Seat Position

Hey guys, got some questions on seat position.

Can standard measurements work across the board on different chassis/manufacturers to get the seat in the right spot?

What is the correct approach to installing a seat in order to get the kart to scale the way you want front/rear and side/side. It’s almost impossible to do this without having a starting point that is very close. Doing it while on scales from scratch would be incredibly difficult and time consuming and you’d probably end up with a seat full of a million drilled holes as you shift it and add weights to different points.

I am going to be going to a new chassis and installing a new seat so I want to know the correct approach to take.



The answer to your first inquiry is no. There isn’t one seat position that works for all drivers, chassis, etc.

However, many chassis manufacturers have “seat numbers” that they include in diagrams or user guides. Tonykart, Arrow, and CRG have nice user guides when it comes to this, and I am sure other manufacturers do as well.

A good place to start would be to measure your seat position in your current kart with reference to where measurements are made on the new chassis (for example, from the front roll hoop to the “hips” on the seat, etc.). Then, I would consult with your local chassis dealer or any qualified chassis representative.

Many chassis may have similar numbers, but likely different tuners and dealers have different values they prefer.

Ultimately, like many things in karting, the answers you may get can vary. The more reference points you get, the better you may be able to determine where your seat likely needs to be.

What chassis will you be changing to?

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Hi, it’s a birel ry30-s5. I actually have the birel seat placement chart for the chassis but it only gives measurements from the top of seat to the front hoop. I wanted to know where to install it left right, so maybe distances from top of seat to each kinpin, but they chart doesn’t mention that

Valid question. Mounting left to right can vary significantly from chassis to chassis and sometimes is Constrained by the chassis itself and the seat support uprights.

Would suggest measuring current kart and contacting MRP for corresponding measurement recommendations!

How much lead do you have to put on?

Roughly 30lbs or so of lead.

Put the seat where it’s most comfortable for you. With that much lead you can move weight around to get whatever numbers you want.

You don’t have to drill the seat and mount the weight to it. Just sit the lead on the frame when you’re on the scales, the numbers will be the same…

This topic and article by @DavinRS is worth looking at too:

Let's talk about Seat Position

Thanks guys.

What about if my seat is smaller that the width of the two main frame rails on the chassis.

What is the correct thing to do here? Should I smack one of the two frame arms to bring it in and get closer to the seat ? And if so which one? Brake side or engine side? Or should I fill the gap with washers?

Fill the gap with spacers vs washers if you can. You can bend the brackets, but if you can avoid that, it’s a good thing.

Thanks a lot for that james.

See attached my seat placement chart from Birel, but it only gives info for front rear placement. How do I know where to put it left right? Screenshot_20180912-224522

Unless you have scales, just center it between the bracket and don’t worry too much about it now. If you have access to scales, then over course get the left and right sides as close to equal as you can get them.

Don’t go all fancy trying to offset your weights for dominant corners, just put it in the center for now.

If you can, get a piece of 1-1.5" nylon/plastic round bar, you can cut to fit in the spaces and drill it . If it’s over 1/2", I personally do not like to use washers. I fill it with a solid piece that doesn’t have the ability to move around as much. Same for under front of seat.

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Thanks guys.

James I actually am gonna scale it but I wanted to know what the correct approach was to mounting the seat and scaling. From what you guys are saying it seems mount the seat as per the recommendations on the chart then put the kart on the scales with fuel etc and then distribute my lead to get the percentages I want?
I want to avoid drilling a bunch of holes in my new seat though this was my biggest concern