Customer Question: What FIA Bucket Seats Are 6 Point Compatible?
Customer question
One of the questions we hear most is whether FIA bucket seats work with a 6 point harness. For the FIA seats we sell, the answer is usually yes: they have slots for the shoulder straps, the lap straps and a slot in the base for the crotch straps. But it is worth being precise, because the FIA 8855-1999 seat standard is tested with a harness of at least 4 points and does not itself require a crotch strap slot.
So the right move is to check the seat you are buying. This guide explains what makes a seat 6 point compatible, where the slots are on steel framed and fibreglass FIA seats, and why the crotch slot is often hidden under a cushion.
- A 6 point harness needs two shoulder slots, two lap slots and a base slot for the crotch straps
- FIA 8855-1999 seats are tested with a harness of at least 4 points
- Most FIA seats we sell have a crotch strap slot, and each listing shows its harness compatibility
- On many fibreglass seats the crotch slot sits under a removable leg cushion
- Some steel framed seats leave the base slot open and easy to see
What makes a seat 6 point compatible?
A 6 point harness has two shoulder straps, two lap straps and two crotch straps. To use one properly the seat needs a guide for each:
- Two shoulder slots at the top of the seat, taking the shoulder straps over your shoulders and back to their mounting points.
- Two lap slots low down on each side of the base, so the lap belt runs across your hips at the right angle.
- One base slot in the centre of the cushion for the crotch straps, wide enough for both to pass through side by side.
Each strap having its own route keeps the belts aligned so they do not slip or bunch under load, and that is what lets the harness spread the forces across your body as it was designed to. The slots are part of the seat’s shell, not just cut into the padding.
What the FIA standard says
The FIA 8855-1999 standard, which most FIA seats on sale are homologated to, is tested with the seat’s occupant held by an FIA homologated harness of at least 4 points. It does not require a crotch strap slot. In practice most FIA seats we sell do have one, but you should not assume it: check the harness compatibility on the listing, or ask us.
Our guide to FIA 8855-1999 and FIA 8855-2021 seats covers the two standards, and your championship’s regulations and your scrutineer are the final word on what your seat and harness need.
A common surprise in the showroom is that the crotch slot is not always visible. The shoulder and lap slots are easy to see, but on many seats, especially fibreglass ones, the base slot sits under a removable leg or knee cushion. People often only spot it once we lift the cushion and show them how the belts feed through.
Other seats, mostly steel framed ones, leave the base slot open as a square cut out. That makes the route obvious but loses a little of the upholstered look. Neither is better; it is a design choice. When you try seats with us, we will lift the cushions and show you the slots so you know exactly how your harness will go in.
Steel framed FIA seats
Steel framed FIA seats are a popular entry point: heavier than fibreglass, but strong and good value. Their simpler construction usually makes the slots easy to find.
Many have a square opening in the base for the crotch straps. The Cobra Monaco Pro is a good example, with a visible cut out that makes the harness route obvious, which first time racers find reassuring.
Not every steel framed seat leaves it open. On the OMP TRS-E the base slot sits under a velcro secured knee cushion, so it looks as though there is no slot at all. Lift the cushion, feed the straps through, and press it back down.
Fibreglass FIA seats
Fibreglass FIA seats are the step up: stiffer shells, less weight and better shaping, and the usual choice for serious track day and competition drivers. The lap and shoulder slots are always visible, but the base slot is usually under the cushions.
Many Mirco seats have split leg cushions, which you can move apart to route the crotch straps without squashing the padding. OMP and Sparco tend to use a larger one piece cushion held with velcro, lifted to thread the straps and pressed back down.
The Corbeau fibreglass seats we have seen do it differently, with a slit in the upholstery over the base slot so the straps pass straight through without removing any padding.
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Why not use a 6 point harness on a seat without the slots?
Not every bucket seat is made for motorsport. Non FIA seats can look similar, but may lack the structure and slot layout for a 6 point harness, and sport recliners and classic style seats do not have crotch strap slots at all. A seat may have fewer slots, forcing straps to share an opening, no base slot, or slots in the wrong place so the belts pull at the wrong angle.
The crotch straps stop you sliding forward under the lap belt, known as submarining. Routed over the front of the cushion instead of through a slot, they cannot do that job properly and can ride up where your body is not built to take the load. If you want to run a 6 point harness, choose a seat whose listing says it is 6 point compatible. Our guide to 4 point versus 6 point harnesses explains the choice.
6 point harnesses to go with your seat
Once you have the seat, you need a harness to match. We list FIA homologated 6 point belts from TRS, which are widely used in rally and track cars, from Schroth, with their high end adjusters, and from Sparco. Garreth’s advice is to buy the seat and harness together, so we can check the slots, the strap widths and your mounting points in one go.
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Are all FIA bucket seats 6 point compatible?
Not automatically. FIA 8855-1999 seats are tested with a harness of at least 4 points, so check the seat’s harness compatibility before you buy.
Do most FIA seats have a crotch strap slot?
Most FIA seats we sell do, often hidden under a removable leg or knee cushion.
Where is the crotch strap slot on a fibreglass seat?
Usually in the centre of the base, under the leg cushions. Lift or part the cushions to find it.
Can I use a 6 point harness on a sport recliner?
No. Recliners do not have crotch strap slots, so a 6 point harness cannot be routed correctly.
What does a 6 point seat need?
Two shoulder slots, two lap slots and one base slot wide enough for both crotch straps.
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