Slow return on hope brake lever piston.

[ishaw]

I've recently built a bike for my wife and fitted some hope tech x2 brakes. Before I fitted them I'd had them stored for a while and noticed one lever was slow to return when activated. I've shortened the hoses (small frame) and completely replaced the fluid and given them a good bleed but the one lever still returns slowly. You can see the piston slowly returning to full extension at the lever. This speeds up through use but I'm keen to understand if this is caused by an underlying issue that needs sorting or if it is just down to lack of use and will sort itself out when used more frequently.

Any thoughts wise people?

Cheers

 

[itscervo]

Lever pivot bolt too tight ?.

 

[ishaw]

The lever is fine, it returns fine, the piston initially follows behind and eventually returns to full extension. As mentioned, this only happens at the start of use and after a few pumps of the lever, it seems to speed up, it's just not as quick or consistent when compared to the other side.

 

[02gf74]

at least three things push the lever back - spring inside the brake, the spring between the pads (SRAM, Formula and Shimano have these so expect hope too) and the seals distorting at the pistons.

Worth removing the calliper and checking condition of the pistons - steel pistons will corrode but I'm guessing they are stainless for Hope and other brands? Clean them by pushing out each one at a time and put a drop of brake fluid to lubricate then as you push them in.

It that fails, then you need to take the master apart ; may need new seals or spring or ?

To rule out which it is, swap over the brake lines as see if the problem moves.

 

[ishaw]

After some frustration today I reckon it's the master cylinder/piston. My reasoning is that unlike the rear brake which returns fine and is nice and clean, the front seems to cover itself in some dark oily residue after a few pulls on the lever. I can also hear a slight squelching when pulling the lever which isn't evident on the other one.

Research suggests a rebuilt kit and/or a new master cylinder is in order and looks fairly straightforward to fit. I reckon I'll give it a go.

When I do this I might as well check the pistons. When I pushed them out, will I end up with a floor covered in fluid?

 

[cherrybomb]

After some frustration today I reckon it's the master cylinder/piston. My reasoning is that unlike the rear brake which returns fine and is nice and clean, the front seems to cover itself in some dark oily residue after a few pulls on the lever. I can also hear a slight squelching when pulling the lever which isn't evident on the other one.

That makes sense, slow lever return is normally caused by air in the system. If it's leaking, then there will be bubbles!

Research suggests a rebuilt kit and/or a new master cylinder is in order and looks fairly straightforward to fit. I reckon I'll give it a go.

Try a rebuild kit, Hope brakes are reasonably easy to work on.

When I do this I might as well check the pistons. When I pushed them out, will I end up with a floor covered in fluid?

Oh yes.

Use a container of some sort. Get the calliper down into the container and push the pistons out SLOWLY.

 

[ishaw]

Cheers, I've watched a few vids on the process so know what I need to do now. Most seem to recommend using the hope bore tool to get one piston out, but it seems a bit superfluous unless I want to change the bore colour (which I do to a degree, but won't be doing as it really isn't needed). Awaiting a reply from hope regarding the kit needed. I've found some on CRC but would feel nicer if I got them from hope somehow.

 

[mattr]

Are the hope pistons short enough to clear the slot in the caliper?

I have a vague memory of one set of mine not physically clearing the slot. So both pistons had to go out through the bore cap......... which I didn't have the tool for.

 

[ishaw]

Not based on an online video I watched, here's hoping it was right.

 

[BertR00t]

Re:

When lubing pistons I use a pair of long nose pliers to hold against one piston so that one extends while putting a piece of wood between the other two if four pots. Never had a piston escape yet.