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Frankenbrakes and brake improvement discussion

Discussion in 'Downhill & Freeride' started by Udi, Sep 2, 2015.

  1. chris_f

    chris_f Monkey

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    Since this is now the de facto "everything about brakes" thread I might as well stick it in here.

    Did my first bike park day on the MT7s, and for the first time since I started riding bike parks I experienced no fluctuations in performance throughout the day. Power was very good, modulation was decent, and pad life seems acceptable. Taking into account the fact that I've gotten fatter and more scared and I drag my brakes like a bitch, I'm pleased with the performance. No fade, no lever-to-the-bar death scares, nothing. Just chugged along outbraking all the available grip my tires could provide at will.

    The levers do not seem very crash resistant but I luckily haven't been able to test that yet.
     
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  2. local717

    local717 Monkey

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    So after 3 solid days of park riding and a ton on my local trails, I can honestly say the XT lever paired with the MT7 caliper is amazing. Great stopping power with a ton of modulation!
     
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  3. 6thElement

    6thElement Schrodinger's Immigrant

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    Put some brand new pads in my Formula RO's over the weekend, even with the pistons pushed fully back into the bores the front just about spins, the rear not so much.

    Got to love tolerances that tight...
     
  4. HAB

    HAB Chelsea from Seattle

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    Any chance they're overfilled at all? Might get a little more piston retraction if you put a bleed syringe (with a little fluid in it) at the lever end, then tried pushing them back.

    The ROs do have very little piston rollback. Good for lever feel, bad for making them easy to align.
     
  5. 6thElement

    6thElement Schrodinger's Immigrant

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    Attaching a syringe is next on my attempt to making them work without rubbing. I don't recall having had them this bad before after a pad change.
     
  6. slimshady

    slimshady ¡Mira, una ardilla!

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    I regularly do what a mechanic buddy calls a "race bleed". After retracting the pistons without the pads in, put the bleed block in and hit it with a rubber mallet. Quickly open and close the bleed screw at the caliper with a cloth rag wrapped around it, a whizz of brake fluid will pop off it. Close it and clean the mess. You'll have the best feel at the lever and enough room to fit the new pads.
     
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  7. sethius

    sethius Chimp

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    Anyone managed to locate a price on the Italian braking system 26mm 2pot bad boys? Finally looks like the brake to replace my long loved v2 choice.
     
  8. 6thElement

    6thElement Schrodinger's Immigrant

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    ^^
     
  9. slyfink

    slyfink Turbo Monkey

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    So I just received my Magura MT-5s. They look so... big compared to my XTs. After I'd ordered them, someone mentioned they came with the 2-finger levers, that have poor ergonomics. So I test-mounted them to a handlebar, and sure enough, they hit my middle knuckle when I try and one-finger brake. Since I have to cut the lines due to internal routing (fuck you bike industry), I'm thinking it may be worthwhile mating them to my Shimano levers. Or is that a bad idea? If I do this, do I need Shimano barbs and hardware to insert into the brake hose? and that's it? Also, what the best tool to cut brake hose with? I have Park cable-cutters... are those ok to use?
     
  10. maxyedor

    maxyedor <b>TOOL PRO</b>

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    Yes, Shimano barb, olive, nut. I've been using some shitty Lifu cable cutters on brake hose for 15ish years, still zero issues.

    Where were the levers mounted? I have no knuckle interference issues with my MT5 levers and 1 finger braking, but I did have to move the lever inboard of my shifter to get the "hook" where I wanted it.


    Got some Cura 4s in the mail a couple days ago, still waiting on the new bike so no time on them yet, but they appear to be very well made. The machining is impeccable. Only disappointment is that the gold anno is a little more orange than I'd prefer, and they really should be offered in purple anno.
     
  11. Kurt_80

    Kurt_80 Monkey

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    Someone from downunder posted this on their Insta, if it's any use

    "What you need.. 1x MT5 brakes (cheap from de Germans) .
    1x M8000 lever (available from @mountainbikesdirect)
    1x MT5 compatible nipple (got mine from cyclingdeal.com.au in a bleed kit)
    Cut the MT5 lever off and connect the M8000 lever as normal using the Shimano olive and barb. Remove grub screw from caliper adjacent to the banjo and insert the MT5 nipple. Then bleed like you'd do a regular Shimano brake. Once the bubbles are out plug the funnel, remove the barb and screw the grub back in to seal the caliper.

    I've never ridden Magura's before but this setup is the most powerful I've ever used. Better than Saint/Zee, Hope V4's and Sram. Modulation is in between Saint and V4.. I'd guess the 8.P pad swap makes them a little more on the touchy side though."


    I asked him about reliability 8 months on, given the consensus here has been the Shimano lever is the culprit for inconsistent bite point. He had no problems yet...

    " just got back from 4 days on the Darkside at Maydena. They were consistent and powerful the whole trip. The front needed a bleed by the end of the trip though but that's because I've been smashing it on the ebike since this post. Either that or new pads. No other issues to report on though. I was worried about fluid leaking through seals etc but nothing yet. Only gripe so far is that you need an extra bleed nipple for the caliper end when bleeding. Annoying if you forget it on a trip etc.."
     
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  12. Sandwich

    Sandwich Pig my fish!
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    No knuckle interference here but they suck ergonomically compared to shimano. I used Channellock clippers to cut my shimano hose, opened with an awl, then popped the olive on and jammed the hose barb on. Worked fine.
     
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  13. slyfink

    slyfink Turbo Monkey

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    thanks gents. I'll start with the Shimano levers, and if it doesn't work too well, I'll revert to the Magura ones.
     
  14. mykel

    mykel Turbo Monkey

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    Cutting cable housing or brake hose?

    Dremel.

    No crushing, no awl, no nail, no trying to open the hole and make it round again.
    No burrs or sharp edges
    Just a nice clean cut.

    In many years so far the only thing it does not work on is the braided Hope hoses as the coating is too soft and gummy.
     
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  15. sethius

    sethius Chimp

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    Sorry, didn't mean formula.

    Those Braking Incas system ones. Aussie distributor knew nothing of them, and can't find pricing anywhere. Their social accounts aren't the most helpful either. Puts me off abit already.

    https://www.bicycle.braking.com/complete-systems/
     
  16. chris_f

    chris_f Monkey

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    The fact that Cedric is their prime ambassador also isn't super promising considering he's riding what could easily be described as the ugliest prototype in the last 5-10 years.
     
  17. 6thElement

    6thElement Schrodinger's Immigrant

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    Drop of fluid out of the levers let the pistons retract that extra tiny sliver I needed.

    Will have to see how they work tomorrow.
     
  18. Carrera911xc

    Carrera911xc Chimp

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    Hey guys, was hoping someone had some insight on the newish 4 pot deores (BR-MT520/BL-MT501). I recently purchased a set of these as my girlfriend needed brakes on her bike. My plan was to swap my M8000 calipers onto her bike and mate the 4 piston calipers to my M8000 levers. After performing the install/swap her brakes feel fantastic (super short throw and very firm), while mine feel mushy and have tons of throw. I've bled hers once when performing the swap, while I've tried bleeding mine several times.

    I did research this a bit and was under the impression that the MT501 lever was basically a rebranded M6000 lever, however I am beginning to have doubts about that.
     
  19. Kurt_80

    Kurt_80 Monkey

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    Are M8000s 2 piston?

    The more technically minded may correct me here, but I imagine that 4 piston systems push more fluid than the 2 piston equivalents. As such, a 4 piston lever is designed to push more fluid per mm of lever travel than a 2 piston lever.

    In that case a 4 piston lever will require little throw to max out the 2 pistons.

    Conversely, a 2 piston lever will require a huge amount of throw to get the 4 pistons to max out.
     
  20. HAB

    HAB Chelsea from Seattle

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    Not really. For brakes that come in 2 and 4 piston versions, having a different lever that pushes more fluid for the 4 piston version would negate the power advantages of having more pistons (really, more piston surface area). It's a matter of mechanical advantage. The higher the ratio of slave piston area to master cylinder area (assuming the same lever geometry), the more power you get. If you scale up both the caliper and lever ends proportionally, you just make a heavier brake that isn't any more powerful.
     
  21. Kurt_80

    Kurt_80 Monkey

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    True, but isn't the mechanical advantage proportional to the fluid required?

    My understanding is, as per the picture below, you need to displace the master piston a lot to move the slave a small amount. And if you increase force at the caliper by increasing the slave area (so go from 2 piston to 4 piston) you need to displace the master piston a lot more. Either that, or keep the pistons/pads closer to the disc (a la Formula) in the 4 piston system.

    That's actually what I was hypothesizing: The 4 piston system requires more fluid to move the slaves a set distance (compared to a 2 piston system). In the former, the master piston displaces more fluid by traveling further per mm lever stroke, not by having greater surface area.

    Hydraulics.png

    Of course, this is just a hypothesis... I could be wrong!
     
    #1261 -   Jul 2, 2019
    Last edited: Jul 2, 2019
  22. HAB

    HAB Chelsea from Seattle

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    Yep, if you put a caliper with a greater piston area and the same rollback distance on the same lever, you'll get more lever travel. I was mostly responding to this part:

    Increasing stroke or increasing master cylinder area are the two ways to increase fluid displacement. You can't make it push more fluid per mm of lever displacement without losing some mechanical advantage.
     
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  23. Happymtb.fr

    Happymtb.fr Monkey

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    No leakage on my caliper, just a lazy piston that got partly fixed with some red grease on the seals.

    I have now cura2 on the new bike and realise that the throw on my shigura must have been increasing over time. Nevertheless the throw on the formulas is very short and the power is coming rather quickly which was a bit surprising at first but I start to like it now. I even got used to having the brake point a little further from the bar than I would like to.
     
  24. Kurt_80

    Kurt_80 Monkey

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    I'm currently running Formula T1s on the big bike; these are the oem version of The Ones without the fancy adjustments. I miss the instant power of the Saints on my hardtail, so I'm wondering about throwing on a bigger rotor.

    So far, all I can see are the Formula 220s and Galfer 223s. Has anyone tried these or others?

    More generally, has anyone just switched to a larger rotor with a reliable but underpowered caliper to make a decent brake?
     
  25. johnbryanpeters

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    I propose that we all revert to Diatech mechanicals.
     
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  26. Flo33

    Flo33 Turbo Monkey

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    There are Trickstuff Dächle HD rotors in 223 mm, but they are stupidly expensive - 100 € - and hard to get.
    I'm running R0Rs on my Reign and the switch to bigger rotors is very noticeable.
    What also helped was running Trickstuff Power pads. They offer higher braking force than the Shimano IceTech sintered ones I ran before. Wear pretty fast though.
     
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  27. Inclag

    Inclag Turbo Monkey

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    So is there any logic to the idea that Shimano calipers piston drag and sticking could result in master cylinder air ingress and master cylinder leaking?

    The way master cylinder piston seals look in cross section it would seem to me that this could be a real possibility if the caliper return was latent to the lever return.

    I ended up moving my Deore levers to my Zee calipers due to my Zee levers leaking like a sieve. Not long after some downhill riding, now my rear Deore lever is weeping oil from by my account, the master cylinder.
     
  28. Kurt_80

    Kurt_80 Monkey

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    Thanks. Did you swap from 203 to 223?
     
  29. Flo33

    Flo33 Turbo Monkey

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    No, 180 to 203. But I'm thinking about another/the next swap.
     
  30. Flo33

    Flo33 Turbo Monkey

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    Where should that air come from? I think normally the area behind the master piston inside the master cylinder is filled with fluid as well. There is a connection between the reservoir and the room behind the piston seal.
     
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  31. manhattanprjkt83

    manhattanprjkt83 Rusty Trombone

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    Just got some of these for the upcoming whistler trip.

     
  32. chris_f

    chris_f Monkey

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    Your death is imminent.
     
  33. kidwoo

    kidwoo Celebrating No-Pants Day

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    Anybody else (like @Nick) using stock cura 4s? I finally got a pair and can't for the life of me get the sponge out. I've bled them multiple times. They grab and engage and all that but that's the most vague lever feel of any brake I've ever ridden. They feel nothing like the 2 piston ones.

    halp
     
  34. Nick

    Nick My name is Nick

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    I had the same spongy problem. Took forever but got them just like my 2s. There must be a hidden void that traps a tiny bubble somewhere. Ended up letting the caliper hang off the bike and slowly pushed fluid up to the mc.
     
  35. kidwoo

    kidwoo Celebrating No-Pants Day

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    You did get some punch with a better bleed though? I dun some good ones already. You using two plungers or an open cup on one end?
     
  36. Nick

    Nick My name is Nick

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    Punch?
    If I grab them hard these brakes can be on/off. Two syringe method. They do not feel spongy to me.

    @jstuhlman also had the 4s. If his plastic handlebar and sea- rusted chain hasn't killed him maybe he'll chime in too.

    Edit. Im positive I have 0.000 air and I like the feel at the lever.
     
  37. kidwoo

    kidwoo Celebrating No-Pants Day

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    Punch: crisp engagement. Not vague
     
  38. Nick

    Nick My name is Nick

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    Not vague.


    I guess I should add I have mine filled with this....




    I know I know, I'm not helping.
     
    #1278 -   Jul 13, 2019
    Last edited: Jul 13, 2019
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  39. kidwoo

    kidwoo Celebrating No-Pants Day

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    What we're you riding before the curas?
     
  40. Nick

    Nick My name is Nick

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    Saint 820
     
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