When the Suzuki RF600R rolled out of the van that the courier used to bring it to me from its previous resting place, it was clear that something was amiss with the brakes. The courier actually had to push it down the ramp out of the van he used and once on the flat, it was virtually impossible to move it by hand. In fact, it was almost impossible to move at all – the engine would barely pull the bike along as I tried to ride it out of the workshop to get some photos. Clearly, the brakes were binding on somewhere.
It’s hardly surprising – the bike had barely moved in the last two years and though it had stood in a garage, brakes are notoriously averse to anything other than perfect conditions. And by perfect, I mean humidity and temperature controlled…
Add to that the fact the hoses and quite possibly, the fluid, were as old as the rest of the bike and would have degenerated significantly over time, next on the to-do list was a full brake overhaul.
This kind of work is never tidy so lots of blue paper roll and off came the hoses with the subsequent draining of old fluid everywhere. The front calipers followed and hit the bench, followed by the rear caliper. It was at this point I discovered why the bike was hard to move; the rear brake caliper was a single, solid mess of caked-on grime and dust and rust – lots and lots of rust.
First things first; purchase the necessary ingredients. I was trying a new brake cleaner, an eco-blend from Qualkem that foamed from a pump bottle, rather than going on as a liquid so it would sit on the surfaces longer to start work. I also ordered up a set of braided brake lines with brand new banjo fittings from Hel and three caliper rebuild kits from All Balls Racing, comprising every replaceable part. Finally, I got a set of EBC HH brake pads that should work nicely on the road and give a little more braking power than stock pads. Oh, and a can of rubber grease and a bottle of new brake fluid.
I started with one of the front calipers, which came apart easily. A blast of compressed air into the fluid entry point and both pistons popped out obligingly. Things inside weren’t too bad – a bit of gelatinous brake fluid, a little corrosion but nothing too bad. A squirt with some brake cleaner, a scrape around the old rubber piston seal grooves, replace the rubber gaiters on the sliding pins (the RF uses sliding calipers on the front) and it was ready for reassembly. The new piston seals went in nicely and with a little rubber grease on them, the pistons followed and slid in and out smoothly and easily. This is simple, I thought.
Of course, those were famous last words. Disassembling the other front caliper, one piston duly popped out but the other refuse to budge. It would slide in but not out, no matter how much air pressure I used. It would move around 1mm in and out, so I got to work with water-pump pliers and WD-40, working it in and out until eventually, it popped out with a bang. Slicing my finger as it did. Joy of joys.
Like the other caliper, it wasn’t in bad condition. The stubborn piston and its bore were grubbier than the others but a bit of time – and care – and it was ready for reassembly like the other side. Once it was all back together, it too worked nice and smoothly.
The rear caliper, however, was a different story. The Suzuki uses a split rear caliper with a piston either side of the disc. Getting the caliper apart was straightforward – the massive bolts came loose easily. However, once apart, it was clear why the brakes were binding – it was solid. The brake pads were virtually welded to the guide pins with rust and I had to use a good dose of BFI (Brute Force and Ignorance) to get them out. With the two halves of the caliper on the bench, one obliged and popped its piston out – surprisingly. Not surprising was the other half resolutely refusing to budge.
Knowing heat can be your friend at times like this, I literally boiled the caliper alive for a couple of hours to see if it would help free things up – it didn’t. In the end, I realised the pistons had castellated grooves inside and I managed to cobble together a rod welded to a socket to get the piston spinning. Like the front caliper, continued use of WD and turning it eventually got it free enough to pop out, at which point the full scale of the horror was revealed.
It was no surprise it wouldn’t budge. There was so much muck and goo behind the piston seals that they were standing proud and gripping the pistons. It took quite some time to clean them up enough that the seals would fit in flush and I spent a couple of evenings searching the internet to see if I could source a better example to begin with. I couldn’t, so I persevered and eventually, got all the alloy corrosion, degraded rubber and brake fluid and the remains of brake dust out of the caliper and put it back together.
By now, I had three working calipers so I refitted them to the bike and set about the new hose set. I retraced my steps with the new hoses, starting at the rear and filled the fluid reservoir before sucking fluid through to the caliper with a vacuum pump, through the bleed nipple. This took a while but eventually, nice new fluid flowed and with my trusty assistant Noah acting on my shouts of “Pump, hold it down, pump” and so on (a father-and-son ritual as old as the Internal Combustion Engine), we had both sides of the caliper bled. A quick check revealed that not only did the rear brakes seem to work to stop the bike moving, they also released perfectly with no binding. Excellent.
Up front, the bike originally used a single hose from the front master cylinder to a splitter block just under the headstock, with a hose from that to each caliper but I’d opted to go for a set of Hel lines that did away with that splitter and used two hoses straight off the master cylinder, one to each caliper. Fitting was fairly straightforward until I came to the calipers themselves.
Up to this point, I hadn’t really noticed that the Suzuki used two different threads for its brake fittings. The rear master and caliper and the front master were one size (M10 x 1.0) but for some reason, the front calipers were different (M10 x 1.25) and the instructions for the Hel lines (which of course I read thoroughly) stated that some Suzukis use more than one thread. The kit had come with all finer-threaded banjos but a quick call to Hel and there were two of the right fittings on my desk the next day.
Getting fluid to the front calipers was more of a task – I left the bleed valves open and allowed gravity to do some of the work and finished by pulling fluid through with the vacuum pump again. Once we’d bled both calipers (farthest from the master cylinder first) the front matched the back in terms of operation – held the bike firm when pulled on and allowed it to move freely when not.
It’s worth mentioning that this was after I’d measured each of the discs for the correct thickness with a micrometre and measured them for run-out using a Dial Test Indicator (DTI) – all were well within spec and as the disc surfaces were in good condition, I left them alone.
So it goes and stops now – the final task before tip-toeing to an MoT test is to make sure it handles. The front suspension feels a bit loose, so the plan is to whip the front forks off and rebuild them and get fresh oil in there. The rear shock is, apparently, not rebuildable so I’ll simply set it up for my not-inconsiderable weight (it has adjustable preload) and give it a gentle run to the test centre and see how we get on. Oh, and a pair of tyres of course…
Hel brake lines
EBC brake pads
All Balls Racing rebuild kits
ProShot brake cleaner