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Seat Bolt Patterns Explained: Every Brand We Sell, Measured And Mapped
The fitment map, hole centre to hole centre
One customer put it better than we ever have: there are literally a hundred plus different bolt pattern variations on the market, even from the same brand. Another was told by a seat seller that their seats have a standard bolt pattern. There is no standard bolt pattern. That single false sentence is behind most of the seats in this country sitting in garages waiting for brackets that do not exist.
So this page is the map. Every pattern across the brands we sell, drawn to scale, with the compatibility calls we make on the phone every day: what interchanges, what never will, and where the clever money goes when the holes refuse to line up.
- There is no standard bolt pattern: base mount seats bolt down on brand patterns that mostly do not interchange
- Sparco and OMP base mount seats share one pattern, 345mm x 271mm, and swap onto each other’s frames
- Corbeau seats are drilled for both big patterns, so they fit the Sparco, OMP and Cobra worlds
- Recaro runs its own 405mm x 290mm pattern: Recaro frames take Recaro only, but OMP frames carry the Recaro holes too
- Side mount seats have no bolt pattern at all: slots and brackets bridge brands, which is the escape route when holes refuse to line up
The one sentence that saves you money
Base mount seats bolt down through four holes in the shell, and those holes sit where the brand put them. Side mount seats bolt through slots in the sides, and slots forgive. So every fitment question splits in two at the first fork: bolting DOWN means the pattern must match, bolting through the SIDES means brackets can bridge. Our base mount or side mount guide covers choosing between them; this page is for the holes themselves.
The four patterns that decide everything
The four patterns that decide almost every base mount question we get, drawn to the same scale. Lay one over another and the holes miss: that is the whole story of the seat that would not bolt in.
Nearly every base mount conversation on our phone lands on one of these four. Sparco and OMP built their seats to the same 345mm x 271mm centres, which their own listings are strangely shy about, and it means a Sparco frame takes an OMP seat and the reverse without drama. Corbeau went one better and drilled their shells for BOTH big patterns, their own 291mm x 330mm world and the Sparco figure, which makes a Corbeau the most forgiving base mount seat you can buy. Cobra fixed backs share that 291mm x 330mm drilling. Recaro sits alone on 405mm x 290mm, on purpose, and their reclining stablemates at Cobra run a wider 405mm x 330mm on their tailored frames.
The full compatibility table
| Base mount seat | Sparco frame | OMP frame | Cobra frame | Recaro frame |
|---|---|---|---|---|
| Sparco (345 x 271) | Yes | Yes | No | No |
| OMP (345 x 271) | Yes | Yes | No | No |
| Corbeau (drilled both) | Yes | Yes | Yes | No |
| Cobra (291 x 330) | No | No | Yes | No |
| Recaro (405 x 290) | No | Yes | No | Yes |
| BRIDE | No | No | No | No |
| Auto Style (345 x 280) | Ring us | Ring us | No | No |
Base mount seats onto base mount frames, hole for hole. BRIDE seats go on BRIDE rails matched by rail type. The Auto Style pattern sits 9mm from the Sparco figure, and whether a given frame’s slots absorb that is a per-frame answer, so it is a Ring us and not a Yes. Cobra’s tailored frames are designed around a named seat, so treat the Cobra column as the starting point and confirm the pairing.
Why the OMP column is the widestOMP frames carry two patterns in their plates, their own 345mm x 271mm and the Recaro 405mm x 290mm. That makes an OMP frame the one piece of steel in this table that takes Sparco, OMP, Corbeau and Recaro base mount seats. When a car changes seats more often than frames, that is worth knowing before the first order.
Recaro: the deliberate lock
Recaro is the second most asked-about brand in our inbox, and half those emails are people discovering their existing brackets will not carry over. The 405mm x 290mm pattern means a Recaro frame takes a Recaro seat and nothing else, and a Recaro seat drops onto exactly two things we sell: a Recaro frame, or an OMP frame with its second set of holes. Budget accordingly when a Recaro is the plan, and read our Recaro Porsche mounting post and Pole Position 993 guide for two worked examples.
Cobra: designed sets, runner included
Cobra do fitment differently: each tailored frame is built around a named seat, so the frame, side mounts and seat arrive as a designed set, and the sliding runner comes INCLUDED in the price, which no other brand on this page does. It changes the maths: a Cobra frame at a higher headline price is often the cheaper complete answer once the other maker’s separate runner is added. The flip side of a designed set is that what is true of one Cobra frame is not automatically true of another, so give us the exact seat and the exact car and we will confirm the pairing off Cobra’s data.
The BRIDE and Auto Style corner
The rest of the map from our own catalogue data: BRIDE rails carry their pattern per rail type, so the rail listing names the type and the car does the rest, and the Auto Style recliners run their own two patterns. The 345 x 280 one is the trap: it sounds like the Sparco figure and it is 9mm away from it.
Side mounts: the world without patterns
Turn a seat on its side and the tyranny of the four holes ends. Side mount seats carry slots, brackets carry more slots, and between them almost any pairing can be made to line up, which is why none of the side mount seats in our catalogue carries a bolt pattern at all. The number that does matter is the fore and aft spacing of the seat’s slots: Sparco fixed backs run 4 x M8 fixings at 290mm centres, straight from Sparco’s own dimension guide, and our Sparco long side mounts fit anything with that 290mm spacing. For everything else the universal multi point brackets below carry rows of slots on the upright face, and they are the part we reach for when a customer’s holes refuse to cooperate. Garreth’s shortcut for the whole page: if the base pattern fight is lost, side mount the seat and the fight is over.
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Runners, and what the millimetres mean
One last number trips people at the finish line. Sliding runners are sized by their HANDLE WIDTH, matched to the width of the seat or frame they sit under, and every runner gives the same travel; no version slides further back. Here is what fits what, width by width:
| Handle width | Who makes it | What it fits |
|---|---|---|
| 290mm and 291mm | Corbeau (Retro and Sportline) and Cobra | Their retro and classic seats, and any frame carrying the 291mm x 330mm pattern. The one millimetre between 290 and 291 is nothing: same family, fits fine |
| 320mm and 370mm | Corbeau (Motorsport STD and L) | Corbeau motorsport seats, handle matched to the seat width |
| 345mm | Sparco and OMP | Base mount seats onto the 345mm x 271mm frames, which is the Sparco and OMP frame world |
| 405mm | Corbeau (Motorsport XL), Cobra Premium and Recaro | The 405mm frames. Recaro’s double locking runner works with OMP frames and Recaro frames |
Runner widths against the pattern families. The three big widths are the widths of the pattern families above, which is the whole system clicking into place. Our runners guide covers fitting detail, and Cobra frames arrive with a runner already in the box.
Every runner we sell as a single listing is below. Two of them carry a handle width choice on the product page, the Corbeau in four widths and the Cobra Premium in 291mm and 405mm, so pick the width from the table above before adding to basket. The genuine Recaro double locking runners are stocked as a two seat set. The Tillett sets are made for Tillett seats.
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How to measure before you buy
Hole CENTRE to hole centre, never edge to edge, width across the seat first and fore and aft second. On a seat, turn it over and run the tape between the threaded inserts. On a frame or brackets already in the car, measure the holes you can see and tell us the car while you are at it. Then check your figures against the diagrams above: a match within a millimetre or two is a pattern, 9mm out is a different pattern wearing a disguise. Send Cameron the two numbers and a photo and the answer usually takes one reply.
Common questions
Is there a standard seat bolt pattern?
No. That claim has cost our customers real money. Base mount patterns are brand families: Sparco and OMP share one, Corbeau drills for two, Cobra and Recaro and BRIDE and Auto Style each run their own. Measure centres and check the table above before believing any listing that says standard.
Will a seat from a brand you do not sell fit your frames?
Measure its base holes centre to centre and compare against the four patterns in the first diagram. Match one and the matching frames fit. Match nothing and the side mount route with universal multi point brackets is almost always the answer.
My holes are a few millimetres out. Can I just drill or slot it?
Not something we will advise on a safety part, and with seats there is no need: the right brackets or the side mount route solve a mismatch without touching the shell. Ring us with the two measurements before reaching for tools.
Do Cobra frames take Sparco seats?
Not as a bolt-on: Cobra frames carry 291mm x 330mm and Sparco bases are 345mm x 271mm. A Corbeau fits both worlds because it is drilled for both. This is the single most common mismatch in our inbox.
Which frame takes the most seats?
An OMP frame. Its plates carry OMP’s own pattern, which Sparco and Corbeau share, plus the Recaro pattern. Four brands, one frame.
Which BRIDE rail do I need?
BRIDE rails are picked by rail type and car together, and the rail type sets which BRIDE seat family it takes. The spacings in the diagram identify a rail you already own; for a new order tell us the seat and the car and we will name the rail.
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The next stepTwo measurements and the car, that is all we need
Measure your holes centre to centre, width first, and ring 0115 647 8650 with the car. Cameron matches patterns all day and has yet to meet a seat that cannot be mounted one way or the other. If you are still choosing the seat, even better: tell us the car first and the holes will never be your problem at all.
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