Hey Ridox, i was wondering about making a gt3 replica by myself (my first tune done with "rigor"), and I want ask you some details about making a tune. Usually what parameters do you leave" real life", power and weight (obviously, otherwise what replica will it be?
), gearing (if you can find them) and also suspension and lsd? Thank you very much for your help
Making a replica is a long and tedious process
You will need to do a lot of research, sometimes not much data can be found online.
The most important part is getting as much data as possible, reviews of suspension parts and LSD also very useful for aiming a target handling that you are trying to replicate. LSD in real life is very much unlike in GT6 LSD tune that most people use ( low initial, low accel and brake ). If you take a careful look on most tuners here in GTP, they will almost always use low value LSD all the time to make the car safer and easier. Sometimes very low, that the LSD is like an open differential ( when initial, accel and brake are less than 10 ) Most real life LSD are tight, responsive and requires the driver to be more precise with throttle, brake and steering, which will give the best lap time possible, which is why aftermarket LSD on the street can be too much for the non enthusiasts, especially in the rain or snow
. If you read through car enthusiasts forums, and in particular discussing LSD/differential, you will notice that most aftermarket LSD are aggressive with preload, locking ratio, some even gives loud chatter when driven ( this is with clutch type LSD, various type LSD like torsen, helical and quaife have distinct traits in torque response, locking behavior and effectiveness )
Also, I have posted this in a conversation with @
cbarbosa regarding tuning :
Here are some of the steps that I used to tune cars :
Before driving and tuning, I would suggest to reset all settings, meaning lowest spring, lowest damper, ARB, neutral toe and camber.
How do you know how stiff the spring needs to be ? You should consider the type of tires the car going to use dominantly. Racing tires generally requires higher spring. The chassis also affect how stiff it needs to be, an easy way is to increase both front and back from lowest by 2k increments, and drive it, check the body roll and how bouncy the chassis when thrown around. Once you find a set value that gives good feel and the car is firm but not too rigid, you can start altering the spring rate balance.
Increase either the front and rear to half the range of adjustment, and drive it again, take a note of the handling changes, does the car benefit from higher spring up front or higher rear, or same rate. If the car drives better to you with higher rear or front, increase the ratio by 1.10, stepping up each time, test it and see how it goes. You should meet a spring rate level, where the spring will start giving negative impact on the car handling. That's the sign to step back in value and find the sweet spot, usually 0.5k step.
Then this :
Here is a part of my method to tuning cars in GT6 - this is posted at Stratos Difficult Car thread :
With spring rate set/chosen, time to tune the rest of the suspension ( Deciding the spring rate also can be done in similar method as with damper below - the higher the grip of the tire, the harder the spring, running racing tires with very soft spring is not advisable )
Damper, here is a simple step that I adapted from the method that I did in real world, start off with all at lowest value, this includes compression, extension, ARB, and zero toe as well as camber. Drive the car on the track where you can be consistent and has variety corners to highlight the car's weakness easily. I would suggest to set the LSD to 5/5/5 first.
Now, make changes to rear compression only, change to max at 10, and drive for several laps, make a note of how the car handle, go back and reduce by 2, 8 then 6 then 4 and so on, this will take time, so use shorter track if you prefer. Once you feel the rear has better traction and rides the bumps well, continue to adjusting the rear extension, set it at max, then one click higher than compression, then same as compression and 1/2 click lower. Make a note of each setting handling, choose one which gives better stability under acceleration on mid corner and exits. Also pay attention to how the car rotates when braking and turning. Now onto the front damper, with the rear setup done, do the same on the front compression, make a note of each value, how the car behaved under braking, hitting bumps, changing directions and corner entry grip. Set to the value that gives the best feel. Then do the extension, find one that gives good braking ability, less understeer/push on entry.
Now the damper is done, time for the ARB, as they are set at 1 front and back, the car will have some roll ( depend on the weight, chassis and spring rate strength ). Increase rear to max, and drive the car, notice how the rear has less roll and much more responsive, but usually becomes tight on the limit. Same steps, reduce and drive until you find a value that feels responsive but give the car good rotation. Do the same with front ARB, at max, it should be responsive but very tight when entering mid/high speed, find the spot that balance the response and entry rotation.
For camber, any value above 0.0 will reduce grip, so use that to your advantage, if you have FF car that still lack in rotation for example, use front 0.0 and rear at 0.5 or above - I don't recommend to go above 1.5, as usually it starts to hit cornering speed and the rear loses grip too easily. For the Stratos, if the front tires is too grippy, use 0.2 for a start, I don't recommend higher than 1.0 as it will be detrimental to front tire grip causing understeer and lower cornering speed. ( this is for 1.08 and below, after 1.09, camber is improved, there are dynamic changes in grip when under peak load / cornering )
Toe : I usually use real world alignment and there's should be no need to use high value if the spring, damper, ARB and camber sorted out. I rarely use more than toe in or out of 0.30 for simple tuning, replicas sometimes uses more than 0.30, depend on the alignment spec in real life. For FF car, 0.10 toe out or less is usually enough with neutral rear at 0.00. Use both toe in for Stratos - as IRL, Stratos HF Stradale owners used front toe in and neutral rear or same toe in as front ( 1mm to 2mm ), don't go too high as it will induce understeer, 0.15 to 0.19 toe in is more than enough IMO.
In general, rear damper changes can be felt on mid to exit of corners, while front damper on braking, entry and steering response/stability ( stiffer front damper = more responsive ) Don't go too stiff with damper, it will cause the car to bounce on bumpy road. A good place to test your preferred damper is at Bathurst and Nurburgring GP/F.
It takes time, sometimes you may drive up to 300km or more fine tuning the suspension.
For LSD basics :
the higher the initial, the less changes to occur between left and right wheel, but this will cause to car to be tighter/understeer.
higher accel : more understeer/tight, better traction, more responsive to throttle, but can be very edgy - break traction suddenly.
higher braking : stable braking, lessen lift off oversteer, tighter entry.
I would highly advise you to try the method above
it's slow and tedious, but good for learning the intricacies of tuning in GT6. I would recommend short track that you are most familiar, where there are tight corners, medium speed and high speed sweeper, something like Tsukuba, Ascari, Brands Hatch GP etc.
And more :
I also add that different car layout requires different approach in spring rate, damper and ARB tuning. For FF car, starting with spring, increase front 1st then rear for nose heavy car then go from there, sometimes lower spring rate at the front work well too. For FR, you have to consider the weight distribution, stiffer rear usually gives more rotation. For MR, lower spring ratio ( closer between front and rear ) usually works best, also heavily depend on how much heavier the rear end is, sometimes lower spring rate at the rear works great ( NSX for example which is similar in real life )
For RR, usually with more than 60% weight at the rear, you will have to use high ratio spring, about 1.30 to 1.5, and even 2.0+, this means you could have 6kg/mm front and 12kg/mm rear or 6kg/mm front and 7.8kg/mm rear. Most of the time, the closer the spring rate difference on RR cars, the handling becomes less responsive, with front lower usually ends in understeer on entry. Never stop experimenting, the most important step is choosing spring rate that works best to you. Sometimes RR/MR cars works great with lower rear spring.
Damper tuning also depend on car layout, with FF you can start with rear damper then front, while FR, MR and RR, you can start with front damper, then rear. For AWD, depend on the car handling balance and torque split, you can start with rear damper 1st
In general, at the front damper, high value increase response, too high comp and ext will increase tightness, high comp, low ext will slow the steering response and entry to mid corner ability. For rear damper, the higher value, the more rotation usually it gives, too high comp, the rear will lose traction easily, high comp, low ext will make the rear slower to rotate on exit and sluggish in high speed steering. Easy rule step, always tune comp first then ext.
So, in summary, use stock ride height,1st step : spring rate, 2nd step : lower ride height until you find the car more stable but not bottoming out on bumpy tracks, best to test it at Foxhole ( green hell ), 3rd step : damper tuning, 4th step : ARB, 5th step : toe and camber. During suspension tuning, you can always fiddle with LSD. Revisit ride height again if necessary.
You can actually use LSD to produce certain type of tune, on a oversteer prone car, use LSD that will induce understeer, then tune suspension to balance it or vice versa. You will need to know your goal in tuning the car, make it safer, a replica, endurance race or hotlap/TT.
And last, a tune made well is not always fool proof, you will often needs to make small changes when the tune is driven on different track, testing the tune on variety of tracks is good practice if the time allows, but often you will find that you will keep changing things on different tracks
Sometimes you need to find a middle point/compromise
If you try my F40 US version replica, it has variety of ride height, and 3 sets of LSD, the tune has been made to work with all of them. Lower front on ride height gives less rotation, while lower rear gives more rotation. Try all ride high setup, and notice how the ride height difference affects the car, then use the 3 different LSD initial on each ride height setup to understand how certain ride height difference can work together with certain initial torque value LSD - also depend on driving style ( match the low front/high rear ride height with lower initial
)
(The closest gap with the leader was 10 sec. or so in lap 6, I thought there might be hope and pushed it a little. Uh oh, no good, I spun out. It can't be pushed. Then I was forced to slow down and watched them pulling away. 
with several ride height setup, spring rate and 2 sets of LSD. Some pictures -comparison real life and GT6 ground clearance will also be added, expect big post.
it's glaring issue when making replicas 
Lowering rear camber will add more grip to the rear 
