Ok, so I’ve read through the tuning guide, and from it I’ve learned alot as far as tire temps, dampers, caster/camber/toe. Also been lurking and learned how to find a baseline for springs in a different thread. There are however a few baselines I need help with still. I don’t know how to find the baselines for ARB’s, diff’s, or dampers, nor how to tune the diff or arbs to affect handling. I’ve noticed through my own experimentation that I like my front ARBS around 5-7 stiffer than the rear, however I don’t really know where to put them on the sliders. As for diffs, I’ve been running 30accel and 15 decel for a while and had good success with that. With dampers I just leave them where their at stock and increase/decrease the numbers to tune handling.
I’m just getting more curious as I’m starting to favor less tires and more power to weight advantage. I have an audi auto union type D in C class I’ve been tuning, and at first it was unbelievably skatey, and refused to take a set. I softened the springs as per the instructions I’d found, and am running relatively soft ARB’s with the front about 6 stiffer than the rear. This has made it set much better and much more drivable, however I feel like if I were to adjust the dampers properly, and maybe even the diff it could just be that much better.
To help with your understanding of ARB’s they are important in redistributing weight and therefore grip from one end of the car to another. If you want more grip on the front wheels you need to soften the front ARBs and/or strengthen the rear ARBs (e.g. for a FWD car). For RWD cars it follows that you need to soften the rear ARBs and/or strengthen the front ARBs. The rest is trial and error I am afraid but if you understand the basic principle you are more than half way there.
For RWD bump (use primarily to control “pitch” of the car):
Start with same front/rear bump. e.g if front is 6.0, also set rear at 6.0
Reduce both by 1.0 until front brakes starts to lock up “gradually”, i.e. not sensitive to brake trigger. This is the front bump baseline
Then further adjust the rear (up or down) until the car accelerates with “gradual” wheelspin. This is the rear bump baseline.
For slightly faster response, increase bump (less than 1.0). For slightly slower response (more grip), reduce bump (less than 1.0).
For RWD rebound (use primarily to control car’s stability):
Use 2X the bump values.
If too stiff (slides around), then reduce by 1.0 until it “feels right” (I don’t know how else to say it) but stay above 1.3X the bump values.
If rebound is too low, then the car will feel “wobbly”.
There are front rebound one can use for additional rear grip and rear rebound controls for braking grip but that’s really fine tuning.
As for the differential, the best place I found to test it out is at Indy Oval. The corner are long and you can really feel the impact of the changes. Plus you have 4 near identical corners in 1 lap!
If accel diff is too high, then the car will want to push (in general) then maybe oversteer. If accel diff is too high, then the car will want to turn in and oversteer. It’s a bummer but any car with enough torque would oversteer. The key is anticipating/controlling it instead of being surprised by it. I would start at 100% accel, run few laps to feel the car, then start reducing by 20%. Once you “feel” the change in the car, then INCREASE it by 10%. This is the accel baseline. From there, it is up to your driving preference to increase/decrease by few %.
This effect is very pronounced in Indy Car with speedway aero kit. At high accel diff., the car struggles to stay on the corner (pushes). At just right diff., the car tracks the race line with much less effort, good for about 0.5s per lap.
On the differential base settings (if your looking for some starting points based on drive type)…Worm has a pretty good basis which he stated in a post in response to another GT with the same question. Just search on this Tuner’s Lounge area. If I find it, I’ll update the post with he link.
I keep seeing posts of this nature,im not gonna say what im really thinking,but try this… tune your car like advised above,run laps testing check times,then put bump at minimum 1.0 then rerun the track and compare lap times. I always run minimum bump,so does that mean i should run bump x2 rebound like advised? i dont think rebound of 2 would work too good. the only time in the past i have run bump stiffness was on forza 3 when tuning cars for nur and positano and camino. but i have found no benefit on here.
As for diff setting,this can vary from car to car,and if you run TCS or not can make a difference in how you would set it.
Not saying im right or wrong,this is just my opinion.
For FWD diff try accel 80-100 decel 0-5,RWD diff try accel 16-50 decel 0-50,4WD diff try F-accel 80-100 F-decel 0 R-accel 70-100 R-decel 0-50 balance 50-70,these are where i have had best results.
Set your rebound by feel,if you dont understand it leave it be and tune the parts that you do understand. My thought process for rebound is if you want more turn in response raise the front,you want less lower it. the rear i usually set by feeling what gives the rear end the best traction and feel out of corners. i often run front rebound high 10-13,the rear depends on many factors but usually ends up between 6-10. this info is based on no formula or method,just what i have observed with testing over all the forza games. ask any top drivers you know on here if they use a formula to calculate the tune or if they set it by feel and testing lap times. I agree a spring calculator can be better than default settings,but i doubt it will better old fashioned getting on the track and testing what works best. this is a game,and often things work well that should not. I drove a friends mini today that had max front bars and minimum rear,it shouldnt have worked well but it run top60 in 2 laps. there is no right or wrong way really,this is why i think testing and tuning to feel is so important.
I think you misunderstand my intentions, I am by no means asking for people to tune my cars for me, just more or less what I should be looking/feeling for to find where everything should be at.
You have all been greatly helpful though. I’ve tried running no bump and low bump and no bump has taken the win for me as far as lap times and drivability go, with the plus side of getting to play around with the rebound to really understand how that effects the car too. For starting out in B class and ending up in C with 1930’s tire compound, this thing grips the road like a kitten to your curtains. I just ran a relatively messy lap around test track and got a 1:06.8.
This is a game and the main science that should be applied is the science of time keeping.
Real world tuning science should be used as a guideline, starting point and for tweaking in a certain direction but the science of time keeping should determine the end result which may mean a top leaderboard tune breaks some of the equations being advised.