Your Chance To Vote...front caliper pistons

This is the state of the pistons on my front brake caliper, after a clean up. Take a close look.



Tomorrow I am going to push those pistons back into their housing in order fit a new brake disc and new brake pads.

If you care to, let me know on a scale of 1 to 5 what you think the chances are of those pistons damaging the bore seals, naturally this will lead to a fluid leak. Remember, those pistons will have to go 'flat' to the caliper housing.

Scoring: (1 being 'no chance' and 5 being 'no problem'.

I don't know how far back the seals are inside the bore so I reckon I'm in with a chance.

2ish to a 3. Clean the pistons as best as you can! Get that rust off of them and clean 'em up good. Pitting severity will determine if the seals will seep. If it was mine I would replace the pistons and seals. That would also give you the chance to see if the seal grooves have any corrosion. It seems no matter how clean you keep some brake calipers the pistons will get pitted. My old Helix comes to mind.

Would that be, “no problem”, “no chance” of “those pistons damaging the bore seals”, or what?

I’m in agreement with sc00ter, I’d replace the pistons & seals too. Especially if this is what you’ve got after cleaning the pistons.

Well, not the answers I was hoping for, however, the master cylinder reservoir is full of gunk anyhow so maybe I should clear the system and be done with it?

Oh Lord, I'm not looking forward to this.

I hate brakes, they just slow you down

I had a bear of a job pulling the calipers apart on my Swing but it had been sitting in a coastal location for a few years and they were well-seized. I can suggest that if you plan on pulling the pistons right out, the easiest way to shift them is simply pump them out as far as you can using the brake levers; you may need a handy-sized spanner or block of wood if one piston is moving more freely than t'other. Then clean off any gunge using a scotchbrite pad or similar (no scratchy!) and finish with some metal polish (I like Autosol). If the pits aren't too deep they will be fine to re-use, and chances are the pits will be outside of the inner seal anyway.

It doesn't look good. I'd be tempted to pump the pistons right out and see if you can clean them up better.
But photos can be deceptive, that corrosion might be smooth enough for you to get away with it.

Brake systems---new parts work best ....if you like stopping!

My thoughts, are you going to keep it and ride it and like not having the same problem down the road? replace and start anew. More than once on various problems I've found " just fixing to get by" means a do over sooner or latter.

Loosemarbles
No compromise, it's your life mate. Just buy new pistons & seals, then enjoy the ride without thinking......... I wonder if they will still work next month

What are they putting on roads over there? I know your bike is old but that's a lot of rust. 1-2 they will leak in the future but who knows? Look for the puddle under the wheel. Even if the inner seal area is not rusted it will be soon enough from outer ones letting water in.

I replaced the rear pistons a few years ago and they're already showing signs of pitting and corrosion around the exposed edge. I never take the bike out if the roads have been gritted, the salt just eats anything it touches.

OK, so the caliper will come off and I'll clean it up and fit new pistons. My next issue is the state of the fluid reservoir here:



I have a spare (below) but as you will see it doesn't look much better.



I'll get it professionally cleaned up but can that corrosion be treated before I reuse it?

OK, voting is now closed. I've stripped the caliper and discovered something quite useless but interesting.

The seals in the caliper bores are far enough back to have allowed me to have pushed the two larger (front) pistons back into the bores without the corrosion on the pistons from reaching the seals. Not so with the smaller (rear piston), that seal sits very close to the top of the bore and would have succumbed to leaking immediately from the corrosion. Just to be 'nurdish' I'm going to measure the precise distance and post it on the end of this thread....if this thread ever ends!

Anyhow, the caliper has gone off to be refurbed and rebuilt so that when it comes back it will be ready to fit back on the bike with new pads to be fitted. BTW, there is a company in Chesterfield UK who do this refurb and rebuild stuff at very reasonable cost. By the time you've costed separate pistons, seals, banjo bolt washers and all the rest of it, it makes having it done by these people a no brainer. Incidently, Honda are in the throes of discontinuing supply of the larger pistons for the front caliper. However, Powerhouse have them in stock, stainless too.

As for the front reservoir, I'm going to choose the best of the two and have one of them cleaned up by local blasting company. Then it's all down to a new reservoir piston kit, a refit and bleeding the system.

I don't know if this next bit has been covered before but I decided to 'bung' the rear lever's brake pipe by pushing an audio XLR plug 'strain relief' onto the banjo hole. The strain relief is slightly conical and went in nicely and so far is not leaking. I'm hoping this will stop the rear brake reservoir from draining and will avoid me having to bleed the rear brake as well. It was my better half who thought of using this strain relief while I was wandering around the living room, deep in thought, muttering..."what do we have that's shaped like a conical tube-like piece of rubber???? It's not the first time that she has resolved one my unresolvable technical issues!

To stop the fluid gravity draining out of the open banjo, one can tie the lever back to the bar at the master; that seals off the fluid intake in the master and stops the dribbles. Sort of counter intuitive but it works, and the same applies to bikes with a hydraulic clutch (which can otherwise slowly push the slave piston out when the slave is dismounted off the pushrod).

Good idea or take rubber cap off of bleeder screw and seal line or master cylinder fitting.

Well gents it's my thought but if I were going to go through all the trouble of replacing and repairing I'd want a full system bleed with fresh fluid from a sealed can. One of the handiest EZ tips I've used is tying back the brake levers and letting it sit overnight after I bleed the systems.

I think my decisions on this proved to be compatible with many of the above comments on this issue.

Here's the upshot: I have fitted new discs and pads back and front. Brand new Honda master cylinder sub assembly. Fully re-conditioned front caliper. New oil seals everywhere. But when I came to bleed the whole system with fresh brake fluid....nothing! Fluid going in and fluid coming out but no pressure. See 'Brake Bleeding Nightmare' on this forum, it's an epic.

I tried my suction pump and the old fashioned way of bleeding without results. In the end I got my local shop to, "collect the bike, get the freakin' brakes working and bring my baby home when it's done". She comes home tomorrow.

In conclusion, I've decided that 'Honda FJS600 brake bleeding' should be included into the national education curriculum, even onto degree level. I know, some of you out there will be thinking....'for goodness' sake, it's not Rocket Surgery'

Please let us know what your shop did to resolve the problem.