ZXR Brake caliper refurbishment Part 3 rear brake

Rear caliper time;

I thought the rear brake was perfect as it seemed to work well. On removing the rear wheel to replace the cush drive, I tested the rear caliper just to make sure all was good and discovered that there was no movement on the inboard piston, whereas the outside piston was moving freely. Having seen the mess in the front calipers I took the opportunity to order the relevant seals and bite the bullet to refurbish this at the same time. I thought the inboard piston might be seized and was hoping that I wouldn’t require a new piston!

First things first, caliper removed and cleaned up with diesel. Like the front calipers, the exposed part of the pistons were in good order, more crud on them than the front but the diesel shifted it easily.

All cleaned up ready for strip down…

Splitting the caliper, what was immediately apparent was the state of the fluid galleries where the caliper halves join.

It didn’t take long to figure out why the inboard piston wouldn’t budge…the gallery was plugged solid. Even chipping away with a screwdriver was struggling to shift it and compressed air didn’t touch it.

The only thing that did was a 2mm drill bit which I turned by hand…

This had been the reason for the piston not moving. As it turned out, both pistons were perfect and all the seals were even in good order. The fluid was a bit of a mess with a fair amount of bits in it.

The old seals were removed, the bores and pistons cleaned out and the replacement parts all laid out…

The new seals were smeared with red rubber grease to ease fitment as per the workshop manual.

Pistons were fitted with some brake fluid to slip them in…

O seal inserted, again with red rubber grease, positioned and caliper joining bolts were subsequently tightened down to correct torque, 32nm.

The old pad sliding pins and springs were cleaned up…

Pads installed with ceramic grease applied to the rear of the pad backing plates and sliding pins…

New seals were fitted to the control arm bearing housing

and finally, all bolted up and bled ready to go. This bled up surprisingly easily…

Rear brake reservoir is located behind the rear bodywork;

Topped off and ready to go…

So that is the brakes all done. Front and rear with goodrich braided hoses and EBC HH Sintered pads all round and fresh Silkolene Maintain fluid.

I’m hoping this should be a totally different beast now on the braking front! The rear caliper should now have twice the power and the fronts should also be functioning as intended.

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