Custom seat mount/ rail material.

mx5002 · Postby **mx5002** » Thu Jul 16, 2015 12:16 pm

I'm about to venture into making myself a set of seat mounts to suit my velo seats. Had a basic set however i want to fit a sliding rail for the drivers seat so the wife can track it too.

The seats are bottom mount so was basically thinking a piece of plate steel or aluminium then cut the insides out to remove weight. I have seen aftermarket ones made from steel that would suit in the usa but after postage blah blah is hardly viable.

Could you use aluminium? What size plate would be thick enough?

Cheers :beer:

mx5002 · Postby **mx5002** » Thu Jul 16, 2015 12:23 pm

What i plan to replicate

hks_kansei · Postby **hks_kansei** » Thu Jul 16, 2015 1:59 pm

First off I'd suggest against using slotted holes since with the vibration of the car, and the huge forces in an accident, the seat will likely slide. Not really what you want.
you'd be better off just having a row of normal holes and moving the seat between them.

As for material, you want strength, and aluminium just won't have it unless it's really thick.
Steel is really the best choice here.

Make sure for all bolts you use good side washers on them so that any load is spread nice and wide.

Thickness, i'd say use the thickest you can get away with, but i'd be hesitant on anything thinner than 3mm (i'm not an engineer, but 3mm steel is still pretyt easy to bend etc by hand)

mx5002 · Postby **mx5002** » Thu Jul 16, 2015 2:06 pm

Thanks kansei
3mm steel was my go to plan.

Just wanted to put it out there.

Also i will only be making holes not slots as the one pictured i guess is to suit multiple styles of seats.

madjak · Postby **madjak** » Thu Jul 16, 2015 2:57 pm

exactly what Kansei said...

I'd also, if you are planning on mounting your harness crutch points off this plate (not CAMS approved) you could add additional holes to each side for a 6-point harness.

Also, I'd run the internal bracing straight back rather than cranking them sideways, unless there is clearance issues.

Seat_Mount_Plate.jpg

mx5002 · Postby **mx5002** » Thu Jul 16, 2015 3:06 pm

Yes that definately makes sense to keep the supports straight madjak. Plus one i bolt the slider rails through it should strengthen it up also

hks_kansei · Postby **hks_kansei** » Thu Jul 16, 2015 3:21 pm

Oh, you're putting the factory rails onto the plate?

That makes this all a lot simpler, no need for bends or anything like that.

You'll just need to bolt the rails to the car, put a plate on top of them and mark the OEM rail holes.
Then do the same with the new seat.

Then cut out the middle as much as you want.

It also means you avoid the difficult job of bending the front edge over like in the pics. (getting an even bend on a piece that long will be hard without a metal bender, or a lot of time with a torch and hammer)

mx5002 · Postby **mx5002** » Thu Jul 16, 2015 3:37 pm

Sorry.. universal rails. The bum of the velo is approx 15mm lower the mounting points down the undersides of the seat. Need more low than the factory rails would allow.

bruce · Postby **bruce** » Thu Jul 16, 2015 4:34 pm

As said, use plenty of metal. Do it wrong and you could die.

mx5002 · Postby **mx5002** » Thu Jul 16, 2015 4:38 pm

Thanks for the tip :wink:

hks_kansei · Postby **hks_kansei** » Thu Jul 16, 2015 5:43 pm

mx5002 wrote:Sorry.. universal rails. The bum of the velo is approx 15mm lower the mounting points down the undersides of the seat. Need more low than the factory rails would allow.

That's fair enough.

In that case, to bend the front down I'd suggest you cut the middle section out so that you're only bending two tabs to go over the mount holes in the floor (maybe aim for 50mm wide ish)

Normally to bend metals I clamp the part in the vice, making sure the vice jaws are lined up maybe 2-3mm below where I want to bend.
I then heat the edge up with a torch (I just use a propane torch, but if you've got a MAP or Oxy then it's a lot better)
Try and get it to a dull red then start with the hammer while applying some tension on the other end with your free hand (use vice grips if it's hot)

Hit firmly with the hammer, but don't slam it super hard. Tap like you would while hammering in a nail, and just like a nail don't try and smack it all in one go.

Once it's the right angle let it cool down at room temp, you don't want to quench it with anything since that (depending on the steel type) will harden it and make it really hard to drill, and also make it brittle.
Letting it cool slowly means it will return to it's original hardness, which allows some stretch before it breaks.

While you can do this without heating, I've found that using the torch helps reduce the likelihood of cracking the outer radius of the bend and weakening it. (hot glowy metal can stretch a lot more than cold metal)

And there's today's home blacksmithing course.