Making Best Use of Telemetry for Tuning on Track


First post here. Thanks to all the tuners who posted guides and built apps, it adds a lot to the game.

I’ve tried 6 different sources of base tunes (apps and spreadsheets) and I’m now at the point where I am tweaking to improve the tune. The main problem I’m running into is others seem to get more use out of the telemetry than I do. For example, to fine tune Camber, the best advice seems to be to use the telemetry with the 3 temps per tire screen, to check that there is no temp gradient across the tire when loaded in a steady turn. Unfortunately those temps aren’t static in any turn, and even if I go off throttle its hard to see what the differences are, make a mental note, pause and adjust. So on that one I’ve been wimping out and just using that other screen where it shows instant Camber - if its zero when loaded, I’m good. So are there other workarounds like that for the other tweaks we need to do?

Springs: it would seem logical that a correctly set up car when cornering at constant speed on the limit would show same suspension travel front and rear on the loaded side (ie 70%F 70%R). Is that right? Is there a workaround like with Camber to get there? Every time I tweak springs F vs R to balance the car like that the telemetry doesn’t seem to change at all.

ARB: probably my biggest ‘huh?’ of them all is watching the friction page in telemetry and trying to figure out whether I need to stiffen the bar to even out the patch size (but to what extent) or slacken them off until the unloaded side turns red. What are those percentages shown next to the tires? What do you guys use that telemetry page for?

Dampers: is there a math relationship between the spring rates and the rebound & bump? Dividing by 90 for rebound, then taking 2/3 to 3/4 of that for bump seems ok, but is there any telemetry that helps me tweak dampers other than a general assessment of how much the susp is moving?

Diff: telemetry doesnt tell me what the diff is doing. Is there any way of getting that off the telemetry?

I understand that some watch the replay to decipher whats going on in slowmo. Is there no graphing anywhere? Seems a big omission from the game if so.

Finally, one unrelated question concerns these leaderboards with best lap times: are the leaderboard times for cars in same homologated class? Is there any way I can Sort to show MY best times in various cars in among all those tens of thousands of results? After all, the entire tuning effort is about lap times, but it’s odd you cant pull up you own best times for any circuit…

It’s far too complicated and inconsistent without a spreadsheet to look over the data.

Best to tune by feel. Understand the types of over and understeer, then tune the car as close the neutral as possible.

Here’s a workflow

Personally and actually , I prepare my cars like this :

I check at first my configuration of parts ,

if for example the rear axle is blocked and , if that the nose of the car does not fit in the corner , with the 2 tire sizes to chose ,

if the car continues to slide , even with races/sports reinforcing bars and adequate tire sizes , it can be the total weight .

for the wheels choice , if the car is heavy , I chose light wheels and vice versa .

Sizes of rims to mount in any case, because it stabilizes, thanks to the tire a little flatter, to standardize the heating on the 3 sides of the tire ,

chose them with car feelings too ,

The other choices of parts are necessarily the same each time . ( Races Options )

For the set up : i think u have to ponder on the gearbox , alignment , anti roll bars , other parameters are easy to set ,

i set first , the gearbox ,

for the gearbox , its easy , because generally the last gear ( the 6th ) does not fit in the gears to pass , on the original configuration ,

so u have to put the 6th on the 5th gear Pinion , and the 5th to the 4rth pinion , I mean wedge them on the same number as the previous one ,

then set the 1st for the start stop , adjust the 2nd between the 1rst and 3rd ,

and adjust the 3rd and the 4rth , 5th , for the different turns on your circuit ,

the 6th for not having a hole after 5th .

The final gear to define the bite of the box by increasing its teeth , so more to the right ,

and i think the long road atlanta is good enough to adjust the gearbox ,

after that for the tires pressure , it also depend of the ride height too ,

if u have increased or reduced ur ride height , match the centimeters , in notches of bars/psi pressure ,

alignment with feelings ,

but if the nose does not fit in the corner, put more negative camber on the nose , and if the rear glide increase the rear ,

without increasing too much the latter , otherwise it will not steer in the corner ,

the caster angle to set with the both front and rear negatives cambers , and feelings ,

but still increase it a little more , than the original ,

anti roll bars , adjust the difference of the front and back , for the turns , u can increase them a little bit , for maintaining stability between 2 corners ,

Thats all for for the research that takes time :

after that , just set the right height , generally +1 or 2 notches above ,

and verifiy by how many millimeters you have increased your ride height ,

to be able to adjust your suspensions ,

i mean if ur ride height was about 18.0 centimeters , and if u put it to 18.7 centimeters ,

then u have to reduce ur springs by 7 , and not 0.7 ,

the rebound to add 7 ,( if its 7 of the ride height ) ,

and the damping to reduce of 7 ,( if the ride height uped by 7 ) .

the aerodynamic settings it’s the same ,

plus 7 digits on each , if the ride height was uped about 7 centimeters ,

other parameters for Turn Feelings , to correct the trajectory angle ,

but the brakes will feel much better with the ride height and the whole setting ,

and necessarily longevity of tires with increased ride height .

and an example on a FF Car ,

i upped the font ride height of 0,5 centimeters , and reduced the back of 0.3 centimeters ,

so i reduced 5 of the front spring , and upped 3 on the rear spring ,

upped 0.5 on the front rebound , and reduced 0.3 on the back rebound ,

reduced 0.5 on the front damping , and upped 0.3 on the back damping ,

upped by 5 digits the front aérodynamic , and reduced by 3 digits the rear aérodynamics ,

and for the tires -0.5 notches on the front tires , and + 0.3 notches on the rear tires ,

with all that , u get a champ car ,

Thats how i do , actually to prepare my cars . And its working well .

The problem with ‘feel’ is that you are experiencing a combination of things. Also, a car that feels great to drive can be slower than one that isnt.

To start to answer my own question, a a brand new tuner I’ve noticed that you can use the suspension telemetry to set ride height lower and lower on a given track until you start to see travel in the high 90’s. You can use the heat screen to tweak camber to get outers juuuuuust higher than center and inner after a steady turn. However, this is best done in a replay, using the triggers to slow it all right down.

At the moment I’m staring at the friction screen on both good handling and bad handling cars to try and see why they feel so.

Yeah but the telemetry readings alone aren’t going to improve your lap times. If you’re tuning for speed you’re making one change at a time and doing a few laps, then making another change and doing a few laps, and so on and so on. When it’s functioning properly telemetry is great for spotting issues that are slowing you down, like maybe your outside rear bottoms out when accelerating out of a corner and causes you to spin.

If you really want to be thorough keep a spreadsheet and record as much data as you can stand.

My advice to you is to resist the urge to always use a base tune, or to apply a formula to everything you run. Of course sometimes those formulas work and give a good result, but other times they create more problems than they solve. Start by setting the brake pressure to your preference and go to a track you’re familiar with to get a feel for the car. From here I like to check telemetry to be sure I’m not bottoming out and that my camber settings are close, and then adjust the car for feel.

From here I make a decision regarding what I want out of this tune. If it’s just a general hopper tune I’ll tweak the handling across a few different tracks. For example, a car that feels just right at Catalunya typically feels catastrophically loose at Mugello or even Brands Hatch. This is because Catalunya has two critical high speed corners that you have to accelerate through that require a lot of fine tuning to keep from plowing off the edge of the track after you open the throttle.

But if this is a car I’m going to spend a lot of time with, like some of the Forza GP cars, I’m probably going to spend some time on track specific tunes that get the most out of the car by testing each tuning adjustment against the clock. You can find a surprising amount of time doing this, but it’s not a quick process.

I tune by the telemetry and by feel and for me what you want is netural for every part of tuning so you can know what to fix and if all parts are nutural you will be able to push the car harder and have more grip and can more confidence.

I try not to band aid fix in my tunes, I try to fix the actual root of the cause and that can mean making the balance go the wrong way on a type of adjustment.

For me balance trumps grip.

I also look for balance, but I think a bias to the front is necessary, as its best to have less roll on front than rear due to stiffer springs (relative) up front. If a car has a weight distribution of (for example) 52%, I will set up the springs to put 56% on front and just 44% on rear, ie +/- 4%

I also deduct the unsprung weight (I assume 10%) so for a 3000lb car @ 52% I would set the front springs to (3000 *0.9) * 0.5 * (52+4)% = 756 and the rear (3000 *0.9) * 0.5 * (100- (52+4))% = 594

I then set ARBS to 20, 20, ride height to minimum, and use the telemetry to see if the suspension is bottoming anywhere. If it is, I either raise ride height (rough tracks) or increase both ARB, and if neither works add 10% to springs. I then use ARBS to dial out understeer/oversteer.

I’m currently figuring out the dampers: I start with rebound at 1% of spring rate (so 7.5 / 5.9 in my example), and bump at 2/3 - 3/4 of that. However, the key is to to get the rear to front weight transfer mid corner working and I’m only just starting to figure that out.

Telemetry seems real useful for dialing in camber and toe, as long as you figure out when its telling you lies (left rear in right turn seems reversed) so hopefully, one day soon, the developers will fix their game and that will work better.

I’m pleased there is now a data out option - apps are being built as we speak. Soon, we should be able to dump data to spreadsheet and plot suspension and slip offline - cool!

Sorry to release my science and I thought to answer all those who sought such explanations .

And and how do I know how many centimeters I have to remove or add , for the ride height ?

Easy , if its a FF u up the front and reduce the rear ,

if its a FR u reduce the front and up the rear ,

how much ?

Easy , you must know the total weight on the front in Percentage , and the total displacement of your ride height ,

and calculate the percentage of this one by what is above 50% .

Example : my car have 59% of the front total weight ,

and 5.8 centimeters of total displacement in the ride height ,

so u take 9% and calculate this 9% of this 5.8 centimeters ,

5.8 multiply by 9 , divide by 100 =

it gives 0.522 ,

so it means that u have to up the front by 0.5 centimeters and reduce the rear by 0.5 centimeters ,

if its a 50% of total weight for all , u must decide what to do ,

thats all :smiley: .

My solution is for not search with a long time the set up , and for maintain quickly the car on the road ,

but after seeing what can do the télémétry , its the best for sure .

I’m wrong do not follow my tips .

I discovered a nice thing , look a little in the forum to find out what it is .

Half of the telemetry doesn’t function correctly & it’s been that way since release, such as the camber always showing as 0 & on the Heat page the tyres on the right are reversed so the outer temps are actually the inner ones etc.

You can however make use of the Heat, Tyres, Suspension & Friction pages to good effect.

Thread resurrection now the telemetry seems to work (apart from the annoying big number glitch on the SUSPENSION screen).

Tuning camber, the accepted method is to adjust until temps on the TEMP screen are even. Some times the results are corner dependent - temps are great on one corner, then have bigger intervals on the next, so I have been looking at the camber reading as a gross error check. My questions are:

Is the camber reading reliable now?

Should the camber readings front and rear be about same most of the time?

If you ever see positive camber, front or rear, should you tune it out?

Dont use telemetry learn how each setting affects handeling and then adjust the car to fix the issues. Once issues are fixed tune to make the car faster. Make adjustment, do laps, see if you go faster if not reset or even try going the opposite way test again and then when u go faster keep settings. With no way to log telemetry to look at it after it’s basically useless.

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I agree with you in general, but some issues have multiple possible causes. I found that running a replay, selecting pause, then using triggers to spool forward and back with telemetry on mde it real easy to see what the numbers were every instant. If the data is there, why ignore it?

Also, the data out feature provides a ton of parameters that can be logged. I started a thread to illustrate the results you can get from that but no-one here in the Tuners Garage was interested.

Doing that doesn’t tell you if that is something that was changed from a slight line change or speed from the previous laps, so without way more effort than it should take it’s not really an useful option. If someone were to make a telemetry app using the api than it would be better.

The reason their are multiple solutions is because of the simplified physics and tuning. The reason baseline tunes work so well on forza.

Now that camber ‘works’ in telemetry I’ve been playing with it to see how different alignments behave in high speed turns.

Lesson learned is that the camber shown in telemetry is camber to vertical, not camber to road surface, so unless you are a track which is flat (most of Airfield) it’s useless.

One I figured that out, it’s useful for getting the alignment into the ballpark before fine tuning.

Now what ive learned about camber is from this video on yt that taught me to make camber zero on the outside while under compression but i also noticed that there was still handling imperfections because the inside camber dosnt match up so what i started doing is taking the side that has more natural camber like for an example. If your taking a corner and the f camber on the inside is 1.3 then the rear inside is 2.3 dont bother trying to match up the side that has that much camber to the front cause all thats gonna end up happening is having an excessive amount of positive camber on the outside rear camber. What you wanna do is make the side that has 2.3 camber on the inside make the outside zero your still gonna end up with like 1.7 or somewhere in between there after that. Take the front camber and add more camber to that side to match the inside tired with the rear inside tire… and as far as the diff goes more accel more understeer less accel more over steer same goes for decell only when off throttle tho. I usally keep my acelleraction between 50 and 80 percent my decelleration i keep between 15 and 45 percent depending on the car will determine what you should put it at. Your tire pressure should be 29 psi on both sides after being heated up. So it should be 29 in the telemetry. Makes them really good and sticky. And that right there is where your gonna get most of your grip from

I dont agree on accel diff. More accel = more oversteer, not understeer. (Decel diff is opposite)

Drive around a track like Watkins and accelerate hard after the apex of the corners; that track makes it easy to see the rear stepping out (= oversteer) if you have too much accel diff.

Just to get some things out of the way. The biggest change you can make to your lap times will depend on your car build, not your tune. I used to do pen and paper suspension calcs (which is a pain for damping), and I’ve used numerous calculators/ spreadsheets. While all of these may result in different tunes, they will all generally bring you within a few seconds of the builds best performance. You are essentially setting up per track and per personal preference when you are tuning.
It also needs to be mentioned that the suspension system and physics aren’t all that advanced. A baseline build between cars will work pretty similarly, each car essentially has the same suspension, there is no trickery. There are no progressive springs, magnetic dampers, or trick McLaren ARBless set ups at play here. Your car is a brick with invisible aero numbers… Its questionable if the game even differentiates unsprung weight seeing as the heaviest wheels are a trademark in many leaderboard builds.

I’ll be honest, just use a calc to start, it will be fine. I use FACR, mainly because of all the ancillary tuning options. I know what I want from a car, the unique issues I may have (Porsche layout), etc… I can set how hard the springs are, how hard the dampers are, the balance, what causes that balance, etc… and I’ll get settings that are damn close to what I want.

Springrate: this is a pretty simple set, based on track, car lay out, and preference. Most cars, a 50/50 will work (Porsche I usually set up for 45/55 or 40/60 concentrating weight up front) , I prefer to tune around 90% to 100% of weight, mainly because almost every car has some measure of down force.

Dampers: this is essentially the resistance to expansion or contraction of the springs. Springs need to be controlled, and this is the control. There are different ways to go about these. There are formulas, different frames of thought, etc… Majority of my set ups fall in the 7 to 9 rebound with 2-4 bump range. Bump will always be lower, but a fair margin, in real life application that’s because Rebound is actually responsible for controlling sprung weight of the car etc, bump controls the unsprung weight of the wheels, resisting their compression into the car. A couple of ways to go about using in game telemetry for this is if the car, when sitting still, is excessively past the the midmark for spring expansion. If the vehicle is moving and you are still having major issues with spring expansion balance or bottoming out, your dampers might be set up too soft for your aero set up. Vehicle weight “rises” as speed increases. There are other tells, if the car is being excessively upset by bumps, your bump damping is set to high (too much resistance to the wheel compressing into the frame) if the car isn’t settling or bouncing, your rebound is set to high or low respective. Like I said, just use a calculator. The real life application of this takes into consideration tire types and their natural damping/rebounding,weight of wheels for bump, weight of chassis for rebound, springrates, etc… When fine tuning, outside of major handling issues like excessive issues with bumps (which never really happens with a calc) just look to balance either end of the car with the opposite. Mainly damping is controlling weight transfer and to a degree roll.

ARBs: Harder set up (spring rate + damping) harder the ARB setting, and vice versa. Tune by feel on sweeping corners. While ARBs may give a slight effect to turn in grip, they generally rear their issues on steady state cornering. Car is understeering, lower front arb (relative to rear), oversteering, lower rear. If the whole car doesn’t like to give you slight adjustments in the corner, try taking a couple of ticks out of both ARBs and go from there. If the car is sluggish to accept adjustments, raise both ARBs. Any issue that you can find from telemetry is better to just go by feel.

Camber/Caster: Camber is another funny one in this game… basically if the car isn’t a race car I find 2.5-1.5 is generally the range I want on both front and rear. Camber is tuned per track, and really you are going for an average here. Trying to get that magic 0 out of every corner isn’t going to happen. Use some common sense, if the track is 8 hair pins and one sweeper, don’t tune for the sweeper. But between 2.5 and 1.5 it’s a pretty sweet magic spot. PS Caster increases your negative camber on turned wheels, so be careful with it. FR I’m usually at 6, AWD 5.5, and FWD 5-5.5.
Camber is one of those setting that it works so far off from reality that it’s hard to be definitive about it. In real world the type of tire, rake angle, caster, will all be taken into consideration. Tire choice being the biggest here, sticky tires apply more force on the suspension, requiring more caster, if Forza was more realistic in this light you’d see race tire camber 3-3.5, Sport would be 2.0ish, and street would be 1.0ish. Forza doesn’t seem to care that a street tire just doesn’t have the grip to require the general 2.0 caster most cars get.

Diff - This is half personal preference and half function of the track. My FR cars are usually 60/25, at least that’s my jump off. Usually I want equal amounts of on-throttle rotation vs off throttle rotation. You know when you are in a corner and you go from accelerating to decelerating and suddenly the car isn’t tracking around the corner the same anymore, or when you get on the throttle and you start to understeer or oversteer, look at your diff.
For Rear and AWD this is going to be pretty similar in settings, but… you want both accel and decel to be as low as possible. The description is a bit vague but 100% means locked diff, 0% means open diff. Unless you are a drifter or drag racer, a locked diff is not a good thing, and you want to be closer to the open diff side. I also have a favorite spot for tuning diffs, Bathurst on the uphill S curves (turns 4 and 5 I believe). So the feel you want out of them is prefference but, high accel to the point that you get vehicle rotation and you can turn with throttle is what you want. Too much accel and your tires will both spin up and you oversteer, too little accel and the inside is going to do [Mod Edit - Abbreviated profanity, profanity and profanity that is disguised but still alludes to the words are not permitted - D] it wants when you need it to grip. The uphill S is perfect because it unweights the inside wheel, I find if the accel is set right, these 2 turn will cause a bit of chirping, basically the second you lose grip it locks and then releases immediately. You want that on just these 2 turns only… But the right setting here for the aforementioned issue seems to be pretty solid for every other turn in the game. Decel is more of a feel, excessive locking will cause oversteer, I usually use the go past and come back method. If I’m at 25 and I’m not getting the off throttle rotation I want, I go to 35, when the car usually becomes a bit of a pita, I start going down, by increments of 2 or 3 until I feel close to what I want.

[Mod Edit - Abbreviated profanity, profanity and profanity that is disguised but still alludes to the words are not permitted - D] After 5 laps one side will be 10% worn vs 5% worn on the other you have a problem. If they are 1 to 2 % of eachother you are usually good. Obviously some tracks will cause more wear due to heavy breaking, take the Nordschleife vs Bathurst, Bathurst will almost always have a slightly higher front wear vs rear. Nordschleife is usually spot on balanced. Things like Aero, I run a weak rear wing on Nord, will cause slight differences, but you should still be within a 1-2 percent window after a couple of laps.