What’s the advantage? As the present 125 KF engines are practically “dead” below the 8000 revs, letting them work at that speed before the clutch engages completely enables you to get a different thrust on drive wheels. But, this isn’t all, allowing the clutch to skid until over 11000 revs, it has also been assessed that also at 9000 revs there is relative skidding between drive shaft and pinion, 10% - you get best drive torque and with it thrust is stronger too. This enables you to mount a final gear with one or two teeth less, making the most of this technical device.
What the tuners were offering, and at a very high price, (€1000 per clutch) was not irregular. They simply use a part of the international karting regulations that we can call “shadow zone”. The initial regulations were stating that ‘’ The engine clutch must be triggered at 5,000 rpm maximum and make the kart with the driver on board move forward.’’ What it wasn’t saying is at how many rpm the clutch completely (100%) stops slipping and this is the ‘shadow zone.
WHO IS USING THESE CLUTCHES:
It must be said that the various KF engines use 2 types of centrifugal clutches. The first is the one that can be described as ‘monolithic rotor with added friction material’ and it is used by VORTEX and IAME (see photo 1).
(photo 1)
The second one is of the type of ‘rotor with springs with added friction material’ and it is used by the other 2 major KF engines, which we are not naming for obvious reasons. (See photo 2)
(photo 2)
It is said that you cannot ‘tune’ the type of clutch that is used by VORTEX and IAME but you can indeed ‘tune’ the one with the springs.
This does not mean that all drivers using an engine other than VORTEX or IAME are using a ‘tuned’ clutch to gain false advantage. The majority of drivers are clean but there are few (and we are talking about fathers) who depend on such ways for giving joy to themselves and their sons. An expert in karting can recognize such instances by just listening to an engine screaming around tight turns or by observing a driver coming strongly out of a corner after a wrong entry which should have made his engine lose momentum.
INITIAL ACTIONS TAKEN BY THE LEGISLATORS:
With “doped” results, which don’t often give a true picture of the actual skill on the field, the legislators tried to find temporary ways of dealing with the problem.
The first action taken was to amend the rules to set a maximum authorized threshold that the clutch slips (see note 2).
What they basically did, in the restricted time they had, was not only to set a method of checking whether the clutches trigger after the 5000 rpm point but also introduce a data logging system (see photo 3)
(photo 3)
To ensure that the slip of the clutch does not exceed the maximum authorised threshold (direct drive clutch, 100%, at 6,500 rpm maxi¬mum, under all circumstances). (See note 3)
Well this is very good news for the International events, but unfortunately on a national level, the local club authorities did not have the means neither the hardware to implement these changes.
As a result we would see the scrutineers at National races only checking whether the clutches trigger after the 5000 rpm point. BUT WHY DO THIS if you are not checking whether the slip of the clutch does not exceed the 6500 rpm threshold?
FINAL ACTION TO RECTIFY THE PROBLEM:
With the new regulations for 2009 (see note 1) both International and National races will be free of such ‘cheating’ and allow the drivers show their actual skills.
NOTE 1:
Technical Regulations – Clutches 18/12/08
A single-type clutch for all KF engines has been defined by the CIK-FIA, for introduction in 2009. It will be a centrifugal clutch composed of a monolithic rotor with added friction material (except in Super KF) and a bell with standardised internal dimensions. All clutches shall be in direct drive (100% engagement) at 5,000 rpm maximum under all circumstances. A miniaturised data logging system allowing the control of clutch functioning is currently under development.
The following are the amended technical regulations of Article 18 (valid from 01/01/09):
* Mandatory homologated centrifugal dry Clutch according to Technical Drawings No. 15 & 16. with clutch weights, and with starting ring attached to half crankshaft unit (or flywheel):
- external diameter of the clutch weights : 80 mm minimum.
- minimum weight (complete clutch with starter ring and engine sprocket) according to the engine Homologation Form.
* The engine clutch must be triggered at 3,000 5,000 rpm maximum and make the kart with the Driver on board move forward; it must be in direct drive (and 100% engaged) at 5,000 6,500 rpm maximum under all circumstances.
NOTE 2:
Article 18, General Regulations for KF4 (as it is in force until 31/12/08)
* Mandatory homologated centrifugal dry clutch with clutch weights, and with starting ring attached to half crankshaft unit (or flywheel):
- External diameter of the clutch weights: 80 mm mini¬mum.
- Minimum weight (complete clutch with starter ring and engine sprocket) according to the engine Homologation Form.
* The engine clutch must be triggered at 5,000 rpm maximum and make the kart with the Driver on board move forward; it must be in direct drive (and 100% triggered) at 6,500 rpm maximum under all circums¬tances.
* An efficient protection (made of aluminum or plastic) covering the centrifugal clutch but leaving free access to the chain or belt must be fitted
NOTE 3:
26 - Control of KF engine clutches by means of a data logging system carried on board karts and sup¬plied by the CIK-FIA
a. This system must be used during the Events, exclusi¬vely for the storing of the data logged. This system must be installed in strict accordance with the mounting ins¬tructions given by the CIK-FIA and must work at all times during practice, heats and races.
b. On decision of the Stewards, the Scrutineers can have a data logging system installed on karts.
All competitors are responsible for the installation, in the “Start” Servicing Park, of the data logging system distributed by the CIK-FIA and they must make it function correctly.
Competitors who have not been supplied with a con¬trol system will be handed a lead ballast with a weight equivalent to that of the data logging system, and they shall mount it on the chassis (according to the mounting instructions given by the CIK-FIA).
It is the Competitors’ responsibility to ensure that the slip of the clutch does not exceed the maximum authorised threshold (direct drive clutch, 100%, at 6,500 rpm maxi¬mum, under all circumstances).
c. At the end of each practice session, heat and/or race, the karts must be available for checking by the Scrutineers in the “Finish” Servicing Park so that they can collect and check the data logging systems, and export the data concerned.
d. This data logging system checks as a minimum:
- The engine speed;
- The speed of the rear wheels.
e. With this data logging system it is possible to analyse as a minimum:
- The engine speed;
- The speed of the rear wheels;
- The ratio between these 2 data.
Once a Scrutineer has exported the data in the “Finish” Servicing Park, he will analyse the data and check that the functioning of the clutch complies with the regulations. Should it be ascertained that the clutch spins beyond the maximum authorised threshold, the Scrutineer will draw up a report for the attention of the Technical Delegate and of the Stewards.
f. The costs connected with the repairing of a data logging system damaged by a Competitor shall be completely borne by the latter.
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