magnumP5's RX-7 Build Thread

[mymmeryloss]

U must be a little guy if u can fit into those seats!

Im only 5'6 and theres no way in hell i would fit into those...

 

[magnumP5]

U must be a little guy if u can fit into those seats!

Im only 5'6 and theres no way in hell i would fit into those...

Ha, not as little as I used to be: 5'-9" and about 160 lbs. The main problem is, despite being a relatively big and heavy car, the FC RX-7 has a very narrow interior so I need to be picky with aftermarket seats. I used to have some Sparco Torino II's and those were a pain in the ass to fit. Never got the passenger's side to work...

 

[magnumP5]

Going to make a call today. If everything goes well the following will be purchased:

OMP WRC seat
OMP steel seat brackets
Sparco 345 Competition steering wheel
Hub adapter

 

[magnumP5]

Everything came in today! I test fitted the seat in the car and I'm worried it's still too high. My head was about 3/4" from the headliner so I think there'll be some issues with a helmet. I think I'm going to go in with an angle grinder and cut off wheel and cut out the stock seat mounting points. They sit up about 1-1/4" off the floor of the car so there is a little headspace to gain plus I'll be mounting to brackets flush to the floor now. I'm only concerned I may be causing some other problem by cutting them out.

I swear I'll take some pictures tonight. God knows this thread could use them!

 

[bbrich57]

You'll have to replace them with something to reinforce the floor plate. Those are a structural piece in any unibodied car.

 

[magnumP5]

You'll have to replace them with something to reinforce the floor plate. Those are a structural piece in any unibodied car.

Damnit! That's what I was afraid of. The front mount runs from the door to the transmission tunnel so I guess that's the structural piece. The rear points aren't continuous so I doubt they are providing much, if any, structural integrity.

 

[bbrich57]

You might be able to add a structural piece below the floor, depending on available room, obstructions, etc... but it should be tied into the unibody structure there too. Otherwise you'll be on your way to flexible flyer territory.
What about adding frame rail extenders to tie the front/rear substructure together and then add a cross brace welded into those? Like completely across the floor, perhaps underneath the tranny?
Or cutting the internal lateral structure down lower and recapping it as you would closing in a frame rail?
I'm not sure what the underside looks like, but surely there is a way to do it w/o compromising rigidity. You might even be able to make it stronger than before. After all, you are dealing w/a 25-30 yr old frame design there and I'm sure stiffening it will only make the car better in the end.

 

[magnumP5]

You might be able to add a structural piece below the floor, depending on available room, obstructions, etc... but it should be tied into the unibody structure there too. Otherwise you'll be on your way to flexible flyer territory.
What about adding frame rail extenders to tie the front/rear substructure together and then add a cross brace welded into those? Like completely across the floor, perhaps underneath the tranny?
Or cutting the internal lateral structure down lower and recapping it as you would closing in a frame rail?
I'm not sure what the underside looks like, but surely there is a way to do it w/o compromising rigidity. You might even be able to make it stronger than before. After all, you are dealing w/a 25-30 yr old frame design there and I'm sure stiffening it will only make the car better in the end.

Yeah, that is definitely the way to go, but unfortunately I have a couple problems:

1) I don't own a welder
2) I can't weld
3) I have no way to getting the car to someone with a welder who can weld

I'm going to recheck tonight what my headroom is with a helmet on.

 

[hat1018]

Yeah, that is definitely the way to go, but unfortunately I have a couple problems:

1) I don't own a welder
2) I can't weld
3) I have no way to getting the car to someone with a welder who can weld

I'm going to recheck tonight what my headroom is with a helmet on.

If it was tight without a helmet you won't fit with one on. Get in touch with Wes he has a welder, and can weld. Only one problem remains, getting the car to him.

 

[bbrich57]

What if Wes got the welder to Magnum?
There are those that will come to you, but it will cost you a bit, unless... you have something to barter with, or a friend (of a friend) in the business.
Are there any local portable, professional welders in your neighborhood? One with a truck mounted generator/welder?

 

[magnumP5]

Yeah, I wouldn't mind providing for someone for a weekend or whatnot. My current idea would be to cut the "top" of of the existing mount and box it back in about 1" lower. There are some wires running in the immediate area and I would need to have a provision for them to pass by/under the seat.

Another thing I'm going to try is to recline the seal a little more to see if that won't help. I should have more headroom than I did with the stock seats as I have a ton more legroom under the steering column so I'm thinking I may have the seat too vertical.

 

[eprx799]

Jon I will check out my rx7 floor tonight and get back to you about how the seat is lowered in it.

 

[PrinceValorum]

Does the new seat have a slider rail on it that's taking up vertical room? Cincy is a bit of a drive round trip, and I'm not sure if you've got 220v in your garage.

 

[eprx799]

Ok Jon I checked out my rx7 this morning the front cross bar that the drivers side seat bolts to is still there, but the rear brackets that the seat bolts to were remove and the floor is flat with a plate weld in to reinforce the floor.

 

[magnumP5]

Jon I will check out my rx7 floor tonight and get back to you about how the seat is lowered in it.

Thanks, let me know!

Does the new seat have a slider rail on it that's taking up vertical room? Cincy is a bit of a drive round trip, and I'm not sure if you've got 220v in your garage.

Nope, no sliders. Just side mount brackets. The bottom of the seat sits about 1/2" off the brackets so I could technically drill out the drear holes 1/2" but I don't know if that's safe or legal, LOL.

Ah no 22V in my garage and no easy way to get it there

Here are some pictures for you guys...
Aeromotive FPR:

Sparco 345 wheel (temporarily installed in this picture):

OMP WRC seat and brackets:

Seat in the car. It actually fits really well; it's just too tall.

Here's what I've got to work with under the carpet:

In typical unibody fashion nothing is level or flat. The piece running from the door to the transmission tunnel with the holes in it is the forward mount for the stock seat. I've read people say it's structural and it's not structural so I don't know. It is boxed in, but the metal is 20 ga at best so I don't know how much stiffness it's offering (I could calculate this). The rear culprits are the rear mounts as they determine where my head goes. Rear right is the limited case and by removing that altogether I gain about 1".

If I had a welder, my plan would be to first cut out the right rear mount. I would then cut down the left rear mount so it was level with the right rear. Next, I would notch out the front mount so it's level with the two rear mounts. I would then run 1/8" or 3/16" flat stock to connect the rear mounts and re-box the front in with the same. I would then have front and rear mounting surfaces that are flat and level and the lowest possible without modifying the floorpan.

Cheap idea is to just cut out the rear mounts and leave the front mount and mount the backets on an angle. I would have to use a spacer on the left rear mount. I have plenty of adjustability in the seat angle so that's not a concern. Again, it's safety and legality.

EDIT: Oh yeah, I got a call from the shop yesterday about my intake manifold. They are supposed to have the flanges in tonight and once they come in they're going to get right to work on the IM.

 

[eprx799]

can you drill holes in the brakets to make the seat sit lower in bracket?

 

[magnumP5]

can you drill holes in the brakets to make the seat sit lower in bracket?

The bottom of the seat is about 1/2" off the bottom of the brackets. I don't think I could drill another set of holes but I could elongate the lowest hole to get the seat lower. Only good for 1/2" at most though. Plus, is that something that would get me in trouble during tech?

Also, just put in an order for an Eastwood 120V MIG. Has specs on par with the Miller and Lincoln 120V units but is ~$100 cheaper.

 

[eprx799]

The bottom of the seat is about 1/2" off the bottom of the brackets. I don't think I could drill another set of holes but I could elongate the lowest hole to get the seat lower. Only good for 1/2" at most though. Plus, is that something that would get me in trouble during tech?

Also, just put in an order for an Eastwood 120V MIG. Has specs on par with the Miller and Lincoln 120V units but is ~$100 cheaper.

I don't think it would how could they tell? Also a 1/2" is a 1/2". And that 1/2" maybe all you need to get your head room.

 

[magnumP5]

I don't think it would how could they tell? Also a 1/2" is a 1/2". And that 1/2" maybe all you need to get your head room.

True. I'll leave that as the last-ditch option.

I attacked the rear mounting brackets this weekend. I cut a solid 1+ inches off each side, which gives me plenty of space to fit the brackets:

The blanket is a fiberglass welding blanket so I didn't catch anything on fire. Afterwards I cleaned everything up so the rear is just about ready for welded. I think the floorboard needs some more massaging:

I caught the blanket a few times with the cut-off wheel, hence the fraying. The next steps involve welding 2" x 1/8" steel flat stock across both sides and using 18-20 gage steel to box it in. The over all height reduction in the rear is going to be about 1 inch. Now I just need the welder...

The really hard part is going to be cutting the front bracket out and welding it with the blanket in the way...

 

[PrinceValorum]

I can't emphasize enough to practice before you start welding, especially if you're new to it. An auto darkening helmet can make all the difference, too. I've been meaning to get one for a while, now. There are plenty of great vids on youtube (and even more terrible vids, as everyone with a welder fancies themselves a master fabber) Your seat mounts are a very important part of the safety equipment, and the last thing you want are crappy welds jeopardizing you or your passenger.

I got some experience attaching 1/8" to sheet metal a few weeks ago, and [at least for my skill level] it's tricky business. I got the best results striking the arc on the 1/8th, letting it pool a bit, and then dragging it onto the sheet metal just enough to get it on, and then stopping. If I tried to do any more than that, it would blow a hole in the sheet metal, and that's a mess to patch up. Let it cool a few seconds, and do another right next to it. Then after 5-10 of those, take a break and let it cool, or start from the other end. You want to get it all tacked in first so it has less chance to warp.

I'm not familiar with the output of the 120v units. I'd guess about 100-130 amps? Are you going to be running gas or flux?