Porsche 962 C Team Joest | Setup Guide

Discussion in 'Car and Track Knowledge Base' started by Thomas Jansen, Apr 17, 2019.

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  1. Thomas Jansen

    Thomas Jansen Sector3 Developer Beta tester

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    Apr 5, 2018
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    Probably one of the most popular additions to the car collection in RaceRoom, the Porsche 962 is an amazing and challenging car to drive. As a fully unlocked racecar, the setup has many degrees of freedom to explore, which is good on one hand, but makes the choices a lot more difficult too. The default setup for this car is very forgiving, which makes it nice to jump into and drive. However, once you get up to speed, you will notice there is a lot of understeer pretty much everywhere. Luckily, there are plenty of ways to solve this, but especially with the massive amounts of downforce playing a role in the setup, it is much less straightforward than on the 934, for example.

     
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    Last edited: Apr 29, 2019
  2. Thomas Jansen

    Thomas Jansen Sector3 Developer Beta tester

    Joined:
    Apr 5, 2018
    Ratings:
    +315 / 0 / -0
    Road America

    Setup & Telemetry



    Gear Ratios

    The default gearing for this track was actually almost perfect, I only made 2nd gear one click longer. That one change does highlight quite a few considerations you can make when adjusting gears, as it really tied the middle sector together nicely. The main reason I wanted a slightly longer 2nd gear was because I hit the limiter slightly before the bridge into turn 4. Both shifting up so close before a corner and staying in 2nd were losing me time, so I wanted 2nd gear to be viable for the whole section between turn 3 and 4. With the one click longer gear it worked out perfectly, as it is now only just out of the turbo range out of turn 3, making it quite easy to get the power down at that slow speed. Furthermore, it moved the point where I have to shift into 3rd after turn 4 a bit closer to turn 5. Turn 5 is not fully flat, so a tiny lift is required there anyway, so doing this lift simultaneously with the gearshift is essentially a free gearshift! You can see all this in my stint video.

    Tire pressures
    As usual, I used the tire temperatures to tune the tire pressures, so making sure the middle tire temperature is right in between the outer and inner temperatures on average. The result makes sense, with significantly more pressure in the left side tires, as Road America has a lot of high load righthand corners.

    Camber
    As this car has very stiff suspension, there is not a lot of body roll, so also not a lot of camber loss in corners. The rear rolls a bit more than the front, so I equalised the camber through the fast corners by increasing the rear camber and decreasing the front camber a bit. This seemed to help lateral grip slightly, especially on the rear, so it seemed like the right change.

    Front Anti-Roll Bar & Springs
    This is where the real balance changes will come in, which was quite necessary on this car, as it was massively understeery pretty much everywhere. My aim was to make the car much more similar in handling to the R90CK, which is already very agile on the default setup. The first attempt to get rid of understeer is usually to lower the front ARB, which I even disconnected completely, as this is an option on this car. This does not necessarily mean that the roll stiffness becomes almost 0, as the springs are still extremely stiff on this car, which also resists roll. As I felt that there was still some more grip to gain on the front, I also started lowering the front springs. At around 520 N/mm is where I started feeling like I was reaching the point of diminishing returns. Large changes like this can heavily affect the effectiveness of the floor to produce downforce, so playing with the ride height afterwards could be worthwile.

    Rear Anti-Roll Bar
    After maximising the front grip, there was still understeer in all corners. The high-speed balance is mostly dominated by downforce ofcourse, but the car also felt reluctant to turn in the slow sections. I ended up almost doubling the stiffness of the rear ARB to the maximum value it can go. However, similarly to the front, because the springs are so stiff, this does not mean that the overall roll stiffness gets doubled as well. With this change, the car finally started feeling agile and willing to turn when I wanted it to in the slow sections. Ofcourse, getting the power down is now a bit less forgiving, but still easily manageable and easier than the R90CK.

    Splitter & Rear Wing
    The splitter option in the setup is more like a 'downforce package' option on this car. The lowest option being optimised for low drag, the second for aerodynamic efficiency and the third option for maximum downforce. Road America requires both high downforce and low drag, so it is an easy choice for the second option here. The effect of the rear wing is very straightforward, a higher angle means more drag and more downforce on the rear. However, you should keep in mind that a higher rear wing setting increases overall downforce too, so it is not always the best choice to lower the rear wing to get rid of understeer. This is exactly why I adjusted the suspension first. I was still getting significant understeer in high speed turns, turn 11 in particular was difficult. It was improved with the adjusted suspension, but definitely not enough yet, so I lowered the rear wing to get the balance to my liking at high speed. I made this setup for the soft tires, which have a lot more traction than the hard tires, so I would recommend adding an extra click of rear wing for the hard tires.

    Ride Height & Floor Downforce
    The downforce produced by the floor of the car is crucial and can be complicated to deal with. It is very much a balancing act, as you want the splitter to be low to the ground, but not too low to prevent stalling the diffuser or making bumps and curbs problematic. Then there is also 'rake' which is the difference between front and rear ride height. You generally need some positive rake, so the rear higher than the front, to make the diffuser work properly. However, increasing the rake also increases drag as there is more frontal surface area. What makes it even more complicated is that the ride heights completely change at speed, as the downforce pushes the car down. Depending on the downforce balance and the difference between the front and rear wheel rates, this can have a large impact on the rake at high speed. Ofcourse this rake value at high speed is exactly what you want to control, as that is where there downforce matters. So always be careful changing this stuff and try to keep in mind what you want to achieve before changing it. Before I adjusted the front springs, I had tried to lower the overall ride height by a few mm to try to get a bit more downforce from the floor. This seemed to work well, though in combination with the lower front springs, it caused more harm than good. The front most likely goes too low, causing a loss of downforce and making curbs harder to use. The default static rake of 2.5cm seemed to be pretty much optimal for the default suspension setup, so I tried lowering the rear a bit with my adjusted suspension, as the front will be compressed further with the lower springs. This increased my top speed slightly and made the handling through fast corners more consistent, so I was most likely getting closer to the original dynamic rake values again.

    Differential
    The effect of the differential can also be quite complicated, but it is a very nice tool to fine-tune the behaviour of the car in different parts of the corner. In RaceRoom higher percentages for the power and coast values give more differential locking in the respective phases. In general, a more locked differential causes understeer while coasting and oversteer when on power. The preload is a locking force on the differential that is applied at all times. The preload is mostly used to control the behaviour of the car between lifting off the throttle and applying the brakes, as that is where coast and power settings have no effect. I find that the power setting has a very similar effect on the handling as the rear toe-in, which allows you to control the amount of rotation you get out of a corner on power. The coast setting is a bit more subtle, with higher values making the car feel more reluctant to turn and low values allowing you to really easily slide the car sideways. On this car I felt it could be a bit more aggressive out of turns, so I increased the power setting by one click, instantly giving much more rotation on power. While coasting, the car was not eager to rotate, so lowering the coast setting made the car a bit more agile in a lot of corners. Similarly for the preload, the car was always a bit lazy when turning in, so lowering the preload made the car a bit looser on corner entry.

    Dampers
    As has been the main story with this car, the weight transfer on both entry and exit was balanced towards stability and understeer, making it difficult to attack corners. To improve the corner entry responsiveness, I lowered the front bump and increased the rear rebound. Similarly, to improve the corner exit, I lowered the front rebound and increased the rear bump. These are generally the changes you want to do for these symptoms, and ofcourse if you want to calm the car down instead, you can adjust the dampers in the opposite directions. Always make sure to check if the behaviour over bumps is still stable, especially on power.
     
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    Last edited: Apr 29, 2019
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