1st tune... could use some help, please :-)

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1

Hi…so, after Jawshe’s post in the general discussion persuaded me to drive without assists (which has improved my driving ability no end, although I’m sure there’s a long way to go), I’ve now taken the plunge to try my hand at tuning, too.

I’ve read through the advice in these pages, and am trying to absorb all this information, but could do with some guidance.

I’ve probably not helped myself by starting with a GT40, which I’m trying to tune specifically for Le Sarthe, anyway, here are the details of my build/tune - any feedback or advice would be massively appreciated, I’m running endless test laps trying to tinker with it, but could really do with a critical eye pointing out any obvious glaring errors or improvements that I could make. Thanks

All stock unless stated:

Carburetor – Race
Ignition – Race
Valves – Race
Pistons & Compression - Race

Brakes – Race
Springs & Dampers – Race
F & R ARBs – Race
Roll Cage – Race
Weight Reduction – Race

Transmission – Race
Diff – Race

Tyres – Race
Wheels – Advan RGII

Tyre Pressure - F 28.5 R 28.5
Gearing – Final Drive 3.66
Camber - F -3.1 R -2.9
Toe – F 0.1 R -0.1
Caster – 5.5
ARBs – F 18.54 R 17.96
Springs – F 445.0 R 470.0
Ride Height – F 3.3 R 3.4
Rebound – F 10.5 10.4
Bump – F 2.9 R 2.8
Aero – R 75
Brake Balance 52% Pressure 100%
Rear Diff Accel. 30% Decel 15%

EDITED - I’ve now edited the build/tune details to incorporate some changes based on the advice received. I’ve no illusions as to this being stellar, but it’s now got me into the top 1000 at La Sarthe (a good 20 seconds behind the top-placed GT40, but that’s a very different build), which, for a 1st attempt, I’m pleased with. That said, any further advice/comments/tips still gratefully received, if anyone wants to build this and try it out, that would be invaluable feedback, and don’t worry, if it’s awful, tell me :slight_smile:

2

Is there something wrong with the way it drives since you did the tune? If there is a specific turn on a specific track where the car has problems, and you post that type of info, some experts here will definitely be able to point out what adjustments you could try.

3

Well… my main concern is the spring settings, I’ve been up and down like a yo-yo trying to decide what works best, but I’m still thinking that they MAY be the root of a general lack of sharpness that I’m feeling. I’m also having to be careful of oversteer when applying power, particularly coming out of the 2 90-degree right handers (La Sarthe), though I suspect that may be my driving rather than the tune, though I wonder if I could adjust the settings to reduce that tendency.

Overall, my concern is that I’ve done a mediocre job :slight_smile: Not that I’m expecting a world-beater for my 1st attempt, but I fear I’m making the car worse rather than better! :slight_smile:

So… turn-in reponsiveness, a slightly ‘floaty’ feel, perhaps, on the straights, and power-on oversteer, that’s my assessment, but I’m doubting my own judgement!

4

I have got your tune dialed in. The one thing you need to add to your build is this. Increase the front & rear rim size. Thinner side wall flexes way less for better tire stability through turns. With both increased to max rim size, you still got A700. I know when you change front rim first, it goes to S Class. However, when you increase rear, goes back to A700.

Front rim size
240/30R20
Rear rim size
290/30R21

Now for the tune fully dialed in.

Tire Pressure
Front 30.6 (set to 30.5 then change to metric and press right 1 time)
Rear 25.8 (set to 26.0 then change to metric and press left 2 times)

Gearing
Unchanged

Alignment
Camber
Front -1.8
Rear -2.4
Toe
Front 0.0
Rear -0.2
Front Caster
Angle 6.8

Anti-Roll Bars
Front 22.10 (go all the way left or right to get the zero to show, then set #)
Rear 18.80 (same ^^^)

Springs
Front 477.3
Rear 521.3
Ride Height
Front 3.6
Rear 3.6

Damping
Rebound
Front 5.5
Rear 7.9
Bump
Front 4.6
Rear 5.0

Aero
Front n/a
Rear 75

Brake
Balance 51%
Pressure 140%

Differential
Acceleration 35%
Deceleration 15%

This car drives like a dream with these settings. Just remember to control throttle through turns. Remember to increase rim size as stated in beginning. Have fun!

1 Like
5

If the car was sliding around (too stiff) or rolling and lifting (too soft) I would say suspension too. But that doesn’t sound like what is happening from what you said there. You also may want to 0 your toe til you sort this out better so it doesn’t play a role itself. But I would trying lowering your rear ARB some. See how that helps. And also I would play around with more negative camber front and rear. Maybe just bring your rear camber much closer to where the front is. Maybe even try -2.5 or even -3.0 for front and rear. Then go from there. Just something to try.

6

Thanks, all and any advice is massively appreciated, this feels like a massive learning curve, I’m enjoying it, but I feel pretty clueless! I’m starting to get a better idea of what the adjustable elements do, but getting from there to optimising everything for the car, the course, and my style is bending my brain.

I’ll give those alterations a try, cheers.

7

Bump seem a little low.
I would personnaly probably run brake balance around 52 %.
Diff is a little high to my taste too.

8

Hi, the bump settings I agree are low, the on-screen advice is for them to be 50-75% of rebound, but then there’s lots of advice on these pages to stick with them in the region of 2… would you suggest maybe doubling them, getting them more towards the 50%?

The brake balance is very much a work in progress, I’d not touched it until today, and my plan has been to try 52% next, so it’s interesting you suggest that. By the way, your guide to tuning for beginners has been one the the posts I’ve been referring to while I’ve been trying to learn, so thanks for that :slight_smile:

As for the diff… I guess the way ahead is to try, say 5% incremental changes to one at a time and see what effect it has… I understand what the diff does during cornering (allowing the wheels to rotate at different speeds to maintain grip), but the effect of the accel and decel settings is still a bit obscure to me. A higher accel setting will make the diff lock more quickly… so that’s more likely to cause a problem when accelerating out of a corner (causing the back end to lose grip), is that right? And the decel sets when the diff unlocks, so a higher setting makes the wheels unlock more quickly when decelerating? Allowing quicker turn-in? Can you tell I’m not a mechanic!?

EliteApices, I’ve zero’ed the toe and altered the camber, that’s definitely sharpened turning response, thank you, I’m going to experiment with the rear ARB now, see if I can distinguish what effect it has.

9

If you want to understand better, put them both at 0 % and go for a test drive.
Look how it react during hairpin exit, look how it react under heavy braking.
This will help you understand better. (Well it did for me :P)

What you want is the diff to be “Unlocked” when you turn, and “Locked” when in straight line.

Lets take this image for example:
http://www.drivingfast.net/images/techniques/racing-line/traditional-racing-line.png

You want it to be locked until the “Turn in” point, and you want it to be locked at the “Run wide” point.
It’s never that easy but you should get the point.

10

I agree. The advice on Bump comes from the most experienced tuners on here. I would stick near what you have and make small adjustments to tweak your handling if you need too. Worm’s sticky has a couple sections on how Bump and Rebound effect the car.

Im glad the extra Camber helped out. Taking advice from others I have been running up to -3.0 or -.40 sometimes and it does work. When you go too far it almost stops helping grip and to me it seems, starts to hurt breaking and overall straight line performance.

As for diff… the reason cars have one is because, WHILE TURNING, your inside tire is actually traveling less distance around the corner then your outside tire. So they need to be able to turn at *different speeds. Hence *differential. So when you *accelerate with it set at 100% they will be locked at the same speed. So if you corner, the back end will kick out on you while accelerating. Or with it set at 0% one tire can spin like crazy and the other will stay on the road. That will keep the back from kicking out (most of the time) almost completely. So you might ask, why not always have it set to 0? There are 3 problems with letting that one tire spin like crazy. First is heat. Too much and there goes some grip in the back end. Second is acceleration. While that one tire is ripping apart the other isn’t doing much of anything and you will lose some acceleration. Third is complicated to explain but I will try. When you have your accel just right (there can be a really nice sweet spot) you can actually get on the gas pretty well while in some corners, and the back end wont stay put solid, and it wont slide way out, it WILL step out just slightly and help to point the car toward the inside of the turn. So think of a long sweeping corner, on the gas, the back end is on the edge of sliding. Its like it helps the car around the corner by being on the gas.

11

I’ll give that a try, can’t beat a bit of experimentation :slight_smile:

12

Forgot to mention Decel. The way I interpret the description of it while tuning is totally backwards. Please double check this but I took this from reading post by Worm whom is quite experienced with tuning.
Raise Decel figure = Less oversteer while downshifting or engine braking

13

That’s a really useful description, so the goal is to adjust the diff accel figure to find that sweet spot… we’re essentially looking for the lowest figure that will provide enough variation in the rotational speeds to allow the use of acceleration earlier while cornering… I picked up figures from another post that suggested that for a mid-engined RWD car somewhere in the range of 20%-50% is typical, so I’ll start at the bottom end of that and adjust.

Looking at open source tunes, decel typically seems to favour a lower figure (the same post I refer to above suggests a range between 10%-50% for mid RWD)… so I guess I’ll hit the lower level and see if I can detect any effect on stability under braking.

With the camber, after reading through another thread, and hitting on one of TG Wormburners post, I’ve used the projected braking distance figures on the tuning screen to help fine tune, and it’s come out at F -2.9 R -2.7.

Now I’m going to mess about with the rear ARB, then hit the diff.

I think I’m getting the bug for this, I never touched tuning while playing Forza 4 to death, but now I’ve started… :slight_smile:

14

Yeah its fun! I have been working hard on it for a little over a month now. Getting a solid grasp on most of it finally. Still learning though. Always will be.
Once you play around with it some more, could you upload it? Or post the build/tune here? I would love to try it. If you do I will definitely give you feedback and let you know how I did with it.

15

“With the camber, after reading through another thread, and hitting on one of TG Wormburners post, I’ve used the projected braking distance figures on the tuning screen to help fine tune, and it’s come out at F -2.9 R -2.7”

So you raised them until you saw braking distance start to drop pretty much? It does make sense. However if raising it further allowed you to carry more speed in a corner, you would need less brakes anyway? Something to think about too. Telemetry is helpful and harmful sometimes. Try to do what makes you faster/smoother.

16

Absolutely I’ll post the ‘finished’ version… I’d really appreciate the feedback, I think I’ve made a bit of a rod for my back with this car and track, could probably have started with something easier, but now I’ve started I want to get to something I’m happy with before moving on to experiment with something else. I’m sure it would be useful to see what somebody with some more experience made of it.

With the camber yes, while I was tinkering I noticed the effect on the projected braking distance, and figured that would be a useful guide, but you make a very good point, and carrying speed through a corner can improve a lap time so much. Bit more trial and error to see what feels best then. I suppose when all is said and done, the tune is a personal thing, whatever works best to suit your own style, for me I’m finding that a hard part of the learning curve, discerning the effects of the adjustments… maybe I need to be more extreme! :slight_smile:

17

OK, I’ve edited the original post with updated details, if anyone fancies giving it a go, please feel free, I could properly use the feedback. And thanks for the advice I’ve received so far, it’s been really helpful. I’ll share this in-game as well.

18

The toe should be 0/0, or maybe .1/-.1, but the way you have it -.1/.1 is going to make the car sluggish in front, loose in back.

19

Thank you… that was my final adjustment, I should have gone back to the guide before I did it! I’ve re-edited the initial post to correct it.

20

Hi! I enjoyed reading through this thread, I certainly learned a lot. I am also completely new to tuning, as well as, new to FM.

@ TallPaul – I build this particular car a couple of weeks back and plan to rebuild per yours to see the differences and check it out per my driving preferences. For a quick experiment, I used my build and placed your updated settings and the car does quite well at LeMans. Now, keep in mind that I am a newbie (so new to game and driving with controller, plus now tuning). Anyway, my build is as follows so you can have it as a reference:

A700

Engine: only added Flywheel (I know Worm says never to get it, yet, it’s just a PI filler)
P&H: ALL race, except STOCK reinforcement
Drivetrain: race clutch (to get to 700 PI), Sport transmission (read through many threads indicating that race does not really buy you that much!), race driveline, and race diff
Tires: Race compound, F 275/50R15 & R 365/45R15, RGII rim (look great gold colored car)
Aero: Forza front bumper

Tune

Final Drive set at 2.95
Tires at 28psi

Rest is within your ball park numbers, still adjusting.