Shimano BR-RS505 repaint project

[familyguy]

I pulled my Cube Attain apart last weekend to start a rebuild process. The condition of the calipers was surprisingly shoddy. The corrosion is evident in the photos. I know the bike wasn't immaculately looked after prior to my ownership, but it was under cover and cleaned off now and then. I've bike-washed it every month or so. So I started debating myself about just ditching the 105/505 setup and sourcing an update for brakes and gears.

Then I thought why not just repaint the calipers, properly channel my inner 19 year old car owner self? Nothing to lose, aside from two calipers, which, being honest, I'm open to admitting I'm a little snobbish about putting back on in this state.

Front:






Rear:







I've seen a few Shimano brake calipers around this era looking like this, even some later/higher models like Ultegra. Terrible paint? Poor prep? Bad metal? Poor maintenance? Dunno. It's not salted roads here, that's for sure.

Based on the video below, I know what should be in them once they're apart. There is a window later this month of a weekends access to a sandblast setup with beads or soda to get them cleaned up.

[antigee]

" It's not salted roads here, that's for sure."

Pom and very happy to have stopped dealing with the (expensive) impact of salted roads....would say that the first rental we lived in here in Melbourne had a pool adjacent to the large open carport...definitely a lot of unexpected corrosion damage to items left out in the car port presumably wind blown corrosive chemical bearing water vapour from the pool

[dmwill]

Seems to be common on the older non-series Shimano calipers.

I'm guessing it's a combination of:

Galvanic corrosion with different metals (the retaining screw is known to get seized and corrode).
Brake dust from sintered/metallic pads and a lack of care/cleaning.
Maybe a history of being ridden in coastal or wet areas.

[familyguy]

It's a 2016 bike, so I'm betting this is mostly due to age and lack of a little cleaning now and then. I don't think it lived coastally and had resin pads in it. Looking forward to getting these apart on the weekend, then maybe blasted if I can sort the timing.

[familyguy]

Spot the fault.



Pretty sure the piston had a hairline crack in it. Pushed them out with a little air and it blew apart in the caliper. Others fine. Explains a slight sponginess in rear brake, too.





Cleared off the more corroded and bubbled areas. Sandblasting done (not pictured), paint tomorrow.

[baabaa]

Spot the fault.

This man is a dentist so we cant show you his face?

[familyguy]

Never underestimate the usefulness of a dental pick in the workshop!



Primed, awaiting paint yesterday. Did that later but left them in the shed so they can dry. Metalshield gloss enamel takes quite a while to dry to a decent hardness.

[MichaelB]

What’s the plan to replace the cracked piston ?

[familyguy]

Unless I find a dead caliper someplace, aftermarket it will be. Shimano doesn't sell replacement pistons as small parts. There are various ceramic or aluminium body/ceramic insert versions available. Lots of forums saying "just buy a replacement caliper, you get new pads with it and they're pretty cheap". Well, sure, you can downgrade it to Altus level for $55 new, or go up to straight replacement for $90. Yeah, nah.

[familyguy]

Got them back from hardening up. Aside from the one I dropped before it dries, looks good.





Now to await pistons arriving and then reassembly.

[familyguy]

So the pistons have been delayed a little. The rebuild will still happen, so will come back to this. In the meantime, a lightly used R7000 groupset is on its way to me which I should hopefully have early next week for fitting

[familyguy]

I did have an idea though.

I found some other paint that would contrast nicely. I have a vinyl cutter. I have the 1970s Shimano logo as a PNG image.



You can see where this is going.

[familyguy]

So, had a bit of an issue. The black enamel was all nice, then I masked it to go acrylic over the top and it peeled the enamel off. To the bare metal. Very weird. I know enamel over acrylic raises issues, but this was a first. Anyway, plan B was to just repaint them in black. Which I did. As a result I have a very faint recessed outline of the mask, visible in just the right angle and light, which is kinda cool.