Fitting an Electric Handbrake #2

In which, i go through some of my reasoning behind my design, and tease you with how hard unidirectional CF is to work with.

estop sizeHere, you can see the E-Stop actuator sat next to the layer of soric I’ve cut out and marked up to show where it sits, and where the cut-outs will eventually need to be for where it bolts through.

You may notice the tapered shape of the soric, and that’s because it’s the shape of the bottom of the transmission tunnel. As such, I’m going to be able to mount this at the very bottom of the transmission tunnel under the gearbox selector bit. This is fantastic because it means I’m getting 2.2 kg of mass right down there at the same level as my arse, and right on the center line, to give the lowest polar moment of inertia possible. What’s more, it definitely means nothing needs to be cut through the transmission tunnel.

Mounting it this way at the bottom of the transmission tunnel means I have the option to add extra strength. If I had welded tabs onto the transmission tunnel bottom and bolted the actuator to that, I would have mechanically coupled the bottom of the tunnel together adding strength (yeayy) but would have done so using the actuator housing which may not be designed for that (boo). It could end up an expensive mistake.

So, I needed a plate that did the coupling and added the strength whilst at the same time weighing more or less nothing. This is a job for … unidirectional carbon fibre. What’s more, the plate needed to be blind-ending for attachment. As in, it needed to be bolted in from below without having to grow an extra fistful of knuckles to put the bolts in place. Thankfully, I’d found these big-head fasteners which do the job.

You sit them on the finished part and bond them in. They’re not designed to be part of the infusion which is both a bummer because that would be a neat solution and also great, because it’s a far more simple manufacturing solution. I used East Coast Fibreglass Supplies to source these.


20140629-134234-49354453.jpgHere you can see them offered up on some 3mm closed-cell core material to give an idea of where they will fit and where they will clash with the necessary mounting holes for the actuator. For the most part, all is hunkeydorey apart from where the tunnel narrows. In the case where it does, I’m going to cut the hard-point own to size.


In the next installment, you can see how I laid up the cloth, and how it totally failed to infuse as a part. As I said, unidirectional is a difficult cloth to work with.

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