Here is my theory on builds.
Brakes - why spend pi on something you very rarely do in FH2 and if you do brake often then you have some fine tuning of your driving (in my opinion). If you are going for balance us decel diff.
Are we talking only 1 pi? Not when you combine it with 3 other things that I would not use in a build.
Joetben - I would drop the cage and intercooler.
I have run a low 59 in a garbage tune but what I think is a decent build.
I will post more if I get it to where I want it.
Ok, i dont think you can get around not braking or barely just by adjusting the diff really. Unless you put race tires on everything wich wouldn’t leave much for acceleration.
Im really curious as to what kind of builds you have
What other 3 things do you not consider for builds?
Because really, running low 59’s without a tune, you’ve spiked my interest.
I know you’re typically way up on the leaderboards, so i’m curious. You clearly know something(s) we don’t.
Think of the Lotus E21 in Forza Motorsport 5 - what happens when you’re in that car driving at 185 mph and you release the throttle; very quickly you’ll be doing 150 mph. You can change that behaviour by adjusting the deceleration diff.
You can accomplish a similar effect in the A45 AMG. That said, I don’t think you can make it all the way around the High Speed circuit without ever touching the brakes and having a “clean” lap.
The race brakes upgrade is good if you need to adjust the balance but otherwise it isn’t that necessary. If I use it it is more of a weight savings measure as opposed to the actual brake upgrade. All cars come with brakes and really the only thing the brake upgrade lets you adjust is the brake pressure so you have to pull the trigger less.
What Eduardo was saying earlier about the Merc is that the following upgrades are unnecessary - flywheel, brakes, clutch, driveline. I have since rebuilt my car without them in lieu of other upgrades but to accomplish that I had to make other changes as well. For example, I kept the upgraded rear tires, I upgraded the front tire widths as well but I didn’t upgrade the tyre compound.
Having driven the car as I built it now (new file shared: joeB 2) and the old one that had upgraded compounds I find that the compound made little to no difference to the behaviour of the car in A Class. Most of the behavioural changes resulted directly from changes made to the tune as opposed to the wheels.
Just curious - stock motor or are you using the V8?
I’m not setting times as quick as you guys in it, but I think I’ve finally come up with something that I’m happy with.
Yes my current fastest is 59.254 i think, and its actually my fastest a class time, which means my ghost is out there.
Im sure you are right about the intercooler and chassis reinforcment satnite. When i built it i i stalled the inter ooler first as it gave me torque earlier and thats what i wanted, but the chassis reinforcment added weight which probably canceled the positives of the extra power in the first place.
Ill see if thats doable. I just dont know if ill be able to play before my vacations 
Meanwhile keep us posted
Wow. I had no idea what I was doing in this car. I followed both Joetben and SatNite’s ghosts and couldn’t get within 2 seconds of them. You guys are #72 and #73, by the way, at High Speed Circuit. Great cars. And obviously different builds. Joetben has no rear aero and SatNite has at least rear aero.
Anyway, I really struggled keeping the rear end under me. Seems like I couldn’t keep from losing the rear end in any sort of corner. Is that because it’s a hatchback? I can’t remember tuning any hatchbacks before this one. I suspect my differential settings are way off. But it could definitely be something else. I even tried race tires at one point because they usually compensate for bad tuning, but I still couldn’t keep the rear end under me. I did eventually use SatNite’s extreme ARB settings and it seemed to help a good bit. I tried those ARB settings in a couple other cars and they didn’t help and might have made things worse. Again, is this a hatchback thing? Have no idea how you guys looked so smooth. Impressive. I suspect I’m going to get a lot more out of this exercise from y’all than you’re going to get from me. Sorry about that. My build:
Street tires
Upgraded front width to 255
Upgraded rear width to maximum
Upgraded lighter rims to fill PI
Race clutch
Race transmission
Race differential
Rally springs
Race ARBs
Sport roll cage
Race weight reduction
Race intake
Race exhaust
Race valves
So cool! I’m going to read through the thread now and drive your cars! I didn’t want to see your builds before I built my own. Hope everybody’s getting at least a nugget or two of knowledge from this…
Oh, and I just shared my tune.
Yes, part of the rear end issue is because it’s a hatchback. Even though there are sedans that may have similar front weight percentages the cars are built different than the hatchbacks and it affects the way they handle.
Try using a considerably lower camber on the rear axle than you might otherwise. At one point I was playing with a hint of positive camber on the rear but ended up not using it. As for the tire compound, I can’t remember if I did settle on the street tires or just decided to completely forego that upgrade altogether in lieu of power upgrades. This came about because with the compound upgrade I wasn’t able to keep up with Joe and Eduardo because of a lack of power. I noticed that the car does really well with a good tune and you don’t need the tires to overcome that if you’re staying in A-Class.
For the differential, here is some advice from such noob wow:
Front Accel: 20%
Front Decel: 0%
Rear Accel: 0%
Rear Decel: 25%
Torque Split: 90%
Now, I didn’t really like these for this car so I made some changes until I got to somewhere I did like. The settings are different than what I would typically use for other cars but then again, so is most of this car. The settings I used are:
Front Accel: 30%
Front Decel: 0%
Rear Accel: 30%
Rear Decel: 20%
Torque Split: 65%
If the rear end is sliding out too much and you’re not on throttle - try lowering the rear ARBs. I think that the really low ARBs in front work rather well for this car but in the rear you don’t want them too stiff. I stuck with something between 1/2 and 2/3 of the way to the right.
With the springs, I’ve kept the rear lower than the front actually but the front and rear are pretty darn close to each other. I think Joetben15 and I used a similar set up for the springs but considerably different stiffness. Mine are pretty low near the far left and his are closer towards the 3rd quarter of the bar.
I drove your car PPI. The tune where you decided against tire upgrades entirely. So stock tires. I actually first ran it on Festival Cross Country against my own ghost. I was immediately reminded why I hated the stock transmission. But then 4th gear in your stock transmission came to life and seemed to have endless pull and overcame my ghost. Eventually my ghost pulled away and won by a couple seconds, but I learned something and re-tuned my transmission for a lengthier 4th gear and it worked out well and I beat my ghost a couple of times afterwards. Your tune was great for cross country, by the way. Solid. No spin outs. Turned well. Didn’t feel rigid or stiff over bumps, which I think was the biggest surprise since you used both front and rear aero and the max ride height on this car is 5.2 inches. Usually when I have too much downforce I’ll hit a bump and go flying end-over-end. I’m guessing you have softer front rebound damping than I normally run to compensate for the aero. And soft bump damping. You already said you had soft springs. That was apparent. You gave us your differential and ARB settings in another post, which seemed cross country friendly.
Then I took your car to Nice and that’s when I started spinning out. Stock compound is brutal. If I had to guess I’d say it was a combination of positive toe at the rear and a differential center balance on the right side of 50 percent. The spin outs were really limited to slow corners, though. When I took it to High Speed Circuit you were glued to the road on moderate and high speed corners and bends. What caster did you use? Would that make difference on high speed bends? I don’t know, overall, I think if you lost the front aero you’d have a dynamite cross country car. But like mine, it seemed to struggle when it was time to go slow.
You gave me a lot of good tips above. I re-tuned ARBs to a more conservative level and that seemed to help the most. More rear camber also seemed to help. Thanks. My tune on this car really couldn’t have been more different from my usual base tune, but I think I finally got to a place I can live with it.
I am still trying to play with the diff a bit to see if that is what may be causing some issues.
I did realize that my aero was set to full and that is what may be limiting my times on the High Speed Circuit. I want to drop the rear aero from max to min because a lack of downforce isn’t causing the rear end instability.
I am not a fan of the stock transmission on this car. It’s an awkward 7 gear box that Mercedes has tuned and built to optimize fuel efficiency and limit the shock of shifting and turbo lag. The motor has excessive lag on power delivery due to large amounts of boost, tons of power and torque, but the company doesn’t want shifts and gas mileage to feel like that of a Lamborghini. On the stock motor this car can go quite fast when it’s not limited - but it is limited by the transmission. Sadly, when upgrading to sport or race transmission this cars loses a significant chunk of PI and is then lacking on potential power. I’ve found that 4th and 5th gears are the best to remain in. Once in 4th, push it til the end then do the same with 5th.
The slow corner spin-outs I would think are attributed to throttle control and an excessively high torque split. I’ve since lowered the torque split to 50% to see what happens.
My alignment is as follows:
Camber - Front: -3.6 Rear: -0.5
Toe - Front: 0.5 Rear: -0.5
Caster: 2.0
The ride height is 3.6" in the front and 3.8" in the rear.
You think I should lose the front aero and keep the rear? Would that help having less down force and weight on the front end?
EDIT: I ran Festival Cross Country with it for a mid 1:32 but I don’t know how that compares to before but it puts it in the top 31 on the track so it can’t be that bad for cross country.
When it comes to the circuit tune then I’m not sure haha, I put in 5 laps at High Speed for a 1:01.001 but I think on the stock tires it needs a few more laps to make sure the tires at up.
Right now I need to run some errands but I’ll keep trying when I get back.
Just keep in mind, this car has not been built for an all around car. I’m focusing on making sure it’s good at circuits. I’ve stuck to Castelletto but I’ll try some Sisteron and Nice circuits as well to see how it drives.
lol you guys are going to freak
From memory:
Sport tyres (max width on rear)
Aero front and rear
Race springs, ARBs, weight redux, diff
STOCK gears
rest went on motor (something like exhaust plus something else that drops weight)
ARBs something like 10/40
The key to rear end stability … low rear bump. I think I am using double figures for rebound. Close to nothing for bump on rear and a little bump on front.
Diff - not telling. Reason is someone helped me a while ago with a tune and I can not reveal it as its not mine. I am still using something close to it.
What I will say is I use a hell of a lot more accel on the rear than what I have seen here.
Also both of my camber figures start with a 3 (negative).
I had part of it pegged to be the rear ARB setting because Joe and I both had the rear end issues with my build even when I had the rear bump set pretty darn low (1.3)
When I first started I did have my diff set the way I normally would - with the rear accel much higher. Perhaps just dropping the center will help.
I suspect the biggest difference in tuning hatchbacks is in the diff settings. Im curious what are your settings, potbox and satnite?
I think mine is like this
Front accel 0%
Front decel 0%
Rear accel 40%
Rear decel 50%
Balance 80%
I used:
Front accel: 35%
Front decel: 5%
Rear accel: 0%
Rear decel: 25%
Center balance: 25%
This is the only car I’ve ever built with a front bias on the center balance. It seemed to help prevent me from losing the rear end. These numbers are WAY different than my usual base tune for an AWD car.
Wow satnight that is weird… it’s almost exactly what I said simply for a how to tune it a page or 2 ago that it appears everyone just skipped right past.
Not really sure why people mess with formulas and try to put so much thought into tuning. What’s worked has almost always worked with forza fairly simple physics.
I tune on feel and latimes and would probably end somewhere very similar to where sat night did as I believe our driving styles are also similar.
Tuned a little bit more the diff
Front accel 0%
Front decel 30%
Rear accel 35%
Rear decel 45%
Split 80%
Managed to cut back my time on high speed circuit to 59.050, couldn’t get under 59 I was aiming for twinborngolf69 (58.908) but he always pulls away at the last two corners. I will try ptg and satnite’s advice about rear bump and rebound. I feel it’s just a matter of putting the power down on those corner exits. Might be the bumps stifness because of the terrain change on there.
Right now the bump is at 8
Rebound 3.4
Or is it the other way around? The top setting is 8 the lower is 3.4. I can never remember what they’re called
I have also tried manual with clutch, but i couldn’t get any faster that manual.
Rear arb’s at 40? seems pretty high
I’ve had them fairly high for a handful of cars but I didn’t think it would do good for is car - give it a try though.
If the rear end can really be held together well with just the rear rebound and bump settings then why not run a higher rear ARB?
I’m running 23.5 but ill make sure to try the 40 setting. the front arb is at 8.5. tried it at 10 but it was slightly too stiff for me and 5.5 (as it was before) was a bit too soft. Thats why i’m wondering, if 3 points can make a big difference how about 16 points O_O
Alright, I have the car totally perfect - or at least I thin so. I called it final and it is shared.If you want I can share the tune and build here but it won’t be nothing that hasn’t already been shared here.
I may not be as fast as Eduardo but I like the way the car feels. I’m trying to set a better time on some circuits now.
As for the ARBs 3 points can be huge. I tried Eduardo and Baby Cow’s setting of 10 and found it too stiff so I dropped it to 5 and I rather like it. It feels better than the 4.2 I was running earlier.
Promenade Circuit: 0:38.1478 ← current personal best
Vitesse Circuit: 1:04.239 ← current personal best
High Speed Circuit: 1:00.005 ← current personal best
Are these your personal bests with the a45 or just your personal best overall? If they are the best times you have regardless of the car, then i would say you have quite succeeded in making a hatchback work properly, my friend. Even if theyre only your best times with the amg I think we were somewhat successful at creating a tune that works for a hatchback wouldn’t you say?
I’ll give your car a spin when i get back from NY maybe thursday. I’m pretty sure our cars feel very similar anyway