UPDATE: The BRZ is back with vengeance! [Can someone help me with this ARB nightmare? Thanks!]

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Ok, so I started tuning and I get the gist of many of the settings and how they impact the cars performance, however, ARB’s are driving me crazy. I really want to know how to do a better job in getting into an “acceptable range” so I can then perform the minor tweaking. Of course, one of my issues is that of being new and not being able to drive many of the top LB tunes because they are “pretty loose” and I do not have the FM5 driving skills (yet) to best control the car.

I have a D-class car that I have been tuning for days and I have tested a big range of front/rear ARB and still have problem handling the car. This range has fluctuated anywhere from as low as 12/7.5 and as high as 29.62/23.86 yet can not still figure out. This car/build only has the option to configure the ARBs and not the springs (Note: also has adj Diff and final drive).

The Forza ARB defaults are 29.62/23.86, the Universal Tuning system in separate thread suggests 14/14, and, a buddy of mine suggested from the FM5 tuning calc app the settings of 17/24.5. As you can see they are all over the map. An actually I have tried all these as starting points then up/down with no luck so far. I either get oversteer (rear tires losing traction at 4th turn on the Oval or hitting the wall at the 1st turn once I am coasting.

I have read many guides and checked out many open source tunes yet they are also all over the map for similar cars, and probably, most of this can be attributed to the driving style and/or experience of the driver with the game. In Worm’s tuning guide he outlines the impact of softening and/or stiffening the rear ARB (Rear ARB soften = decrease oversteer or increase understeer
Rear ARB stiffen = decrease understeer or increase oversteer)…thus, should I focus initially just on the rear ARB until I can manage the car then move on to tweaking the front ARB? And, where is the best starting point, Forza’s default or UTS?

All ideas are welcome. BTW, I do not want the “answer”, just guidance on how to proceed with my testing and learnings. Thank you!

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UPDATE (April 26, 2014)

OK, so I am a little stubborn, I decided to give the BRZ one more try thus proceeded to get it out of the garage and I have good news to report. After all the help from the peers here at the forum and more learnings, I made a couple of changes to the BRZ. The initial goal was to get into the Top 100. A couple of nights back I got my first-ever “Top 100” with this 2013 Subaru BRZ on the Indy Oval. I was struggling with this car for about a month and I decided to revisit it based on what I have learned since then. I changed my springs, ARBs, and Reb/Bump…and…walla…from #159 (1:04.129) I went to #105 (1:03.814), to #99 (1:03.737) braking under the #100 mark…AND FINALLY…

I made some minor tweaks and…got #56 (1:03.426)! I made some minor add’l changes, yet, no add’l improvements. I think this tune (for this car & track) is pretty good, yet, my driving still needs a lot of improvement.

I will be posting the build/tune and would love to get some feedback. Please refer to the post in 2nd page for details. Thanks!

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What is the car, what is the build and what is its purpose?

Also can you add rollcage, heavy rims or aero that drops PI enough to get adjustable springs?

What is the characteristic the car has that you are trying to tune out or improve upon?

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Eduardo – let me try to address your questions, I’ll do my best…

  1. The car is the2013 Subaru BRZ set for D-class in the Oval. I actually have 2 builds for this car, my first build was with Race Springs and I was able to tune the car from a #699 (1:05.844, 3 secs off top 10 and leading BRZ’s) with a base tune in 4 laps, to being able to hit 1:04.129 (#143) in the LBs. On a separate thread we were working through getting inside the 100 range as the purpose.

After that, I noticed that 2 of the 8 top BRZ’s had tunes shared so I proceeded to download these onto a duplicate car and noticed they both have ARB’s and just stock springs. Thus, my purpose now was to try to beat my Spring build and understand/learn why these other top LB builds were better. Are ARB’s better for this specific car/track at this class, or are springs?

  1. Both builds have roll cage. Played with both heaviest and some lighter rims. Class will not accommodate springs and ARBs, I purchase just about all parts trying match different configurations and no luck. In addition, I will probably still have the issue of my original ARB questions.

  2. I need to improve both over and understeer in various parts of the oval track, primarily the turns (into and out of) at speed.

Hope this helps. Any suggestions? Thanks!

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First the best advice i can give is to work on one side of the car first (front or rear) Get the car stable on front or rear then go to the other.

Now its hard to give you an idea of how to fix a car if i know nothing about the car at all. Without having more info it will be very hard to help figure out the answer without sending you way off course. I dont need everything the car has but at least some general facts about the car like… what car is it, drive type, is it really heavy or light, and what kind of track are you wanting to run it on.

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Thanks ERS Johnson! Please see my response above to Eduardo for a couple of your questions. The car is the 2013 Subaru BRZ, front engine, RWD, 2838 lbs (54%), 2.0L (200 hp, 151 lb-ft torque). Running on the Indy Oval.

Thanks for the interest in helping out!

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The way i tune arbs is i loosen them in the range of 60 to 80 percent then adjust one unit at a time untill i get acceptable handling at the apex.i would use springs for oversteer or understeer not at the apex.without springs you could try aero or maybe differential.

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Thanks freakinout! The 60-80% you mention, I am assuming is from the Forza base tune correct? With this PI I can only afford street aero. Refer to prior post above for my build with springs.

Oh, good idea with the differential, I had not moved that anywhere. My current setting is 30/15 (RWD).

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By the way, one of my personal objectives/purpose is to get a handle on ARBs since I have several other cars I am having issues with yet want to focus on this one as a learning.

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Lol for some reason I thought it was the BRZ at Indy Oval hence my questions.

That is one project car I attempted but failed with. I would try Stiggles suggestion and then post under what circumstances the car is misbehaving.

One thing I realised when I tried that project is the quicker drivers were driving smoother than I was so make sure you consider that side of things too.

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You gave up, lol! I am a little stubborn, we’ll keep trying just for a little longer. You are right about the quicker/smoother drivers. I tried the #9 LB tune and it was a nightmare to drive, yet, when I saw the video along with running it’s ghost it was incredible painful (or frustrating may I say) to watch these drivers how they can produce driving miracles.

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The stats on the car/build are: 6.0 / 4.6 / 6.6 / 7.1 / 4.5 for speed/handling/accel/launch/braking.

Lateral g’s = 1.12

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If its understeer and over steer and your only other adjustable part is the diff I would set the roll bars at 15/15 and tune the diff. It sounds like that’s your problem

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Thanks Stiggles! Yes, I have both issues at different turns in the track. Sometimes both issues surface depending on how I control the car. I will certainly be looking at the Diff. BTW, I had looked at a setting of 14/14 and still had problems, yet, did not play with the Diff at the time since I just wanted to fix one issue and it may well be that I was trying to fix in the wrong setting/part. Again, thanks for the suggestion.

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Here is a quick update of my tests so far. So I used 2 starting points, one suggested by Freakinout (I set the ARBs at 70%), and the other by Stiggles (17/17) and modifying the Diff. Then I started first working on the rear sliding on my on turn exits (turns 2-4) and started getting such under control with the rear ARB set at 12.70. However, this induced an understeer at turn 1 and hitting the wall. So, is it the setting of the front (moved from 20.72 to 19.70) ARB or the rear ARB that is the problem for the understeer? Should I focus on the front ARB now? (which I will be trying yet don’t want to start guessing!) It seems the ARBs are tightly coupled thus do tuners end up with a back and forth of these settings (versus focusing on one problem at a time)? Thanks!

Back to testing… (by the way, chaining the Accel Diff setting did help a little)

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since you only have 2 tunable parts try this, set the diff at 50/50 and the ARBs at 20/20

if the car is oversteering when you lift off the throttle then you need more decel
if that car is understeering when you lift off the throttle you need less decel

if the car is understeering in the middle of the turn lower the front ARB
if the car is oversteering in the middle of the turn stiffen the front ARB

if the car oversteers when you hit the throttle turn down the accel ( to a point, when you get just one wheel spinning turn up the accel 2-5% and focus elsewhere to reduce oversteer )
if the car understeers when you hit the throttle turn up the accel

if no matter what you do you can’t get rid of the understeer at corner entry then you need to slow down more
if no matter what you do you cant stop the tires from spinning exiting the corner then you need to apply the throttle either later or more gradually

if i had to guess your end set up will end up around 16/20 on the ARBs and 20/40 on the diff but do the above test first

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Thanks Stiggles! I’ll test some of this today and see what comes out of it. The car is certainly doing somewhat better with my settings changes yet still challenging to drive on the Oval.

I understand the font when it either under or over-steers and correcting for such, however, I am still a little bit confused with the rear and it’s impact. For example, if I turn OK thus I am assuming the front of the car is behaving appropriately, yet, if now towards the end of the turn the rear of the car tries to go by me (turning left, rear goes further left) is that a rear understeer? I think of it as oversteer. Again, thanks for all the inputs!

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The car drives terrible. There isnt a lot you can do to make it drive better. Your inputs are more important. The bumps in the track are what makes it a challenge. You pretty much have to keep the understeer because too much turn-in upsets the rear a bunch. Lost count how many times I spun out.

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I agree with you Swerve, this little BRZ is hard! By the way, I did see you sitting at #13 (1:02.716) with your BRZ, nice job! How do you do it? (not the tune, but the driving part at that track)

When you say my inputs you mean my steering control along with the throttle at the turns?

Regarding the bumps, I did watch the videos of the top 6 BRZs and noticed that on most of them the front tires do jump a little and lose traction from the track. I understand that can somewhat be corrected with the Rebound/Bump settings if you had these adjustable.

I’ll try your suggestion to allow for some amount of understeer so I do not lose the rear. Yes, my number ONE problem is that many times I try to follow the Forza line and it is too much to ask and start spinning. Yet, if I wait longer to turn then I have the wall to deal with.

Thanks for your inputs!

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Patience though I did rage quit after a bit because I wasn’t able to run a clean lap that was on par with my dirty ones.

Yea by inputs i mean your driving. If you miss turn one, you will be unable to make it up in the other corners assuming those were done perfectly on a previous lap. The brake line is all wrong on the track. If you follow it with this car you will either drift or slap the wall on exit. For turn 1, 3, and 4 a slightly wider arc is needed than what the line shows and it is difficult to hit.

I dont recall having to let off the gas though.

And yes the car badly needs suspension upgrades for this track. The stock suspension is very stiff which is terrible on indy because of the dips in the track.

When you do hit the right line the car is on the verge of spinning or slapping the wall really hard. Subtle moves with the thumb stick are needed to counter what you’re feeling. It’s a challenge.

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Thanks Swerve!

Yeah, I was trying to follow the yellow (I mean blue) brick road, and I guess that does not work for this car! I did notice I did do better with some of the wider turns to handle the car yet nervous get you when you see your headed towards the wall. However, I love a challenge – thus, I’ll keep at it.

On the suspension, I do have a build with the springs an it is my PB (#143, 1:04.129) and I know I can push that one a lot further. However, why do the top LBs w/BRZ using the ARBs? If you do not mind sharing, is your BRZ w/springs or ARBs?

It be great if I can provide my tune/build, and you, Loco and others could race them and provide me with fdbk. I like to know how much impact is my driving versus the build versus the tune.