Build 56. Rear Hub Part 2 (Brakes)

The second part of the rear hub is attaching the brake discs and calipers.

Discs

The discs were possibly the most straight forward of the lot, they are both in the same box and it is pretty heavy (they were in a larger box marked "Axle" for me, along with the calipers, pads and all the bolts required). I simply got both the discs out, and also the large washers and drive shaft lock nuts. I put the car into Reverse again and then I worked out which lock nut goes on which side (they are handed and one will screw on anti clockwise!). I also measured the lock nuts before ordering a socket to fit them.

Both of mine were 42mm, but I got caught out by the fact that they are slightly tapered, and I actually measured the side which presses up against the washer, this turned out to be 41mm on each and so I ordered the wrong size and had to send it back, I wasn't happy, but I did think it was odd given everyone was saying the current nuts are 42mm and not 41mm!

Fitting was a case of of slotting them on as below and then tightening them up. The manual calls for 270Nm, my wrench (30cm long) only goes up to 100Nm, so I torqued it to 100Nm for now, and then when the wheels are on I plan to use my 60cm bar and apply my weight (off the ground) at a fixed point along the bar. I'm approx. 75kg and so if the breaker bar is horizontal to the nut, I work out that if I apply all my weight at 0.367m along the bar, then that should be a pretty good guess at the correct torque.

In simple terms, "Torque = Distance x Force" thus "Torque / Force = Distance" so "270 / (9.81*75) = 0.367m". Either way it's not that important as this will all be checked at the PBC, but I'd like to get it near enough.

Calipers

Then onto the calipers, straight away I noticed that one of my spacers was slightly the wrong size, I decided that I would simply order a new one direct from Caterham parts, it is next day delivery and was only a few pounds. I chose this rather than send an email to CC and ask for a replacement as they usually take a couple of days, and I wanted to get this done now. Each caliper is handed and has a letter engraved on it which makes it pretty simple.

First I attached the caliper support to the DeDion ear using the larger silver bolts, making sure that it has a split washer and washer on it and as usual I put some copper slip on the bolts just for good measure. I passed these through the ear and then put the larger spacer washer on the bolt as it came through the ear (Again with some copper slip on it). These were then torqued to the required amount (which I think was 47Nm but I can't remember off the top of my head here!).

Next I got the pads out of their box, and the first thing I did was to bend the springs out a bit more. I'd read on a few other blogs that these pads with the up rated brakes can rattle as the spring is not quite bent correctly by default. I didn't want to take this risk so I bent them up a bit to ensure they were in contact with the caliper plate (this is the thin aluminium bracket you have to install in the larger caliper piece) when they were installed.

The manual calls for copper slip on the back of the pads. You basically need it anywhere it is in contact with the pistons and the caliper itself, I learnt this trick on Wheeler Dealers so it is probably quite common knowledge to those in the trade.

Next I inserted the black caliper pins into the back of the caliper support into the rubber grommet, I noticed that inside the rubber grommet was already pre greased so I was happy to just slot these in as the manual states.

Finally I attached the thin metal plate into the larger caliper piece and then slotted the caliper over the discs, and then used my finger to push in the black pins to allow the caliper to sit correctly over the brake disc. Then using a bit of Loctite on the bolts, I inserted both bolts through the caliper and into the pins and torqued to 20Nm. You will need a thin 15mm spanner on the black pin nut to be able to torque it all up tightly.

Then I attached the brake lines to the caliper, here is a handy tip to bend the lines without worrying about kinking them - use a long socket to bend it around as shown below.

Timelapses