Contaminated
26 Apr 2011

Contaminated

Thought I’d fixed the disc brake probs (rear stuck piston and front leaking

26 Apr 2011

Thought I’d fixed the disc brake probs (rear stuck piston and front leaking fluid) as everything seemed fine during the 3 hour enduro. Even though the average lap speed at the enduro was relatively high, the max speed each lap was relatively low, with only a few light squeezes on the brake needed to make it around the course. It was a really enjoyable ride but I guess didn’t test the brakes enough provide a definitive verdict on my maintenance efforts the previous day.

Yesterday I headed out with Julien for a short afternoon spin at the Hippie Track. Descent speeds on the hippie easily push past 50km/h when you’re having a crack at it, and includes several critical braking points. The whites of my eyes lit up like a Christmas tree when I arrived at the first braking point and squeezed the brakes to find both the front and rear brake were very close to MIA, not much retardation. Eek.

I then did some low speed tests and was amazed at how little braking there actually was regardless of how hard the levers were yanked, and how weird the brakes sounded. Looking at the generous build up of dust around the brake pads front and back I must’ve been way too heavy handed with the drops of oil around the pistons, and more importantly nowhere near particular enough cleaning everything up before re-assembly, leading to contaminated brake pads front and back. Dirty bird, DOH!

Everyone seems to have their own method of dealing with contaminated brake pads – wipe them, soak them, boil them, bake them, torch them, sand them, file them, fry them, toast them…  I opted for the one method everyone agrees works — replace them, and clean the rotors. At  ~0.5mm the rear pads needed replacing anyway, might as well do the front pads too.

New pads, clean rotor but still ShittleLX brakes

New pads, clean rotor but still ShittleLX brakes

I was very particular this time around with cleanliness – a bunch of clean rags, clean cotton buttons around the pistons, clean hands when installing pads.  I cleaned the front and rear rotors with Isopropyl Alchohol, sourced from the local chemist. By this stage there was way too much clean for a machine that fangs around in the dirt — it was freaking me out 🙂

Isopropal Alcohol AKA rotor cleaner

Isopropal Alcohol AKA rotor cleaner

Also lots of methods online when it comes to how best to bed in new brakes. There’s a sealed downhill road just over the hill from home so I just did half a dozen or so runs down stopping hard on each brake followed by one run down a nearby moderate single track descent.

First impression: Wow, fresh brakes equals a LOT more stopping power, sweet! So easy to stand the bike on its nose, I’ll need to reset the braking finger on each hand to ‘gentle’.

I’m hoping to head back out to the Hippie Track tomorrow if time permits for a few runs. Should make the braking situation clear one way or another!

Leave a comment
More Posts
Comments
Comment