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Rank: B-Class Racing License
#1 Posted : Sunday, June 9, 2019 5:34:53 PM(UTC)
Rank: Racing Permit
#2 Posted : Wednesday, June 12, 2019 2:56:03 PM(UTC)
Messed around with this a bit and it seems pretty solid, but I do have a question: How are you determining motion ratio?

==

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.

Edited by user Saturday, June 15, 2019 6:58:16 AM(UTC)  | Reason: Not specified

Rank: B-Class Racing License
#3 Posted : Friday, June 14, 2019 11:04:14 PM(UTC)
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).

Edited by user Saturday, June 15, 2019 12:39:58 AM(UTC)  | Reason: Not specified

Rank: Racing Permit
#4 Posted : Saturday, June 15, 2019 3:57:04 AM(UTC)
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.
Rank: B-Class Racing License
#5 Posted : Saturday, June 15, 2019 5:13:07 AM(UTC)
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.
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#6 Posted : Saturday, June 15, 2019 6:40:24 AM(UTC)
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.
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#7 Posted : Saturday, June 15, 2019 7:21:27 AM(UTC)
Probably.. Mods are the only content, the tires never had realistic values.. fun to play with for a while.
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#8 Posted : Saturday, June 15, 2019 3:06:02 PM(UTC)
Originally Posted by: Mr Pinstripes Go to Quoted Post
Messed around with this a bit and it seems pretty solid, but I do have a question: How are you determining motion ratio?

==

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.


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.

Originally Posted by: Mr Pinstripes Go to Quoted Post

Regardless, it takes a lot of the guesswork and trial-and-error out of getting a "flat ride" setup on the car. Excellent stuff.

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.

Edited by user Friday, August 2, 2019 6:32:42 AM(UTC)  | Reason: aero AOA, not flat ride

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#9 Posted : Saturday, June 15, 2019 6:03:01 PM(UTC)
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.
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#10 Posted : Saturday, June 15, 2019 8:03:41 PM(UTC)
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.

Edited by user Saturday, June 15, 2019 8:13:20 PM(UTC)  | Reason: Not specified

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#11 Posted : Sunday, June 16, 2019 1:07:44 AM(UTC)
"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."
http://speed.academy/how...ates-eibach-koni-marcor/
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#12 Posted : Sunday, June 16, 2019 6:14:47 AM(UTC)
Originally Posted by: NumberlessMath Go to Quoted Post
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.

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.

Originally Posted by: NumberlessMath Go to Quoted Post
What sway bars and damping are you running that lets such a stiff setup bottom-out?

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.
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#13 Posted : Sunday, June 16, 2019 8:39:22 AM(UTC)
Originally Posted by: NumberlessMath Go to Quoted Post

Curious on how you came up with the values for the dampers based on the ride frequency.
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#14 Posted : Sunday, June 16, 2019 6:05:21 PM(UTC)
Originally Posted by: Mr Pinstripes Go to Quoted Post
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.

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.[/quote]

Originally Posted by: Mr Pinstripes Go to Quoted Post
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'll get internet again next month and install FM7.. I'm confident about what works in FH4 (1k hours), less so of FM7.



Originally Posted by: EpicEvan777 Go to Quoted Post
Originally Posted by: NumberlessMath Go to Quoted Post

Curious on how you came up with the values for the dampers based on the ride frequency.

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.


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#15 Posted : Monday, June 17, 2019 7:01:12 AM(UTC)
Originally Posted by: NumberlessMath Go to Quoted Post
Originally Posted by: Mr Pinstripes Go to Quoted Post
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.

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.


Originally Posted by: Mr Pinstripes Go to Quoted Post
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'll get internet again next month and install FM7.. I'm confident about what works in FH4 (1k hours), less so of FM7.



Originally Posted by: EpicEvan777 Go to Quoted Post
Originally Posted by: NumberlessMath Go to Quoted Post

Curious on how you came up with the values for the dampers based on the ride frequency.

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.


[/quote]
I was just curious, it's very similar to what it should be irl in terms of rebound especially.
Rank: B-Class Racing License
#16 Posted : Monday, June 17, 2019 3:40:47 PM(UTC)
Depends on which row you choose, they scale up faster than* spring stiffness

Edited by user Monday, June 17, 2019 3:41:44 PM(UTC)  | Reason: spelling

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#17 Posted : Monday, July 1, 2019 7:22:26 PM(UTC)
Also of note, when increasing spring rates, critical damping coefficient increases by the square root.. if 400lb spring and 4.0 rebound works for you, 800lbs and 5.7 rebound should feel equally bouncy. The lack of actual units on Forza dampers make them impossible to set without test driving. In both FM7 and FH4, the tuning menu is annoyingly far from the initial pause menu state, compounding the inefficiency of setup.
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#18 Posted : Thursday, July 18, 2019 11:05:06 AM(UTC)
Hey, I just realized I applied the weight correction factor on the damper balancer incorrectly, resulting in more damping than should be on the light end of the car. It's fixed now.

I only noticed as I was adding a second damper section, with inputs for current spring rates. The new, "Ratio-matched" column, reads the weight distribution and chosen spring rates to output balanced damping ratio values. If your ride rate is balanced front to rear, at 100% scale on the new dampers, they should read exactly the same. If the rear ride frequency is lower, the rear dampers will scale down accordingly. If you try this, and flatly correct your rear damper rate like this

frontdamper/frontspring*rearspring=reardamper

You'll find the table gives a touch more rear damping. This is because the weight of the vehicle is equally a factor in effective damper stiffness as spring rate.

Happy tuning!

Edited by user Thursday, July 18, 2019 12:28:05 PM(UTC)  | Reason: Not specified

Rank: B-Class Racing License
#19 Posted : Wednesday, July 24, 2019 2:27:23 PM(UTC)
Originally Posted by: Mr Pinstripes Go to Quoted Post
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)


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.

Edited by user Wednesday, July 24, 2019 2:29:58 PM(UTC)  | Reason: Not specified

Rank: B-Class Racing License
#20 Posted : Wednesday, July 24, 2019 11:42:05 PM(UTC)
With race suspension you can use the exact same spring rates both in Forza 7 and Horizon 4 just with a different scaled damping since they employ different damper ranges.

Edited by user Thursday, July 25, 2019 12:57:40 PM(UTC)  | Reason: Not specified

Rank: B-Class Racing License
#21 Posted : Thursday, July 25, 2019 11:08:17 AM(UTC)
Forza 7 has Race and Drift suspension only, no rally. The spring range for Race/Drift in Horizon is 2.01 to 4.50hz on a 50% car. The spring range for Rally suspension is 1.42 to 3.18hz on a 50% car. The max ride height for Rally is around an inch more than Race suspension.

I'm confident the damper units are the same--try the same springs and dampers on a car with rally, then race suspension. See if it turns different lap times.

Do you pay attention at all or do you just come onto the forum and say things?

Edited by user Thursday, July 25, 2019 11:09:14 AM(UTC)  | Reason: ride height

Rank: B-Class Racing License
#22 Posted : Thursday, July 25, 2019 1:01:28 PM(UTC)
I was referring to race suspension only. But never mind, you seem to know better.

Edited by user Thursday, July 25, 2019 1:06:24 PM(UTC)  | Reason: Not specified

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#23 Posted : Friday, August 2, 2019 1:23:01 PM(UTC)
Originally Posted by: NumberlessMath Go to Quoted Post
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.

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