Hope Brakes – Bleeding

These are the basics for bleeding Hope hydraulic disc brakes which use the open system; the original 2-piece Minis and M4s (silver) and the Mono series (black/gold until ’06 then silver/black from ’07).

Hope brakes are designed to operate with DOT 4 or DOT 5.1 brake fluid. These are both glycol based fluids and can be mixed, although it’s advisable to flush the line through with the new fluid to maintain a constant performance. DOT 4 will typically have a lower boiling point than DOT 5.1 and be more viscous (thicker). DOT 5 (silicone-based) and Magura/Shimano-type mineral fluids are not compatible with Hope (or any glycol-based) systems. Using DOT 5 or mineral oil in your Hope brake will damage the rubber seals and require a full strip-down and cleaning of all brake components. Unless you flush and clean the system straight away, chances are that a seal change will be required. If that’s why you’re here, check out the caliper overhaul guides listed over there on the right…

In case you’re wondering, Hope brakes are filled with DOT 5.1 at the factory.

1. Remove the wheel from the bike and the pads from the caliper to prevent contamination.

2. Push the caliper pistons back into their bores so that they are flush with the caliper. Initially, the pistons should be left free to move as this will make it easier for the fluid being flushed through the system to push any trapped air out; however, once the system appears bled, I insert a small block of wood between the pistons and then pump another two or three lever pulls worth of fluid through to confirm that the system is completely free of air. Keep a check on the pistons before the block is in place to make sure they aren’t extending as you bleed.

3. If necessary reposition the brake lever so that the lever and master cylinder (MC) is horizontal to the ground.

4. Remove the MC cap using a 2mm allen key (2.5mm on the newer, flat-top bolts or T10 Torx on the Moto levers) and remove the rubber diaphragm.

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 on the nipple. The free end does not need to be submerged under brake fluid.

6. Fill the MC reservoir with brake fluid.

7. Open the bleed nipple a ¼ turn. Slowly pull the brake lever to the handle bars and hold. Close the bleed nipple. Release the lever (watch the fluid being pulled from the MC reservoir). Caution, squeezing the lever too fast could cause brake fluid to rise out of the reservoir. It’s not always necessary, but you can give the lever a gentle pull (a couple of mm; not to the bars!) before opening the bleed nipple, as this will help to push any trapped air from the system. If you do this, take care that you aren’t extending the pistons.

8. Repeat step 7. until no air is seen coming out of the bleed nipple. Keep an eye on how much fluid is in the reservoir; you’ll need to keep filling it as you go. Caution; if bleeding a rear brake, be careful not to spill brake fluid onto the front caliper and rotor.

9. Ensure the pistons are fully retracted in the caliper, the pistons may require manually pressing back.

10. Place a rag around the MC to catch any spillage and fill it to just below the top, so that the top of the concave edge is level with the top of the MC.

11. Place the diaphragm back into the MC and allow the fluid to overflow. Placing one end of the diaphragm onto the MC first then ‘rolling’ it into place, pushing out the excess fluid, will make sure you’ve also expelled any unwanted air. 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.

12. Fit the MC cap and gently tighten. Caution, do not over tighten cap as you are only sealing the rubber diaphragm; use the short end of the Allen key. (At this point you may want to refresh your pads. Trace a figure 8 on a piece of 100ish sandpaper until the pad surface is evenly cleaned/deglazed. You’ll need to bed* the pads/rotor back in if you do this).

13. Before you replace the pads, refit the wheel and double check that the caliper is perfectly centered over the rotor (full guide can be found (link under construction)). When you’re happy that everything is aligned the pads can be refitted. Pull the lever several times to allow the pads to reset themselves to the rotor. Check that both/all pistons are moving evenly so that each pad touches the rotor at the same time. If, when the lever is pulled, the rotor can be seen flexing, push or pull the rotor against the piston(s) that are extending further to allow the ‘lazy’ one(s) to move out. You may (will!) find this procedure easier to do if you have somebody to operate the lever for you while you concentrate on manipulating the pistons. Don’t rush this part; your brake is designed to work with both pads hitting the rotor at the same time. Improperly set-up brakes will not perform as well as they should, will feel soft and vague at the lever and will be more prone to making unwanted noise. You will be rewarded for your 20-30 minutes of initial set-up…

14. Give the lever a few pulls and check all fittings for leaks.

* ‘Bedding in’ is the process of matching microscopically the profile surface of the pads and rotor, which basically gives the maximum surface area contact possible and thus better braking. Here’s what Hope have to say about bedding your pads in;”To achieve the maximum braking effort the new brake pads need bedding in. Bed in the pads by riding a short distance with the brake applied, it also helps to pour clean water over the caliper and pads whilst bedding in. This procedure will achieve good braking performance but will reach its full potential after a few rides.”

Head outside with a bottle or pint glass of fresh, clean tap water. Get up a head of steam and brake hard. Pour water liberally over the caliper. Pedal off again, this time with the brake applied lightly. As you pedal you’re going to feel the pads bedding in to the rotor. Keep going, pulling the brake gradually harder as you have to pedal harder. Do this for 20-30 meters and then pour water over the caliper again. Repeat a mix of hard stops, water; brake/pedal, water until your brakes are how you like them. I can get two brakes bedded in under 10mins using this method. They’ll improve further after a little trail time, but at least you’ll have decent braking to begin with.

Comments…

For some reason, this page has been receiving an inordinate amount of SPAM, so I’ve now disabled the comments function. If you have any questions regarding this process, please ask through one of the other Hope service guides.