Teams will once again be allowed to use rear brake blanking during races, a provision initially dropped for the 2024 season.
The rule change has been introduced by way of the Further Supplementary Regulations for this weekend’s Betr Darwin Triple Crown, and would presumably be given effect for future events by way of Supplementary Regulations for each.
Front brake blanking is still prohibited in races but allowed in practice and qualifying sessions.
Further Supplementary Regulation 1.2 for the Hidden Valley meeting states (including mark-up):
1.2.1 At this Event, note the following amendments to Rule D19.3.1 and note the following new Rule D19.3.2:
D19.3.1 Front brake blanking components as listed in the VSD for each make of Car listed in Rule C1.2.1 are only permitted to be used or changed in accordance with the below table:
| Session | ||||
| Blanking % | Practice | Qualifying | Race | |
| 0% | 0% | 0% | ||
| 25% | 25% | |||
| 50% | 50% | |||
D19.3.2 Rear brake blanking components are only permitted to be used or changed in accordance with the below table:
| Session | ||||
| Blanking % | Practice | Qualifying | Race | |
| 0% | 0% | 0% | ||
| 25% | 25% | 25% | ||
| 50% | 50% | 50% | ||
The old Rule D19.3.1 was simply the first of those two tables, without distinction between front and rear brakes, and hence prohibited any blanking of the latter during races.
While Triple Eight Race Engineering did not push for the change, Red Bull Ampol Racing Team Manager Mark Dutton explained the rationale to Speedcafe, outlining how brake temperature can climb during a stop and thus create instability.
“It wasn’t brought up by us – it was brought up by other teams – so I think there’s different logics behind it, but most of them are just stabilising the temperatures and the thermal effects of the brakes,” he said.
“You want your brakes to be, especially in the rear, as consistent as possible.
“You don’t want them to change their mu or their coefficient of friction too drastically throughout a stop because that means your brake bias is thermally shifting.
“To put it another way, imagine you’re braking into a corner; your rear brakes, just through the temperature change, are getting more bitey.
“It can give you turn-in oversteer and make you oversteer into the corner, just from the temperature change from start to finish of even just a single braking [application].”
The blanking could also be used to keep brake temperature more consistent and hence reduce the risk of thermal shock which could conceivably cause warping.
As for how the blanking is applied, the method is quite simple.
“We used to do these years and years ago, so it’s not a new thing,” remarked Dutton.
“You basically blank the vanes from the inside of the disc, which just stops the air from flowing from the inside of the disc to the outside.
“You can blank the vanes fully or different amounts, so you’re reducing the amount of air going through them.
“It’s just a thin strip of stainless steel that you put in, throw a couple of pop rivets in, and it’s probably cheapest part on the car.”
In other technical matters (although blanking is officially a sporting matter given it is regulated by Division D of the Operations Manual), the Further Supplementary Regulations for Hidden Valley also include a rule change pertaining to devices which can be used to vary the temperature of various components/fluids.
It has separately been explained to Speedcafe from within the paddock that the regulation is more a clarification rather than a rule change in a practical sense.
The further supplementary regulation reads as follows:
1.3.1 At this Event, note the following amendments to Rule C4.4.1:
C4.4.1 Accessories and devices which have no influence on a Car’s behaviour are permitted subject to the prior approval of the GMM. For example, equipment which improves the comfort of a Car’s interior (lighting, heating/cooling, etc.). In no case may these accessories and devices increase the engine power or influence the steering, artificially vary the temperature of any part of the Car (with the exception of Driver cooling), transmission, brakes or road holding either directly or indirectly, unless permitted within the Rules or listed below.
C4.4.1.1 Teams are permitted to heat engine oil, engine water, and transaxle oil via an external closed loop fluid heater whilst in the garage.
C4.4.1.2 Teams are permitted to use a heating pad fitted to the oil tank as specified in the GSD.
C4.4.1.3 Teams are permitted to blank the front facia air intakes for the retention of heat whilst in the garage.
This weekend will also be the second with the lower minimum tyre pressure of 15psi.
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