Help Needed - Fitting a race seat

[slimzimma]

Sorry mods not sure where to put this...

Currently helping a friend turn his E39 528 into a track car. When it came to installing the race seat the supposedly 'universal' subframe was too small to span the gap between the seat rail points.

I'm looking for some advice on where I could get a subframe that would fit as I've had a look about but cant seem to find anywhere so any help would be great!

[Matt UK]

When it comes to race seats, you may find it easier and cheaper to get a good metal shop to fabricate something for you, rather than looking around for something off the shelf that 'fits' perfectly.

[300bhp/ton]

Matt UK said:

When it comes to race seats, you may find it easier and cheaper to get a good metal shop to fabricate something for you, rather than looking around for something off the shelf that 'fits' perfectly.

Either fab up some brackets to use the existing seat mounting points, or you'll have to fab up some new mounting points (proper safe plated ones) to suit the race seat.

[andye30m3]

In my 205 we welded 2 bars between the cill and the transmission tunnel and then used the standard side mounting brackets to to bolt the seat through the bars

Edited by andye30m3 on Wednesday 12th January 10:56

[RobM77]

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

[Matt_N]

andye30m3 said:

In my 205 we welded 2 bars between the cill and the transmission tunnel and then used the standard side mounting brackets to to bolt the seat through the bars

Same as my Colt.

[RobM77]

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

[The Wookie]

RobM77 said:

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

ETA - Think of a rearward impact to understand why seat mounting strength is extremely important

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

You'll need to weld bosses into a saloon car. Caterhams are a bit different, and that's basically the reason why you should always fill the void behind a tillet with expanding foam, so that if (when) the seat breaks off in a crash, the seat doesn't fall back and make the belts useless.

Edited by The Wookie on Wednesday 12th January 11:31

[RobM77]

doogz said:

RobM77 said:

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

I commented because i've fitted seat rails to a couple of tin top race cars, and the floorpans under the original seat rails are very flexible, they're not designed to have a load applied there.

I find it hard to believe the seat in a Caterham isn't fixed in some way. You might be harnessed in, but what's to stop the seat moving around under lateral G?

The problem isn't so much the bending of the plate tbf, in the case you're specifying, it's the fatigue, the bolt will, over a not very long period of time, elongate the hole in the 2mm plate, or whatever it's bolted through, and work it's way loose. Again, seen it happen in a Fiesta.

Seat rails in a racing car are extremely unusual. Most have fixed seats. Seat Rails can be done within the regs though I think (check the Blue Book).

Two part foam (or vacuum bead bag) seats are used in Caterhams, Radicals and all single seaters (up to and including F1, although they use carbon now it's the same principle). They are not fixed to the car in any way. They rely on a combination of being a snug fit in the cockpit and the fact that the driver is strapped in tight to stay in place.

Regarding the "washer" plates, I've never seen holes elongated in them, ever. They are 5mm steel!

Edited by RobM77 on Wednesday 12th January 11:37

[RobM77]

The Wookie said:

RobM77 said:

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

ETA - Think of a rearward impact to understand why seat mounting strength is extremely important

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

You'll need to weld bosses into a saloon car. Caterhams are a bit different, and that's basically the reason why you should always fill the void behind a tillet with expanding foam, so that if (when) the seat breaks off in a crash, the seat doesn't fall back and make the belts useless.

Edited by The Wookie on Wednesday 12th January 11:31

Tillets are unusual in Caterham race cars though. In RSA we had about 30 to 40 cars and only a handful had tillets. Caterham Midlands recommend expanded foam seats because the contact with the body is snugger, and therefore distributes force better in a crash.

[The Wookie]

RobM77 said:

The Wookie said:

RobM77 said:

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

ETA - Think of a rearward impact to understand why seat mounting strength is extremely important

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

You'll need to weld bosses into a saloon car. Caterhams are a bit different, and that's basically the reason why you should always fill the void behind a tillet with expanding foam, so that if (when) the seat breaks off in a crash, the seat doesn't fall back and make the belts useless.

Edited by The Wookie on Wednesday 12th January 11:31

Tillets are unusual in Caterham race cars though. In RSA we had about 30 to 40 cars and only a handful had tillets. Caterham Midlands recommend expanded foam seats because the contact with the body is snugger, and therefore distributes force better in a crash.

Yes, I know I had a foam seat (couldn't get my arse into a tillet), the point is that in a rearward crash your weight is being taken up by the rear bulkhead, either directly with expanding foam or via the tillet. In a tillet without foam, in a rearward crash the seat will almost always break off the mounts. Also, in a side on impact your weight is taken up by the sides of the car and the tunnel

In a saloon car, you don't have that rear bulkhead or side panels to hold you in, so in a backwards or side on crash the seat mounts will be taking all your weight.

[RobM77]

doogz said:

RobM77 said:

doogz said:

RobM77 said:

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

I commented because i've fitted seat rails to a couple of tin top race cars, and the floorpans under the original seat rails are very flexible, they're not designed to have a load applied there.

I find it hard to believe the seat in a Caterham isn't fixed in some way. You might be harnessed in, but what's to stop the seat moving around under lateral G?

The problem isn't so much the bending of the plate tbf, in the case you're specifying, it's the fatigue, the bolt will, over a not very long period of time, elongate the hole in the 2mm plate, or whatever it's bolted through, and work it's way loose. Again, seen it happen in a Fiesta.

Seat rails in a racing car are extremely unusual. Most have fixed seats. Seat Rails can be done within the regs though I think (check the Blue Book).

Two part foam (or vacuum bead bag) seats are used in Caterhams, Radicals and all single seaters (up to and including F1, although they use carbon now it's the same principle). They are not fixed to the car in any way. They rely on a combination of being a snug fit in the cockpit and the fact that the driver is strapped in tight to stay in place.

Regarding the "washer" plates, I've never seen holes elongated in them, ever. They are 5mm steel!

Edited by RobM77 on Wednesday 12th January 11:37

When i say rails, i don't mean adjustable runner type things, the seat is rigidly fixed. I mean 2 sections of steel, fitted transversely across the floor between the sill and tunnel, onto which sidemounts are bolted.

So are these "washer plates" welded to the floor then? Not quite the same as the seat just being bolted through the floor.

Just as I described above... I'm not saying this is a good idea, and I race single seaters anyway so I've no need to champion it, but the vast majority of racing saloons that I've seen have the seat bolted straight through the floor, with a plate either side of a specified thickness acting as a sort of washer. A friend of mine has got welded bars on the floor of his racing Metro like Wookie mentions above, but I think he's in a minority, at least in club racing.

[RobM77]

doogz said:

RobM77 said:

doogz said:

RobM77 said:

doogz said:

RobM77 said:

doogz said:

RobM77 said:

Most racing saloons and sports cars that I've seen have their seats bolted straight down through the floor. I've never seen one that re-uses existing seating mounting points.

You sure about that? Floorpans are a bit thin and bendy to mount a seat on.

You'd think so, yes! Bear in mind the driver is strapped to the car though, not the seat. In the single seater I race (and the Caterham I used to race) the seat isn't actually fixed to the car at all. Saloon race seats are of course heavier than the two part foam seats single seaters use, but still a very low percentage of a driver's mass.

I may be wrong, but from memory that's how saloon and sports car seats are done, with a plate of a minimum specified width, depth and thickness either side of the floorpan to distribute the load.

Most saloons have two rails in the floorpan to mount the standard seat runners on, and these are way too high for a racing seat, so the brackets supplied with a racing seat are usually intended to fit around these, rather than on them.

There must be some tin top racers on here who could confirm or deny this?

I commented because i've fitted seat rails to a couple of tin top race cars, and the floorpans under the original seat rails are very flexible, they're not designed to have a load applied there.

I find it hard to believe the seat in a Caterham isn't fixed in some way. You might be harnessed in, but what's to stop the seat moving around under lateral G?

The problem isn't so much the bending of the plate tbf, in the case you're specifying, it's the fatigue, the bolt will, over a not very long period of time, elongate the hole in the 2mm plate, or whatever it's bolted through, and work it's way loose. Again, seen it happen in a Fiesta.

Seat rails in a racing car are extremely unusual. Most have fixed seats. Seat Rails can be done within the regs though I think (check the Blue Book).

Two part foam (or vacuum bead bag) seats are used in Caterhams, Radicals and all single seaters (up to and including F1, although they use carbon now it's the same principle). They are not fixed to the car in any way. They rely on a combination of being a snug fit in the cockpit and the fact that the driver is strapped in tight to stay in place.

Regarding the "washer" plates, I've never seen holes elongated in them, ever. They are 5mm steel!

Edited by RobM77 on Wednesday 12th January 11:37

When i say rails, i don't mean adjustable runner type things, the seat is rigidly fixed. I mean 2 sections of steel, fitted transversely across the floor between the sill and tunnel, onto which sidemounts are bolted.

So are these "washer plates" welded to the floor then? Not quite the same as the seat just being bolted through the floor.

Just as I described above... I'm not saying this is a good idea, and I race single seaters anyway so I've no need to champion it, but the vast majority of racing saloons that I've seen have the seat bolted straight through the floor, with a plate either side of a specified thickness acting as a sort of washer. A friend of mine has got welded bars on the floor of his racing Metro like Wookie mentions above, but I think he's in a minority, at least in club racing.

I'm not saying you're wrong, i'm interested.

But are these pads welded to the floor then? I asked, but you haven't answered?

I'm sure they'll be done the way they are for a reason, but to me, it makes sense to keep the mounting points off the floor. Trip through the gravel and you scud a rock, say, that could detach the seat from the car.

And has been said, you might be held in the with the harness, but if the seat moves backwards, that's not much use.

I've seen plenty cars at hillclimbs and club racing, as well as at national level (MINI's again) that have the set-up that i (and Wookie) mentioned, and tbh i don't think i've ever seen a seat bolted through a floorpan, even with welded pads. They might stop the bolt moving locally in the floor, but there's nothing really to stop the entire floor moving globally, since they're usually made from tin foil (joke, before anyone gets uppity)

As I said initially, I'll have to check this with saloon racing friends of mine, but my memory is of the seats bolted through the floor with these plates acting like large washers. No, the plates are not welded to the floor.

[mat205125]

300bhp/ton said:

Matt UK said:

When it comes to race seats, you may find it easier and cheaper to get a good metal shop to fabricate something for you, rather than looking around for something off the shelf that 'fits' perfectly.

Either fab up some brackets to use the existing seat mounting points, or you'll have to fab up some new mounting points (proper safe plated ones) to suit the race seat.

The term "universal" with these kinds of subframes should be taken to mean "Gives you a bit of a head start, however will still need some fabrication / trimming / drilling to fit in different cars", rather than mean "a 10 minute nut and bolt job to put in"

[drmotorsport]

In my Fiesta's i've always had welded bars running from the sill to exhaust tunnel and then had standard sidemounts for the seat either welded or bolted to the bars. This seems to be normal practice elsewhere around the paddock. Also as most floorpans are not flat it makes sense to create a level base for the seat to mount too.

[slimzimma]

Thanks for the help all should be able to sort it now!