Seat hole positioning
 

Morning.

I'm just about at the point of stripping my chassis and having it powder-coated. All I have left to do is weld in the seat support rail.

But I have no seats :(

Is there a 'universal' hole position for the seats, or do different seats have different hole positions? I don't want to have to damage the lovely paint on my chassis if I do it wrong.

From my experience - you need the seats to know where you will mount them. If you haven't had the seat in position and sat in it (whilst making brum brum noises)- how do you know that the:

Pedals
Steering wheel
Harness mounts
Gear lever
Handbrake

Are in the right place to suit you?

I am using Triton race seats mounted on Rover Metro seat runners. These are mounted to 3x40mm strips welded across the chassis between the outer rails and the TT rails. My holes are located 215mm and 545mm forwards from the front face of BR12.

This arrangement allows my seats to go as far back as the chassis allows and forwards into a 'nose-on-windscreen' driving position. As jps says though you should ideally have the seats if you want to be 100% certain.

Sorry to hi-jack this thread but as it's along the same lines thought I would ask here.
I am fitting my seats using box section is it ok to use rivnuts in the box section or will it be a problem for the I.V.A.
I have got my seats from Robin hood and their seat runners so I have all of the dimensions I need just thought I would check on the suitability

Arfon

Going to depend on the seats. I'm using lotus exige seats with the stock runners. The drivers was on sliders and passenger was fixed. I more or less had to rebuild the passenger seat frame to clear the chassis. So what I'm saying is without the seats your going to be grinding off that powder coat. They were one of the first things I bought since a bunch of other parts depend on them... that and I wanted to be able to sit in the chassis and make vroom sounds. Without them pedal placement, steering wheel placement, and even engine placement is pretty difficult.

One way round this problem of not having the seats is to make the mounting tubes universal, if you stop thinking of every thing being 90' to every thing else then it frees up some options. If you weld the tubes solid around all four sides you can then just drill through and bolt them in later.

That doesn't mean that the holes will line up you get either the front pair or the rear pair but that doesn't mean that the other pair will come in line with your steel work and if it doesn't then you will either be cutting half of what you have already done to move it of adding even more steel and weight.
The only real benefit I can see in that is you are adding triangulation to the floor.
just my humble opinion.

Arfon

If your using seat runners then you can put the bolts through the channels, most of them seem to be around the same sort of length. You don't have to use the holes that are in the seat runners as standard you can drill more holes in them. It's not about getting the holes to hit the middle of the tube at a predetermined point it's about making the build process more flexable.

It's as long as it's broad no real benefits as you have got to drill 6 holes instead of 4 no real logic to it

Arfon

I think box section is usually reinforced with crush tubes - which is why I used 3mm flat bar - just seemed simpler. Plus the whole thing will be supported by the floor anyway - so box seemed like overkill...

Still can't see a decent solution other than getting your seats and mocking it all up. It's the only way to be sure it's right...

I totally agree with you be patient and get your seats and then you know you are right, that is what I did and don't forget measure twice drill once or in my case I think I measured about six times until I was satisfied.

Arfon

Get your seats
fix the runners
Fix flat bar across runners
place in position
tack weld flat bar to chassis shielding seat from spatter(:o so you dont get mini burn holes in your seat :o )
remove seat and runner then fully weld
QED

My advice - have the flat bar over length by a couple of inches either side - clamp it up against the bottom of the chassis (i.e. - where the floor will go) then you can play about shifting it nearer to / further way from the transmission tunnel - if required. I certainly had to tweak my seat side-to-side - so actually laid it all up on a piece of chipboard clamped to the bottom of the chassis - and marked it all up before cutting the flat bar.... That also meant I could remove the seat fully to keep it safe from spatter before welding.

Any use? NTDWM - but ETDW someone else on here!

http://www.ebay.co.uk/itm/1511182102...226%26_rdc%3D1

are they IVA friendly? - No headrests

I ended up modyfying my MX5 runners to fit my new seats. Welded the runners to a 40x5 flat bar, which was drilled and bolted to the seat, then welded a 25x25x2.5 RHS crossbar to the runners, one at the front, and one at the back. Spent hours getting my rails in line on the chassis (also 25x25x2.5) then bolted through and through with a M12x75 bolt, with nylocks on the underside of the car.

My passenger seat was easier, because I don't want it to move, so I made a 40x5 flat bar square frame drilled and bolted to the bottom of the seat, then welded some 50x25x3 RHS at the front and back to give the same height as the drivers seat. Set my rails again then drilled through. Both my seats can be removed easily as the nuts are on the underside of the car. Although the only downside is my rails for my seats don't mirror on the chassis.

I'm 6ft tall with long legs, my missis is 5ft 3 with short legs, so for me the seat needs to be fully back, for her, it needs to be fully forward.