Mate gave me her bike to look at as her brakes didn’t work. That was an understatement, both levers pull completely to the bars. Now I’ve had spongy brakes before, but both just not even moving the pistons when pulling to the bar seemed rather odd. Removal of both sets of pads revealed oil contamination.
My assumption is that having not used it for around a year the seals have rotted or something, however seems odd that both are like that. And there wasn’t huge amounts of oil that I could see.
Brake caliper is an m447. Are they known for doing that? Not really familiar with shimano mtb brakes, trip to bike shop worth it? Or is it new caliper(s) time?
If you've infinite time to spare then they might be recoverable - possibly with new seals/o-rings. However, the price of replacements is so low that I don't think it makes sense to try to fix them.
This would do.
It's worth a flush with fresh oil - like run it though a bit. It's amazing how black and cruddy looking it can be, yet fresh oil and bleed they are good to go.
I boiled my front brake in Spain. At home the pad was glazed, rotor blue tinged, and oil was black. I sorted them when I got back. Yesterday I managed an endo without problem...
I’ve not had m447s but i’ve got various iterations of shimano slx brakes. Slx tend to go soft (long throw of the brake lever) if not used for a few weeks, especially if hung vertically on a wall. They come back to life with a few pumps of the lever, or in the worst case a quick bleed. The m447s are mineral oil and look to have the same bleed port on the lever as slx. The slx ‘funnel type’ bleed system is excellent and easy to use and i think m447/m445 uses the same. I’ve had no seal failures across many bikes and many years so unlikely that’s the problem.
<edit> woops missed the bit where OP mentioned brake pad oil contamination</edit>
If you’ve infinite time to spare then they might be recoverable – possibly with new seals/o-rings. However, the price of replacements is so low that I don’t think it makes sense to try to fix them.
Kinda what I’m thinking!
Probably leaking calipers, a known Shimano problem. Not too expensive to solve if you can find stock, Altus calipers retail at £14.99 inc new pads, but importers have no stock at the moment.
It’s worth a flush with fresh oil
New pads + oil is more expensive than the brakes linked above. I’d just be throwing them at it
Me, I'd spend 10 minutes an end on a bleed, if that doesn't seem to fix it I'd replace the calipers.
After a quick bleed they'll be one of three things: fixed, seem fixed but give up after a bit of use or no better. In cases one and two you'll not notice in the stand and I'd wait and see - if it's been sat in a garage that long chances are the failure isn't going to be catastrophic given fair warning the use the bike is likely to get.
I had a pair of Deores both fail at the same time. It put me off Shimano brakes.
You can get a set of Clark M2 brakes with rotors for £60 from a number of places.
Was just going to post what was said above.
I had a similar issue when building another N+1 bike for my good lady last week.
In my spares bin I've got about 10 Shimano calipers, 4 levers and a good number of disks.
Was prepared to get a set working out of them but remembered seeing a few threads here about the bargain Clarks kit.
3 days later I had a front and rear set with 180/160 disks for £65 delivered , direct from Clarks ebay store.
Came assembled and ready to go, although I needed to split the rear to go through the frame. Luckily they also had a barb and olive per end and went together really easily.
Not sure how it is done for the money truth be told but, the brakes seem to work really well once bedded in.
My spares bin is now scrap metal bin. Lifes too short.
