stacer

A carriage bolt would work, but putting any bolt down through the rails is difficult because the bolt head won't fit through the gap in the sliders, and you can't angle the bolt to get it into the hole. And you don't want to grind the head down too much to get it through the gap, because that could possibly impair the integrity of the bolt to hold down. I wound up just prying the rails apart slightly, long enough to push the bolt head through. With the bolt going down, the sliders had enough clearance to go over the bolt head, unlike when the bolt was going up and the nut, washer, and bolt end stuck up and impaired the slider. When I positioned the seat, I did it so that the front of the rails (without the mounting brackets) lined up with the front seat cross brace mount on the Z. To get the seat rails to fit in the rear, I had to take a hammer to the rear cross brace and pound it back a half inch or so. Easy to do, and not noticeable (and probably easy to return to normal) when done. Then the rear of the seat rail (again, sans the Honda mounting brackets) butted up against the rear cross brace. This provided plenty of fore and aft movement and more leg room. My problem is the seat back tilt, hitting the roll bar, so if the seat is all the way back for long-legged people (not me), then the seat back is pretty much straight up. The seats hit on the side, not the top. If you don't have a rollbar, no problem.

Shika--there is actually more space between the cushion and the door panel than the racing seats that I had in there before. Plenty of room to reach down and grab the belts or work the seatback latch, even with the door closed. The wings on the racing seats rubbed ever so lightly on the door panels with the door closed. No problem with that with the s2k seats.

I finally got my S2k seats into my 72 Z. Much thanks to shika805 for his ideas and posts on installing his S2K seats. I did a very similar install, with one or two changes for my particular situation. I have a bolt-in roll bar which limits headroom and tilt. So I needed the seats to sit as low as possible. I thought I would have to modify the Z's seat brackets for this to happen, but what I did instead was to take the front mounting brackets off the rails (as well as the rear brackets). This is easy enough, drilling out the rivet and grinding down the welds. I then lined up the front of the rails with the Z's front seat mount, and used the rivet hole in the rails to mark where to drill a hole in the seat mount bracket. I used grade 8 bolts to bolt down through the rails and the mounts. To be on the safe side, I took a piece of 1/8" steel, 3/4" wide, and ran it underneath the lip of the front seat mount, and bolted through it as well. I'm going to go back and put a third bolt in the middle of the seat mount lip and the piece of reinforcing steel. I think that will make for a very sturdy platform. If someone has welding skills, they might want to weld the reinforcing strip instead of just bolt it. The biggest challenge was getting the bolts through the rivet holes. The bolt heads were just a wee bit too big to push through the gap in the upper half of the rail. It was easier to push the bolt up from the bottom, but doing so made the bolt just a slight bit too tall, limiting the fore and aft slide adjustment. So I just took a pry bar and pried the upper halves of the rail apart just enough to push the bolt head through. This is where I had to have help, to get someone to push the bolt through while I held the sides of the rail apart. I did the back mount using the same kind of arrangement as shika805, though the rails were lined up differently, because of the way I did the front mounts. This required drilling a new locating hole through the rail to attach the crossbar to. Here's a thought. If you want the seats to sit even lower, you can mount the rear crossbar ON TOP of the rails (instead of under), with the rails outboard of the rear seat mounts. I was actually setting up to do this, but without making some changes to lower the front brackets as well, all this did was put the rear of the seat lower, and it felt like I was sitting uphill. But I bring it up in case someone wants to sit lower. As they are, the seats are just right for my 5'8" height, and there is headroom to spare. The seatback angle is also perfect for me, but for someone taller, who might want a little more angle on the seatback, that's now limited, mostly by the rollbar hitting the SIDES of the seat (not the top). The other thing I did was to paint the plastic piece on the back of the headrest, to match the body (Viper Red). These pieces are always scuffed on s2k seats anyway, and only require light sanding to clean up. Finally, I'm using racing belts atached to a harness bar on the rollbar. There is a belt retainer on the outboard side of S2k seats which does a great job holding the belt on that side. You can order these retainers from Honda for less than $20 apiece shipped, and I've ordered two of them to install on the inboard side of the seats as well, to hold the inboard belts. I will try to post some pix. I really, really like these seats in the Z. They are very comfortable, very supportive, and look as if they were made for the car. Plus I know they are safe, and now, installed very solidly.

It does look good and doesn't sound very difficult at all. You've given me some great ideas for doing this myself. The one question I have is how high do you sit now compared to before? In the pix, they look like they're at a good height, but when I put my S2K seats in to test fit them just resting on the stock Z seat mount brackets, and sat in them, they sat pretty high. I'm also 5'8" and the headroom seemed really limited this way. I was pretty sure I'd have to cut into the seat mount brackets to lower the height an inch or more. Plus you've put in spacers as well. What do you think about how high the seats sit?

I also have some S2k seats awaiting installation in a 72 240Z V8 conversion. I looked around at the different options for seats, and liked these or the Recaro’s out of a BMW 320, but couldn’t find any of those that didn’t need serious work. It wasn’t easy to find the S2K’s, either, but it might be even harder to install them. I have test fit the passenger side. The only problem is that the seat sits way too high if you rest it on the stock seat brackets. I read on this forum that this a problem. My solution will be to cut out both the front and rear brackets, and then bolt the seat rails flat through the floor. This requires a commitment, because it can’t be undone. FYI, the bolt flanges that curve down on the front of the rails can be easily bent to sit flat on the floor. I’m curious as to whether or not there might be a bit of structural integrity lost in cutting out the front seat brackets. I’m not too worried about it, because I’ve had the Bad Dog subframe connectors welded in under the floor pans to accommodate the V8. I also had reinforcement metal welded in above the floor plans, running over the subframe connectors below, as well as some backing plates above the floor pan for the JTR transmission mounting bracket below the pans. So it’s pretty solid and well reinforced. Still, I was thinking that I would fabricate a ¼ inch thick X 2 inch wide piece of steel to run crosswise flush across the top of the floor pan where the front bolts would bolt through, and use a similar backing plate underneath the floor, both front and back. I may also have to see if any spacers are necessary to get the correct height. So mostly all cutting and drilling. I have not yet test fit the driver’s side, but from what I’ve read on this forum, the seats should also fit, at least in 240’s. Apparently, they don’t fit as well in the 280’s owing to a different transmission tunnel design. But if there is a problem, I’m ready to do some pounding to provide clearance. I am also using 5 pt racing belts instead of seat belts, so the seat belt receiver on the seats can be removed. The S2k seats have seat belt retainers on the outboard side. Racing harnesses fit through these. I am looking for another set of retainers so I can also mount these to the inboard side of the seats for the racing harness. I have a roll bar and harness bar already installed. I read on this forum where someone was thinking about modifying the rails on the S2K seats in some way so that they would sit an inch or so lower. I couldn’t see how this would be done, so haven’t pursued it. Maybe someone else has some thoughts?