Worth getting a piston press/seperator?

londoncommuter

I'm fancying some bike fettling this weekend and was going to have a look at replacing my first ever set of disc brake calipers. Is it worth getting a piston spreader tool or just bodging it with a screwdriver? Does that change if, on inspection, the pads are fine?

I can get a Park one for £12 so I'd probably go for that over a few quid less for Superstar/Wiggle etc:

http://www.chainreactioncycles.com/park ... -prod37248

How long should pads last by the way? I've only used mine for around 9 months on 12 mile round trip commutes / I'm not heavy and don't brake that much. On the counter to that, I suspect they've been rubbing slightly so may have worn slightly faster than that would indicate.

Thanks

cooldad

Assume you mean changing pads, not caliper.

Just use a screwdriver before you take the old pads out so the pistons don't get damaged.

And how long is a piece of string....

veronese68

What CD said, screwdriver between the old pads if you're going to replace them.
How long the pads last can vary greatly. In wet or gritty conditions they tend to wear out faster. Different pad materials vary in durability as well.

londoncommuter

cooldad wrote:

Assume you mean changing pads, not caliper.

Just use a screwdriver before you take the old pads out so the pistons don't get damaged.

And how long is a piece of string....

Sorry, yes, just pads.

I suppose the reason I ask is that there is a reasonable chance the pads are fine so I didn't want to a) gouge them with a screwdriver if that could happen and more importantly b) it's always cool to get new tools.....

In reality though the tools do just look like a pointy bit of metal so a screwdriver looks fine and even if it was essential I guess would only be used once a year so not worth getting a fancy one.

I was just going for the G02A-R resin pads (for 105 caliper) at £8 a pair. Any reason not to?

cooldad

Just look at the pads in situ - you can see if they still have enough material left.

joey54321

Put a bit of cloth/old tshirt/washing up rag over the screwdriver first if you are worried about gauging the pads, though I think this is even more important if pushing the piston directly.

pilot_pete

Or, just undo the retaining bolt with a screwdriver, remove the pads, inspect them, then put them back in if they are ok. I’ve not had pistons close with the pads out if I haven’t pulled the corresponding brake lever. If you need to put new ones in as the old ones are worn, then simply slip the old ones back in, use a screwdriver to spread them before remov8ng and replacing with new...

PP

buckmulligan

Not sure which calipers you have (you said 105, but there aren't any actual 105 branded calipers) but I would strongly recommend against the screwdriver method up against the pistons directly.

You can get away with it on MTB calipers that have metal pistons, but road calipers are more commonly fitted with ceramic pistons and you run the considerable risk of cracking them and plunging yourself into a world of mechanical grief.

As others have said, just look at the pads and see how much material is left, there's no need to touch the pistons at all unless the pads need replacing. If you do need to push the pistons in, use a proper press or anything with a large flat surface that ideally covers the whole surface of the piston, not a screwdriver or allen key.

cooldad

Or, as has been mentioned a few times, push back, then take the old pads out.

veronese68

BuckMulligan wrote:

If you do need to push the pistons in, use a proper press or anything with a large flat surface that ideally covers the whole surface of the piston, not a screwdriver or allen key.

Like leaving the worn pads in there to push against?

buckmulligan

Yes, that is a possibility, but as mentioned that (1) may damage/contaminate the pads if you're planning on reusing them and (2) increases the risk of pushing the piston back wonky and getting it jammed.

The latter is fairly easy to do on the BR-RS785 calipers that I have on my road bike so I'd recommend taking the pads out and using an appropriate tool.

I speak from bitter experience :oops:

Never had a problem in many years of messing around with bulkier and sturdier MTB hydraulic calipers (bigger caliper bodies, deeper pistons, metal construction); IME you have to be more careful with the road stuff.

londoncommuter

Many thanks for all of the comments so far. Mine are the same BR-RS785's. Anyone else had issues with these or was Buck just unlucky?

graeme_s-2

I tend to use an old metal tyre lever to push mine back in. I've used a butter knife before. Seems to work fine.

I've used the following pads, all on the same commute, all year round, on the same bike, rotors etc:

SRAM organic - 1,057.7 mi (seem to recall these had a bit of life in them when I changed them, but I'd already taken them out to inspect so stuck the replacements in)
Superstar organic - 3,523.2 mi
SRAM organic - 1,431.2mi (these are now down to the backing plates, and the bike is sat in the garage waiting for me to fit some FWE organic pads from Evans)

Unfortunately Superstar haven't had the pads I need in stock for ages now. Be interesting to see how the FWE ones last.

(my experience is all with SRAM Rival 22 hydraulic callipers).

veronese68

BuckMulligan wrote:

Yes, that is a possibility, but as mentioned that (1) may damage/contaminate the pads if you're planning on reusing them and (2) increases the risk of pushing the piston back wonky and getting it jammed.

Agreed on point 1, but if not replacing the pads you shouldn't need to push the pistons back. I understand shouldn't doesn't mean the same as won't.
Not managed point 2, but I've not got Shimano road hydraulics.

cooldad

AFAIK Superstar have stopped bringing pads in - they are concentrating on stuff they can make here.

Really annoying as all I've used for years have been their kevlar pads.

graeme_s-2

They said something similar to me when I was looking for new pads ~1,400 miles ago. Annoying indeed!

buckmulligan

Yeah, same here.

Emailed them a couple of months ago asking about availability of one of their out-of-stock pads and they basically said they wouldn't be getting any more stock in.

Disappointing as they were great.

graeme_s-2

Evans FWE organic pads come in the SRAM road shape, and are cheap. Just need to see how well they work and how long they last now!

https://www.evanscycles.com/fwe-sram-ri ... s-EV266311

pilot_pete

I use Uberbike pads in my RS785 calipers. They do various compounds. I find them superb.

PP