The Motegi GP, very demanding for brakes and tyres
One week after the Formula 1 race, MotoGP, with the Movistar Yamaha MotoGP team sponsored by BMC, is coming to Japan for the 15th competition in this year's World Championship being held October 13 to 15 at Twin Ring Motegi. Built by Honda in 1997, the track is located in the hills surrounding the city of Motegi on the island of Honshū, the biggest island in Japan.
The name Twin Ring comes from the union of the English word Twin with the German word Ring, which is representative of the two tracks found here: an oval one and a street circuit that intersect between turns 5-6 and 11-12.
Of course the MotoGP bikes use the street circuit, which stands out for having very few fast corners and many slow ones interspersed with medium length straights. There are seven corners that the bikes have to take going less than 100 km/h.
It is this abundance of 2nd gear corners that has made the track one of the most demanding on the brakes, ever since its debut in the World Championship in 1999. It is really difficult to cool the discs down between one braking section and another.
The perfect tarmac translates into good grip and improves the braking torque discharged, but as a consequence it increases the stress that the brakes are subject to. This is why the FIM regulations require the use of 340 mm discs, exclusive for this track.
According to Brembo technicians, who assist 100% of the 2017 MotoGP pilots, the Twin Ring Motegi is very critical for the brakes. On a scale of 1 to 5, it earned a 5 on the difficulty index, exactly the same score given to the track at Sepang and the two European circuits of Barcelona and Spielberg.
The demand on the brakes during the GP
Of the 14 corners on Twin Ring Motegi, ten require the use of the brakes and on five of these, the riders apply the brakes for more than four seconds. This explains why the braking systems are being operated for 35 seconds per lap, which is equal to 33% of the entire race, a record percentage for the World Championship matched only by Jerez.
Since there are three braking sections of modest length (between 41 and 94 meters each), the mean deceleration is not high, it stays down at about 1.1 G, but his is still higher than that registered by a Honda Civic Type R when braking from 100 to 0 km/h.
Summing up all of the force applied by a rider on the Brembo brake lever from the starting line to the checkered flag, the result comes in at more than 1.2 tons. Practically speaking, this is equivalent to 25 ASIMO robots designed by Honda and displayed inside the museum at Twin Ring Motegi.
The most stressful braking sections
Of the 10 braking sectionson the circuit, three are considered very harsh on the brakes, while four are of medium difficulty and three are light.
The one that puts the most stress on the braking systems and the riders (1.5 G in deceleration) is the90° corner at turn 11. The MotoGP bikes arrive at it going 308 km/h and then brake for 5.2 seconds to slow to 86 km/h. In this short time span, the riders apply a 7,6 kg load on the lever while traveling 263 meters and the pressure of the Brembo HTC 64T brake fluid gets to nearly 13.2 bar.
At turns 1, 3 and 5 the deceleration measures 1.4 G. Turn 5 in particular stands out for the force demanded of the riders (7,9 kg on the brake lever) and the brake fluid (13.6 bar) in order to slow down from 270 km/h to 76 km/h in 4.9 seconds and 222 meters.
The measurements are more contained for turn 3, but still they are higher than the average of the other corners on the track. The bikes have a braking space of 211 meters and 4.4 seconds to reduce their speeds by 177 km/h (from 271 km/h to 94 km/h).
Very hard job for the tyres too
With demanding braking and hard-acceleration zones over the circuit’s undulating configuration throughout its six left and eight right-hand bends, the track is very stressful for the tyres, especially due to its abrasive surface. With all these factors – allied to the lower temperature which can be expected at Motegi at this time of the year – the tyres available need special attention to give the best performance for all riders and machines. The range of three front Michelin Power Slicks in soft, medium and hard compounds will be a symmetric design, whilst the rear compositions will be asymmetric with a harder right-hand-side to manage the increased turns which that side of the tyre has to contend with, and the compounds for all tyres have been specifically picked to match the track’s demands. Wet weather is always possible in Japan in October and the Michelin Power Rain tyres will be in a soft and medium option for the front and an extra soft and soft version for the rear, with all tyres being a symmetrical design.
As the season reaches its climax – with just four rounds to go – the championship is still wide open with the top-five in the title chase covered by just 56-points and with a maximum of 100 still up-for-grabs it looks like being a close finish.
Piero Taramasso – Michelin Motorsport Two-Wheel Manager
“As we head towards the business end of the season – where the title will be decided – we have one of the biggest tasks we have to undertake all year. The three fly-away races present a massive logistical operation and we have already sent over 70% of the tyres – we will have to allocate – by sea-freight and then the rest we will send by air. It is never easy trying to guess what the conditions will be like, especially in Australia, but we have some good experience from last year and that will make sure we are prepared for most things – unless it snows! The first race in Japan is on a track that can create extreme stresses, especially with its hard-braking zones such as 90-degree turn, so we need to have tyres that can cope with these, as well as having good warm-up properties as it can be quite cold at Motegi in the mornings. The track has good grip levels and we will be taking the tyres that we are sure will perform at the best levels and ensure the show is as good as it has been all season so far”.
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