In part one of this story, I talked with Team Need For Speed FIA GT3 driver Edward Sandstrom about the complexity of setting up a racing car, including issues like wing angles, suspension, tyres and data analysis. Over the next two parts we'll move on to how Edward and Team Need For Speed then practically apply these principles over a typical race weekend, starting with Edward talking us through the evolution of a set-up over a race weekend, using the last round of the 2011 FIA GT3 Championship as an example. We'll then finish up with a summary of how the team works with the drivers over a race weekend to get all the necessary set-up work done.
There are two hour-long free practice sessions during an FIA GT3 race meeting, followed by a two-part, hour-long qualifying session (one for each of the two drivers of each car, setting their starting positions on the grid for the two races) and then the two hour-long races, which include a single pitstop for the driver change. Of course, set-up preparations for a race start well before the weekend.
Edward: We started the first practice session with a car set-up based on a test at Hockenheim held just before the Zandvoort race. We had tried to achieve as much downforce as possible with both rake (which means we raised the rear a bit to influence the flow under the car) and through maximum rear wing angle. The camber settings you have to finalise from temperature information when measuring the inside and outside of the surface of each tyre. Sometimes the split can be higher with less amount of camber when the tyre slips too much, but generally it gets hotter on the inside the more camber you have.
Zandvoort has fewer right corners so we use more camber on the left side: the range can be from 1.5 degrees to nearly 4 degrees, so it's a wide spread depending on your philosophy of spring rates and roll stiffness. It's really easy to pick up rubber on the the right-hand side tyres at Zandvoort and it was actually a problem later in the races; it's hard to say how you can avoid it. Instead, as a driver you have to rip it off with slow exaggerated turning into the left corners. You can really hear when the rubber goes off and hits the inner wheel well. It's not optimal to use toe settings just to avoid this and then risk bad handling.
To optimise braking and initial turn-in, we applied some toe-out. Generally I always use between 1-2mm each side. But sometimes during my career I have used toe-in as well. It depends sometimes which Ackermann steering geometry the car has. You really have to test what you prefer as a driver and what runs best on the car. Toe-in is for sure most common on the rear axle, but to avoid mid-corner understeer I prefer to not have too much. Even half a millimetre can be a big difference, but as it produces mid-corner understeer it also can give you more traction and less power oversteer out of the corner. For sure toe-in on the Z4 GT3 is to handle the power.
The first free practice session was in the mid-morning of Friday: Edward and co-driver Abdulaziz Al Faisal ended up a lowly 27th with a 1:46.660s lap (fastest time was set by the #24 Reiter Lamborghini Gallardo with a 1.39: 915s). Claudia Hurtgen and Csaba Walter in the other Team NFS BMW Z4 set a 1:41.895s lap, ending up 7th.
Edward: This was actually a really bad session for us. We hadn't realised how bad the condition of the tyres were from Bratislava, and at Zandvoort tyre degradation makes a huge difference as the track surface really eats tyres. As we were trying to push more to get a better lap-time, we just destroyed the already worn-out tyres. The car was all over the place and lacked grip in every single moment. But as we only have one new set of tyres and had planned to run this set in the second session we kept on going.
Afterwards we realised this wasn't the very best choice, but we didn't fully understand the problem with the tyres until the session was over. With hindsight it's always easy to say what's the right thing. We could at least get some data, but in general we were so much off the pace that everything was quite hard to judge in terms of set-up changes.
Because of the state of the tyres after the session we had to stay cool and not change the car too much. As a driver I instead went through the data to see how the driving looked from this perspective, and tried to visualise how the speed would change with new rubber on the car. Our next run would be on fresh tyres: then you know it's time to step on it and use them as much as possible from the start. It can be tough if you aren't prepared in head.
Things looked better after the second practice session: #6 was up to 10th place with a 1:40.868s lap, 7/10ths off the fastest car, the #45 HEICO Mercedes SLS. #7 was back in 18th, but worse was that Csaba Walter had hit the barriers head on at the Hugenholtz corner (luckily a relatively slow left hairpin), dropping fluid and bringing the session to a premature halt – and requiring some emergency bodywork repairs back in the Team NFS pit.
Edward: The tyres made a huge difference. All the problems with huge understeer and oversteer was suddenly gone and now you could use the car as it was more predictable and much easier to drive. During the session we played around a bit with the rear ride-height to fine-tune the balance. If you lower the rear you gain traction, but that often creates mid-corner understeer.
We also use the dampers to work the tyres and to generate balance front to rear. Harder rebound works the tyres more and in combination with harder damping makes the car feel sharper. Even then I'm sensitive if the front gets too sharp and you easily fall through into understeer.
I like to drive the car over the front tyres into the corner and have a good feeling about how I can rotate the car. It means I need a range of front grip so I can feel what's happen in the steering wheel. Not too soft, but definitely not too hard. I also use the front roll-bar to adjust the feeling. As always it's a compromise because you need a more stable front in higher speed to not influence the downforce too much. So the target is to nail both with a good combination between damping and roll bar. It is possible to adjust all these settings during a session.
The only problem is that the limited time available forces you to try out changes in a short time. Therefore you have to be switched on while driving and use your feeling as much as you can. It can be hard to judge without doing a back-to-back test, but you don't have that chance in a one-hour session shared between two drivers.
What's also crucial during this part of the race weekend is to nail the tyre pressure. They are often a bit higher for qualifying where you want to reach the peak pressure between laps two to four when the tyres are at their best. You always have to find the right baseline in the cold pressure on each tyre that allows you to reach the perfect warm pressure out on track. Often you have to start with around one tenth lower in the rear than the front as they generates more heat.
After the session we checked the camber and temperatures and found out we weren't too far off. We didn't raise the right side that much before qualifying – often we then use a bit more camber with new tyres, as in the short term they have enough grip to give you the needed traction. The aim with new tyres is to always to optimise the grip they give. As a driver it's about being on the limit without exceeding it: you can find so much time if you don't overdrive on new tyres and instead let the car flow.
Experience helps you to judge if the set-up will stay neutral with new tyres or not. With the wider rear tyres you have by percentage more grip on the rear axle, so good advice is to have a slightly oversteering car on used tyres and then put new ones on.
When starting a qualifying if you aren't using tyre heaters one of the most important parts is to bring the tyres up to temperature in the right way. If you go out and just push too hard the rear will take the load and you may have problem to get the fronts to follow until they are warm and the pressures have reached their optimum. I normally try to put a lot of attention to this. You also have to make sure you've got clear space on the track when the tyres are ready. There are lots of aspects to nailing the perfect qualifying.
Saturday morning qualifying was riddled with red flags that caught a number of teams out – including Team NFS. First of all an Aston Martin DBRS9 ground to a halt with an oil fire during qualifying for Race 1 and had to be cleared; then one of the Ford GTs lost control on the fast sweepers at the back of the track, slamming into the barriers and causing a 45 minute delay to the start of qualifying for Race 2 whilst the Armco was repaired and the damaged car recovered. Edward's only lap left them mired in 27th for Race 1; ATF could only manage 22nd for Race 2.
Edward: Hmmm, this was one of the days when you want to restart a session. We waited quite long and gambled a bit to get the perfect track conditions. It was really cold outside and we wanted the others to put some new rubber down in the track before our try. I left the pit with 10 minutes to go and passed the pit once to make sure the tyres where coming in perfectly. When they are there you definitely feel it and I felt it in the end of my warming-up lap. I started my hot lap and had a very good first turn with really no traffic in front.
When you then see the red flag waving it's so frustrating. I slowly made my way back to the pit to not use any more of our black gold than necessary… But you always know the best way for new tyres is to use them at the first attempt. Wait for next try. Green again. Out and the warming-up procedure went quicker. Right spot on the track three corners before the start/finish and on it again. Good feeling, but then turn two and the red flags were waving again!
Now you get a bit stressed. Time was running out. Even if the session time is stopped you still have to complete your out-lap before starting a flyer, and the clock said there were just four minutes to go. One lap could be possible if we waited a bit in the pit to avoid traffic, but today it wasn't even possible to do this lap. The barriers were too badly damaged and the session was stopped – and I hadn't set a time! Disaster. The car felt so good but the gambling didn't pay off – instead it ruined a lot of the weekend at Zandvoort. Aziz did his qualifying later but didn't find the grip I had felt. A change of grip level is also something common at Zandvoort.
Race one kicked off with the low sun hitting the cars obliquely at the rolling start: Edward made great progress during his opening stint, overtaking a car a lap and making his way to 12th by lap 13. ATF emerged from the driver-change in 13th, but couldn't make up any more places in the face of stiff opposition.
Edward: For the first race we ran a bit less camber and less air pressure, but the same toe values. I don't think we changed much more than that. I was starting near the back of the field and had to really nail the start. The car felt very good and the grip level was there.
I had some problems with understeer in the faster corners, but these were mainly created because of lost downforce when being on the bumper of the car in front. When driving in dirty air the aero influence is relatively high on the Z4. I had to plan my driving and not be too close to other cars at certain points on the track.
The tyre degradation was there, but not as high as I maybe had expected. I manage to make my way through from 24th to 12th during my stint and still have reasonably good tyres left. But the pick-up on the right front was noticeable. First it can feel like you have a small puncture, but when you hear the rubber smashing, then you know. When the tyres slowly start to go off you feel more problems keeping the car stable when powering out of slower corners.
You also have to pay attention to not entering open corners too fast and with too much trail braking, as the rear easily steps out on the Z4. The pressures were fine in the pitstop, but you always consider the possibility of lowering them if needed to get some grip back. Often the laps just after the stops can be a bit faster than the ones before. After that the degradation takes off again: it goes in steps. You can keep maybe three laps within a range of two-tenths and then the times goes up some tenths. If you are too aggressive it can be more up and down, so you really have to pay attention to not push over the limit. Just on it!
The car didn't feel too bad during race one and we were actually only three-tenths off the best time when driving in traffic. Our theoretical combined lap-time was the best in the field, so we just made some small changes to get the tyres to last a bit better: a softer rear roll-bar and even lower tyre pressures.
Race 2 was held on midday on Sunday. ATF took the rolling start in #6, but immediately suffered when a car in front of him started spewing oil: the windscreen was covered in an oily sheen that he had to suffer with for his stint. Edward was on it as soon as he took over the car: again he made a place a lap, but after making his way up to 13th couldn't progress further.
Edward: I was driving the second stint. I was very aggressive in my efforts to catch up time and overtake cars, but that meant I took a lot of the edge out of the tyres and in the end I suffered from bad traction and really had to take care. Still we were fast, but the track felt less grippy than the day before. Faster corners were okay, but in the slow corners I really had to stop and rotate the car slowly to avoid the rear stepping out. This is often the case in the second stint, but I felt this track was harder on the tyres then normal.
So what could we have done better? Hard to say, but the obvious thing would have been to qualify better to avoid all the overtaking, which would have reduced the wear on the tyres. We also suffered from turn-in oversteer into slow corners and I have a feeling we need to make sure the car rotates slower in these areas to stabilise it better – this would help to not stress the tyres as much.
Indeed our race speed was as good as the others but I felt the tyres were completely dead five laps from the end. This we have to solve to next time. Analysing and again analysing – that's life in racing.