Chatter costing Casey Stoner vital time, says HRC crew chief
25 April 2012 10:34
The severe chatter issue that has plagued Casey Stoner on Honda’s new factory RC213V machine is costing the reigning world champion precious tenths-of-a-second per lap.
Stoner’s Repsol Honda crew chief Cristian Gabbarini says the chatter, which is a vibration on braking and corner entry, means the Australian is being prevented from being able to push at 100%.
Stoner has been handicapped by the chatter issue ever since new softer construction tyres were introduced by Bridgestone after riders requested better initial warm-up performance to avoid a spate of nasty high-sides on cold tyres.
HRC technical staff haven’t been able to find a solution to the chatter problem and a new or modified chassis is expected to be made available for Stoner and Repsol team-mate Dani Pedrosa to assess during a forthcoming one-day test session immediately after the Estoril race in Portugal.
The chatter issue was a major factor for Stoner during the season’s opening round in Qatar earlier this month and Gabbarini told MCN: “It is difficult to judge but I think it costs him some tenths for sure. It is impossible to push at 100% because you don’t have the feedback from the tyres, so you must keep some safety margin. The grip conditions are what can make a big difference. In general the new rear tyre amplifies the chatter a lot in our bike and we knew this right from the beginning when we first tested the softer tyres. In some circuits we have reduced to an acceptable level but in Qatar it was lot. Every time we go out on track we find a different condition so the chatter increases or decreases always."
"Unluckily for Casey it is from the beginning of the corner when he brakes to the end of the exit. Through the whole corner he has chatter. So from the moment he brakes to the moment he picks up the throttle, he has chatter. It is just that it moves from the front to the rear. Basically the sensation is that the tyres are jumping across the surface and you can see this easily on the data. I’d say the tyres jumping on the ground is the perfect way to describe this problem. We have some ideas to improve it but if something is coming from the factory then sure it is welcome because with a problem like this we must work to solve it as quickly as possible. I don’t think it is a problem we can’t solve but we have to think about it and work hard. Maybe we can modify something. Usually when the chatter happens it is a combination of grip levels, stiffness of the tyres and stiffness of the chassis. It is too early to say what is the issue.”
The chatter issue is also having an impact on team Pedrosa but Gabbarini feels Stoner’s issues maybe exaggerated by his riding style.
He added: “I know Dani suffers a bit with this problem but less than Casey. But a lot can depend on the riding style. Casey is a rider that puts a lot of force into the tyres to find good grip, but when you are putting that level of stress on the tyres, the chatter increases. He brakes really hard and deep into the corner, so this puts a lot of force on the front, and he likes to pick up the bike quickly to exit and that creates a lot of force on the rear.”
Stoner believes radical solutions like a completely new frame are going to be a last resort measure to fix the problem but he told MCN: “We have a limiting factor with chatter, so I think if we can get rid of most of it we will be right. The boys do have a heck of a lot work to do to try and fix that because I'm not the only Honda rider with this issue. So if we can fix that then it will be happy days. If they (HRC) find something through their studies then that is great but if they need something new then we might have to do that. But that's a last resort, we are going to try and get everything we can out of what we have got."'