Hope M4, does nay have the power!- Mtbr.com
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  1. #1
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    Hope M4, does nay have the power!

    So I've just fitted some M4s to my bike (not the mono or tech versions) and I'm just not getting the power out of them that I'd like.

    Not sure what the problem is but here are some things I've noticed:
    - Pads are evenly spaced either side of the disc, as they should be.
    - Pistons don't seem to be getting quite the same amount of movement (front moves less than back, or vice versa, not quite sure now I think about it).

    I have the 203mm floating rotor so I was expecting to go flying over the handlebars every time I so much as looked at the brake lever. Maybe I was just expecting too much but I'm getting far less stopping power than I did with my old, run of the mill, v-brakes.

    I was assured they'd been recently bled before I bought them so I'm assumingthat nots the problem.

    Any ideas? Bear in mind these are the first pair of disc brakes, let alone hydraulic disc brakes, that I've ever used.

    Thanks.

  2. #2
    Meh.
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    Have you given the brakes time to bed pad material into the rotors?

  3. #3
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    If the pads are bedded in, check them for signs of contamination. You could try freeing the pistons up by extending them and spraying with silicone, then working them back and forth. There's every possibility that the seals have had their day, in which case you'll need to overhaul.

    Do you have a picture of the lever and caliper?

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  4. #4
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    I have no idea!

    How long should that take in terms of hours/miles?

    The answer is 'probably not' as I've just taken it for a couple of quicks spins, with a little tinkering inbetween to try and figure out the problem (I thought it might be uneven pad position).

  5. #5
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    SteveUK:
    I'll try and get some pictures up soon, otherwise, what should I be looking for?

  6. #6
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    Quote Originally Posted by Bolt-On
    SteveUK:
    I'll try and get some pictures up soon, otherwise, what should I be looking for?
    The pictures are really just to satisfy my curiosity and get a feeling for their general condition, although whether or not the rotors have gone on the right way around is also on my mind. You've bought them used, I presume?

    Bedding in shouldn't really take more than a dozen or so good, hard stops. Just don;t leave the brake applied when you come to a halt as it can imprint a profile of just one portion of the rotor upon the pads. You can start from scratch by sanding the pads, cleaning the rotor and then bedding them in on the street.

    Are you happy that the calipers are aligned over the rotor? You'll lose power and feel if the rotor is running at a slight angle through the caliper/pads. Have you had your fork and frame tabs faced?

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  7. #7
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    Quote Originally Posted by SteveUK
    Are you happy that the calipers are aligned over the rotor? You'll lose power and feel if the rotor is running at a slight angle through the caliper/pads. Have you had your fork and frame tabs faced?
    I'm pretty happy that the calipers/pads are evenly spaced either side of the rotor, and also that the rotor is on the right way round (although I'll double check).

    Not sure if that's what you mean by the calipers being aligned and also not sure what you mean by having the fork and frame tabs faced...?

    Thanks for your help.

  8. #8
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    Not sure if that's what you mean by the calipers being aligned and also not sure what you mean by having the fork and frame tabs faced...?
    Facing is the process removing excess paint or metal from the frame/fork tabs that the calipers bolt onto. They're cleaned up so that they are perfectly at right-angles to the axle, thus leaving the caliper (and its pistons/pads) perfectly at a right-angle to the rotor (which is held in place by the wheel hub/axle).

    Checking the tabs - by setting the facing tool up to them - is usually the first thing to do if you're having brake performance issue. It may not always be necessary to remove any material, but it eliminates the frame/fork mounts from the equation. Your local shop should do this job for around a tenner.

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  9. #9
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    Alright, I'll see if they do that.

    Otherwise I've just found out that the caliper is actually a Hope Mono M4... not too happy about that. I've told the person I bought it from and might not have the brake much longer...

    Going to try sanding the pads and cleaning the rotor.

    Thanks again for your help.

  10. #10
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    Otherwise I've just found out that the caliper is actually a Hope Mono M4... not too happy about that.
    The Mono M4 is a great brake (when working properly!). How come you're unhappy about it?

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  11. #11
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    Quote Originally Posted by SteveUK
    The Mono M4 is a great brake (when working properly!). How come you're unhappy about it?
    Only because, from what I've read, the regular M4 is more reliable and more powerful... I like my kit to be rugged and relatively maintenance free and from what I've read the Mono M4 is not that.

    I'm still going to give it a try though. Also just discovered that the retaining pin wasn't there so I'm trying to fashion something temporary out of wire =/

  12. #12
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    Only because, from what I've read, the regular M4 is more reliable and more powerful... I like my kit to be rugged and relatively maintenance free and from what I've read the Mono M4 is not that.
    I think you've been misinformed. The Mono M4 caliper is same design which Hope have used right up until current Tech line-up, and even then the only difference is that the new one has four equal-sized pistons; the caliper design is essentially the same. The only known 'issue' of the early Mono M4 was in the non-phenolic pistons, which were easily damaged and would get stuck after the damage affected the seals.

    I believe you're correct, though, in that the original (two-piece) M4 was more powerful, but at the expense of modulation. If the Mono is slightly less powerful, the available modulation more than makes up for it. People still use the Mono M4 for DH duties, so you shouldn't be too concerned about having been robbed of a powerful brake. I also think that you'll find it easier to get caliper spares (seals/pistons) for the Mono as the design is still in use. Although you'll need a couple of special tools for the caliper bore caps, a full overhaul is still a relatively simple job (link). Keeping the pistons cleaned/lubed on the old M4 isn't really any different to doing it on the Mono design. Components in the lever assembly were still used up until the switch to the Tech lever (2008), so you shouldn't have any worries in regards to maintenance.

    Is it the actual pad retention pin you're missing?

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  13. #13
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    i find with the tech m4 its there when you need it, bedding the brake in is needed and get some good pads as the ones come with it are poor i have found.
    as steve said "As long as the rotor/rivets clears the fork, a miss is as good as a mile"

  14. #14
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    Quote Originally Posted by SteveUK

    Is it the actual pad retention pin you're missing?
    Just the r-clip. Some more reading suggests that the r-clip falling out is a common problem.

    I've given it a few more rides, being deliberately heavy on the breaks and I'm pretty sure it's improving, albeit a little slowly.

  15. #15
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    Just the r-clip. Some more reading suggests that the r-clip falling out is a common problem.
    Yeah, it wasn't a great design. The later (and current) pins have a small hole in the end and a spring-type clip. You can just cut a 2cm piece of paper clip and wrap it around the groove in the end of the pin. Not pretty, but it'll stop the pin coming all the way out if it does happen to work loose.

    Where in the UK are you?

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  16. #16
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    Quote Originally Posted by Bolt-On
    I was assured they'd been recently bled before I bought them so I'm assumingthat nots the problem.
    How does the lever feel?

    If it feels spongy (there should be a very definite change in feel at the point where the pads meet the disc) try re bleeding them yourself or taking them to a shop to get it done. Just because they were bled doesn't necessarily mean the bleeder did a good job of it...

  17. #17
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    Not sure about the particulars since the OP is clearly new to hydro brakes and perhaps proper setup procedure.

    I will say you'll have a hard time finding a better modulating setup than a Mono M4 with a 203mm rotor.

  18. #18
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    Quote Originally Posted by Bolt-On
    I have no idea!

    How long should that take in terms of hours/miles?

    The answer is 'probably not' as I've just taken it for a couple of quicks spins, with a little tinkering inbetween to try and figure out the problem (I thought it might be uneven pad position).
    The instruction I got was to do about 20 gentle stops with each brake ... before riding the bike on trails. So, I would pedal up and then gently engage the brake and then progressively increase pressure to come to a complete stop ... not slamming on the brake. I did this 20 times on each side.

  19. #19
    I think I need to Upgrade
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    Quote Originally Posted by gjenkins@
    The instruction I got was to do about 20 gentle stops with each brake ... before riding the bike on trails. So, I would pedal up and then gently engage the brake and then progressively increase pressure to come to a complete stop ... not slamming on the brake. I did this 20 times on each side.
    Depending on what pads you have it will take more than 20 gentle stops to bed them in. Also if the caliper isn't aligned properly with the rotor it will have a negative impact on braking power.

  20. #20
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    Bleed them then see what happens.
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  21. #21
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    My Tech M4's with 203mm front and 185mm back can stop me on 5c piece , they are the best brakes ever IMO , i went through half the Juicy range , Shimano range and elixirs , but the Hopes best brakes hands down , i even bought a set of the X2 pros for an XC bike, knowing they wouldnt be anywhere near as powerful as the M4's but still have the best modulation ever .... and hope carries every single nut/washer/seal/clip to rebuild or fix all of their brakes if needed.
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  22. #22
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    can someone identify what model and year this m4 came out? also its weight.. reviews would highly be appreciated. someone is selling this and i am thinking of getting them. thanks people!

  23. #23
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    There'll be a date on the front of the master cylinder; something like 04-03. That'll tell you exactly when the brakes were made (assuming that they're the original levers for the calipers). I think the Mono calipers replaced the two-piece version in around 2004.

    The lever (Mini) was used until a small redesign in 2007 and has a nice feel to it, if a little flexy compared to the revised model. The two-piece caliper was supposed to be more powerful than the Mono which replaced up, perhaps by dint of a larger pad material surface area. The pistons are the same size, and could be replaced with the Mono's phenolic ones if you want/need to. The caliper and lever are both still fully serviceable.

    How much does this person want for the set? Do they come with rotors?

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  24. #24
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    no rotors & adaptors.. just the one on the picture.. he wants $180 for it. think its a good buy? he doesn't know the year model.. are these better than getting shimano xt's? someone is also selling for the same price no rotors as well.

  25. #25
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    Just as an additional bit of info to the OP and others. The biggest change I have felt in Hope brakes (have owned orig minis, M4, Mono M4, Mono M6 ti, and now currently two sets of new lever mono M4s)....has been pads. Hope has over the years run pads form several companies. Some have been OK...none have been great IMO.

    Air in the lines, bleeding is a very obvious feel (levers falling to the bar). WIth good lever pressure, yet lack of brake grab/power, this is 100% a friction issue between pad and rotor. Contamination can be an issue (clean the rotors with pure isopropyl alcohol or acetone...and do NOT touch them. Pull the pads and lightly sand (just rough up the surface) the contact surface with fine sandpaper on a flat surface.

    If this does not give you the grab you want, look at an aftermarket pad. I generally run EBC reds. THey wear quickly, but are quiet and have great friction.

  26. #26
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    Does Hope make phenolic pistons that will work in the older M4 calipers? I would love to run sintered pads in my calipers. It was fun to try the sintered pads and see how fast it would take for the fluid to boil with the stainless steel pistons. Answer, about 15 seconds of serious braking and then viola, no braking whatsoever. But, I knew that would happen. Good squirt with a water bottle got me back to the car for a pad change. I hear the newer Ti-6 are using the phenolic pistons. I am wondering if one of the diameters from them is the same as the old M4 pistons?

  27. #27
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    It's already noted up-thread that the phenolic pistons will fit the older M4. It's only the design of the caliper which has changed over the years; all three M4 caliper designs used the same size pistons (two small; two large)

    It was fun to try the sintered pads and see how fast it would take for the fluid to boil with the stainless steel pistons. Answer, about 15 seconds of serious braking and then viola, no braking whatsoever.
    Your brake fluid needs replacing. Pads may be contaminated.

    What use is a philosopher who doesn't hurt anybody's feelings? -
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  28. #28
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    On the M4's you can use the old Shimano XT and Grimeca pads. The ones with 4 piston calipers. The older XTs come in a Sintered pad and an Organic pad. I have the Mono M4's with an 8" rotor in front and a 7" rotor out back. I use the organic pad in the front and the sintered pad in the rear. If I use the sintered pad in the front, the power is overwhelming and not balanced so I switched to an organic pad and now it still has plenty of power and better F/R brake balance. One finger for any riding except DH or aggressive XC.
    I'm getting ready to build up a new frame and ordered the new Tech M4s. Really like the new lever/MC design.

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