Reworking the Emergency Brake

Today was definitely a car day — I started off going up to Pat McMahon’s shop where we had a mid-winter “Cobra” get-together (although it was too cold for anyone to actually drive their car there). Coffee, donuts, good conversation and free parts. You can’t go wrong with that. I actually came back with a few items I will find useful — a bus bar I can use for a better set of grounds behind the dash, some battery cable boots (which I needed, as I had none on my battery or alternator lines), and best yet another set of the decals I had bought to use as icons for my dash and console switches. I needed an extra set, but balked at paying another $20 for the one extra sticker I needed.

After returning home, I got to work on the car — I was planning on playing with some emergency brake arrangements, and starting to build the center console.

As it turns out, like usual, I didn’t make the progress I’d hoped, although I spent a solid four hours working in the garage.

At least half that time I spent mostly staring at the transmission tunnel and trying to visualize various configurations of parts that I could get in without removing the transmission or emergency brake, and without losing future access to the transmission tunnel. I also played with mocking up three or four arrangements of mechanisms for the emergency brake, both where it was and moving it to the left side of the driver’s seat.

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I tried in vain to remove the emergency brake cables, but because of the way the clips were holding them in place, I just couldn’t get them out without being able to grab the cable itself from behind so I could apply pressure to the clips. To do that, I had to remove one of the riveted and siliconed panels — the rear of the transmission tunnel. Drilling out the rivets also required removing the seats.

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It turns out the silicone really grips tightly — it tore the powdercoating off the rear of the cockpit. Thankfully it didn’t peel beyond the point that it had been adhered, so it will be invisible when I re-attach it. I may do so using screws and rivnuts, as it turns out its a handy panel to be able to remove.

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With the cables detached from the mount, I could get a better sense of how much play I had in them. I had been thinking of a couple options — either rigging a lever setup where I could pull the two cables using a third cable, which would run behind the driver’s seat to the e-brake handle, moved to the left of the seat, just below the door, or some sort of a lever setup giving a bit more leverage with the handle where it was. It turns out both were really more complicated than I could reasonably do with the tools on hand — I really needed to be able to cut and weld an assembly to act as a pivot and lever as well as weld in a different crossmember in the transmission tunnel to support it.

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After a good bit of futzing around, I realized the best option I had that would not involve going out and buying a welder was to bolt a different cable bracket at the top of the tunnel and use the rest of the brake mechanism as-is. This got rid of the awkward angle on the cables, and I figured would help lessen the effort to engage the brakes. I started off drilling a couple holes in the crossmembers and using a couple long 5/16″ bolts to mock up the location for the bracket.

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Having the bolts stick up above the crossmembers was going to cause me problems with the transmission tunnel top and console assembly, so¬† I drilled the upper hole bigger and dropped shorter bolts into the bars. I don’t think this weakens anything in any way that is concerning.

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With that done, I just re-assembled everything, and ziptied the cables up above the driveshaft. The brake works far better now, and there’s more clearance around the driveshaft. In a car with a solid rear, this wouldn’t be an option because of the driveshaft moving around, but in an IRS car, the driveshaft never moves, so there’s no chance of it hitting anything.

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Another shot showing the assembly bolted in — the old bracket can be seen just above it in the photo.

I’m still waffling on the design of the console. I’m definitely leaning towards both a center console and a storage console/armrest between the seats. I’m still trying to determine if its better to use the aluminum trim as I’ve been planning in between, or build up a more “engineered” console that spans the length of the cockpit.

I’ve got at least three or four more days without snow where I can leave the Miata out of the garage, so hopefully I can make some progress this week on the console. I may have to mock up a couple options out of cardboard to get a sense of how I want it to go together.