Brakes - Part 3 - Rear

 The rear calipers supplied AK Big Brake upgrade kit usually are designed to work with 295mm diameter by 10mm thick rear discs (non-vented).  As my donor car came with 305mm diameter by 20mm thick vented discs I was keen to retain this setup.  Fortunately, HiSpec (who make the upgrade kits for AK) were able to adapt the spacer between the two halves of the caliper to accommodate my larger and thicker discs.

As at the front, the new rear calipers are larger than the original donor single-pot items but weigh in at 1.7kg compared to the 2.06kg of the originals.  They also benefit from two pistons per side to improve the application of braking pressure to the pads.

Size comparison - original caliper looks very sad in comparison

2 pistons per side compared to the single piston original

New Ferodo pads (left) are similar in size to the originals

I ordered some new rear discs from EBC brakes.  I went with their USR Sports Series disks which are slotted and come in a black thermic coating to help combat corrosion.

As with the front calipers, the kit comes with new brackets and bolts to fix onto the rear hubs onto which the callipers are attached.  I fitted these and torqued the mounting bolts to 60Nm/44lbf-ft.  

New caliper mounting blocks and bolts - with confirmation that they have been adapted for 305 x 20mm discs

I inserted the brake pads before installing the calipers - again this could be done with the caliper on the car but I figured it would be easier to do it on the bench (or floor as it turned out).  For the rear pads, the kit comes with some springs which need to be slid onto the outer edge of the pads.  I remembered to give the back of the pads a smear of copper grease before inserting them into place.  They are secured by two pins held in place with R-clips, the springs on the pads need to be eased under the pins as they are inserted to hold the pads into place.

Brake pad spring installed on the outer edge of pad...

...and a smear of copper grease added to the rear of pad...

...before pads inserted into caliper and held in place with retaining pins.

The last task before the final installation of the calipers was to adjust the handbrake adjusters on both sides so that the handbrake pads were just rubbing on the inside of the discs (although I think some further adjustment may be required at a later date). I could then bolt the calipers to the mounting blocks and torque the bolts up to 60Nm/44lbf-ft.  

Rear brake discs and calipers done!

And with that, I have probably reached the stage of the build that I was originally hoping to get to at the end of 2019...so only 3 years behind schedule!