of this is significant higher tire temperature in the front and increased tire wear.
 

Latest News

Are you buying car setups?

  • Yes

  • No


Results are only viewable after voting.
Back
Top