I've updated the way that the USD rule will be implemented with immediate effect. This has been reflected in the 2019 Class Rules, however here it is again for everyone's information:
Upside-down Rule ("USD rule") definition and execution:
Where a class stipulates the USD rule, the car must drop away from a C7016 Scalextric Single Lane Half-straight 175mm (henceforth referred to as the "test block" or "block") that is held still in an upside-down position. The test will be done by first ensuring that the braid is flattened against the guide, then placing the car on the block and turning the block upside down horizontally while holding the car in place. The car is then released. Once either the front or rear wheels (or both) drop away from the test block, the car has passed the test. The car will NOT be rolled back and forth on the block to help it locate a spot where it drops away. The car will NOT be touched once it is released. It must fall off the block unaided. If a car fails the test, it must be adjusted until it passes the test. This adjustment must not be made by raising the braid. The car must be tested as it will race. Magnet stacking is allowed. Any weight added to the car must be positioned within 2.5" (64mm) and ahead of no further back than the rear axle.
Helpful link: Some ways to fine-tune for passing the USD rule
Update to the implementation of the USD rule
Re: Update to the implementation of the USD rule
Guys,
I've removed the radical change I made yesterday which eliminated the guide flag from the USD equation. The main reason for this is because many cars have up/down movement on the front axles and this would have to be removed for those cars to pass the test, something that may be difficult and not necessarily in the interest of good setup for the specific car. Also, we sometimes set cars up for the front to ride on the guide (as opposed to the front tyres) which allows for relatively easy adjusting of downforce by adding spacers to the guide to raise/lower the car's front ride height.
Instead, the rule now states that the braid must be laid flat against the guide before placing it on the test block. It is neither fair nor right to intentionally raise the braid in order to pass the test with a car that is effectively ILLEGAL from the downforce perspective, when the braid is then flattened to drop the guide deep into the slot for racing with more downforce than it should have.
We are all trying to make our cars as fast as possible, but we need to do the right/ethical thing and always abide by the rules and the by intent of the rules. Let's enjoy and respect each other's competitive companionship without breaking the rules.
I've removed the radical change I made yesterday which eliminated the guide flag from the USD equation. The main reason for this is because many cars have up/down movement on the front axles and this would have to be removed for those cars to pass the test, something that may be difficult and not necessarily in the interest of good setup for the specific car. Also, we sometimes set cars up for the front to ride on the guide (as opposed to the front tyres) which allows for relatively easy adjusting of downforce by adding spacers to the guide to raise/lower the car's front ride height.
Instead, the rule now states that the braid must be laid flat against the guide before placing it on the test block. It is neither fair nor right to intentionally raise the braid in order to pass the test with a car that is effectively ILLEGAL from the downforce perspective, when the braid is then flattened to drop the guide deep into the slot for racing with more downforce than it should have.
We are all trying to make our cars as fast as possible, but we need to do the right/ethical thing and always abide by the rules and the by intent of the rules. Let's enjoy and respect each other's competitive companionship without breaking the rules.
Re: Update to the implementation of the USD rule
Guys, my last post above was a bit harsh. When it comes to the USD rule, please just flatten the braid when your cars are being checked.