Category Archives: Karting Technical Tips

Technical karting articles written by experts, coving engines, chassis, braking, tuning and more

Tech Tuesday: Winter and a balance of Brakes

Brake products can be very expensive, especially if you’re buying genuine branded products. Motorsport can be expensive and budgeting can be right in winter season. It might be worthwhile for you to investigate and switch things up then, improving the brake inefficiencies to try and find ‘the pace’ Good braking techniques can help you win races, you don’t have to have the fastest machine out braking your fellow competitors.

In the cold and wintery conditions, metal takes longer reacting to heat, by logic having a soft or a medium pad compound will react quicker to friction upon the disc, reaching operating temperature easier than a hard brake material..

Also, look at the weight of the brake disk and its performance as a lighter disc will react to friction from the pad material which in turn raise the temperature far quicker than a heavy brake disc, in a similar way that a hard pad material will require more time to react to friction / heat than a softer compound. The Combination of pad material and disk compositions for your best performance so choose intelligently. If in doubt about what components to use you can always ask the brake manufacturer or their agents / distributors.

Written by Dr Vic Eacott – Director of Motorsport Development

Tech Tuesday – Top 5 Rib Protectors under £120

Ribs are pretty important, inside that cage of bone is all of your important organs and damage to your ribs can not only be very painful, but it can put you out of action for months while they heal up. Not good at all. So to stop this happening you’re going to need to buy a rib protector, these vary in price but also vary in styles and features. Here are five good ones for you to consider that won’t break the bank.

alpinestars

Alpinestars Bionic rib support

Alpinestars Bionic rib support

It may not have the smoothest name but this mid-range rib protector from Alpinestars is packed with ergonomic features to optimise driver safety and comfort. The Rib panels themselves are made up from 3mm dual density padding with a polymer shell to dissipate energy away from an impact. It is also fully adjustable in the form of the front and shoulder straps as well as velcrow adjusters in the back for a comfortable and secure fit.

£114.95

kevlar-sparco

Sparco Kevlar rib Protector

Sparco Kevlar rib Protector

This Sparco rib protector has rigid sides made from a Kevlar composite for strength and lightness; this combined with the padded inner lining makes this rib protector very strong. It also has adjustable shoulder straps and a large velcrow front strap for comfort and a secure fit.

£86.36

ribtec

Tillett Ribtec rib protector

Tillett Ribtec rib protector

The design of the Ribtec is a simple one, but it’s very effective, the hard shell distributes pressure across the body while the soft inner lining absorbs impact. It has holes for efficient ventilation and one large strap at the front for adjustment. Accessories are available in the form of shoulder straps for extra comfort.

£86.40

omp_kk047e

OMP Carbon Rib Waistcoat

OMP Carbon Rib Waistcoat

This carbon rib protector from OMP has been redesigned to allow the maximum driver mobility whilst maintaining a high level of protection. All closures are buckle-less for safety and the tough carbon outer shell is very light and the padded lining is very comfortable, all this makes for a very un restricting rib protector.

£99.00

sparcospk7

Sparco SPK-7 Rib Protector

Sparco SPK-7 Rib Protector

Sparco have improved the design of the previous rib protector and this time it includes protection to the chest in the form of breast plate on top of the protection to the ribs shoulders and back. The padded inner provides protection and comfort while the adjustable straps make sure the protector stays securely in place.

£119.94

This article was published in Karting magazine in September 2015 and was written by Michael Killingworth

Like this article? Then read more Tech Tuesday here:

Tech Tuesday – Top 5 Setup Tools

Tech Tuesday – 7 things to check on your kart

Tech Tuesday: Wet Chassis Set-Up

CARLO_V3

Leaning to the outside while negotiating a bend helps increase the grip of the outside tyres

Some drivers love racing in the wet, others hate it. But it is also true that liking or disliking the wet depends a lot on what performance one has in these track conditions. Kart set-up is extremely important in wet weather and driving itself changes completely. Wet conditions set-up The main critical aspect of wet conditions is the extremely low grip of all four tyres. This leads to understeer entering bends and oversteer exiting them, with really low traction. Also braking becomes extremely difficult with frequent locking of the rear wheels. To help reduce all these effects, which persist even when rain tyres are fitted, we must really work on kart chassis set-up. First of all we must balance the chassis to give maximum front grip and maximum rear grip! A narrow rear end increases rear grip as does a wide front end for front grip. The front end can be be made really wide by fitting long front hubs. Now work on the front angles. Caster should be increased to the maximum so it gives incidence to the front tyres when entering a bend and reduces understeer. Camber should be set to zero with the driver sat in the kart. Finally, some toe-out gives some advantage. Sometimes, especially with not very tall drivers, it is important to lift the seat to raise the centre of gravity.

Edgar's Hyundri Super One MSA Series, MSA, KF2, PFI, RSF, Ben Barnicoat, ART.

Love it or Loathe it, At some point it’s going to rain, the right set up makes the world of difference.

This creates a greater momentum when running along a bend which helps increase grip on the outside tyres. Of course if you have to add weight to reach the minimum weight limit then add it as high as possible on the kart seat. Seat stays should be loosened to give more flexibility to the chassis and a stiff rear axle fitted. This last solution though, in my opinion, gives little advantage, since the speed and grip of the chassis are so low in wet track conditions that the forces acting on the chassis are also reduced. This means that the chassis flexes very little and the rear axle may not flex at all. As in dry track conditions, tyres are very important. Pressures should be much higher than for slicks on a dry track since in the latter conditions the tyres heat up much more. Be careful though that, when using rain tyres, all the tyre print is touching the ground and not just the centre section. You can check that after your first run. If you only run on the centre then the tyres won’t last as long and grip will of course be reduced. How to drive in wet track conditions As we have already started to see, in wet track conditions one important thing is to put a lot of load on the outside tyres, front and rear. This can be done by even eliminating some load from the inside tyres. So when driving in wet conditions the position of the driver’s body is extremely important. To give as much grip as possible always lean towards the side where you want to increase the grip. So when running along a bend lean to the outside.

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Go on slicks they said…

An even more sophisticated movement of the body is to lean to the outside and towards the front when entering the bend and then lean backwards towards the outer rear tyre when exiting the bend. This will help reduce understeer entering the bend and also reduce the oversteer exiting it. Another important factor to consider is that in wet conditions it is much better to brake earlier and concentrate on the exit of the bend. Locking the wheels when braking can make you lose control, time and spin. Also, in general, never accelerate with the front wheels turned. Accelerate only when the front tyres are straight and parallel to rear tyres, or almost so. The most important thing though is to drive the kart on completely different lines from those used when track is dry. When the rubber laid down on on the track becomes wet it becomes extremely slippery so it is much better to find grip on wet but clean tarmac. The best line to follow is to run the bend all the way round the outside where rubber has not been deposited. In some bends another possibility is to go out wide when entering the bend and then to cut in to the inside. Finally, to help comfort and concentration, it is a good idea to buy a wet suit to keep your body dry and warm. All these points are just a start, you must gain experience of driving in these conditions and fine tune your kart’s set-up to optimise performance.

 

Like this article? Then read more Tech Tuesday here:

Tech Tuesday – Terry Fullerton’s 7 ways to improve Karting

Tech Tuesday – Axles

Tech Tuesday: Kart Aerodynamics

An aspect often not estimated is the aerodynamic factor acting on a kart chassis and its driver. Since a tenth of a second is vital for a kart driver to win, we must consider that on particularly fast tracks and even more for fast 125 cc shifter gear chassis high speeds generate an important resistance of air on the kart. This is determined by the laws of physics that show how resistance to penetration in air is proportional to speed if such speed is minor to 100 km/m, but changes to a proportion to the square of speed for values over 100 km/h. Many kart chassis constructors are in fact now projecting front and side plastic bumpers also looking at good aerodynamic penetration.

DD4_8032

No, not that kind of areodynamics…

Aerodynamics on chassis

A kart with its driver has a very bad CX factor, which is the coefficient of aerodynamic penetration. This aspect, even though front area of kart and driver is limited, is determined by the total absence of front cover to driver and kart and by the turbulence that is generated behind the driver who represents nearly 45% of the front area of the entire system. So, for a start, a more compact position or maybe having the driver slightly lied down can give significant improvement to aerodynamic penetration and so also to performance.

Lateral bumpers

Side protections already give good effect since they cover rear tyres reducing turbulence and increasing penetration. So when widening rear carriage see if tyres are still sufficiently covered. Some companies like Tecno have studied both side and front bumpers to optimize fresh air flow towards the radiator obtaining better engine cooling.

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The OTK M6 Bodywork was designed with areodynamics in mind due it its slippery profile

Front bumper

It has the function of course of  protecting from front collisions with other drivers or obstacles, but has also a good aerodynamic effect. First of all to work well the spoiler must be kept as low as possible to reduce turbulence of the air passing under the chassis. Such turbulence in fact would slow down the passing air which would “stick” to the chassis reducing its speed.

The air moving over the front bumper makes it work like a spoiler pushing it down and increasing front grip. Over 100 km/h such vertical force can be equal to 4 kg, but really under such speed the effect is limited, and becomes secondary respect to aerodynamic penetration.

Working in such way on the front bumper gives only positive effects: better aerodynamic penetration and small increase in front grip.

Base protection

Base protection is used to position the driver’s feet and to protect him from eventual stones coming from the track. The three surfaces of the front spoiler, the base protection and the inferior surface of the seat make a continuous surface. They must for this reason be on the same level so that any edge is avoided and air flow is free to pass smoothly under the kart. Some technicians say that a ground effect can be obtained on fast tracks curving slightly the base protection, but such work seems to be too complicated compared to the result.

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The ‘Big Nosed’ Prokarts have a large Nassau panel to divert air away from the drivers’ un-areodynamic legs

The driver

The driver has really, as already anticipated, a bad aerodynamic penetration. Feet and legs will direct air flow towards the chest of the driver and slow down the kart, or laterally if well positioned. The front number plate help to limit such effect and will have to be as wide as possible to cover the driver and also will have to be well positioned to connect itself to the legs.

The arms of the driver will have to be positioned well in contact with the body only moving the forearm to turn the steering wheel. This will also help a better aerodynamic penetration. An additional effect is that this position will send air flow towards the engine or radiator helping engine cooling.

Finally it is clear that small drivers (once more) are helped on an aerodynamic point of view. I have myself seen on the Parma track in Italy tall drivers loosing much of their advantage on the three long straights of the track.

Head down, Alfie Brookes tries to gap the field in the Honda Clubman class. - edit

Testing

With shifter gears kart it can be quite simple to see the effect of aerodynamic penetration by reaching a certain speed on a straight and pulling the clutch suddenly. The kart will go on running along and we can measure the speed of the kart (we must have a telemetry system that measures speed with a sensor on front wheels) after a certain number of metres (300 for example). Try this test with different configurations of the kart bumpers and driver positions. Of course testing must be done with exactly the same track conditions (possibly the same day) and no wind. If wind or grip of the track change results will be completely unusable since the effect of these two parameters are similar to the aerodynamic resistance.

Like this article? Then read more Tech Tuesday here:

Tech Tuesday – Honda GX200 vs. Gx160

Tech Tuesday – 7 things to check on your kart

Tech Tuesday: Top 5 Setup Tools

As you probably know, set up is a crucial part to the whole driver/kart package. If it’s out then you can expect to be off the pace. This is why you want the whole job of setting up your kart to be quicker, easier and more convenient. Here are five tools which do just that.

Iztech Chassis Alignment Brackets

These chassis brackets from Iztech are used to check the squareness of your chassis frame when a jig is not available. This is because kart chassis’ are prone to bend after a while due to taking kerbs or being involved in accidents. The brackets are universal fitting and work by hanging them under the kart to check for alignment by hanging axles underneath.

£30

zte_chassis-brackets

R3 Magtronic Laser Alignment system

The R3 lasers fit to the stub axles of your kart using strong magnets to stay in place.  Then, using the spirit level on top make sure that the lasers are level before making any precise toe and castor adjustments. This way you can be sure that all the front geometry set up is accurate to the millimetre.

£246

r3r_mag_laser_align_f

Alto Kart Chain Aligner

Aligning a sprocket properly can be a pain. If it’s out you will just chew up a sprocket and likely lose a chain along the way. But this chain aligner from Alto is a cost effective and easy way to accurately align your chain to minimise wear and increase reliability, it’s also much cheaper than laser variants.

£18

alt_chain_align_tool

Crankshaft locking tool

This tool simply slides onto the engine and locks the crankshaft and clutch assembly on clutched engines in place so that the nut can be undone. These are often a little different depending on the engine you have so it’s best checking beforehand.

£10-20

jag_676205

Castor and rear bumper tool (OTK)

This tool from Alto helps you alter the castor easily on OTK’s multi hole system as well as fitting the OTK rear bumper bolt collar which can save time in changing front end geometry setup and bumper changes should the bolt break or bend.

£20

R3 mag

 

This article was published in Karting magazine in October 2015 and was written by Michael Killingworth

 

Like this article? Then read more Tech Tuesday here:

Tech Tuesday – Seat Basics

Tech Tuesday – 7 things to check on your kart

Tech Tuesday: Weight And Seat Positioning

Even though many parameters determine the grip on each tire, everything is finally led to the vertical force acting on each wheel. The greater such downward force is and the more the grip between the tire and the asphalt.

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Centre of gravity

The centre of gravity is the point of a system (chassis plus engine plus driver) where one can consider all the weight concentrated. Once we define this in a kart, and generally such point is positioned in the stomach of the driver, we can calculate all the forces acting on the kart concentrated in the center of gravity. For example the weight of the kart can be concentrated in the centre of gravity as the sum of all vertical forces when the chassis is not moving (weights multiplied by the gravity acceleration). We will call “a” the longitudinal distance between the centre of gravity and the front carriage, and “b” the distance from the centre of gravity and the rear carriage. So we will be able to say, following the laws of the physical equilibrium, that the vertical forces acting on respectively on the rear tires (Fp) and the front tires (Ff) will be equal to:

Fp = Pvehicle * (a + b)/b,

Ff = Pvehicle * (a + b)/a,

where Pvehicle is the total weight of the kart (chassis, engine and driver) and:

Ff + Fp = Pvehicle.

We are making an approximation considering the weight of the kart a force.

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Leaning can als help you look cooler, not just distribute weight…

Effects of weight distribution variation

So the variation of the position of the seat of the chassis along the longitudinal length of the kart varies the parameters “a” and “b”, which means that also weight distribution of the kart varies between front and rear tires. Generally the longitudinal movement of the seat has a maximum value of around 4-5 cm, but a few centimetres determine great differences in weight distribution. For example the distance between front and rear carriage is generally in karts around 104 cm. With front weight equal to 40% and rear equal to 60% the centre of gravity is 41.6 cm from the rear axle and 61.4 cm from front carriage. If we move the seat 2 cm to the front of the chassis distribution will be 42% on front tires and 58% on rear tires. Such variation of 4% of the weight could appear a small quantity, but can really determine great difference in kart performance. If we move the seat of the chassis towards the front carriage the vertical force on front tires will increase and the force on rear tires will decrease. This will automatically determine an increase of front tire grip and a reduction of rear tire grip. So moving the seat to the front increases oversteer and moving it to the back increases understeer. The variation of the two parameters “a” and “b” will not vary directly shifting the seat. In fact the movement of the seat will determine a movement “c” of the centre of gravity as follows:

c = Pdriver/Pvehicle*x,

where “x” is the movement of the seat.

So it is extremely simple to setup the basic grip on the four wheels just by the right longitudinal positioning of the seat of the chassis. After such positioning the other parameters of the chassis will vary the forces on the four wheels for fine tuning.

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leaning too much can also hinder your driving…

Generally weight distribution must be regulated to have 60% of the weight on the rear tires and 40% on front tires. It is also true that every chassis has its own particular regulations for what concerns weight distribution. Ask your chassis builder or shop for the right values of weight distribution between front and rear tires. Such parameter is really too important to be mistaken. In addition to this we must consider that weight distribution should be equal between right and left tires on the front and on the rear. Because of the engine positioned on the right hand side, the seat will be slightly shifted to the left hand side of the chassis. This is of great importance especially when braking before a curve, since the balance of the chassis will be perfect, and the kart more stable in such phase, only if left and right wheels will have the same grip acting on them and the centre of gravity will be in a central position respect to the wheels.

Also the driver, especially in wet track conditions, can move inside the seat and vary weight distribution. For example moving your body forward when entering a corner helps front grip, and moving the body backwards when exiting a corner helps traction. This, also thanks to lower speed of the kart, has great effect on wet track conditions.

Next issue we will proceed consider weight distribution on the four wheels varying centre of gravity height, which will also determine great effects when running along a curve.

Like this article? Then read more Tech Tuesday here:

Tech Tuesday – How to read your tyres

Tech Tuesday – 10 ways to get the best performance in TKM

Tech Tuesday: Rear axle choice

The Rear axle is one of the main elements to influence chassis setup. The stiffness of the axle determines behaviour of rear part of the chassis, making the kart oversteer or understeer, and changes strongly the balances of forces acting on the chassis.

1As we know in fact kart behaviour along a curve is based on the possibility for the internal tire to lift off the ground since there is not differential system on rear axle. Now a softer axle bends more and quicker than a stiff one. This means that a kart can reduce grip on rear tires, and increase oversteer with a softer rear axle and vice versa with a stiff one. Very simply, but always considering there must be a balance in kart setup between front and rear stiffness, increasing rear axle hardness gives better grip on rear tires, but difficulty in entering curves, because of too high grip on rear tires compared to front tires. The opposite happens having softer axles.

But which are the parameters that vary rear axle stiffness? They are three, material, thickness of tube wall, diameter of the tube. Along the years chassis have shifted from having full tubes of small diameters (25 mm) to having hallow tubes as rear axles with increasing diameters from 30 mm, to 40 mm, and in recent days to 50 mm. What happens is that a tube which bends with an elastic deformation returns to its initial straight form after the kart exits the curve. This return to initial shape can happen with different speed and promptness.  A stiffer axle is quicker in returning to its straight shape, and this determines faster reaction of the kart in having the internal tire back on the ground when exiting the curve. The two rear tires touching the ground give more grip and the possibility to accelerate after the curve. So material of the rear axle determines different setup of the kart. Some materials are surely better then others in their elastic capacity to regain initial straight shape. Much effort is being done by kart constructors to find materials with better elastic characteristics. Thickness of the tube also acts on axle stiffness R with the following formula:

IMG_1563

The material, wall thickness and diameter of an axle all affect set-up

R is proportional to: a * (d22 – d12), where d2 is the Bigger diameter axle gives surely a better look to the chassis. But the practical difference is that for physical reasons, which we will not go deep into, a bigger diameter axle is more reactive than a smaller diameter one. So the shift to larger diameter axles has had the aim of increasing reaction of the chassis exiting curves and giving the possibility of accelerating earlier.

But it is not only stiffness of the axle to act and change setup. We know that rear carriage width also acts on rear tire grip. The wider the carriage, the lower the grip. First of all this is due to the fact that a longer rear axle, and a wider spacing between rear tires, permits greater deformation and bending of rear axle along curves. It is somehow equivalent to having a softer tube. On the other hand another effect is that rear carriage width increase makes the rear tires lift with more difficulty. Rear carriage is flatter on the ground and even though rear grip decreases, eventual sliding of rear tires is smooth and uniform, easily controllable. If we reduce rear carriage width rear axle becomes stiffer, grip increases, but rear carriage is less stable. Internal tire lifts without rear axle bending much. What happens is that external rear tire blocks itself laterally on the ground instead of sliding. But as soon as lateral force is too strong rear external tire suddenly looses grip along the curve, with fast lateral slides of the rear of the kart, which becomes much more nervous and difficult to control. With high drivers this effect is even more evident since centre of gravity is positioned higher and momentum on kart increases. That is why high kart drivers usually tend to have wider rear and front carriages.

Finally now we know which parameters act on rear axle stiffness, amongst these usually the type of material is indicated by a lettering on carved on the axle. Also we know how stiffness acts on kart setup. Finally we also have seen that rear carriage width acts on rear axle flexibility and on general chassis behaviour along a curve.

Like this article? Then read more Tech Tuesday here:

Tech Tuesday – Terry Fullerton’s 7 ways to improve Karting

Tech Tuesday – Best helmets under £350