Kart seat positioning
Kart seat positioning is a difficult but important job. The driver is half the weight of the vehicle and if
their weight is out of position the kart will be unbalanced and difficult to set up. Many manufacturers
will give you a set of dimensions, which can be confusing unless you are using the exact shape and sizeof the seat that was used to get their positional information in the first place. Therefore, to get thecorrect balance in the chassis, it is important to understand where the drivers back is in relation to therear axle. These instructions are to help with attaining the most common position for the average
70kg driver. Sometimes a compromise position will have to be used for smaller or larger drivers.
To accurately fit a kart seat, place a flat sheet of plywood, or something similar, on your kart stand,then space the chassis tubes from the wood to give you the correct ground clearance.
(For ultimate accuracy use the Tillett T Board TRACK fitting jig. Please see below for information.)
5mm is usually the maximum dimension that you can set the base of the seat below the tubes with amodern chassis. If you do not have this low point information, set your kart up on a very flat piece ofground with the correct tyre pressures. Take a note of the distance the seat protrudes below thechassis tubes when you have around 15mm clearance between the floor and the seat base. Next place
the seat back on the chassis sitting on the wooden board or the T Board track fitting jig. Held like this
it is stable and easy to hold in the ideal position. (Tip: A weight placed inside the seat will help keep itstable and upright.) As most seats have a flat on the bottom it is usually best to use the set angle
provided by this.
Using both the height of the seat flat and the important “axle to drivers back” dimension shown inthe diagram below, you can put any seat in any kart and the driver will always be exactly in the same
position in relation to the rear axle. The current average seating position for a 70kg 1.80m tall driveris 15 cm, whereas with a KZ chassis the dimension would be further back at 13.5cm. A shorter juniorwould use around 18cm.

50 mm Axle

Measure gap to one sideof the spine depression

Use a weight at the front of
the flat bottom to stabilise
the seat while measuringMeasure this gap

The seat should protrude below thetubes no more than 5mm maximum

Average seating position
15 cm single gear adult 13.5cm KZ, both with 50mm axles
16cm Cadet/Minikart 25mm axle

Be aware that historic karts always needed the seat set further away from the axle. Pre-2005 chassis
with a 40mm diameter axle used around a 21.5cm gap and karts aged from 2005 to 2009 with a
50mm axle approximately 18 cm. If the kart has a 30 or 40mm axle you will need to compensate forthis by changing the gap dimension accordingly.
Please note that bolting a substantial amount of lead weight to the back of the seat can make adifference to the seat position. It forces you to position the seat further forward to achieve the samebalance.
With the seat in position, check that all seat stays are parallel to the composite. If the flat metal tabs
are set at a different angle, bend them with a large adjustable spanner until they exactly match theangle of the composite. They do not have to be bent to be close to the composite and the gap can befilled with nylon or aluminium spacers without a performance penalty. However, do not use rubber
spacers, not only will this allow uncontrolled flexing which will break the edges, but the bolt will beeffectively loose, acting like a saw, moving in and out as the seat twists, cutting a slot and allowing
the seat to drop.
To mark the holes, place a blob of paint on the end of a long bolt and pass it through the four main
stays spotting all four holes without moving the seat. If there is a gap between the seat and the stay,pass the bolt through the tab at 90° to the seat stay. Drill all four holes accurately and when fitting
the bolts use the correct number of spacers to keep the composite from being twisted out of its
naturally moulded shape. Make sure to maintain the seat in the desired position, then tighten thebolts until very tight. If you use a flexible VG or Vti seat in an adult kart without any extra seat stays
only using the four main chassis stays. On the main two upper stays it is advised to pop rivet
aluminium support plates against the composite.

The seat is then in place and you can then fit any extra seat stays and lead weight required. Weightbolted on the sides and under the front between the legs should be slightly spaced away from theseat with nylon washers. This helps the seat flex around the rigid lead and stops breakages. Also
bend the lead in an arc under the front, this is done so as not to pull the composite out of its
naturally moulded shape. If water pipes and data cables are to be fitted, make sure that any hole
drilled for a cable tie is more than 5mm away from the edge. Holes drilled too close to the edge cancause a crack.

Keep the head of the extra seat stay bolts away from the top edge of the seat. Fasteners that are
fitted too near the upper edge will bruise the ribs or point load a hard shell rib protector. Try and use
low profile washers up around the rib area if possible. This will not only help the ribs but also stops
any hard rib protectors from damaging the race suit. The countersunk washer from the lead boltsshould also be kept away from the contact points where the hip and leg bones touch the seat.
When you are fully satisfied with the performance of the kart, record the position of your correctly
fitted seat. Keep the “seat to axle surface” gap and the seats lowest point dimension. For a specificdriver setup, it also helps to keep a measurement from the centre of the Tillett badge to the top of
the steering wheel and one from the front toes of the seat to the pedals. Finally, make a note of thesize, shape and rigidity that you have used. To prepare the seat for wet weather, drill two holes forwater drainage at the lowest point of the seat.
Your seat is then ready for use on the track.

T Board Track
The T Board TRACK has been designed to speed up the accurate fitting of a kart seat whilst at thecircuit.
Totally adaptable on any chassis.
Drops quickly into place without lifting the chassis.
Adapts to cope with obstructions like battery boxes and fuel pipes.
Converts to suit 28, 30 and 32mm chassis diameters.
Can be flipped upside down to suit engines on the left.
Fitting a kart seat is one of the most time consuming jobs for a mechanic, but it is also one of themost important elements of setup to get right. This is because the driver is around half the overall
weight of the vehicle. Therefore, their position within the chassis needs to be fully understood andcorrect every time. The lap times are likely to increase if the seat is set just 5mm out.
Understanding the optimum position is made even more difficult when you consider the manydifferent seat shapes, sizes and driver seating preferences.
The T Board TRACK uses a lightweight but rigid carbon plate and four magnetic height setting bar
assemblies. These assemblies hold the plate in a precise location which sets the low point of theseat. The jig can then be easily dropped onto the chassis in seconds. The seat is then placed on
the board and by using the magnetic carbon slide rule, you can measure and hold it accurately at
a set distance from the axle, all future seats are then easy to fit in exactly the same place every
time.