Tuning Clinic!

Hey guys… I had an idea for the experts to help us noobs and intermediates out. I had some random tuning questions, but rather than spam the board, I figured I’d take the time to kick off the “tuning clinic”. People ask questions and experienced tuners answer them. Make it a one stop shop. I’ve read the tuning guides but not all of them address the specific things I’m looking for. Anyways here’s the format I’m thinking of with two questions:

Issue: Lift-off oversteer
Class: A-class
Car: Various
Controller: Wheel (TMX)
Question/Problem: Seems like no matter what I do with springs/dampers on a wide range of cars I get some degree of lift-off oversteer with my A-Class tunes. It happens right at the point after I let off the brakes coming into 2nd-3rd gear hair pins, or if I tighten my line while coasting/letting off the throttle. Is this a problem with my driving technique or is there anything I can do to stabilize the car. Any ideas?

Issue: Bouncy/unstable front end
Class: S-Class
Car: Porsche 997 GT3 RS 4.0
Controller: Wheel (TMX)
Question/Problem: Pretty simple… front end of this thing never feels planted. I have full aero on it but the issue happens around medium speeds (~3rd gear stuff). Is it just the nature of the car?

What do you guys think of this idea, and can you give me some help? :slight_smile:

(Note, I accidentally made this thread in the FM5 forums, mods please delete that one)

Issue 1 - increase decel until problem goes away

Issue 2 - Could be part of the nature of the car, but sounds like bump and rebound are poor. Raise front rebound to around 12 and lower front bump to around 3 and see if that helps, if so tinker around with those.


Playing with the shocks did it… I had a similar problem with a few other MR cars in other classes and going nuts with the front rebound seems to have calmed things down. Now that the car is under control in the middle of the corner I can fine tune the balance elsewhere. Thanks!

I totally missed the decal thing. That 100% did it. The shocks helped mask it but made the cars understeer too much and didn’t work on every car. Decel is a much quicker and more reliable way to stabilize turn in. I’d argue the LSD might be the most important tuning aspect of the car… everything else is fine tuning to taste.

Speaking of turn in though, is there any way I can quicken it? All my cars are really stable but at the expense of response. I’m trying to get the front end to dart in without having the back loose.

Ride height is definitely key as well… I’ve noticed specifically on older 911s that the front loves to bottom out.

Okay, here’s one-Bathurst. On the drop from the Skyline into the Esses and again as you drop into Forrest’s Elbow, people have many problems with either plowing straight on into the walls (more prevalent in a front engine car) or having the back end get light and loop the car backwards down the hill (mid and rear engine cars). The scattered tires in every race I’ve ever done there suggests this is not just my problem! I’ve found a couple of workarounds but they tend to introduce as many problems as they solve, as an example, on a mid-rear car I’ve run the brake bias way to the front to prevent the rears from locking up with all the weight off of them, which causes a nasty push everywhere else and increases overall stopping distance. What do the actual good tuners and drivers do?

Line choice and poor braking.

Doesnt matter the tune, but if you approach the essess in a straight line and are generous braking you can hit the first 3 essess with minimal turning. After those you usually gas it a tad and the brake for 4th corner. If the car is a power build you’ll have to brake a little more here to avoid a bad entry to that downhill left-hander that open to long back stretch.

If the car has more grip you will make your time up in this section with a little more aggressive braking.

I’ve seen players use LeMans build cars (all power, no handling parts, and no tires) and run top 5 on the leaderboard in lobby with this approach. It was a show of skill I tell ya.

Edit: As for tuning it’ll vary but generally it’s more of hanging on than anything else. My focus is more on acceleration and top speed out of turn 1 and the downhill left-hander that leads to back stretch. So much time is lost if your car can’t get out of those corners quickly. You can literally lose a few seconds if the car scrubs too much speed. After that I focus on left-hander on back half of track that leads to the essess. The outside wall approaches quickly and too much braking will lose lots of time. If I can get to where I can tap the brake or let off gas and turn and then floor it without hitting outside wall I’m happy.

To me those are the 3 corners that can make or break a good lap and the tune needs to do well. All other corners it’s more of adapting to what the car is giving me.

So, really, it’s down to my (and I would submit most average players) biggest issue-consistency. I can hit that line Swerve talks about eight or nine times out of ten, but on that tenth time, and especially when trying to run someone down or run away from someone, get it just a little wrong or hit the brakes too hard and too late and away she goes. I’ll pull down a few rivals from the good end of the leaderboard and watch them, most people near me are making the same mistakes I do.

I will mention the car that gave me more fits here than any other though- the Ford GTLM. I think it’s sprung way too stiff stock, and it seems to be a little more prone to ending up pointing the wrong way than it really should. Which is a shame because it’s a really nice car to drive right up until you’re looking at where you just came from. Ended up basically copying the settings from the surprisingly similar Riley DP (weight and balance wise, anyway), seemed to help things quite a bit, but not solve them completely.

Brake earlier

Best advice ever!!! Reader of advice scratches head and says “brakes” with a confused look on their face!!!

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Myself included, people dont like to hear that its them that is the problem and not the car and thinks the car should be fast and tuned for how they drive, when often how they drive is just wrong. This is especially noticable from those outside the top 1000, they want to believe that everyone faster has some secret formula. While a proper built car can make a difference its not going to change the fact that you are 5 seconds off pace on a 90 second lap.

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You’re 100% correct sir, and that’s coming from someone who’s lucky to get anywhere near the top 5000. The only secret formula for pace is practice.
(I still think the Ford GTLM is sprung awfully stiff, though. Especially notice it with a wheel, have less of a problem with a controller, still there, however.)

You very well could be correct on that. However i find it is more often the dampers than the springs. Springs for overall balance, dampers for controlling movement.

Yea I have been playing with tunes over the last week or so and it looks like dampers control transitions while springs/sway bars control overall balance and grip. Dampers can still affect grip though… like I found that if I set front rebound too strong the car just understeers regardless of what I do with the springs/sways.

Something else I’m seeing is the more weight there is over the nose the weaker the damping should be up there. It’s really weird and very different from how I tuned in FM4… I’m having to really learn from scratch

Another very critical thing that springs and swaybars do is keep the suspension from bottoming out. Dampers obviously play a part here too, but if your outside rear is loaded while accelerating out of a corner and you let it hit a curb, say somewhere with rough ones like Hockenheim or Sebring, and that corner of the car runs out of bump travel, you’re going to be looking at where you just came from so fast correction won’t be possible. The reason that happens is because the moment the suspension bottoms out your spring rate goes to infinite because it can’t compress anymore and the energy it couldn’t absorb lifts the entire car off the ground. Obviously it’s not good when the tire you’re asking to do the most work suddenly lifts off from the pavement.

So before you lower the car or adjust the spring rates do a lap with your eye on the telemetry to be sure you’ve got the suspension travel to spare. I’ve recently seen one car go from undrivable after only installing the race suspension upgrade because if the inside wheels clipped a curb it’d bounce up on two wheels to amazing after raising it a few clicks.

Also, with dampers, I personally prefer to do small adjustments for effect. Occasionally if I’ve felt the need to increase the spring rates I’ll bring up all the damper settings by an equal amount, but most of the time I’m adding just a couple of clicks to address how the car behaves in transition. In my opinion it generally doesn’t take much to have a noticeable effect on how the car handles.

Yea I got a formula (well I don’t know the actual formula) for rebound springs directly related to weight % of the car

if the car is 50% front

I go 10,10(rebound)

51% I got 9.9,10.1

so that the front weight % is connected/related to the rear rebound.

40% = 11.0, 9.0

Its only a guide and its not close to perfect but that is what I use and its way better than defualt.

to increase turn in the best way is to stiffen the front springs. however another quick thing that works well without effecting much else is to increase front toe a few clicks.

Won’t stiffer front springs make the car understeer more? I know IRL a popular mod for FWD cars is a rear sway to help things rotate. I figured that would transfer to Forza too.

Swerve answered it pretty well also, but yes it will make it have less mechanical grip. Stiffer usually means less mechanical grip yet increased responsiveness. You can fix the mechanical grip portion of stiffening it in the dampers.

Eventually, yes. The way I like to think of it is when braking and turning if front springs are too soft they can’t absorb the weight transfer. In my mind I see the tire rubbing the inside finder well and various components at the bottom of the car lightly scraping the tarmac.

Not sure if that’s accurate but I’ve always been told to tune springs for starting and stopping and everything else for cornering.

And of course I’m tuning a rwd swapped vw and nothing seems to work well. Pretty sure ride height and rebound have to be drastically different and maybe something goofy with the front toe. It’s a fast build but sketchy.