Post Silverstone thoughts

[bmwbadboy]

What an amazing day and amazing track. My first time at GP circuit, finally I get to see some left-handers !

Lots of BMWs ! Someone here on forum said that he has stopped seeing those, I totally disagree. I would say 20% of bikes were S1000RR.

Managed to make 2:26 towards the end of the day on fresh Dunlop D212 rear. I did take an instructor for 2 sessions to learn the lines of this track, since it was my first time there.

So, as you might have guessed by now, I have problems with Dunlops again! I think I've learned to account for ambient temperature and avoid cold/hot tears, but this time around I got this:

So this is E compound of D212 GP racer slick.
Today, this tire did 5 out of 6 sessions. 4 sessions it was perfectly fine, it got destroyed towards the 5th.
As you can see, it didnt get torn along the whole diameter, just 1/3 of it.

I started the day (lower temp in morning) with 22ps after 80C warmers, lowered it to 20psi after 1st session and kept it like that. Thru 4 sessions, tire didnt exhibit any tears at all.
TC was set at -5 whole day.

My thinking is:

1. I'm not getting bike upright enough before I roll on the throttle -> too much pressure on right side + possibly TC intervened and due to its pulsating nature of cutting the torque, destroyed the tire.
2. Tire worn out
3. Tire defect


What do you think ?

 

[bmwbadboy]

One thing to add regarding rear shock settings....

I've done 4 sessions with -1 reb, -1 comp and noticed this wavy tear on left side. So for 5th session I dialed them both to 0.
I doubt it would have such a big adverse effect on right side of tire...

 

[bmwbadboy]

-5 is vertually no tc

I hear you, but that's not the case on stock model (no RCK) in slick mode. At -5, the lamp is flashing out of every corner if I'm hard on the throttle.

ofc the fact that it's flashing can mean many things, and most obvious is that I'm not getting bike upright quick enough before opening it up, which is my bad.

 

[MoranC1]

*nowhere near expert*
But would 20psi not be too low even with warmers? Ive only ran a cbr600 at a few trackdays and ran 30psi with no warmers on bridgestone s20/21s . Im assuming this could be totally dofferent with slicks?
Im a car master technician and anytime we see tearing like that (both outer edges) its due to low tyre pressure and the tyre flattening out and rolling over itself in turns.

 

[alex]

*nowhere near expert*
But would 20psi not be too low even with warmers? Ive only ran a cbr600 at a few trackdays and ran 30psi with no warmers on bridgestone s20/21s . Im assuming this could be totally dofferent with slicks?
Im a car master technician and anytime we see tearing like that (both outer edges) its due to low tyre pressure and the tyre flattening out and rolling over itself in turns.

Doesn't work like that for bikes. The tyres are shaped totally different for motorcycles.

NTEC construction from Dunlop uses a stiff carcass and low track pressures.

- Alex

 

[MoranC1]

Yea even though shaped differently it would still flatten under load when on corner exit if the TP is too low?
Even motogp are only allowed to run around 26psi at min i think?

 

[pof]

Pressures seem good, i run 32f 22r off warmers and maybe a little lower in spain. The dunlop are one of the longest lasting tyres i know and getting 4 days out of a rear is not unheard if let alone 4 sessions. Its got to be worth some cash to have the suspension looked at and maybe get it "adapted" to your riding style

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[bmwbadboy]

Pressures seem good, i run 32f 22r off warmers and maybe a little lower in spain. The dunlop are one of the longest lasting tyres i know and getting 4 days out of a rear is not unheard if let alone 4 sessions. Its got to be worth some cash to have the suspension looked at and maybe get it "adapted" to your riding style

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To be fair this one lasted almost 2 track days. I installed it at Donny 2 weeks ago.

22psi with medium compound on a hot day gives me a cold tear after 4-5 sessions I got to be 20 after warmers or maybe even 19 if it's a very hot day.


I tend to think now, Endurance compound is a bad choice for a very hot day like yesterday...

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[bmwbadboy]

Yea even though shaped differently it would still flatten under load when on corner exit if the TP is too low?
Even motogp are only allowed to run around 26psi at min i think?

These are Dunlop recommended pressures...
17psi cold, 20psi after warmers, 23-25psi off track.

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[alex]

Yea even though shaped differently it would still flatten under load when on corner exit if the TP is too low?
Even motogp are only allowed to run around 26psi at min i think?

Different tyre makes can be very different in pressure requirements, you can't compare. Thats why we gathered and stickied all the tyre info from the manufacturers in the Racing and Pitlane sub forum.

Yes of course there is deformation, thats the aim, to get it to deform the right amount. But where you're delaminating the compound from the carcass you've gotten something wrong. Track temps, pressures, compound, throttle, suspension, geometry...all have an effect. Have a read on cold tear and hot tear.

There are 4 compounds of D212, there are then Racer and Pro options of them (latter being faster). Then there are the Premium KR106/108's which are another step on, and have their own compounds. Thats 12 different rear tyres alone, then you have consider all the factors using them.

- Alex

 

[MoranC1]

Awesone, must have a look at that sticky. As i couldnt comprehend using a tyre at 17psi lol

 

[P0u1]

I hear you, but that's not the case on stock model (no RCK) in slick mode. At -5, the lamp is flashing out of every corner if I'm hard on the throttle.

ofc the fact that it's flashing can mean many things, and most obvious is that I'm not getting bike upright quick enough before opening it up, which is my bad.

That might be the problem then, if your TC light is going crazy it is most likely slipping and destroying tyres. Just a thought

 

[bmwbadboy]

That might be the problem then, if your TC light is going crazy it is most likely slipping and destroying tyres. Just a thought

Probably, in combination with hard compound. I'm still learning ...

 

[P0u1]

Probably, in combination with hard compound. I'm still learning ...

You may be better switching to a medium compound, should hopefully grip abit better without spinning up.

Like other people have said check your suspension but it looks like overriding to me.

I'm no racing expert but you shouldn't be going through tyres like that.

 

[bmwbadboy]

All in all you can ignore all my post trackday thoughts.

This particular tire wear has nothing to do with TC or compound.

The problem - incorrect suspension setup.

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[MacRR]

Can't say I find that much of a surprise but how have you come to that conclusion and what are you going to do about it?

 

[bmwbadboy]

Can't say I find that much of a surprise but how have you come to that conclusion and what are you going to do about it?

I've got help from Dave Moss, who saw the problem straight away, told me what needs to be tuned (across multiple sessions on track) and that eventually helped to get rid of this nasty tear in Dunlops.

Bottom line issue - rear tire doesnt have enough weight on it, doesn't stay long enough on the ground to generate and maintain heat and hence tears apart. Nothing to do with riding style/TC.


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