Hi All,
I'm currently working on the seats in my Cobra. This has been a fun exercise trying to work out the ideal seating position for me.
I'm a bit of a funny shape with a long torso. In most Cobras I seem to be looking at the top of the windscreen frame from the drivers seat. The plan was to get myself as far down as possible in the car. There are a couple of factors working against me and the main one being the ADR requirement for adjustable seat rails.
I couldn't find any seats for the Cobra that I really liked. Price or style or shape/support put me off most of them. What I wanted out of the seats for my car was the lateral support given by a fiberglass race seat but with the clean looks of a low back with a seperate head rest. I didn't want to spend a fortune so it looks like I'll have to make or modify something.
I picked up a pair of new fiberglass race seats on ebay complete with the adjustable mounting rails. I got them for a bargain price of about $160 each shipped which I thought was cheap enough that if I bollox up modifying them it won't break the bank.
First thing to do was sort out mounting the rails. Back when I had the body off I made a couple of modds to the chassis to make life easier for someone working by them selves on the car. One of the mods was to drill out the threaded mounting for the inner front seat mounts and drill right through the chassis cross member. I then welded in a crush tube so I could bolt right through the rail. This might not make sense at first but it will later.
Here's a pic of the welded in crush tube. You will also notice the boss welded on for the battery strap to bolt to.
Later with the body on and bolted down you can see the core mat in the floor that gives it it's strength without adding too much weight. Normally the seat rails are just bolted down straight through the floor and onto the chassis. The floor with it's core mat is very strong and resists bending but it can be easily crushed by bolting through it. I decided to drill the holes through the floor out to 22mm with an arbour I made tha uses the hole in the chassis as a guide. I then machined up some bushes that limit how far the bolt can be tightened down. They clamp the floor to the chassis but not so tightly that the core mat gets crushed.
I also machined them with a 3mm lip that raises the rail slightly off the floor. This is to help keep the rail clear of the carpet (when it's finally fitted) and also to clear the edge of the door lock post there it's bonded to the floor. The rail was hitting on the edge of it and not running all the way back.
Here are two of the bushes fitted and the rail ready to bolt down. The long bolt at the front is the one that goes right through the cross member.
Now the reason for putting the crush tube in will be clearer after looking at this pic. I used hex bolts and their heads are locked in and can't rotate because of the channel in the rail where they run through. This lets me spin the nut on from underneath without needing anyone to hold the head of the bolt from inside the car. It also lets me unbolt the whole seat and remove it by just undoing 4 nuts from under the car and without dismantling the seat. Having the seat as low as possible means no clearance to get your hand underneath it.
One of the things I like about the fiberglass seats is that there is only 25mm of foam and 5mm of fiberglass keeping your bum off the floor. This is about as low down as I can sit with the adjustable rails in place.
The fiberglass seat stripped of it's covering got some attention from the jigsaw and was rapidly turned into a low back seat. All that remains to do now is bend up a tubuar top rail to add some strenght in the back and support the head rest mounting. This will get fiberglassed in and the whole thing will probably get another couple of layers of mat inside it to stiffen it up. Then they are off to the trimmer to get some red leather wrapped around them.
The seating position is good with plenty of leg room. The seats really support you but are surprisingly comfortable even with just the foam squabs dropped in. They should provide heaps of support for track days. I reckon the only way you would feel more secure and supported is if you lined them with velcro and wore fury pants. Those of a more hairy persuasion could probably wear no pants.
Cheers