Tuning Basics

So you want to be a better tuner eh? Well you are going to need help! No... not from me.... You need a tool (again.. not me).... Tool? There are tuning tools for FM4? Yep.... Most of us don't really know what we are doing when it comes to tuning a race car without some help or education. Well, there are several things out there that can help you...

If you have Microsoft Office Excel (97-2010), then Slave Munky's tuning spreadsheet is where it's at. This thing is AWESOME, and will provide the best base tune you could want. Check it out on the FM4 forums HERE. This is what I use (and it was just updated today for the March Car Pack), and I can tell you it works! Slave Munky and team are constantly working on making it better, and it shows. It is also accompanied by two training videos to help you get started tuning.

Now... If you have an iPhone or iPod touch, there are two apps out there that work pretty well. Once is called "Forza 4 Gear" (F4G), and the other is called "ForzaTune 4" (FT4). They do cost a little bit (I think $0.99 or $1.99), but they do the job.

• I've used (and still use) both of them, and can tell you that FT4 works great for lower class (up to B and some A) tunes, as well as getting drift and transmission tunes.
  
• F4G works good for all classes, and even lets you set choose a controller or wheel based tune. It works well for all classes, but I've had a few issues. The first is that you cannot specify what downforce you are running like in FT4. What happens is it "provides" you with the optimal DF to run. The problem there is that is will spit out numbers lower or higher than the car's aero can actually do. This is especially true for lower class cars.

All in all, they will all give you a good place to start. I preffer Slave Munky's Spreadsheet, but they all work. As I said, I still use FT4 for Drift tunes and for quick tunes on lower class cars.

If you need help or have any questions, please just ask! If you think you question is stupid, or are afraid to ask in a public forum, shoot me a PM....

Happy Tuning!!!

EDIT: Link to Slave Munky's Spreadsheet (Version 4.4 - March 2012) on my Google Docs site...

I always wanted to try and tune things myself...reading VVV Worm's tuning guide on the forums and trying to figure out what the settings did to my car. And I could never do it right, I always ended up making the car worse than it was stock. So I tried out slave munkys calc and it gave me a nice place to start. Now I just tweak little things to get the car to my liking and it works

I found the slave monkey calc sets the springs high and the arbs soft which made the cars feel slippery, so after much reading of worms guide and with reference to diy-racetuning.net (and a few others I cant remember) I wrote a google docs spreadsheet to calculate the initial spring settings as per the Xtreme Skills formula on the guide. I then use the slave monkey calc to get gearing (it seems an excellent starting place) and normally have to double the arb/bump/rebound settings from the slave monkey calc which gets me a more supple and less slippery car. In addition I can enter arb/bump/rebound etc and modify them by a factor easily (to keep things in balance).

Link to spreadsheet:
docs.google.com/spreadsheet/ccc?key=0Ai0-HCijSclrdHFVV1gtdmJXcEFSeXRNOS1Wa0dfSGc


I started learning to tune in earnest a few weeks ago and interestingly I have probably learned more about my driving than tuning. Because most of the changes are so subtle it makes you really focus on how they 'feel' and that increased sensitivity can then feed back into tuning process.

I also find it helpful to download a decent tune from the storefront to use as a baseline reference (from a feel perspective).

N.B. The links aren't proper because I havent been a forum member for 7 days!

Do you guys have a general setting for tire pressure? Or do you tailor it to specific tracks? I've used the FT4 app and it lists 28 (or 28.5 - can't remember) psi for front and rear tires. I think the default in Forza is 30 psi for both. I'm sure there are all kinds of considerations and variables, but I was just wondering what your quick tune settings are for front/rear psi. Thanks!

jgooman,

can you give a little mor direction on how to use that spreadsheet? I can't figure out how to enter any values into the cells -
Thanks

I use what the Slave Munky calc spits out and go from there.... The way I check for optimal pressure and suspension tune is to do 6+ laps on the track I want to tune for in open play Hot Laps section once I have a stable base tune. Once I complete the laps, I watch the replay (remember, there is no reply when doing test laps in the tuning section) switching between the suspension telemery, overall alignment and temp and the real-time tire temp screen.. This data will show you any suspension bottom outs, alignment issues or under/over tire temps.

VVV Worm's guide is great working towards a fine tune (http://myforza.net/f4/rimlist.php?range=128&page=1), and I do agree on the point on Slave Munky's table being a bit soft. I usually set the Spring Rate mondifier to 120%, the Rebound Modifier to 125%, and the Bump modifier to 150%. That seems to firm up the suspension just right. As far as the ARB's go, I find the base 100% good for most tunes, and increase it as needed... The "Cause and Effect" addition to VVV Woorm's guild is GREAT for figuring out what to fine tune (see below)


EFFECT ON VEHICLE & POSSIBLE CAUSES
.....* Straight Line Instability
..........+ Too much rear wheel toe-out.
..........+ Not enough rear downforce.
..........+ Too much front downforce.
..........+ Not enough rear toe-in (under hard acceleration) –presumably for RWD.
..........+ Too much front toe (either in or out) – car darts over bumps.
..........+ Front ARB is way too stiff – car darts over bumps.
.....* Instability Under Brakes
..........+ Front end darts or wanders – too much front brake bias.
..........+ Car wants to spin – too much rear brake bias.
.....* Response
..........+ Car feels heavy and unresponsive.
...............> Too much downforce.
..........+ Car feels sloppy and is slow to take a set in corners.
...............> Too little shock.
...............> Too much body roll (not enough spring and/or ARB).
..........+ Car responds too quickly, is twitchy, and slides easily.
...............> Too little downforce.
...............> Too much shock, too much spring, and/or too much ARB.
...............> Too much tire pressure.
.....* Understeer
..........+ Corner entry understeer – car won’t turn in at all.
...............> Front tires not wide enough.
...............> Too much front roll stiffness – ARBs and/or springs.
...............> Not enough front bump – shocks.
...............> Not enough front downforce.
...............> Too much dynamic camber on front wheels (not enough static negative camber).
..........+ Corner entry understeer – car turns in initially then starts to push.
...............> Too much front toe-in.
...............> Rebound too stiff – shocks (not enough droop travel).
...............> Not enough front downforce.
...............> Bump not stiff enough – shocks.
..........+ Corner entry understeer – car turns in and then darts.
...............> Insufficient front suspension travel in either or both directions – shocks.
.....* Oversteer
..........+ Corner exit oversteer – gets progressively worse from the time throttle is applied.
...............> Too much rear roll stiffness.
...............> Too much rear camber.
...............> Too little rear downforce.
...............> Too little rear toe-in.
...............> Not enough rear spring, shock, or ARB – allows car to roll over on outside rear wheel.
..........+ Corner exit oversteer (sudden) - car takes its set then breaks loose.
...............> Not enough rear suspension travel (too much shock in either bump, rebound, or both).

CAUSES & EFFECT ON VEHICLE
.....* Springs
..........+ Too much spring – overall
...............> Harsh and choppy ride, lack of tire compliance.
...............> Can’t put power down on corner exit - excessive wheel spin.
...............> Car slides too much.
..........+ Too much spring – front
...............> Initial understeer.
...............> Front end breaks loose in corners.
...............> Front end breaks loose over bumps.
..........+ Too much spring – rear
...............> Oversteer when power is applied on corner exit.
...............> Excessive wheel spin.
..........+ Too little spring – overall
...............> Car bottoms out.
...............> Car feels like it’s floating.
...............> Sloppy response.
...............> Car is slow to take its set.
..........+ Too little spring – front
...............> Front end hits ground under brakes.
...............> Too much body roll on corner entry.
...............> Initial understeer – car won’t point in.
..........+ Too little spring – rear
...............> Too much squat under acceleration, and the resultant increase in negative camber.
...............> Car falls over on outside rear wheel causing power-on oversteer.
.....* Anti-Roll Bars
..........+ Too much ARB – overall
...............> Very sudden turning response and little feel.
...............> Car slides or skates instead of taking its set.
...............> May dart over one wheel bumps or diagonal bumps.
..........+ Too much ARB – front
...............> Corner entry understeer that gets progressively worse.
...............> Steady state understeer in the middle of sweeping turns.
..........+ Too much ARB – rear
...............> Corner exit oversteer when throttle is applied.
...............> Excessive sliding coming out of corners.
..........+ Too little ARB – overall
...............> Car is sloppy and lacks response.
...............> Car is slow to transition, especially in chicanes and esses.
...............> Car rolls too much resulting in too much dynamic, positive camber and the resultant loss of cornering power due to decrease in tire traction.
..........+ Too little ARB – front
...............> Car rolls over onto outside tire on corner entry then ‘washes out’ (understeer).
...............> Car lacks steering response and is slow to change direction.
..........+ Too little ARB – rear
...............> Back end doesn’t want to rotate on corner exit under power (difficult to throttle steer).
.....* Shock Absorbers
..........+ Too much shock – overall
...............> Very sudden car with harsh ride, sliding, and wheel patter.
...............> Car crashes over road surface irregularities.
..........+ Too much rebound adjustment
...............> Wheels do not return to road surface quickly after displacement.
...............> Inside wheel pulls off the road surface in a corner.
...............> Lack of tire compliance over bumps and surface undulations.
...............> Car may be jacked down in long corners.
..........+ Too much bump adjustment
...............> Initial reaction to bumps and curbs is harsh.
...............> Initial chassis roll slow to develop.
...............> Car slides rather than sticks.
...............> Driven wheels hop when the power is put down.
..........+ Too little shock – overall
...............> Car floats a lot in ride and oscillates after bumps (under-damped).
...............> Slow and sloppy response.
...............> Chassis rolls too quickly.
..........+ Too little rebound adjustment
...............> Oscillates after bumps.
...............> Doesn’t put the power down well.
..........+ Too little bump adjustment
...............> Initial bump reaction soft.
...............> Car dives and squats a lot under brakes and under power.
...............> Car rolls quickly and falls over outside tires – front tire on corner entry and rear tire on exit.
.....* Wheel Alignment
..........+ Front toe-in – too much
...............> Car darts over bumps, under the brakes, and during corner entry.
...............> Car won’t point into corners.
..........+ Front toe-out – too much
...............> Car wanders under the brakes.
...............> Straight line instability especially over one wheel and diagonal bumps.
...............> Car may point into corners then refuse to take a set
...............> Understeer as a result of tire scrub in long corners.
..........+ Rear toe-in – too much
...............> Rear feels light and unstable on corner entry.
...............> Car slides a bit in corners rather than rolling freely.
..........+ Rear toe-in – too little
...............> Power on oversteer during corner exit.
..........+ Rear toe-out – any
...............> Power oversteer during corner exit.
...............> Straight line instability.
..........+ Front wheel caster – too much
...............> Excessive physical steering effort (probably non-applicable with the XBOX controller)
..........+ Front wheel caster – too little
...............> Too little steering feel and feedback (also probably non-applicable with the XBOX controller)
..........+ Camber – too much negative
...............> Inside of tire will be hotter than the rest and wear faster.
...............> Front tires – reduced braking capacity (dive)
...............> Rear tires – reduced acceleration capacity (squat)
..........+ Camber – too much positive
...............> Outside of tire will be hotter than the rest and wear faster.
...............> Rear tires – corner exit oversteer and reduced tire traction.
...............> Rear tires - If extreme may cause corner entrance instability.
...............> Front tires – too much body roll and understeer after car turns in.
.....* Tires
..........+ Too much tire pressure
...............> Harsh ride.
...............> Excessive wheel patter, sliding and wheel spin.
...............> High temperature at center of tire.
..........+ Too little tire pressure
...............> Soft and mushy response.
...............> High tire temperatures at inner and outer edges.
...............> Reduced contact patch

SouthernFist7 wrote:jgooman,

can you give a little mor direction on how to use that spreadsheet? I can't figure out how to enter any values into the cells -
Thanks

You have to enable editting more than likely. Should be just below the Excel Ribbon...

For those of us that have android phones, marketplace has an app called forzadroid. Helped me get a good base time on some cars, others cars not so much. But its free and worth looking into.

SouthernFist7 wrote:jgooman,

can you give a little mor direction on how to use that spreadsheet? I can't figure out how to enter any values into the cells -
Thanks

You should be able to save a copy to your Google account, but I have enabled editing anyway.

Green = input, orange are the outputs. It works best if you refer to the DIY race tuning guide.

I've had that sheet of scenarios for a few weeks. I am definitely looking into that spreadsheet. The thing that stinks is right now, I don't think my internet is working with my laptop

Just download the one by slave monkey and you won't need the internet connection.

I found a pretty good website providing a lot of helpful descriptions and tips for tuning in FM4...

http://diy-racetuning.net/index.html