[Joe33]

I got some Hope m4s, the rear works really good. The front acts strange. It has no power unless its been used hard and heated for awhile. Then after it sits overnight it starts all over again. When I took the pads out there were little oils rings on the backs of all of them. I swaped pads and got the same results. The rear working good and the front with no power. Both brakes feel good at the lever.

So the only thing I can think of is that somehow oil residue is getting on the pads. I emailed Hope but they never replied back. So maybe out of all you Hope users on the board there might be a solution?

 

[Brian HCM#1]

Sounds like the caliper seals are bad, probably should be rebuilt.

 

[Joe33]

Do you know where I can buy a seal kit?

 

[Brian HCM#1]

Directly from Hope.

 

[Joe33]

Thanks for the info. I'll try calling them.

 

[Zaskar Rider]

I have that same exact problem with my front M4 but with mine there is no sign of fluid leakage anywhere. Strange...

 

[Brian HCM#1]

Originally posted by Zaskar Rider
I have that same exact problem with my front M4 but with mine there is no sign of fluid leakage anywhere. Strange...

The brakeline may be bad.

 

[WestCoastHucker]

Originally posted by Brian HCM#1
The brakeline may be bad.

hey brian,
i have a c2 that recently started to not let the pistons retract back into the caliper. if i remove the pads and try to push the pistons back in, i get nothing. as soon as i open the bleed valve the pistons suck right back into place. i have rebled them twice and they keep doing the same thing. any ideas on why this is happening?
mike

 

[Brian HCM#1]

Originally posted by WestCoastHucker
hey brian,
i have a c2 that recently started to not let the pistons retract back into the caliper. if i remove the pads and try to push the pistons back in, i get nothing. as soon as i open the bleed valve the pistons suck right back into place. i have rebled them twice and they keep doing the same thing. any ideas on why this is happening?
mike

Sounds like your not getting a good bleed. Are the pistons pushed flush with the caliper when bleeding? Here are bleeding instructions for C2's.

Bleeding the XC4 and Closed 2 disc brake
Item number references refer to the diagram of the Pro lever in section 5.1. The
procedure is identical if you have a Sport lever.
Wear safety glasses.
1. Remove the wheel and brake pads to prevent contamination.
2. If necessary reposition the brake lever so that the lever and master cylinder is
horizontal to the ground.
3. Remove the master cylinder cap (item 23) using a 26mm spanner.
4. Place the closed end of an 8mm spanner over the bleed nipple on the brake
caliper. Fit a length of clear plastic hose (approximately 30cm) onto the bleed
nipple and place the free end into an empty container. The hose should be a snug
fit and not fall off, the free end does not need to be submerged under brake fluid.
5. Fill the master cylinder reservoir with brake fluid.
6. Open the bleed nipple a 1/4 turn. Slowly pull the brake lever to the handle bars and
hold. Close the bleed nipple. Release the lever. Caution, squeezing the lever too
fast will cause brake fluid to squirt out of the master cylinder.
7. Repeat step 6 until no air is seen coming out of the bleed nipple. You will need to
keep refilling the reservoir during this operation. Caution, if bleeding a rear brake
be careful not to spill brake fluid onto the front
caliper and disc.
8. Unscrew the reservoir piston from the master
cylinder cap. Note that this is a left hand thread,
see Figure 5 .
9. Place a rag around the master cylinder to catch
any spillage and fill the master cylinder to just
below the top surface.
10. Place the reservoir piston into the master cylinder
and allow the fluid to overflow. Gently push it down
until it rests on the ‘O’ ring seal and clean away the excess fluid.
11. Screw the silver adjuster into the piston (note, this is a left hand thread and is part
of the master cylinder cap) until the cap makes contact with the top of the master
cylinder. Press gently down on the cap and thread it clockwise until it is tight then
tighten with a 26mm spanner. Screw the thumbwheel of the adjuster (item 25) anticlockwise
to the limit of its travel.
12. Open the bleed nipple a 1/4 turn to allow the pistons to retract into the caliper. The
pistons are spring loaded and should return on their own but may require manually
pressing back. Close the bleed nipple and remove the plastic hose. Caution, do
not over tighten the bleed nipple. Wipe away any spilt fluid from the caliper and
lever.
13. Replace the pads and insert the wheel.
14. Adjust the silver thumbwheel to obtain the desired lever travel.
15. Check the brake for correct function and that there are no any system leaks.
Figure 5

Bleeding the Open 2 and DH4 disc brake
Item number references refer to the diagram of the Pro lever in section 5.2. The
procedure is identical if you have a Sport lever.
Wear safety glasses.
1. Remove the wheel and brake pads to prevent contamination.
2. Push the caliper pistons back into their bores and insert a spacer between the
pistons to prevent them coming out during the bleed operation.
3. If necessary reposition the brake lever so that the lever and master cylinder is
horizontal to the ground.
4. Remove the master cylinder cap (item 22) using a 26mm spanner.
5. Place the closed end of an 8mm spanner over the bleed nipple on the brake
caliper. Fit a length of clear plastic hose (approximately 30cm) onto the bleed
nipple and place the free end into an empty container. The hose should be a snug
fit and not fall off, the free end does not need to be submerged under brake fluid.
6. Open the bleed nipple 1/2 turn. Screw an M5 bolt into the master cylinder piston
(item 21) and pull out. Caution, the piston may suddenly pull out and splash brake
fluid. Close the bleed nipple.
7. Fill the master cylinder reservoir with brake fluid.
8. Open the bleed nipple a 1/4 turn. Slowly pull the brake lever to the handle bars and
hold. Close the bleed nipple. Release the lever. Caution, squeezing the lever too
fast will cause brake fluid to squirt out of the master cylinder.
9. Repeat step 8 until no air is seen coming out of the bleed nipple. You will need to
keep refilling the reservoir during this operation. Caution, if bleeding a rear brake
be careful not to spill brake fluid onto the front brake caliper and disc.
10. Ensure the pistons are fully retracted in the caliper, the pistons may require
manually pressing back.
11. Place a rag around the master cylinder to catch any spillage and fill the master
cylinder to just below the top surface.
12. Open the bleed nipple a 1/4 turn. Place the piston into the master cylinder and
allow the fluid to overflow. Gently push the piston down until it is 1mm below the top
surface. Close the bleed nipple and remove the bleed hose. Caution, do not over
tighten the bleed nipple. Wipe away any spilt fluid from the caliper and lever.
13. Fit the master cylinder cap and gently tighten with a 26mm spanner.
14. Replace the pads and insert the wheel. Pull the lever several times to allow the
pads to reset themselves to the disc.
15. Check the brake for correct function and that there are no any system leaks.
When to change the brake fluid
For high performance usage, typically downhill racing and applications that use lots of
braking effort it is recommended you change the brake fluid once per year. For normal
use change the fluid every four years.
To change the brake fluid follow the preceding instructions for bleeding the brake and
ensure that the master cylinder is filled (and pumped through) at least four times.