Transalp Rear Brake Leak

Marvo · Mar 3, 2016

I have a Honda Transalp and recently took a bit of a tumble a week ago whilst I was navigating a steep ravine. A couple of broken bones in the back of one hand and some rib damage I've been taking brandy for but the problem isn't the scrapes and bruises to myself, they'll all heal, the biggest worry was I noticed hydraulic fluid leaking onto the wheel rim from the rear brake caliper.

First time I saw it I cleaned up the leaked fluid from the brake disk and wheel rim meticulously so I could look the next day and figure out exactly what was leaking and where. Next day there was nothing, everything was bone dry. I took the bike for a quick 10km run and gave the rear brake a workout. Even then there was still nothing.

I thought it might have been a once-off thing because of the bike having been upside down during the tumble but I kept an eye on it every time I walked past it just in case.

Then yesterday out of the blue there was fluid visible again on the disc, the wheel rim and the wall of the tyre. The bike hadn't been ridden or moved so I was puzzled as to what the heel might be the cause.

telectrix · Mar 3, 2016

voodoo.

Marvo · Mar 3, 2016

I whipped out the compressor and impact wrench and removed the rear wheel and the brake caliper. I removed the pads and cleaned it up and took off the dust covers from the pistons. Everything looked immaculate, no signs of weeping or leaking of fluid. I put the caliper over the brake disk and put the system under pressure, still nothing. I left it under pressure overnight and even then everything was still dry as a bone.

I was officially stumped, I could hell find a leak so I reassembled everything and took another test ride to confirm and still nothing.

Then this morning there was more fluid visible on the rim but after getting upside down under the caliper it looked dry. I was officially depressed by this stage and just cleaned the leaked fluid up with a view to further investigations this evening.

Barry White · Mar 3, 2016

Just a thought I wonder if when riding it the fluid is burned off and when stood its leaking but that dont explain the leak not been apparent when stood earlier. I am not familiar with bikes are the fluid reservoirs sealed (therefore affected by barometric pressure) or are they vented like cars?

Marvo · Mar 3, 2016

Arriving home this evening I unlocked the house and started to get my tools out ready for the next round. As I'm walking down the driveway dragging the compressor behind me I see the dog walk past the bike and barely breaking his stride he cocked his leg up at the back of the bike and released about 5cc's of **** on the rim of the back wheel. He took one step and slightly altered his angle of attack and promptly released another 5cc's on the pile of tools next to the bike.

Luckily for him I couldn't catch him, my ribs are too sore to run at any speed but after about 4 hours of work the mystery was solved.

[ElectriciansForums.net] Transalp Rear Brake Leak

ruston · Mar 3, 2016

Marvo said:
Arriving home this evening I unlocked the house and started to get my tools out ready for the next round. As I'm walking down the driveway dragging the compressor behind me I see the dog walk past the bike and barely breaking his stride he cocked his leg up at the back of the bike and released about 5cc's of **** on the rim of the back wheel. He took one step and slightly altered his angle of attack and promptly released another 5cc's on the pile of tools next to the bike.

Luckily for him I couldn't catch him, my ribs are too sore to run at any speed but after about 4 hours of work the mystery was solved.

View attachment 31685

Classic. I hope you didn't lick your finger to see if it was fluid.:smile5: