Written By: Grahame Butterworth
With the ink now drying on the technical regulations for next year it’s a good time to go through them and highlight some small but significant changes which will come into effect on January 1.
We’ve already flagged up the change to the wet tyres which are being replaced with a new ‘green’ spec tyre incorporating totally new construction which testing shows will give more grip yet still have great life. Let’s shed a little more light on them.
Aside from having a totally new look to the tread pattern, their design and construction are quite different as is their diameter. Both front and rear tyres increase in circumference by 6.5cm, that’s 85cm at the front and 91.75cm at the rear. They weigh per set 0.5 kilos more than the old ones.
That extra size is very deliberate. It helps the tyres to better cut through deep water. And at the same time and with no need for you to get a spanner out, it raises the ride height of the kart – a vital factor in gaining grip.
In terms of gearing there is always a good discussion point around what to do. Do you leave it the same to have a softer throttle response and less wheel spin or increase the number of teeth on the rear axle sprocket?
Most people add about three teeth to make sure the engine is on the best power band. I’d suggest the situation will remain pretty much the same because almost certainly the kart is going to be quicker around and coming out of corners. But of course testing will tell. They will be available late November/early December so order yours now because they will be in high demand!
Next comes full confirmation of an issue which cropped up during this year and that is the use of special rear axle bearing mounts and flanges which enable small changes to the kart wheelbase as well as to the rear ride-height.
Effectively what they do is to allow the bearing mount bolts to be moved by small amounts and hence to allow more variation in settings. So for example you can go higher and shorter for the wet or a tight track, and then maybe longer and lower for a fast open track.
But don’t get fooled into thinking that they will make a massive difference because they won’t. But they might just add that fraction of time top drivers crave. Note you must make sure in making the adjustments that you don’t make the wheelbase outside the MSA rules of 101cm to 127cm. Most TKM karts are around 104cm to 106cm.
While we are on the chassis let’s also just touch upon something that has become the most frequently asked question on older karts – the TKM sequential plate and side bars.
The rule is simple, TKM homologated karts only are permitted to use modified old style sidebars to allow fitment of the latest CIK approved side pods. But in order to do this the kart must still have in place its TKM sequential plate mounted adjacent to the brake side rear axle mount.
And let’s further underline the fact that this dispensation does not apply to any other karts. So you must have a TKM homologated kart with sequential plate to take advantage of the rule.
Next to the engine, and here there are some changes aimed specifically at helping you drivers remain legal and with everything in good tight condition.
First comes a change to the rule regarding the fin rubbers introduced some years ago to help reduce noise. They do a very good job in keeping at bay complaints over noise – but they can seem a bind if one falls out in a race and you get excluded.
The new rule allows for one individual rubber falling out during a race or qualifying, and that will be penalty free so long as the missing rubber is replaced by the next race. A real bonus to those who get accidentally caught on this one.
While we are on the subject of these fin rubbers remember that where you have an engine with fins maybe broken you are allowed to cut off the rubbers in a block that are hanging free. And to make sure your other rubbers don’t come out make sure the fins are clean and free from oil when you put them in and use some adhesive like super glue to secure them firmly.
Next to checking the inlet and exhaust port settings. These are critical to maximising performance but also easy to get tripped up on and receive an exclusion.
New from Tal-Ko is a special feeler gauge, part number: TFG025. This has been specially manufactured to make checking and setting much easier. It is available from Tal-Ko for just £3.00 + vat and should be the only feeler gauge used by all scrutineers and engine builders doing technical checks in future to ensure consistency.
Finally another common-sense move – this time concerning worn or stripped threads. As we all know threads that are constantly in use can become worn and with time to the point where they are stripped and ineffective. For a very long time the use of Helicoils to repair them has been permitted.
A new system similar, but different, in the way in which it repairs threads has now come on the market and appears effective and so this has also been added to the list of approved items. Called Time-Sert, the repairs are authorised on all threads excepting that for the spark plug which must remain a Helicoil.