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Mk3 Spitfire Seat Runner Help


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I need some advice regarding my late Mk3 Spit seat runners.......

I've taken the seats out ready to do some prep work on the floor pan before fitting the sound proofing and then the new carpets.

When I removed the seats I could see one of the previous billion owners had created some form metal frame on the bottom of the seat runners, it seems so that the seat runners can be attached to the floor.

You'll see from the picture there are two sets of circles, red and yellow.The yellow circles are the bolts from the actual seat runners but these havent been used to attach the seat to the floor pan as they dont match up with the holes in the floor.

The locations of the red circles are the positions where the holes in the floor pan are and this is why i'm assuming the previous owners have had to make up the frame to be able to attach them to the car.


The advice I'm asking is.....are there varying sizes of seat runner for a late mk3 ?




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Hi Peter.

That frame is something one of the previous owners have bolted in place so they can attach the usual frame to the floor pan.

Basically the holes on the runners on the normal mk3 frame dont match up with the holes in the floor. Hence why i'm asking if seat runners are made in different sizes because the holes in my floor pan dont match what would be the standard bolt locations (shown by the yellow circles).


I wonder if because it was a really late mk3 that it had different seat runners originally?

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Nope, all mk3 seats were the same. And I am assuming that the later seats used the same holes in the floor. (Based on the fact replacement floors now come with the holes predrilled and the nuts welded underneath, though that was not always the case)

Are there the original nuts welded to the underside of the floorpan? 

That metal frame is just builders metal strapping....I would be very inclined to dump it and then re-drill the floor if necessary. It also means you won't have the frame fitted off the floor by those bolt heads. But do use thick washers between the floor and frame when fitting, it makes allowance for the carpets and stops the seat runners bending up in the middle. Seat fixing bolts were 1/4UNF

I also wonder if somebody has fitted alternative seats at some point, drilled the floor for those, and when the original seats were refitted made this frame. OR fit the oroginal fllor holes/nuts fracture as is common, and so the holes were moved? Who knows....

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Hi Clive,

Thanks for your feedback and advice.

I didn't see any nuts welded to the underside of the floor pan but if I'm honest I wasn't looking for any and the underside is cover in sealer. I'll take a proper look at the weekend incase they're hiding.

Thank you also for the heads up regarding the washers/carpets, duly noted and I'll make sure that happens.



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It all depends on what floorpan you have; are they original or where they ever replaced?

Most floorpans available these days are a one-size-fits-all, usually designed for late Spitfires, and so earlier seats which are narrower won't line up with the mounting holes.

When I had the floorpans in my early GT6 replaced, only two of the holes lined up, and I had to ignore the captive nuts on one side and drill new holes for the original seat runners.

As the guys have posted already, that's a non-adjustable frame that someone has made themselves and so they've had to adapt the fittings. You should be able to obtain original runners and attach the seats as originally fitted, if you want to.

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I was just going to say more or less what  Colin has said. The new floors I fitted to my Mk3 have captive nuts on about 13" centres, where as the runners are 11,3/4" (don't quote me on these measurements - I've just taken them with a tape measure under the car). I used the inner holes and drilled new outers and used nuts and washers.

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Nothing gets past you guys. I think the original runners are in place, just bolted through that strapping.

I would guess the floor pan has been replaced at some point and as Colin says, the holes seem wider apart than I would need.

Busy day at work but I'll strip that frame off tonight and see if the runners ARE there then take them to the car at the weekend. Im guessing there shall be some drilling and welding to do.


Thanks again, I'll update you all later

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Yes, they are there, you can see the adjuster lever.

No real need for welding, but I do suggest fitting good sized spreader plates (very large, thick washers?). Maybe tack nuts to them, then fit and tack to the floor if you wish. Does make seat fitting easier if the nuts are fixed.

The unused fittings could just pop a bolt with the head removed in there. Or a bit of sealant. 

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All sorted. I used the 2 holes that were already drilled closest to the gearbox tunnel on both the driver and passengers side then drilled 2 new holes for the rails near the doors. I also used 3 penny washers under each runner to lift the rail off the floor.

Grommeted and sealed the unused old holes and all's well. Now time to find myself some sound proofing before putting the carpet in.


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