Haynes Roadster Seats

The Knock-On or Butterfly Effect

How could the seats possibly effect the length of the front suspension push-rods?

I had been a little lazy or even over confident. I had used somebody else’s CAD model of a bare bones racing seat for my dimensions. Part of my argument was that if I couldn’t find a seat that fitted, I’d either cut some up or make them from scratch.

The problem was that a couple inches of seat padding could be the difference between your knees being around your ears or nice and comfortable out in front. Moving the pedals and/or the steering wheel would cure this, but this is quicker to say than to do.

Much of my time in the garage is actually spent staring, or randomly clamping things to the chassis, mocking stuff up, until either until I get hungry or in this weather my toes turn blue.

If I were to fit seats with extra padding what would happen?

The available room for the pedals decreases.
This would have the following effects:

  • The position of the brake master cylinder will change causing it to foul the engine.
  • The route of the exhaust manifold will change causing it to foul either the starter motor, engine mounts or front 4×4 prop-shaft.
  • The pedals might change from bottom hinged to top hinged

The steering wheel would move two inches forward
This would have the following effects:

  • The steering shaft to the front wheel moves closer to the engine limiting lateral engine movement
  • The angle of the shaft would change causing it to foul the exhaust manifold
  • A steering UJ mount would move cause it to foul the horizontal coil-over shocks
    This would cause:

    • The position of the front cantilever to move forward slightly
      This would cause:

      • The length of the front suspension push rod will shorten

If the steering wheel moves two inches forward should the side profile of the car be changed, making access still possible when the roof is in place? This would mean a new scuttle. Would the scuttle be big enough for that Austin Mini heater sitting on the shelf or would one of those modern micro-heaters be needed?

I could go on and on……………….. But hopefully you get my point

Action was needed

I bought a complete interior from a 2000 Saab 9-5 for £20 on fleabay. I found that if I searched for ‘leather seat’ there were dozens of results as you’d expect, but they often went for nearly brand new money. However, when I changed that search to ‘leather interior’ the list was smaller but the prices were a fraction of the cost of a single seat. I’m not a great fan of leather seats, they always seem a little hard or slow to warm up, but for an open top car, they might be a more water resistant option.

One front seat has some stretched stitching but everything else is in very good condition. Sure, they were an 80 mile round trip away, but the £4+ in loose change that has fallen out of them so far goes some way to cover it. Luckily there is an upholsterer at the other end of our road and with the leather from the rear seats and side panels I have plenty spare and it’s already colour matched. I reckon 30 minutes of saddle soap and these seats are going to be perfect.

This chassis is 4 wider than an original super 7 but one of the major differences for me, was I put as much triangulation into the central tunnel as I possibly could.

Apart from the obvious strength advantages this extra triangulation this gives, the extra chassis width combined with the smaller tunnel gives me about 5 inches of extra width per side between the top of the tunnel and the side of the car.

Haynes Roadster Gearbox Tunnel

The seats I chose were 21.5 inches at the widest point so I doubt if they will win prices for being small. Once the metal work and levers for height, tilt and fore/aft movement was removed they lost about ¾ inch. More importantly for me, the sides became slightly flexible. With these modifications done, they slipped smoothly into the spaces with only minimal compression. That compression actually gives the seats a little more lateral support.

Haynes Roadster Locost Seats

The central console (top of gearbox tunnel) and the gap between seats will be filled with a sculptured leather panel that visually joins the two seats together. Two more panels will be made to mould the seats into the sides of the car to complete the moulded look.

The Good New?

It turns out there were several pieces of good news. Luckily, the ‘butterfly effect’ has minimal impact.

  • The CAD model of driver I had used was 6ft tall and both me and the missus are under 5ft 7″.
  • The Saab seats actually compressed to fill the gap, meaning that they could actually sit nearly 2″ further back than the solid CAD models.
  • My Ford Sierra steering column is adjustable. With the steering wheel fully forward, access for both of us is ‘plenty’.

All of the steering and brake components can stay exactly as per my drawings. However, should something unplanned crop up, I know I have a little unexpected free-play to shuffle things around.

Locost Leather Seats

The seats are a little unconventional looking for a Locost or Haynes Roadster, but they grow on you quickly. Being quite short, my head stops short of the top of the seat back, so I could remove the headrests, but for now they will stay. Having sat in them with a brew, thawing out my fingers, I am very glad I went for seats from a ‘luxury’ class car rather than a ‘sports’ car. I think I will really be grateful when I go over the first pothole. Having replaced nearly half of the suspension joints with rose joints and those low profile 255/35/19 tyres, any extra padding is going to be very welcome indeed.

With the seats in place, I can now continue with several jobs that had previously hit dead ends.