Rethinking the aft firewall

 I mentioned a while ago the curious oversight of not having a firewall between the fuel tank and the engine bay, and deciding to add one. I even cut some aluminum for that, but never actually drilled any holes to get it on the car.

But further thinking (always a challenge) and further discussions with my uncle have led me to change my design for this firewall. To wit, I am putting it forward of the frame, rather than aft; and I am going to be attaching it with screws rather than rivets. 

The idea here is that it may be easier to approach the front of the engine (to replace the timing belt, for example) through the firewall than the engine hatch, and may prevent having to pull the engine. Who knows, I may never need to do this, but the option will be there.

Here you can see the lower portion of the firewall installed with Clecos. I'm currently working on tapping all of these holes for 8-32 screws. The upper portion will go in later.

Here's the fuel tank I will be using. This is not the tank that came with the kit - that tank has a couple of design, uh choices, that I'm not very happy with. This tank has less capacity, but I like it better overall.

Driver's seat is getting closer

More progress on the driver's seat today. It's a little unnerving drilling holes in a seat you paid good money for, but it just has to be done to get these into the car - and it's what these are designed for.

Through some experimentation, I've chosen a height and an angle for the mounting of the seat, so I got the brackets mounted to the seat shell itself.

Then I got the bracket bolted up to a piece of steel. This will get bolted in turn to the frame of the car. I still have some massaging to do to get the location fine-tuned, so I have deliberately cut the steel longer than needed. I've also left stock on the aft end, as I need to weld on a tab for the harness.

This is how it all goes together. The steel will get trimmed, shaped, and painted before it all goes in the car in its final position.

I used hardware-store bolts for today's work, but I have good bolts on order for the actual assembly. 

Starting to fit the most important bit

 

That is, the driver's seat. It's just on some wooden spacers for now, but I have some aluminum brackets and some plans to get all that bolted to the chassis. I have to say, for a pretty bare-bones racing seat, this Kirkey seat is a pretty good sit. It's an aluminum shell with pretty minimal padding on it, but it's kind of like an old wooden rocking chair in that it fits me way more comfortably than it sounds like it would.

I can't really completely finalize the position until the fuel tank and aft firewalls are in, but this is really close to where I will sit. I'll add five-point harnesses in both chairs as the build continues.

I can't wait to be able to turn the bonkers on.

The saga of a single hole

 

Next thing to install is this bracket, which is the bit that the accelerator pedal will be mounted to. I need to drill a 3/8" hole in the frame member there at the top to accept a rivnut. The issue is that the welded bracket for the pedal box and steering column is only about 5" away, meaning I can't get a straight shot to the hole location.

Here's my marking punch as an illustration. I want to make a dimple so my drill bit won't wander, and I can indeed get my punch into that space, but there's no room to swing a hammer to make the mark.

One quick trip to the hardware store later, I have the spring-loaded style of punch, so I can mark the hole without a hammer. The punch fits, but only just. It works, which is the important bit.

I 3D printed a little centering collar, so I could get the center of the hole in the bracket.

OK, now the hole is marked, but I still can't get a straight shot at it with a drill bit. I just don't have a drill that short.

I do have this tight-clearance right-angle drive, though, so I was actually able to get the pilot hole drilled. But my 3/8" bit doesn't have a 1/4" hex shank, which is that this drive needs.

Another quick trip to the hardware store later, I have a step bit with a 1/4" hex shank, and I am able to start drilling this hole. And it even mostly worked!

I say "mostly" because the right-angle drive couldn't take the torque, even though I was going slow and putting only light pressure on the bit. It ejected a circlip while I was using it, and became useless. I did fix it once, but it immediately broke again.

I literally finished this hole by turning the step drill with a ratchet.

So, saga of the single hole complete, I did manage to get the hole cut, and install the rivnut.

Then I bolted the pedal to the bracket, and bolted the bracket to the car. It's really starting to look good in the area of the controls. 

Tomorrow, I'll be hooking up the accelerator cable, and then looking for next steps.