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I have a 2009 Triumph Tiger 1050 that gets ridden very rarely.

Took it out this morning and the front brakes felt very ineffective - looked at the wheel and it seemed like there was a bit of oil on the sidewall of the tire, and the brake rotors (at least on one side). Not a river, but enough to wet a 3-4 inch section of the sidewall.

I cleaned it all off and left it sitting with some clean shop rags on either side and wrapped around the fork. Checked the brake bleed valve and where the line connects in - all could tighten up a little but not crazy loose. Forks had a light coating of oil & dirt, nothing too crazy, but not bone dry. Pumping them up and down hard a few times didn't produce an obvious leak.

Any suggestions on how to diagnose further? I know I will need to soak pads & rotors in acetone and/or replace pads, but I want to find the source of the problem first.

  • Oh, and I checked the brake fluid level - looks about middle of cylinder on handlebars. – lunix Jul 31 '18 at 13:56
  • Was the wet sidewall originally below the caliper? Have you checked the pistons? And do you know the difference between oil and brake fluid? – Solar Mike Jul 31 '18 at 14:18
  • Unclear where the wet sidewall started out, as unfortunately I set off before I noticed. I know that oil and brake fluid are different, but not how to identify them from each other .... to be more precise, I noticed an oily residue that could have been either oil or brake fluid. I had assumed the forks were hydraulic and contained oil (ie were another possible source of the contamination) but maybe that's not true. Not sure what I'd check on the pistons other than visually for leaks and maybe that they were moving OK and not stuck – lunix Jul 31 '18 at 19:36
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It's not oil or fork fluid, I think you have a leak in your front brake caliper (whichever side you saw the fluid on), which is why your braking seems ineffective:

  • You're losing brake fluid, which is why your brake fluid is low in the reservoir
  • Air is being sucked into your brake lines, air compresses so they are spongy

As for what's happening my guess is that you have a failed gasket in the caliper. You'll need to replace the caliper with a new or refurbished one, or refurbish it yourself with a gasket kit which isn't hard to do. Once you do that you'll need to bleed the system thoroughly to get all the air out. Also clean the pads, rotors, etc with brake cleaner.

If it were me I'd do both calipers; if one side went then the other may too.

  • Seems to make sense, but the I've had the bike from new and it only has about 7000 miles on it. Wondering if there's some way to confirm it ... wrap the caliper in paper towel and squeeze brake lever hard repeatedly ? – lunix Jul 31 '18 at 15:24
  • That's a test I'd recommend @oxfl, however you'll need to bleed it first as if there's air in the system you won't get any fluid out. Make sure you keep your brake reservoir full as you do it, and use the right fluid! 7000 miles isn't that much, but the fact is the fluid is there so something has failed. – GdD Jul 31 '18 at 16:12

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