Mounting a kart seat is often simply looked at as driver comfort. Even the most experienced of drivers can find fitting a new seat a daunting task. This is because it requires a reasonable amount of precision, and it is an important part of the kart for several reasons.
So how do you mount a kart seat? By following these 9 steps, you should have your go-kart’s seat installed within 15 minutes:
- Have your kart stood on a trolley
- Put your seat on the beams
- Measure from the front of the seat to the front carriage
- Mark the spots where you are going to drill
- Drill the holes
- Bolt the seat into the side mounts
- Fasten the bottom part of the seat
- Mark and drill spots for the bottom seat mounts
- Bolt the bottom of your seat into the chassis mounts
However, you should know that there are some very important factors to consider when mounting your kart seat. Your seat plays a much bigger role on your kart than just your comfort. In this article, I will explain why that is, and what options you have to customize it to your driving style.
Why Is Your Kart Seat So Important?
Many drivers set their seat according to their own comfort levels in the kart. However, your kart seat is such a crucial part of your kart’s chassis and overall handling ability. This is because your seat will become the heaviest weight (the driver) on the kart. Therefore, it is the single most influential factor when it comes to the center of gravity affecting your kart.
The seating position has a huge effect on the setup of the kart. Therefore, seating can be used as an effective setup technique when trying to find the right balance for your kart. You are changing how your weight is distributed to each of the four tires.
Having your seat in the correct position will significantly help you. Your kart will be well balanced, and you will be able to feel your adjustments better when it comes to actual chassis set up. Having your seat in the incorrect position could mean that your kart is not responding to your setup changes as you would expect, making it both confusing and frustrating for you.
This means that you might need a completely different setup to your usual to get your kart balanced. From there, every adjustment you make to your chassis will have an unpredictable effect. Many drivers struggle to correct their oversteer or understeer balance by using hundreds of different variables, but often it is simply the seat being out of position.
What Position Should My Kart Seat Be In?
A good place to start is the standard factory setting. These recommended seating positions will be designed to get the weight of the driver in the correct spot on the kart. Of course, everyone has a different weight and height, so you can begin with the base setting and test from there. I will give more details on how you should adjust your seat further into the article.
Another factor to consider is which class of kart you are running. If you have a kart with a lot of power and need more traction and rear grip, you need to increase the weight over the rear tires by moving the seat further back. If you are running a kart with less horsepower, you want to keep your weight distribution more forward to not weigh down the rear tires too much.
However, if you move your distribution too far back over the axle, your kart will not be able to lift the inside rear tire through corners (see the importance of that in our article about rear track width). If a track has more grip, your seat is likely to give you more of an advantage if it is set a bit further forward.
I will be discussing this further in the weight distribution section below.
The angle at which your seat is set has quite a large effect on how the weight of the driver is distributed over the rear axle. Bear in mind that if you have a flat-bottomed seat, mounting it normally will give you the correct angle. Rounded seats take some measuring, and this can be made easier using a measuring tool which sits on the rear axle, this tool is called a T-board.
Typically, the standard angle is around 55 degrees.
Having a higher angle, means that the driver sits more upright in the kart, and more weight is being pushed down onto the tires, giving the kart more side bite. Side bite is a term used by drivers to refer to the amount of grip and traction you have throughout a corner.
Having a lot of side bite means that the rear of your kart has a lot of grip (it feels glued to the track). Having less side bite is having the rear of the kart feel looser (i.e. more oversteer).
If the driver is taller, you want to have less of an angle on the seat to help distribute the weight more heavily over the rear axle. Having a lower angle on your seat will also help you on high grip or high-temperature circuits to give you less side bite and higher speeds. However, most championships have a minimum seat height, so be sure to double-check that.
The height of your seat from the bottom of the frame will also affect your kart’s handling. Many variables determine the levels of grip on each tire; however, the main factor is the vertical force which is acting on each wheel. A greater downward force means more grip between the tire and the track.
Taller and bigger drivers will want the seated mounted slightly lower than the main rails. A safe height is about 5mm below the rails. Going any lower than this will mean your seat scrapes along the ground while driving, especially in fast corners when your chassis flexes a lot.
You can also raise the seat by stacking sprockets under the seat while you are mounting it. This is easy to do and will provide a consistent measurement. This is useful for shorter and lighter drivers who need to get more of their weight down onto the tires. Normally in this case, 2 to 3 sprockets should work, however you can use as many as in necessary.
You may notice on some karts, that the seat is mounted slightly crooked when you look at it from above. The left side of the seat will be slightly further forward when compared to the right side. The difference is typically only about 5 to 10 millimeters.
This is actually not a mistake. Some drivers rotate their seats very slightly to achieve an advantage in their braking. Having their weight shifted slightly more to the left puts more weight on the brakes and can improve braking power.
Many drivers do this, but less experienced drivers overlook this small detail and always mount their seat straight. The resulting advantage may be very small, but if you are fighting for a tenth of a second it may help you gain that.
Quick Setup Guide For Seating Position
When testing these adjustments, making your changes 10mm at a time is usually a good standard. In all cases, doing the opposite will have the reverse effect on your kart:
- Moving your seat further back – more rear grip and traction; more understeer
- Moving your seat further forward – free up the rear axle (make the wheels spin faster when accelerating); more oversteer
- Higher seat – more grip; good for wet or low grip conditions; helps smaller drivers
- Higher angle – more grip; more side bite; good for wet or low grip conditions; helps smaller drivers
Other Factors To Consider:
Size and Shape
These factors are all about driver preference and what is most comfortable to you. Some drivers prefer to have a tight-fitting seat while others prefer to have some space to move around in their seat. The seat should always be able to support you, especially through fast and flowing corners.
A general rule to check the fit of your seat is to be able to fit a finger’s width in between the driver and the seat all the way from the chest down to the hip of the driver. A seat that is too large will throw the driver around in it too much which could result in some bruised ribs.
It also means that you won’t be able to feel what your kart is doing, making setups really difficult. If your seat is too big, a good way to compensate for that is to get seat foam to fill the gap. However, I have found that its best to get a good rib protector to wear under your race suit.
Different seat types are available in terms of stiffness. This could be determined by the material which the seat is built from, and also the thickness of the seat. With the seat being considered as a part of the chassis, the stiffness of the seat affects the overall rigidity of the kart’s chassis.
Soft seats free up the rear of the kart, so these are recommended for high grip circuits and karts with low horsepower. Softer seats will mean that the inside rear will lift quicker and earlier.
Stiffer seats are recommended with high horsepower karts because the inside rear wheel will not lift as early, and will also move back onto the ground and allow you to accelerate out of corners quickly.
At the end of the day, these are variables that depend on the type of the track and the weather conditions. It is all determined by whether you gain more of an advantage in rotation or acceleration.
Generally, the safe option is to go for a medium seat stiffness, as this will give you the most balanced result. However, if you have the time and the budget, it can be worth testing the different types of seats to see which best suits your driving style.
Moving the seat lengthwise (forward and backward) on the chassis is how you distribute the weight on your kart. The total possible movement of the seat is around 4 to 5 centimeters. This may not seem like a large amount of movement; however, small adjustments make a huge difference in your kart’s balance.
Generally, the wheelbase of a kart is around 104cm. With the standard weight distribution (which is 40% front and 60% rear), your center of gravity will measure 41.6cm from the rear axle and 61.4cm from the front carriage.
If the seat is moved 2cm forward, the weight distribution will then be 42% front to 58% rear. This 2% difference in weight distribution may seem small, but it can have a huge effect on the kart’s handling.
This means that the vertical force acting on the tires will be more focused on the front tires, and less on the rear. Therefore, you will have more grip on the front tires and less on the rear, increasing oversteer.
Generally, weight distribution is most balanced at a 40/60 split, and you would not stray far off that; the further you get from that balance point the more unstable the kart will become. When you get towards a 50/50 split (moving more forward), the kart becomes nearly undrivable with the oversteer.
Seat stays are used often by kart racers. These are silver bars that look like your seat mounts. They can be added and removed very easily to increase or decrease the stiffness of your chassis.
One seat stay per side helps to lift weight off the inside rear wheel, whilst at the same time pushing more force down onto the outside rear wheel. Adding more stays will stiffen the chassis more and keep your kart flatter through corners.
You’ll often see karting drivers leaning when cornering. This is especially the case in wet weather conditions. This is a way to change your weight distribution on the fly as needed. If you move your body weight forward in your seat when entering a corner, you will have more front grip, while moving backward when exiting a corner will help your traction.
Similarly, if you push yourself back while braking, you will have slightly more stopping power due to the extra weight being put on the brakes and rear axle. A good way to practice this is to go for a few sessions in an arrive and drive rental kart.
Practice different leaning techniques and see how it affects your lap times and cornering ability. Try pushing yourself back against the steering wheel as you try to brake later and later. The slower the kart, the more effective your leaning will be.
Seat Mounting Steps
Below you will find a 9-step guide for a quick seat installation. This might not be set to your height and weight, or your driving style, but it will give you a basic guide to a standard factory seat set up. If you have a Tillet T-board, this can be useful to make adjustments to the angle of your seat.
Have your kart stood on a trolley. Ensure that you have a base for your seat. When your kart is on the trolley, have two round bars put underneath the kart (even some axles could work).
These are two beams that go straight across the bottom of the kart. These will keep your seat in place and ensure that it does not fall below the chassis while you are mounting the seat. Using two beams will give you a more stable base to work on.
Put your seat on the beams, and ensure that the mounts match against the seat itself. Use a weight to keep the seat in place.
Flat bottomed seats are easy since they sit on the beams and the angle of the seat will be more or less accurate. If it is a rounded seat, you will need to wedge the back of the seat on the axle to ensure the angle stays the same.
Next you want to measure from the front of the seat to the front carriage of the kart using a tape measure. Note, this is the front of the chassis, not the front bumper. Be sure to measure both the left and right sides to ensure your seat is not uneven.
550mm from the front of the kart is generally a good place to start (but always check the manual for your specific kart to be 100% sure). This generally gives the 40/60 balance you are looking for and can be adjusted around 10-15mm as needed by driver preference.
Mark the spots where you are going to drill into the sides of the seat (top half left and right sides). Mark these points using a marker and try to be as accurate as possible. If your seat isn’t fitting close to the side mounts you can use a hammer to bend them into place.
Drill the holes into the seat. If you prefer, you can remove the seat from the chassis to make the process easier.
Put the seat back into the chassis and bolt it into the side mounts. Make sure you use the right lengths of bolts and the right number of washers for your kart’s specifications.
You can now take the beams out from under the kart as the next part is fastening the bottom part of the seat.
This is when you can adjust the angle of your seat as you feel necessary. Make sure the bottom of your seat is parallel to the chassis. If you need it lower, the maximum should be 5mm below the chassis. If it’s is too far below the chassis, it will scrape along the track.
Also ensure that it’s not too far up as this will affect the handling of your kart. Once you’ve found your angle, use plastic spacers under the seat to keep your seat at the right angle.
Use the marker to mark your spots for the bottom seat mounts and drill the holes where you have marked the spots.
Use your spacers from step 7 to set your seat angle back to your preferred setting. Bolt the bottom of your seat into the chassis mounts.
The seat itself is a much more crucial part of the chassis than most drivers think. Most fit the seat to their comfort, when it is, in fact, the other way around. You should make yourself comfortable around the seat’s correct fit. The seat will determine your kart’s handling performance based on its position and characteristics. This is why it is so important to mount a seat properly.
I hope that this article has helped you to understand why correctly mounting your seat is so important, as well as how to correctly mount your seat.