Tubular seat rail installation

Discussion in 'Track Prep & Tech' started by A.N. Other, Aug 14, 2006.

  1. A.N. Other Banned after significant club disruption Dec 5th 2

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    Thought I’d post up a few pics of a seat rail install I’ve just completed. It’s in a Mk1, but the ideas / process is transferable to other cars. I have to say that this job is easy to underestimate – it looks simple, but get it wrong, and you know about it, every time you sit in the car. Aside from welding in a cage, or fabbing up turbo pipework, downpipes etc, to do this properly is a tricky fabrication job.

    So I thought it would be worth sharing…

    Please do not follow this approach if you are preparing a car for the Mk2 Golf GTI Championship - please see the the regulations concerning shell modifications first.

    Firstly, get rid of bits not needed:

    Original seat rails have gone before this pic – 6 or so spot welds per side (visible on inspection), plus 4 Mig’d bits, top & bottom, at each end. Takes a while to get these out as it is, and patience is needed to avoid angle grinding through the floor!

    [​IMG]

    Front seat support won’t be needed either – buzz off the spot welds (the indentations where can be seen), angle grind and power-file the Mig’d sections against the sill. Power file off the spot weld heads also, and use a heat gun and solvent to remove the factory wax where it sat.

    [​IMG]

    Tidy and hammer back the double skin where the support passes through the tunnel (shown afterwards):

    [​IMG]

    Then get the seat plus seat brackets into the car on two blocks of wood, the same height as you expect to have the seat…. And sit there a lot. Ponder, ponder, ponder where the seat will be best placed, to keep the seat shoulder wings off a roll cage (if installed), occupant’s heads off the roof etc etc. Time well spent. Mark roughly where you want the seat to go, and note where things could get tricky.

    Decide at this point where the seat belt eyes will go also.

    Seat rail end supports need making up next – I used 1.4mm steel plate. Nibbler used to cut it out of the steel plate, and bench grinder to neaten up.


    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Next make up the seat rails. I used 38.1mm CDS tube in 3mm thickness from Merlin Motorsport – though you should be able to use less thickness than that. Use dummy wood, or cardboard tube ideally to mock up a pair, since the ends will need profiling to suit the contours of the inner sill / tunnel. With the end plates sat loosely against the sills, there will be countless trips to and from the bench as you trim the tubes to suit the sill profiles. And I mean countless. My goal was to get this passenger seat pictured as far back and as far down as possible, and profiling the tube ends takes an age, since the sills are all curves.

    Next up, make the seat fixing tabs. Custom Cages use threaded steel inserts, TIG welded through the seat rails – but you could get away with bolts welded to the underside of the tube – but don’t strip ‘em! MIG tends to be tricky, ruining threads with too much heat if not careful.

    I went for the seat tag option – happened upon some 2.5mm thick box section which was just the job, and saves using a sheet metal bender or vice hammering:

    [​IMG]

    Grab a hole cutter and things start to take shape:

    [​IMG]

    [​IMG]

    Trial fit – yep, job done:

    [​IMG]

    Three more to make. I used wide box section, since this allows the fitment of various width seats – just in case etc.


    The seat needed to be 100% square in the car, so time to cable tie everything up, put the seat in, and shuffle about again for a test fit. Try to decide when the pressure of your shoulders on the seat shoulder wings is equal when looking straight out of the windscreen.

    [​IMG]

    [​IMG]

    The great thing about having the seat, the brackets, and the rails all connected is that it becomes it’s own jig, squaring everything up, so make sure it’s tight, pre seat rail position decision. Time very well spent again.



    Once decided, tack in back plates, and tack the tags onto the seat rails, but leave the rails unconnected. Haul the seat, brackets and rails out, and seam the backplates in:

    [​IMG]

    [​IMG]

    [​IMG]

    Then grab the seat again, still connected to the rails and tags, and place in the car. Check that the end plates haven’t warped with the heat and still allow the seat to sit where you had it before. Tack the tubes in, seat out, brackets off, and seam the tubes in.

    Where the tags are close to the tunnel, I had to remove them again to weld in the rail – the benefits of just a couple of tacks meaning they can easily be removed, but with the important trace of where they need to be put back on.

    Finally seam the tags on.

    All in:

    [​IMG]

    Then clean up with a wire brush....

    Painted (Upol etch primer on the welds, from Halfrauds, plus top coat):

    [​IMG]

    Sorted [:D]

    Final job was to etch primer and underseal the underside of the car where the paint had burnt off from the back plate install.

    Seat rails can be a lot easier to install if you don’t remove the original rails, use square section rail tube and just drill them straight through…. It’s all a case of what finish you’re after though.
     
    Last edited: Nov 18, 2007
  2. RobT

    RobT Forum Junkie

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    top job m8 - very reasonable - slight comment, belt eyes are supposed to go into the chassis independently of the seat fixings - for added safety - can I see eyes fastened to rails ?

    so at 30 p/h + travel costs, that job owes you 3K LOL
     
    Last edited: Aug 14, 2006
  3. A.N. Other Banned after significant club disruption Dec 5th 2

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    Yep - there's one eye in the seat rail - I could have put it through the floor area where it rounds up to the sill, but felt that structurally the floor offered less support. Easy enough to move though.

    I was wondering what the Blue Book would say - which is where the 'independent' comment comes from I presume?

    Perhaps it's 'on the edge of reason' ? :lol:

    But the 3k price tag - nah, it's a bit low TBH! Double time after 7pm!
     
    Last edited: Aug 14, 2006
  4. GVK

    GVK Forum Addict

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    Tob job Chris, makes my box section welded in and drilled through look a proper bodge!
     
  5. RobT

    RobT Forum Junkie

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    will check blue book tonite - right on the edge of reason I would say :lol:
     
  6. I V - mk1 16v Forum Member

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    Ditto, proper job Chris, Christ even GVK's made mine look like a bodge![:$]
     
  7. badger5 Club GTI Sponsor and Supporter Trader

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    good old blue book... :)

    nice progress there Chris.

    been fabricating myself this weekend too... cuts/burns/bruises & sprained back to show for it too.. LOL - the things we do eh!
     
  8. A.N. Other Banned after significant club disruption Dec 5th 2

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    I think that just sums it up!

    But we're still here! [:D]
     
  9. badger5 Club GTI Sponsor and Supporter Trader

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    masochistic tendancies
     
  10. infinity

    infinity Forum Member

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    Nice work !!!
     
  11. Dogwood Forum Member

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    Looks good Chris.

    Got a bucket for the Lupo but haven't got it in yet. Wasn't going to bother but gonna get me finger out now and clash it in pre-ring'. Need to build a subframe, hence today at work has been mostly about procurement of box section and 3mm plate!
     
  12. POL

    pol Forum Member

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    interesting position for the lap belt eyelet on the bar. i can only assume this is because you have encroached upon the std seat belt mount hole on the sill with the runner positions?

    out of interest where has everyone put their crotch belt eyelets? if you follow the blue book regulations then they should be on the floor up to an angle of 20 degrees to the rear. if you put them onto the floor then it will obviously need strengthened as the metal is not very strong. however if you only plate on a section of 40cm sq or whatever the recomended is then surely the surrounding floor area is still a weak point?
     
  13. jamesa Forum Junkie

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    Good work Chris.

    fyi..

    Willans harness installation instructions are very good in helping to determine eyebolt locations, they pay particular attention to the angle of the belts for maximum retention.

    I also find that:

    None of the existing Mk1 seatbelt anchorages suit eyebolt locations.
    Fuel and brake lines interfere with location of crotch strap eyebolt location, again Mk1
     
  14. fthaimike Forum Addict

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    excellent thread, this should go into a permenent DIY area on here
     
  15. barny Forum Member

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    Good info Chris, nice to see it !

    Looks like you wernt the only one working on a mk1 this weekend. Spent a couple of hours shot blasting the inner wing on the osf of shells pea green - fecking rust ! Its about the only bit its got too !

    I was wondering if that seat box section could/should come out ....
     
  16. vrbanana Forum Junkie

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    Must be fabrication week, Ive been welding lumps to the corrado as well. Anyone want to see the burns????[8(]

    Nice one Chris, nice to see you finally do some work;) :lol: any more pics of the rest of the car?
     
  17. altern8 Forum Junkie

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    nice work i was quoted 150 for two sides to get mine done like that
     
  18. barny Forum Member

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    Ahh the joys of owning a welder ! Mines sat in the back of the other garage, behind two golfs and a landrover !

    Good to see/hear a potential track **** on the way for Chris - its been too bloody long !
     
  19. A.N. Other Banned after significant club disruption Dec 5th 2

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    I was looking at the eyelet location for that side, and angle-wise, it seemed perfect at the seat rail. The seat is passenger side, so has been moved back so far that the sill mount hole is too far forward. I've got Willans instructions by the way, and I agree Andrew.

    I can easily move it rearwards to resolve the Blue Book issue, have it right etc - may have it done for the w'end.

    Crotch eyelets are a pain. Spoke to RobT earlier and it seems that if four points are not on the seat rails, then it is possible to have a scrutineer take the view that the crotch strap can pick up on the seat rails - which mine do. Certainly the 20 degree angle is nigh on impossible to achieve.

    The floor is just pure tin anyway, especially with the crossmember removed, so plating follows the rule, but achieves little IMO.

    No more pics yet - hopefully some on the Internet after this weekend!
     
    Last edited: Aug 15, 2006
  20. badger5 Club GTI Sponsor and Supporter Trader

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    my crotch belt loops under my seat rail.
    no scrutineer issues
     

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