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i need to rebuild a hope tech3 e4 caliper, it seems the stainless steel pistons (of the tech4 variant) can now be had off a few suppliers. HBSP432, has anyone fitted these to the older caliper.
looking at the exploded diagrams all the seals/borecaps are the same size/part no.s etc
https://www.hopetech.com/_repository/1/documents/E4-Caliper-Exploded-view.pdf
Not tried it yet but I'm sure Hope said they were backward compatible.
I could use a bucket of these (well, 32 to be precise).
Having said that, I'm not sure what problem I'm suffering that these would cure.
Plus, I've just stripped, cleaned and bleed them all so I don't fancy going through that again too soon.
Why use stainless pistons?
Hope will refurbish calipers for not much more than the cost of a set of pads iirc
Why use stainless pistons?
The piston sides suffer terribly because as the pad wears more and more of it is exposed,.
What you get is a roughened surface that doesn't want to return when you fit new pads.
Previous stainless pistons
Which are those 😕 Hope to my knowledge have never used SS for piston material.
Discussed on a recent pod cast, pholenic pistons cope with the generated heat better than stainless but need regular lubing or they get sticky. Previous stainless pidtons needed less lubing but don't cope with the heat build up as well. The new stainless pistons have a pholenic insert iirc so get the best of both.
Here it is
Which are those 😕 Hope to my knowledge have never used SS for piston material.
The older 2 piece callipers.
My 2002 M4s had metallic pistons which I assume were stainless after listening to the podcast linked above.
The phenolic pistons are much more fragile too, prone to chipping. Less maintenance with the new stainless ones, win win.
First gen Monos were steel as well, the first change to the lineup was phenolic pistons. Pretty sure they were stainless as none of mine have ever rusted.
i fancied ss as i had wrongly thought hope were fit and forget, which after 3 years of no lube the previous pistons had a few chips and one had to be drilled out.
i quite enjoyed stripping down and reworking the caliper. therepeutic
I was keen to try this, my 2 pairs of E4s are forever needing lubed so I'm keen to try them. Last I heard from my local shop was that they couldn't get them yet. Where have you found that is selling them? Cant see anything obvious on Google yet.
Activesport on eBay have the smaller size:
@balfa, as ta11pau1 says activesport on ebay, also has a website (buxton based) , stuck them in my basket and got a 5% offer, but rang my local shop and they've managed to order them in, i had a ebay search email alert setup, as activesport said it was unlikely this year, when i messaged him 3-4 months back..
these pistons have ended up costing me more than my pair of tech4 V4 brakes i got off wiggle when they launched :0(
First gen Monos were steel as well, the first change to the lineup was phenolic pistons. Pretty sure they were stainless as none of mine have ever rusted.
That would have been the inner core. The outer bit was alloy, with a loose fitting inner section that vibrated in use, which is why minis squealed like they did.