Nem GTA3 hanem GT3
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#411
Limited Slip Differentials : LSD helps the car when pulling away and during cornering. It does this by making sure that the driven wheels both rotate at the same speed. Without an LSD turn in too fast to a tight bend and you will spin the inside wheel through loss of traction, which ultimately scrubs speed and time when you exit the bend. Alternatively the LSD will help the car to corner as well. However by making the near side wheel turn slower than the offside wheel when cornering you will hook the car round to the right meaning that you can enter the right hand bends at a faster speed than without the LSD. Really it's a compromise on the type of circuit your racing at whether it consists of mostly left or right hand bends.
LSD Initial : This purely dictates how much the values stiffen or loosen the differentials. A higher setting will maximise the biggest acceleration and deceleration values and a lower setting will have the reverse effect.
LSD Acceleration : A lower setting will mean the wheels spin more independently of each other and a higher value tightens up both wheels which will increase the grip especially when you pull away. Also, by delivering the same amount of power to each driven when pulling away you will help the car to pull off in a straight line and reduce any torque steer (the effect of the car pulling to the left or right under acceleration depending on which of the driven wheels has more power).
LSD Deceleration : This is the complete opposite of the Acceleration settings and will help the control and turn in of the car under braking. A higher setting will tighten both wheels up delivering the same amount of power to each. The result of a higher setting will be that the car will now have more turn in force and will decrease the chance of spinning. However set the gearbox differential up too tight and on a rear or front drive car you will cause understeer because the back will want to push the front on mid corner.
Gearing and Ratios
The gearbox settings can be quite a daunting prospect when setting up the car. By pulling all the individual elements apart it makes it really easy. The higher the auto slider the slower the acceleration but the higher the top speed. The settings are individual to each and every circuit as a tight and twisty circuit like Autumn Mini will mean you should run a gearbox with short gearing or a low autoset. Take the car out onto the circuit chosen with a standard autoset of say 15. The fastest way is by keeping the engine in the power band, as much of the time as possible. The gearing is very important in achieving this. Each gear has an individual value, all of which are controlled by the final ratio. A lower final ratio will also increase acceleration but reduce top speed. As every car has a different power-band the gearbox should be tailored to suit each engine. Starting with a final value of 3.400 and an auto set of 15 it will act as a good basis to run the car around the circuit. If you find you're not even close to using the all the revs in the top gears then bring down the auto-slider until on the fastest part of the circuit you are using the maximum amount of revs without hitting the rev-limiter. Once you are happy with the general setup of the final ratio and auto-slider you can now touch the individual gear settings. Each bend will have an optimum gear to get you through the fastest without running off the circuit. If you're approaching a right hand bend and you're just having to use fourth because third is on the rev-limiter it will mean fourth will drop you away from the power-band. Take the setting for third gear and reduce its value. This will now mean that it will change from second into third lower down the revs thus giving you more available speed through the turn, maximising your speed and letting you change into fourth at the right point. Shave just one tenth per corner by maximising the gearing and you've possibly saved yourself a second per lap.
Power-Torque Graph
Right-o, so what's all this about powerbands and rev limiters? Basically the powerband is where the engine of the car is working at its best. It's where the performance of the engine will be at its most optimum. Figuring out where your car needs to be revving to be in the powerband is fairly easy. You go into the settings screen, and select one of the engine options such as turbo, na tune, or any other engine modification. There will be a small graph in the bottom left of the screen with lines going through it. This graph shows exactly where the engine works best and where the ideal shifting point is located. Using this information gleamed from this graph it can be put to use in racing and tuning.
The orange line on the graph represents the horsepower that is used as the revolutions per minute (rpm) are increased. The blue line shows the torque at relevant rpms also. To represent what exactly each value means we'll take a car we'll be using as a tuning example later on. Get a hold of the Lancia Stratos and fully mod it up. Everything you can get a hold of until you are left with a race bodied nifty wee car. Enter the settings screen in one omode or another and bring up this graph. Examine it for a scond or two. Looking at the blue line on th egraph we can see that the torque is at its peak at roughly 35kg/m (confirmed by the text to the right of the graph) across the space of 5000rpm to about 7500rpm. This means that if you have your gears set up to be within this range you will be running the engine at its best performance possible.
Now, the orange line. Simply this shows you the point at where the power tapers off in each gear and ultimately the best place to shift gears. In this example it can be seen that it peaks at just before 8000rpm. Using this data you can go and test shifting and you'd end up shifting better at roughly 7900rpm. The car will acclerate pretty well and hold good speed through the range of 5000 to 7500rpms.
Looks difficult but when you break it down like that it is quite simple to understand and will without doubt help you in setting up your gears which we will glance upon in the later example in the Stratos at Midfield Raceway. Check it out for more information.
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Tuning Procedure
Example 1 - Mazda RX-7 Type RB '97 at Red Rock Valley Speedway
Let's not use a low powered car. After all we want to know how to tame the rear wheel beasts that cause us nightmares. Correct? Exactly! We want to take a car that oversteers and kicks like a mule and put it on a track where this kicking is most evident. So what car will we use? We'll use a fully modified Mazda RX-7 Type RB '98. Everything possible, but not the LSD, traction control and stability controller. Red Rock Valley will be the track used. So let's take our car out in stock form. I'll list the following as steps.
- A quick spin around the track in stock settings show a few things. First, the car has an awful tendency to understeer at inopportune moments. It also seems to want to spin when you get to the lower gears and get the power on. Another thing immediately obvious is that the stock gearing just isn't going to cut it. So, we move on...
- Whack the downforce up to max on both the front and rear. Change the autosetup in the gears section to say 15. Let's see how that works out.
- Hmm, the car is immediately more stable. The gears seem to be working at the minute but we still have that nasty understeer at the exit of the corners.
- Back to altering a few settings I immediately put the ride height to 89/135 to see if we can get good acceleration from this little tuning trick. Maybe the car will work maybe it won't. It's down to testing it. We want the car to be a little more responsive as well so I put the dampers on both bound and rebound up to their maximum values of 10/10.
-Another run around the track reveals what? The car still understeers slightly but it isn't as bad. Why? The car is now more responsive due to the dampers. We're also getting out of the corners faster due to the ride height setting. An explanation for this ride height setting? Basically with a high rear value the car when accelerating throws all of its weight to the rear. When this weight hits the rear it pushes the suspension and thus gives the wheels more traction on the track. Hence faster acceleration. Take note, this ride height trick doesn't work all of the time, only on a few select cars.
- We need the car to be a little more responsive which means we need to stiffen up the springs. We want to keep the balance of the car as it is at the moment until we are happy with the cars response times and reactions. So add 10.0 to each spring setting. This means the car springs are now 18.6/16.5.
- Try another run. Result? Very responsive. Almost exactly as I would want the car. Problems? Understeer and a nasty tendency to oversteer mid corner. Let's use the stabilisers to eradicate that effect.
- Set the stabilisers to 5/6 and see what happens. A few laps show the effect has almost disappeared. Normally the stiffer the settings the better so we'll increase this to 6/7. Another quick test reveals that those settings work just as well as the softer settings. Still not happy with that understeer problem. So stiffen the rear springs so they are harder than the front. Maybe try 18.6/19.0?
- Another spin in the car shows the setup is working very well indeed. The corners are being taken at a higher speed. Maybe slightly slow on the straight due to the camber but nothing a few tweaks won't help. Maybe try without camber?
- No, definitely needs camber, the car doesn't stick as well in the corners without it. Set the camber back to default.
- Let's try fiddling with the gears. I suggest the final ratio should be changed to get just a little more acceleration. Change it to 4.110. Maybe the fourth gear needs a little tweak to ensure getting around that first corner at the best rpms available.
- At this stage it is down to fine tuning the car and seeing what the best settings are. If you want to go the stable and consistent way then soften the springs up a little to get the car to behave better. But, if you are wanting to go the fast and risky route, which I did, then fiddle around with the camber, gears and springs.
I spent another half an hour on the car getting the setup just the way I wanted it and produced a fast lap of 1:05.117 with room for improvement. The final settings were as follows :
Spring Rate : 18.0/19.3
Ride Height : 89/135
Bound Dampers : 10/10
Rebound Dampers : 10/10
Camber : 0.9/0.8
Toe : 0/0 (didn't find any merit in changing these - maybe personal preference though).
Stabilisers : 6/7
Brakes : 12/12 (No need to change, perfect as they are).
Autosetup 15 then :
1) 2.811
2) 1.920
3) 1.267
4) 0.930
5) 0.735
F) 4.110
Max Downforce.
The result is a setup that can produce consistent fast time if the car is run at the speeds the setup was designed for. It may be slightly unstable but that was the compromise between fast and stability. I went for fast. That quick example is by no means the only way to tune a car. In fact I probably did things the wrong way around. Used the wrong technique but as I said previously, it has worked in the past and it continues to do so for me. Use that information at your own risk. We'll move on to a couple other cars now that are different form this one.
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Example 2 - [R]Lancia Stratos at Midfield Raceway
The Lancia Stratos will be or little project this time out and we will be focussing on stability and gearing rather than outright speed. Get a hold of a Lancia Stratos and add all the modifications that you can except for Traction, Stability and Limited Slip Diffs. We'll take the car to the arcade disk and give it a few runs around Midfield Raceway and see if we can get it good enough to handle the bumpiness and instability at the Horseshoe turn in sector 3.
- A few runs around the track in stock settings and you can see immediately that this car needs a good kick up the backside for it to be even remotely enjoyable. The gears are lacking, the stability is poor in turns and very slippery but it needs to have that oversteer tuned out of it.
- Back in the settings screen we turn the downforce up to its maximum values of .42/.70 and we need to sort the gears out temporarily. Set the final gear ratio to 4.110 and then change the autoset to say... 13? Okay, we'll just soften the rear spring rate to 4.0 to see if the oversteer and sliding is reduced any.
- Still too twitchy but better in some respects. The top end of gear 5 seems to be okay for the course but 3rd seems to be hitting the rev limiter too soon on the Horseshoe with fourth feeling as if it is bogging down too much. Do we go to fix the gears or the stability? Stability. Gears are important but we can't judge them properly if the car is spinnng on every second corner. Lower the ride height to the minimum to see if we can instill some sort of ease on the suspension. Try altering the dampers both bound and rebound to reduce the oversteer. Say maybe 9/7 and 9/7.
- Woah! As slippery as a bar of soap in the communal prison showers. We'll reduce the dampers down a bit to see if the stiffness is the problem... try 6/5 and 6/5 also a good idea is to remove the camber values to 0.0/0.0.
- Definitely not as tail happy but sector three in the Horseshoe is a nightmare. Might be worth considering increasing the rear camber value to see if we can instigate some form of grip and soften the rear all around. Bound to 6/4, rebound to 6/4, springs to 4.1/3.5.
- Interesting, very stable for the most part and actually a nicely driving car now. Sector three is not great as the Horseshoe turn always seems to jostle the rear about too much. The solution is to soften the rear suspension again. Again we'll lower the rear springs and see what that brings. Down to 4.1/3.0 and the car seems quite good and at a good starting point for fine-tuning.
- So far the cars handling is perfect for me. Others may like to tighten it up a little more but I always like the car on that edge of control so that if you get the line wrong you'll know it. The gearing is the next task. Third gear isn't hitting where we need it to go when we want it. It needs to have a little better topend. Not as bad as I first thought though. Fourth seems to be slowing though, needs more acceleration. 2nd gear is okay for the last left hander into the tunnel at the end of sector 3. Fifth is fine and first is never used so we'll just give it as much top end as we can without interfering with the other gears. A quick fiddle with the values to get the following...
1) 2.633 (Makes first faster at the top end)
2) 1.935 (default setting, no need to change)
3) 1.350 ( Just slightly faster so we can take the horseshoe perfectly)
4) 1.075 (bit more acceleration and compensation for 3rds better top end)
5) 0.817 (perfect as it is, enugh room if we get a good run out of sector 3)
F) 4.110 (value we previously set)
- After another test we can see that 3rd needs slightly more top end to get it around and out of the Horseshoe at optimum speed and power without sacrificing anything during a shift. We'll set that value to 1.330. 5th gear 'sounds' as if it is bogging down but it appears to keep speed and accelerate okay. No need to touch it at the moment.
- Another few laps and we can see that the setup is good enough to use. Possibly a good starting point to fine tune it to your own style or to make it faster. What you have now is gears that are in the right range for several of the turns and the handling is reasonable and a good sight better than stock settings.
Now, what do you do with this setup? Several things. You could stiffen up the car all around to see if the balance will stay the same and hopefully by stiffening it up you will get faster and more responsive. The gears cold be tweaked minutely to get the absolute optimum for either manual or automatic transmission and for each drivers own style of driving and shifting. A couple of km/h (or mph) could be gained on the massive front straight by attempting to reduce the rear downforce value to possibly .65 or thereabouts without causing the car to go out of control through the rest of the lap.
Spring Rate : 4.1/3.0
Ride Height : 93/93
Bound Dampers : 6/4
Rebound Dampers : 6/4
Camber : 0.0/0.4
Toe : 0.00/0.00
Stabilisers : 3/3
Downforce : .42/.70
Brake Balance : 12/12
Final 4.110 and autosetup 13, then :
1) 2.633
2) 1.935
3) 1.350
4) 1.095
5) 0.817
F) 4.110
The setup I leave here isn't perfect but it is the main points of the tuning procedure I put up earlier. The stage we are at is the finetuning of each variable to get the best performance. Fiddle, tweak and you'll learn what each thing does. It's not as if you'll break anything. If you experiment you might come across a better setting than this and make the car more stable in a better way without sacrificing any speed.