Details in the pages.
New variant of the compact version with damper tuning by damping ratio, under the assumption Forza damper units are n/mm/s. https://forums.forza.net/turn10_postst153947_Ride-frequency-tuning-calculator.aspx
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Messed around with this a bit and it seems pretty solid, but I do have a question: How are you determining motion ratio?
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Edit to add:
I’ve run a dozen or so builds/setups through the spreadsheet now, and it does an excellent job of getting a workable setup right out of the box. I do think the frequencies need to be set higher than they would in the real world (probably 2.0 Hz as a dead minimum, and going up from there), as even at 2.2-2.4 the cars I’ve tested ('65 Shelby Cobra and '73 Porsche Carrera) have barely had enough travel to keep off the bump stops, even with the ride height at or near maximum. That may be an “old car” thing, though.
Regardless, it takes a lot of the guesswork and trial-and-error out of getting a “flat ride” setup on the car. Excellent stuff.
I’ll consider shifting the range up, or copying the tables to separate the FH4 (original) and FM7 versions. How stiff are your stiffest good setups? Anything over 3hz? Only on P or R cars? I want the range to exceed some consensus of usefulness by 10-20% in both directions, as to not limit experimentation… It still doesn’t support tuning certain offroad vehicles in Horizon by default, which can go nearly as low as 1hz.
Just a reminder, flat ride by virtue of spring frequencies is a passenger-car thing. That approach to spring tuning is irrelevant when accurate, performance-oriented damping is applied.
What you will see by balancing your ride frequencies in a stiff performance car, is even response and feedback from all 4 corners. Some FWDs/AWDs will not rotate well in any condition without stiffer rear springs. High-downforce racecars need extra rear support to maintain proper aero AOA at speed… some use a 3rd spring. Street cars, and most cars even with aero in FM7, don’t see enough aero force or sensitivity to aero for that to matter, so simply balancing the ride frequency and shifting up or down to find a comfortable rate works well, in my experience.
After playing FM7 for a couple days, I agree. Stock tires aren’t much slipperier than race tires, and need good support. The physics implementation overall seems to favor stiffer suspensions. 2.3 to 3hz was the happy range for the cars I tested, as opposed to 1.9-2.6 for Horizon.
Heh. Glad I’m not going insane. I try to stay as objective as possible when testing/adjusting a setup, but confirmation bias is always a concern.
I’ll eventually get around to trying out the updated sheet (weighted damping settings sound very promising), but my wheel got put away for my son’s birthday and hasn’t made its way back out to the living room yet.
I found this in a discussion about wheelbase/track width ratio:
“While a suspended vehicle will damp out rough steering inputs to an extent, a kart will expose them in a very upfront way. This in my opinion, is what makes karts such good learning tools.”
That’s why soft springs are fun: one need not be as precise, or quick to react, to loss of grip. From ~1.5 to ~2.5hz, precision improves at the cost of stability. Somewhere in the upper 2hz range, the tradeoff turns to grip over rough patches vs downforce support/ride height, because at those rates the car is neither relaxed–the springs tend to react faster than the driver and car’s yaw are comfortable–so are rarely “behind”, nor wanting for precision (unless the damping isn’t ideal).
I still have no problem running <2.0hz in Horizon 4, but in 5, it’s like you said in FM7, 2.2 to 2.4 is about as soft as is even drivable (on the road). This is curious, as my experience outside Forza has been that softer springs are more relaxed, if not easier to drive outright (when properly damped, not freakishly overdamped like FM4 setups were–that game loved soft springs too). One factor seems to be, the steering is so slow, it often resonates with the roll moment at the rates I’d like to use in A and below: close to and below 2hz…throwing the car into oversteer. And Forza still rejects rather than embracing oversteer, so soft springs can’t make a fun, tossable car like they did in FH4.
TL;DR Soft springs give the car a sort of breathing room, averaging the disturbance of driver inputs and bumps, reducing the precision required to work the tires for all they’re worth, consistently. It feels like T10 coded the physics to feel that way even on stiff springs…so stiff springs handle oddly but ok, and soft springs are undrivable.
Edit: I have to install FM7 and verify that mildly underdamped setups wasn’t the actual reason soft springs gave me trouble. And I know I don’t like some aspects of the tires and steering but at least, if I could play it, like FH4 and FH5, pretend nothing about it bothers me and everything is great, wouldn’t have to say soft springs are undrivable because of subtly misguided game design goals
The spring values in Forza are wheel rate. There is no motion ratio, nor true suspension geometry in the cars. Many games handle suspension this way… Beam.NG and LFS are the only games I know of that tune in spring rate, into kinematic suspension (Assetto has semi-realistic suspension but seems to tune in wheel rate, according to the Car Engineer dev app… Not sure).
Sounds plausible, but how’d you (or others) go about figuring that out? There a thread somewhere you can link to? I’ve played around with the guts of GT Legends before, but that game had nice, easy-to-understand text files that spelled out exactly how the game modeled everything. Never even considered trying to reverse-engineer Forza’s mechanics, but I’ve always been curious how it actually functions under the skin.
Just my observation between Forza and other games such as CarX and an old sim called Racer (http://www.racer.nl/). In any car that fails to respond well to balanced frequencies, it seems chassis related. Ferrari F50 and Abarth Spider are 2 off the top of my head. Certain cars like the Volvo wagon and '09 Focus RS, and JCW Mini used to have problems oversteering that suspension couldn’t solve. Those I think had their rear roll centers (car config) values set too high, practically if not parallel with the CG.
Gotcha. I’ve noticed a few cars (Lancia Stratos for one) that definitely seem wonky. Might have to check out that Racer; sounds pretty slick from what I’ve read, and my Precambrian computer may actually be able to run it.
Probably… Mods are the only content, the tires never had realistic values… fun to play with for a while.
The Cobra (B600; 2379 lbs @ an estimated 52.0% weight distribution; stock tires, no aero) is currently using 2.3 Hz front and 2.5 Hz rear and is at 4.9" ride height front and rear. It’s enough to keep it off the bump stops on the Nordschleife, but travel is in the high 0.90s on several of the corners according to in-game telemetry. The Carrera (also B600; 2192 lbs @ 42.5%; Street tires, no aero) is at 2.5 Hz front/2.6 Hz rear and is at 5.5" front/6.5" rear ride height. It does max out travel on some of the harder corners, but just barely. I haven’t noticed it actually bottoming out at all.
I doubt I’d personally ever run anything over 3.5 Hz (even with modern, high downforce race cars), but I prefer softer suspension setups than most people, so I’m probably the worst person to ask about a “typical” usable range. If I had to hazard a guess, though, I expect a range of 2.0-4.0 Hz would cover most peoples’ needs in FM7. I’ve never played FH4, so I can’t comment on that at all.
That’s bold of you to set a higher rear ride rate. I could never stand to drive RWDs in Horizon with a higher rear than front ride rate honestly. What sway bars and damping are you running that lets such a stiff setup bottom-out? It’s ok if you hit the bumpstops occasionally, as long as it’s driveable.
“Most people” look at the default range and think, middle must be medium-stiff. Realistically, middle is about 2.7hz, which is very stiff for a street car, even for a race-built car with aero. FM7 cars have little downforce compared to FH4 cars. FH4 cars have so much downforce you have to raise tire pressures substantially as top speed increases with some cars to prevent severe contact patch deformation.
In FH4, my happy range for Dirt or all-purpose A tunes is around 1.9hz. 2.2 for S1. 2.4-2.5hz for S2 or S1 with heavy aero. I think I could drive some cars at 2.7 with the right dampers… on a track with minimal bumps (most FM7 tracks are buttery smooth compared to FH4). This is from memory, before FH4 broke when I tried to move it to a different drive, then I used a script from Github to uninstall Microsoft default apps that normally can’t be uninstalled, which made FM7 not launch even though it was installed still. I might play FH4 again this winter if I have internet. I didn’t play FM7 enough to build a library of successful tunes.
Passenger car setup or not, it really does seem to help stabilize most cars over bumps and harsh transitions. It doesn’t make a huge difference most of the time, but on tracks like Rio and Sebring it’s pretty noticeable.
The Cobra is using stock bars, so probably almost nothing (wasn’t enough PI in the build to install sways). Damping is currently R=5.5F/6.0R - B=4.0F/3.5R with very minimal adjustment from my initial “start point”. For the Carrera, the ARBs are still at my initial of 20F/R; damping is at R=7.0F/6.5R - B=4.5F/4.0R, again only slightly adjusted from start.
Just checked a Cortina I ran at last week that did astoundingly well for one of my builds. D400 1708 lbs @ 51.0%. Frequencies are 2.98 Hz F/R at 5.5" ride height (almost minimum), ARBs are at 15.7F/14.3R, and damping is R=6.3F/6.8R - B=5.0F/R. I started off with much softer springs (around 2.3 Hz front/rear), but the car was happier with stiffer springs. I did briefly test a flat ride setup (I’m going to guess around 2.6 Hz front and 2.7 Hz rear) and it showed a lot of promise, but I didn’t have time to re-tune the rest of the setup to work with it.
I’m happy I found this thread. I have been trying to conceptualize the units for damping in FM7. It’s impossible to figure what number = critical damping as the weight of each car changes and there is no unit of weight assigned to the damping adjustments. So I have been using the damping as a 1-10 = 100% or 10 would be critical damping. It seems to work.
Also depending on the car you are trying for flat ride it matters what your targeted frequencies are. For example I run on my '16 gt3rs the following:
springs fr: 335 (2.3hz) using the speed academy formula while assuming a .98 motion ratio and a .95 ACF
Springs rr: 609 (2.53hz) or 10% flat ride, the faster your avg speed the less important flat ride becomes edited a math typo
I picked the ride frequencies using OptimumG’s suspension guide rule of thumb:
0.5-1.5hz for passenger cars
1.5-2.0hz for sedan race cars and moderate downforce cars
3.0-5.0+ hz for high downforce cars
I do experience 100% suspension travel but no reall “bottoming out” moment.
Rebound fr: 5.3
Bump fr: 5.8
Rebound rr: 7.7
Bump rr: 6.9
The damping is organized that way because higher bump ratios are beneficial and will improve handling the most. It is worth while to run more bump in the front to help support the outside tire while cornering. Rebound bias in the rear (overall front and rear following the 10% flat ride delta) is important because with more rebound than bump you will jack the car down. This allows for faster settling in the rear which is what we want.
For the roll bars, Porsches are a little finicky in that, they need a large rear bar. If it were a front engine car you would need a larger front bar since the higher rear spring rate will cause a larger roll moment at the front. And roll bars are your primary roll resistance contributor.
In general all of the GT cars can run 3.0hz+, however, all of the normal passenger cars will struggle because the chassis are not as stiff and you can tell the difference right away in game.
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With stock weight distribution, entering the weight, distribution, and initial spring settings of an installed adjustable suspension, and the correct average damping/bump ratio in the calculator, the calculator’s numbers match the initial damper settings. Ergo, the relativity of the initial settings indicates that the damper tuning parameter is coefficient, not ratio.
You need to know the ratio in order to derive the coefficient. Also we do not have the velocity of the damper at a given moment in time. Based on the singular nature of the adjustment it is a linear system and does not offer a digressive setup such as PCars.
"We decided to try Suspension Frequencies at the aggressive end of the Hz range for track cars, running the numbers for 2.5Hz (150 cpm) up front and 2.3 Hz (138 cpm) out back."
Curious on how you came up with the values for the dampers based on the ride frequency.
I’d put heavy wheels on it if necessary to lower the PI… and maybe try 18/25 roll bars on the Porsche with equal ride frequencies front/rear… It looks like you’re compensating for the understeer in the roll bars of both cars by increasing the rear spring rate, which does work in a pinch but is not ideal especially for RWDs where corner exit traction is often a premium.
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I’ll get internet again next month and install FM7… I’m confident about what works in FH4 (1k hours), less so of FM7.
From the Help page:
Anti-roll bars, springs, and dampers are all balanced separately. That is to say, the various stiffness rows for springs don’t correlate to the rows for damping.
They aren’t related. The damper values are weighty^0.5*[scaling factor] with a spread of 4x. I don’t tune for 100% critical damping, but for reference, squaring (4x) the spring rate causes a 2x increase in critical damping, whatever the mystery units are, and doubling the weight (2x) only increases the critical damping point 1.4x. Assuming the min and max balanced damper values extend beyond ideal settings for the range of spring rates, there is enough spread to choose from, and specific amount and balance should be done by test driving.