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Old 01-19-2007, 03:53 AM   #1
Join Date: Apr 2005
Location: River Oaks
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andrave probable wing man
HOW TO: build your own seat rails for bottom mount seats

A lot of people have expressed interest in learning how I build seat rails using stock sliders for aftermarket bottom mount seats, so I snapped a couple pictures as I installed my latest racing seats into my vert

Start by taking a set of stock seats and remove the plastic trim that runs along the sides under the bottom cushion. You will see a bunch of bolts which all need removed. If you are going to be keeping your stock seat belts, leave the large bolt that holds the seatbelt fastener on the inside rail.
Keep all the bolts you removed for later.
Pull the rails off the seat assembly. You will probably need to drill out a rivet that holds on the seat back release cable, though some seats have a c clip that holds this in. Once the rails are removed, toss the crappy smelly worn out stock seat. You will end up with something like the first pic (make sure to keep the metal wire that runs between the seat rails as it is much easier to keep the stock one than to have to make something else work later).

Once you have the rails removed, the first thing you need to do is measure the distance from the bolt holes in the bottom of the seat to the edge of the seat. This distance will tell you what size angle iron you need to purchase to create your new rails. In this case the holes were within 2.5" inches (just barely) so I decided to go with angle iron that had 2.5" sides.

Now you need to figure out what length of angle iron you need. The stock rails are around 15" long, so unless your seat uses bolts that are unusually far apart from front to rear, you will want a 15" long piece of angle iron that will bolt to each seat rail.
You will need about 15" of angle iron PER RAIL and there are 2 rails per seat, so you will need around 60" total for two seats. Lowes and Home depot are not the cheapest places to buy steel, but they do have sections of angle iron just the right length to cut 4 15" sections and have very little waste.

Because of the hump in the driver's side floor of the 240sx, the stock seat rails are different and most aftermarket stuff tries to space it flat before it adds the sliders. This is where reusing the stock sliders will buy you some extra headroom. If you flip one piece of angle iron you will find that it evens out the seat perfectly, making up for the difference of the "hump."

Go ahead and hold the angle iron up to the stock seat rails. You can see that around 3 bolt holes per side will be useable- and you can reuse most of the high strength factory fasteners at the same time. If you hold the angle iron to the seat rail and poke a sharpie through the bolt holes, you will have just marked where you need to drill the angle iron for those bolt holes. I recommend starting with a small pilot hole and using a step bit to bore it out, because you are so close to the 90 degree angle on the angle iron, a regular drill bit tends to step out from the angle and put the hole too high on the iron to bolt up to the rail.

Once you have your holes drilled, go ahead and bolt up the angle iron to the rails, and bolt the rails back in the car. measure the width from one piece of iron to the opposite piece of iron and compare that to the width of your seat.

With these seats, I could tell that the seat bottom was too narrow to simply bolt the angle iron directly to the seats and the rails as I have done before on larger reclining seats such as Recaro's.

This meant I would need another section of steel to go between the pieces of angle iron to bolt to the base of the seat.

For this, I chose some flat steel, again from the local home depot, cut it to the length I had just measured (between the seat rails) and then drilled holes on each end to attach it to the angle iron. Once you have done this, then you can determine where to drill the angle iron so that the flat steel will liine up with the bolt holes in the bottom of the seat. Once you have it lined up, then you need to drill the holes for the bolts that will go through the flat steel and into the seat base.
A little cheater trick I use is to stick a regular crayola crayon in the bolt hole in the bottom of the seat, and then carefully position the seat how you want it to sit. When you pick the seat back up, the crayon will leave a mark on the steel exactly where the holes need to be drilled.
Once you drill the holes you can then bolt up the seat. If all your measurements were made correctly you can then bolt the entire assembly into the car.
I will have the finished pictures posted up ASAP, they are on a different memory card.
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Old 01-18-2012, 07:43 PM   #2
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GummyTaco917 probable wing man
Woah just what I was looking for.. Looked everywhere for this write up except here haha

Does anyone have more pictures of stock rails on bottom mount seats?
1989 hatch ka24e one camin'! ~ lily (in progress)
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Old 01-18-2012, 07:55 PM   #3
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Im welding up my own using flat bar and the flanges off the rail. ill post pics this saturday when Im done
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Old 01-19-2012, 11:58 AM   #4
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Are you just bending them to be on the outside of the rail and running from one rail to the other rail? Meaning you dont have to weld anything hu?
1989 hatch ka24e one camin'! ~ lily (in progress)
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