To be able to confirm the position of the hole in the firewall for the gear shifter cables, I first needed to have the seats in place and then decide upon the final position of the (cabin) gear lever. So the seats had to be installed.
The requirements in the national Vehicle Standards Bulletin (VSB 5B) for Australia states that the seat frame should be constructed from 25mm x 25mm x 2mm RHS (square tube) - I used this a basis to work from a decided to utilise a beefier 32mm x 4mm flat bar for the mounts. The standards do specifically state that where the mounts are affixed to an un-reinforced section of the floor pan, each attachment point must be reinforced by the use of a plate of not less than 50mm x 50mm x 3mm thick. Sliding seat mounts must also have a minimum of two bolts per side, of 8mm diameter. The VSB standard does not state the type of bolts to use, however the CAMS motorsport Schedule C.8 states that a minimum of high tensile grade "8.8" bolts are to be used.
So after some sketching of a few designs, I came up with seat mounts are certainly over-engineered, but it's my safety that is at stake in an accident. The design called for the use of (per seat) 4x M10 bolts (also grade 8.8) to mount the Swift seats to the brackets, 4x M8 bolts to mount the rear section of the brackets through the (reinforced) floor pan and 5x M8 bolts to mount the front section of the bracket to the rear side of the cross member. During an accident situation with this design, a large percentage of the foward force would be directed into the bulk of the cross member giving it more strength rather than using just four M8 bolts through the floor pan (although the four single bolts is still a valid design that would adhere to the appropriate safety standards). Like I said - over-engineered.
I previously purchased a pair of seats from a 2nd Gen (~2007) Suzuki Swift from a local guy who buys damaged and insurance wrecks, strips them down and rallies them. With only 30,000km on these seats, they were in very good condition and their width indicated they should fit in a Mini... snugly.
The first step was to put the whole seats in the Mini and determine the best position for them. This was a combination of the right height, foward and lateral positions. One must for me was the ability to use the sliding mechanism in it's full range. When I installed some custom seats in my previous Mini, the seat would hit the rear map pockets when pushed back, and being 185cm I could certainly have used a little more leg room. This requirement meant the seats had to be pushed inward to stop them fouling against the rear pockets, which actually has the benefit of better lining the driver up with the slightly offset steering wheel.
The height of the seats was positioned to allow the sliding mechanism to move over the top of the cross member if for some reason a short person drove the car and had to move the seat forward.
The sliding mechanism of the seats were first removed and a I welded a quick frame to hold them in place (and square).
Using the 32mmx 4mm flat bar I created either side of the frame (with some solid gussets) then welded a brace to hold the two pieces together. The following couple of photos are for the drivers seat.
The outside half (next to the door)
The inside half which has the pieces angled to clear the exhaust tunnel. Note that on the long top piece there are 2 holes for the bolts with M10 nuts welded underneath, and a further hole that have been slightly countersunk for a locating pin that the seats have.
Because the seats have been positioned inward more to avoid fouling against the rear pockets, the seats actually just touch other, almost giving the illusion of a bench seat. My wife and both sat in the seats as below and being so close wasn't an issue for rubbing shoulders and the handbrake lever was still easily accessible (albeit slightly awkward to reach down to).
The front section of the seat mounts are bolted to the rear of the cross member and I used M8 Rivnuts (aka Rivet Nut, Nutsert) for this. I first had to fill a couple of the factory holes in the cross member as they were where the rivnets would go. Watching some episodes of American Hotrod on Foxtel a few months ago gave me the nice idea of tacking a piece of wire to the fill piece to hold it in place so it doesn't fall through the panel.
The 5 rivnuts in place
As for the rear section of the mounts, the VSB 5B standard requires that the centre line of the bolts need to be aligned with the top or bottom of any corrugation and be complemented with a shaped backing plate underneath. Unfortunately I forgot about this when I was making the mounts and ended up with the holes NOT aligned. Instead of remaking the entire mounts again, I intend to cut out part of the corrugated sections where the bolts will go through the floor pan and replace it with some flat sheet. This will have the advantage in which the nut that will be welded underneath will not sit lower than the rest of the floorpan. Details will be forthcoming in "Seat Mounts Part 2" when I hopefully get time to do it next weekend.
The requirements in the national Vehicle Standards Bulletin (VSB 5B) for Australia states that the seat frame should be constructed from 25mm x 25mm x 2mm RHS (square tube) - I used this a basis to work from a decided to utilise a beefier 32mm x 4mm flat bar for the mounts. The standards do specifically state that where the mounts are affixed to an un-reinforced section of the floor pan, each attachment point must be reinforced by the use of a plate of not less than 50mm x 50mm x 3mm thick. Sliding seat mounts must also have a minimum of two bolts per side, of 8mm diameter. The VSB standard does not state the type of bolts to use, however the CAMS motorsport Schedule C.8 states that a minimum of high tensile grade "8.8" bolts are to be used.
So after some sketching of a few designs, I came up with seat mounts are certainly over-engineered, but it's my safety that is at stake in an accident. The design called for the use of (per seat) 4x M10 bolts (also grade 8.8) to mount the Swift seats to the brackets, 4x M8 bolts to mount the rear section of the brackets through the (reinforced) floor pan and 5x M8 bolts to mount the front section of the bracket to the rear side of the cross member. During an accident situation with this design, a large percentage of the foward force would be directed into the bulk of the cross member giving it more strength rather than using just four M8 bolts through the floor pan (although the four single bolts is still a valid design that would adhere to the appropriate safety standards). Like I said - over-engineered.
I previously purchased a pair of seats from a 2nd Gen (~2007) Suzuki Swift from a local guy who buys damaged and insurance wrecks, strips them down and rallies them. With only 30,000km on these seats, they were in very good condition and their width indicated they should fit in a Mini... snugly.
The first step was to put the whole seats in the Mini and determine the best position for them. This was a combination of the right height, foward and lateral positions. One must for me was the ability to use the sliding mechanism in it's full range. When I installed some custom seats in my previous Mini, the seat would hit the rear map pockets when pushed back, and being 185cm I could certainly have used a little more leg room. This requirement meant the seats had to be pushed inward to stop them fouling against the rear pockets, which actually has the benefit of better lining the driver up with the slightly offset steering wheel.
The height of the seats was positioned to allow the sliding mechanism to move over the top of the cross member if for some reason a short person drove the car and had to move the seat forward.
The sliding mechanism of the seats were first removed and a I welded a quick frame to hold them in place (and square).
Using the 32mmx 4mm flat bar I created either side of the frame (with some solid gussets) then welded a brace to hold the two pieces together. The following couple of photos are for the drivers seat.
The outside half (next to the door)
The inside half which has the pieces angled to clear the exhaust tunnel. Note that on the long top piece there are 2 holes for the bolts with M10 nuts welded underneath, and a further hole that have been slightly countersunk for a locating pin that the seats have.
Because the seats have been positioned inward more to avoid fouling against the rear pockets, the seats actually just touch other, almost giving the illusion of a bench seat. My wife and both sat in the seats as below and being so close wasn't an issue for rubbing shoulders and the handbrake lever was still easily accessible (albeit slightly awkward to reach down to).
The front section of the seat mounts are bolted to the rear of the cross member and I used M8 Rivnuts (aka Rivet Nut, Nutsert) for this. I first had to fill a couple of the factory holes in the cross member as they were where the rivnets would go. Watching some episodes of American Hotrod on Foxtel a few months ago gave me the nice idea of tacking a piece of wire to the fill piece to hold it in place so it doesn't fall through the panel.
The 5 rivnuts in place
As for the rear section of the mounts, the VSB 5B standard requires that the centre line of the bolts need to be aligned with the top or bottom of any corrugation and be complemented with a shaped backing plate underneath. Unfortunately I forgot about this when I was making the mounts and ended up with the holes NOT aligned. Instead of remaking the entire mounts again, I intend to cut out part of the corrugated sections where the bolts will go through the floor pan and replace it with some flat sheet. This will have the advantage in which the nut that will be welded underneath will not sit lower than the rest of the floorpan. Details will be forthcoming in "Seat Mounts Part 2" when I hopefully get time to do it next weekend.
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