Hi guys – newbie here to say hi and hopefully get some advice on disc brakes I am having some issues with……

Biked when I was younger – but work/life/kids etc etc got in way – based in Glasgow… engineer/motorcyclist/dad of 2/car nut….

In 2017 I got myself an Orbea Alma H10 27.5 2017. Unfortunately due to foot injury the bike saw little use with very little miles covered.

Link here –
https://www.tredz.co.uk/.Orbea-Alma-H10-27-5-Mountain-Bike-2017-Hardtail-MTB_95387.htm

Bakes Shimano M506/BR-M4447

I recently noticed that the rear brake was squeaking very loudly and despite taking it to a shop to be serviced with “I think there is a small oil leak” I was told that it was just road contamination, I went out after service and the disc was greasy and the VERY LOUD noise returned almost immediately. So I am concluding there is a leak……

So I was hoping someone could advise on the best course of action.

I believe it can only be the piston seal or the banjo bolt? Can either of these issues be repaired and if so what’s the reliability of the repair. Are these calipers known to have issues? Should I plumb for a straight replacement, and if so do I do the calipers or the lever and caliper as I note they come ready bled. Also what other considerations do I need to think about – rotor size/fitment/caliper mounting etc etc etc….

Please forgive me naivety but this world is all new to me. I have previously rebuilt motorbike calipers and can service and work on cars – so am sure am capable – but the options with regards MTBs brakes is just overwhelming me a little…..

Thanks so much

Hello and welcome.
It could be a few things: misaligned calipers, contaminated pads or disc so hard to pin down without seeing it.

By squeaking, do you mean this happens when you brake or does it happen all the time? Is it a squealing / honking sound or more scraping?

If it’s contamination then you can try cleaning the rotors with isopropyl or brake cleaner and even rubbing then down with fine grit Emery paper. Same with the pads but if they are badly contaminated then they may need replacing.

It is possible that you have a leak so to check you should clean the rotor and caliper well with isopropyl so you know there is no oil present then pump the brakes hard repeatedly and check again. If they are losing oil then the lever should feel spongy as well. Is that the case?

To answer some of above….

The leaver is spongy and braking force weak – when I have my kid on the back it can’t even lock the wheel…..

No noises under normal running but massive loud honk when braking

Don’t think misalignment as they worked fine for a while then this started and they do feel greasy when compared to the front.

I am on hols just now with no tools/garage – just a loud bike – hence the guessing – but I was just looking to have as much info as poss prior to starting the job when home

Leaking pistons is a common problem. Easy way to check is remove your pads and see if there is a circular patch of oil on the back from the piston.

If so replace the caliper.

Discs can be saved with a good clean using disc brake cleaner ( I get mine from Wilko’s) then a little heating with a blow torch to burn of the remaining contamination.

Shimano calipers from that era have a known fault that means they will leak oil if you are unlucky.

I should know, I’ve had one returned under warranty and another died just outside. But a couple of others which are fine.

Many *many* threads on this.

If it’s inside 2 years old, Shimano seem pretty good about replacing – take to your LBS in the first instance.

Otherwise buy a new caliper and switch it over – it’s pretty straightforward if you can follow simple instructions.

Since it’s mineral oil inside, you don’t have to worry about getting brake fluid spills.

HTH!

Since it’s mineral oil inside, you don’t have to worry about getting brake fluid spills.

Only if you don’t mind spilling toxic mineral oil everywhere.

If you’re not sure whether you have a leaking piston, clean them out with isopropyl alcohol, pop a bit of tissue behind the pad and give them a good pumping. That should produce a little ring of mineral oil if that’s the issue.

Sounds like it is though, and the only fix is a new caliper.

As mentioned above, Shimano don’t supply spare piston seals.
Means a new calliper. Any recent Shimano MTB 2 piston caliper will be fine, rotor size is determined by the frame/spacer fitted.
About £25, they come with pads.
I’d probably just look out for a deal on a complete brake if it’s not under warranty

Having suffered the same issue with this era of Shimano brakes (M785), I ended up so exasperated at the lack of Shimano spare parts and serviceability that I rage bought some Hope brakes knowing that if I ever had an issue I could rebuild them like a normal bloody caliper!
It wasn’t the cheap option but damn am I happy with the Hope brakes. Swapping over the caliper with a new SLX two-pot would’ve been a much more economical solution.

got nothing to say except welcome to the forum.

+1 for Hope brakes.

Yeah, I’d not buy Shimano again, I still have some hope brakes from 20 years ago. Should have learned from that.

Guys – thanks so much for posting – really helpful and has bolstered what I read from the tinternet…..

So my choices are pretty much going to be a straight swap caliper or a new pre-bled lever/cable/caliper.

So – anyone willing to suggest any specifics at all? FYI this is the type of cable connection I have – are they all the same?

If you go for an SLX caliper it will be a straight swap. You’ll just need a bleed kit. Epic bleed solutions do good kits and instructions

I think an SLX is a banjo bolt which mine is not….. happy to be educated though??

If it is then worst case is you’d need a new hose or I think you can get a straight to banjo adapter

Hey guys – so here is a wee update…..

Firstly – thank you all for the advice – its appreciated and defo gives me a practical way ahead…. So cheers…

I have spoken to the bike shop who sold me the bike and discovered the bike went out of warranty last month – so after a brief conversation the bike shop seemed quite willing to sort repair but not even remotely interested in contacting shimano or Orbea – as its out of warranty and that’s that…..

However – and please just accept this as my opinion and obviously they vary – I am a bit of a consumer warrior and under consumer rights 2015 – there is details of how long you can reasonably expect something to last and that is should be fit for purpose, regardless of what the manufacturer states and I have had some success in this area previously…

I did have a very brief conversation with the bike shop guy about this – and he seemed pretty unwilling to entertain this – given me ever excuse under the sun, from bikes being washed too little to too much, the type of rider use to Scottish weather and road salt etc etc etc and on and on….

BUT I don’t think it unreasonable at all to tackle Shimano on this subject, especially when, since researching I have come across plenty on the internet to suggest their product failures of this nature. My view on this is further bolstered by the fact that “your case” is significantly bolstered if you paid a premium for the product or service and I am quite sure shimano would consider themselves a premium brand…..

Are bikes different from anything else – if for example you bought a £2k Meile dishwasher rather than a £300 candy one – and you were well up on this consumer stuff I am pretty sure you would take them to task if it failed….. are bike makers somehow different – I was warned bikes just aren’t made how they used to be and require lots of servicing and money spent…. So whats going on….. do they just sell “cr@p” and get away with it…..

I do FULLY appreciate the easiest plan is to fit a new caliper (given the cost) and crack on……. But it aint me jack – it aint me 

Discuss?

stubobby- I am wholeheartedly with your intentions. When I buy something I really do expect it to be fit for purpose. And that is for in excess of one year. A larger and larger number of organisations are realising the benefits of ‘good’ customer service if they warranty their kit after 12 months but unfortunately not all do so yet.

Sounds like the problem you have been having is similar to the one I had. After asking and thinking about trying to change pistons I eventually followed the advice in this old thread and fixed my brakes for a matter of pence – well happy.
In my case it seemed to be that lack of frequent use cases the o-ring between the two halves of the caliper to fail. Not sure about more modern versions of Shimano caliper as I am living in the past 🙂

stubobby – do both. Shimano have to change something about the design as it’s a common occurrence. But for speed, I would also just get a caliper and a bleed kit and get it fixed, so you can ride and fight your case at the same time.

So, who else’s birthday is it today then?

Paul McCartney.

Same page you and me mate – for the costs involved I’ll just fix it – but defo be writing to Orbea and shimano….. anyone got UK CONTACTS for them 😂😂😂