[Clogan]

Well, I feel like a dummy. Bled the brakes before using only the bleeders down on the wheel, by the calipers. This time I used the bleeder up top on the hand brake lever assembly. I got bubbles. Now the front brake is good as new. Be interesting to see if problem recurrs. Hope not. Anyhow, I'll not be needing a rebuild kit or new assy.

Lesson I keep learning over and over: try all the easy stuff first!

 

[Clogan]

Sorted! Great! I missed this whole thing but I did want to chime in. First, I have swapped out a stock m/c on an Aprilia with a Brembo RCS and, HOLY COW!, it was great. A really good m/c is absolutely amazing. Second, do you know of the trick for removing bubbles from the lines by zip tying the lever to the bars overnight? I have to do that regularly with both the front and the rear brakes on my GT to keep the lever/pedal feeling firm so I don't think you are all alone on this.

Interesting you should mention the zip ties. I'll make a note of that.

My bike had been sitting up for a bit over a month, while we enjoyed the holidays and endured an unusual cold snap. I typically ride at least weekly, so I wonder if the 30-day lay up had anything to do with the brake getting so mushy? Hmmm...

 

[Clogan]

Thanks for the lead, but it appears that your part is for a 12mm piston. I'm pretty sure (not positive) mine is either 15mm or 16mm.

Clogan~ For reference - I rebuilt my '15 front master cylinder with KTM's kit (part number #: 61302032000). It may be different for the GT's however this may help. Note: I also replaced the slave with a Rekluse version.

 

[Clogan]

FWIW, the good folks at KTM World, where I often buy parts, tell me that there is no rebuild kit from KTM for my bike. They recommended buying the entire front brake lever/reservoir/bracket assembly, costing $400 or so. Before I do that, I may just try to disassemble mine (if disassembly is possible), clean it, and put it back together. Seems prudent before spending $400.

Wonder if Brembo sells rebuild kits?

Anyhow, most folks are closed today for the New Year's weekend. Guess I'll wait until next year.

 

[Clogan]

Did you do the work on the master cylinder, or did you have a shop do it? Do you recall part number for MC repair part? My lever slowly "leaks down" as I squeeze and hold it, so I'm pretty sure it's the MC. I'd prefer to buy a rebuild kit vs. a new MC due to the cost.

I just had the same thing happen to my 2017 SDR. This whole riding season was a total waste. Broken radiator, leaking clutch slave, lost the friction material on a front brake pad, then the front brake master.

Thank god this thing wasn't expensive...