HOPE retro-fitting old and new

[old_coyote_pedaller]

Re:

The reservoir caps either Closed or Open are the same whether it's a Sport or a Pro lever.

I think what dyna is maybe getting at is that the Closed systems, XC4s with 4 cylinders and the C2s with 2, have small springs inside the pistons/cylinders to retract pistons after lever is released.

As I've never tried it with the XC4 disc brakes I have, they were 2nd hand when I got them but were then replaced with Original M4 brakes with Mini levers, if the retracting springs were to be removed from the pistons/calipers of the XC4 or C2 brakes they might just work OK with the Open levers. The pistons would function the same way as the Open system caliper pistons as the only contact they would have with the caliper cylinder is the piston seal, the same as the Open system. What retracts the pistons on the Open system is the fluid being pulled back from caliper by piston in the lever when it is released. There is a return spring in the lever to push piston back when lever is released.

 

[dyna-ti]

Systems are different.

I stick to the instructions. Open to open lever, closed to closed lever
The lever internals are so radically different as are the caliper pistons,that without telling someone theyre mistaken, i withdraw any advice.

Try it if you will, but should your brakes fail youve only yourself to blame.


tootle pip ;

 

[old_coyote_pedaller]

Re:

Yes the systems are different, that's obvious.

But what is so radically different about lever internals?

My idea about the pistons in caliper may not work as the pistons on Closed system are screwed into caliper, at least they are on the XC4 brakes and it looks to me they do on the C2 brakes too. Simply removing the spring washers wouldn't be enough, the threaded part would have to be removed too, either from the piston or the caliper body. The piston, in my opinion, would then work in same way as on the O2 caliper, provided that you used the correct cap for the reservoir on the lever, the Open cap without the adjusting knob.

I have used an Open system lever on a Closed system simply by changing the Open cap to the adjustable knob Closed cap. No problem whatsoever.

 

[dyna-ti]

Were it gears or anything else i'd say try and see.

But brake failure can lead to death or life changing injuries.

Can i ask though because it is bothering me.
Remove the top cap on a closed C2 and remove the plunger from inside the cylinder ? correct ?
Then place the O2 diaphragm on along with its retaining ring, and top off with an O2 lid ? Correct ?
Do you remove the deflection plate from inside the cylinder(under the plunger) ?

 

[fastrider gus]

sounds like I don't have enough bits to work with, I might just rebuild as they are and put them on something they fit properly! just picked up some M4s with tech levers that will fit what I need, not retro at all but I really dig em.
I do remember brake failure well! many years ago running rear brake only, hayes cable disc which didn't work well to begin with, the pads fell out while full pelt down a steep drainage ditch next to a busy road and got confronted with either head on traffic or a steel fence at the bottom. had to jam my foot in the back wheel and dodge cars, bit of a fluke but came out unscathed. no more of those shenanigans!

 

[old_coyote_pedaller]

But brake failure can lead to death or life changing injuries. No shit, really?


Remove the top cap on a closed C2 and remove the plunger from inside the cylinder ? correct ?
Yes but the plunger and cap with knurled adjuster should be in one assembled piece.

Then place the O2 diaphragm on along with its retaining ring, and top off with an O2 lid ? Correct ?
Essentially, yes. Cannot find my box of spare XC4, C2, and Pro and Sport levers both Open and Closed.
Can't remember if there is an actual diaphragm(rubber) or a piston/plunger similar to the Closed system but without the screw thread in it for adjuster.

Do you remove the deflection plate from inside the cylinder(under the plunger) ?
Do you mean a small plate like inside the Mini lever reservoir that covers the hole for fluid in bottom of reservoir? Cannot recall there being any in the levers on the working systems I have, but as above can't find them to check. Removing them shouldn't affect how they work, if there are any.

If I could have found the lever I changed from Open to Closed I would have posted a pic of it for you.

There's something else I did that you wouldn't like. I used Pro levers with the Open cap on them to run a set of Original M4 front and Mini caliper rear brakes.

"The M4 caliper
A caliper with 4 pistons.
The caliper has the word
HOPE machined onto the
side and M4 written next to
the caliper number.
Open system.
This caliper must be used
with a Mini lever.
185mm front caliper shown."

"The Mini caliper
A caliper with 2 pistons.
The caliper has the word
HOPE machined into the
side.
Open system.
The caliper must be used
with a Mini lever.
165mm front caliper shown."

The blurb above from the Hope manual says you mustn't but it worked with no problem at all. The brakes had the same lever movement and feel that they did with their original but not M4 or Mini calipers.

Hope :facepalm: this answers your questions.

 

[old_coyote_pedaller]

Re:

Short post to update info.

Eventually found the spare, older Hope brakes after 3 searches, they were in a box buried under a Cannondale bikesworth of Coda cranks, Coda disc brakes, Coda saddle, mechs etc. Why couldn't I see them the other 2 times I looked? :facepalm:

Andy is correct

that it is a rubber diaphragm in the Open Pro lever under the cap.
It also has the small deflection plate Andy referred to as well. Think the purpose of this plate is to stop the brake fluid skooshing up when bleeding the brakes when the cap and diaphragm are off. Ask me how I know.
This is the Open Pro lever on the Original M4 system, the one it shouldn't be used with according to Hope.

 

[PaulE]

Re:

If you want a clean look to the mounting, try and find an old number 9:74 calliper half fit the brakes. That was a direct mount to the second generation manitou mounts which are the same as modern post mounts.