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Thread: Building bucket brakes

  1. #1
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    25th March 2004 - 17:22
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    Building bucket brakes

    Here are some random thoughts and hints about building a bucket with adequate & safe brakes

    Maybe a Sticky Mods?


    Over the years I have witnessed many novel & imaginative setups. On the other hand I have seen some howlers bordering on the downright dangerous. Last weekend I witnessed the probably the worst Muppet engineering I have ever seen.


    This is by no means a complete guide and I am by no means beyond making dumb mistakes or logic farts



    I will largely omit drum brakes except to say that they are largely crap with too small hubs or leverage from both ends to be effective without thoroughly expensive classic parts, but most people will find a disc end.

    Brake mounting bolts
    Don’t use ally bolts anywhere near brakes. Levers, disc, and calliper mounts should have good quality steel bolts (or titanium if yer a wanker).

    Brake levers
    C’mon pattern levers are cheap. Ball ends taped on are not kosher or justifiable. Beware the wrong lever. Also must have some free-play to the piston or the return hole will get blocked when hot. Attn with a file on the brake light switch tab or stopper will increase this. Don’t use an ordinary bolt, the threaded part will dig into the pivot. Grease this pivot.
    Make sure the lever cannot be obstructed by anything; say if your throttle housing slips.


    Brake lines:
    Divided opinion, but generally a braided line will be a stella improvement over a 20yr old rubber line. Make sure they are made long enough for when at full extension (wheelie) but not so long they will drag or be at a crazy angle. Consider routing & guides to avoid damage in suspension use.


    Brake plates
    This is where I lose sleep. They have a large force exerted on them. Some thin ally plate with the calliper stuck on it will twist & bend in several directions every time you clamp the brakes on a decent size disc from 80kph. This won’t do pretty things to your disc & ally fatigues in this application if it's flexing. Stiffness & strength are key. Start off with 10mm min plate & thicker if you need to significantly step the plate. Make a template from plywood & get someone to cut the plate & machine steps/ thread for mounting bolts. You may need to take a couple of hits at it to get the step the right thickness so the calliper is centralised & not rubbing. Obviously pads should cover the disc swept area nicely.


    Sticking brakes
    Bent or coned disc, muppet mounting, sticking pistons or sliding pins, dodgy wheel spacers. Or blocked master cylinder vents or return hole (see levers).


    Brake discs
    The most expensive component & easiest to damage. You shall need to check it is straight & flat (not cone shaped). The former by spinning the wheel with a pointer taped on the forkleg almost scraping the disc. Attempts to straighten discs are usually temporary. Maybe 25% successful. Glaze can be removed with sandpaper
    Mounting a disc on another wheel is possible but use your noggin. They have a large force exerted on them. One can get away with a thinner disc than stamped on for WOF, but don't push it, esp if disc gets hot. You can clean up grooves by giving it to someone with a lathe & careffuly holding some sand paper on a block against it. I said carefully. A flapper wheel on a disc grinder can be mounted on lathe for a 'bush' but surprisingly effective result. No legal responsibility on above or any statements. Ah heck just send it to precision grinders or whatever.

    Bleeding brakes:
    Read up on internet. With non std fittings you may need to lift front of the bike up to get the bleed nipple to the top of any air pockets. Look carefully if this takes a long time to bleed.

    Brake pads
    Will need replacing if worn with angle or any oil contamination. Glazing (but not contamination) can be removed by wiping on medium sand paper on a flat surface. Quality varies, you may have to try a few brands till you get one that suits your disc material.


    Getting the best out of current setup:
    Calliper Pistons must be un-seized, sliding pins free with high temp grease. Old setups should be pistons pumped out & seals carefully removed with a pick or small screwdriver down the edge but not skewering it. Clean out gunk behind pistons & white build-up in seal grooves (read up how to get them out). Clean totally. Inspect seals. Largely the main inner seals if undamaged will be fine if square in section. Outer Dust seals are less important, but if deformed can pull or jam the pistons causing excessive lever travel or dragging respectively. Replace as required.
    Corrosion damage to the pistons or the ally bores can often be dressed gently with pot scourer, but at some point are irretrievable.
    Master cylinders are a little more difficult to dismantle but the above applies. Seals more likely to need replacing. Clean cap vents. Replace rubber doffer in the cap if torn. Really.

    Wheel spacers
    These aren’t hard to knock up to suit a new wheel, but to get them parallel and the right thickness is the trick. You mustn’t need to dramatically lever them in when fitting a wheel, nor have the axle pull in when done up. This x10 importance on forks.

    Upgrading braking power, mix & match:

    OK assuming you’ve checked the above. Like everything else leverage is key. The bigger the disc the more the leverage. The bigger/longer the brake lever the more the leverage.

    A big disc is nice, but weight is a consideration. A more modern calliper with decent pads is worthwhile. I found a decentish calliper off an RG150, but turned out to be a rear & the pads available were all rubbish.

    Hydraulic advantage: Often misunderstood, but the basic simple rule is “smaller the master cylinder & more piston area in callipers the more leverage”.

    Just like moving the pivot point of a lever closer to the object you want to lift, - the more leverage you get. It gets easier to pull the long lever & lift the heavy object. But the downside is the object (pads) move less.

    So If you put a master cylinder from a twin calliper setup on a single calliper you will get a wood like feeling from the lever & no power. Conversely a too small a cylinder will produce excessive lever travel (some of which may be gained back from braided lines). There will be a sweet spot where you will get a good feel of leverage & power. Most single setups will have a ” (12.7mm) bore (cast on cylinder bottom). A reduction to 11mm for example can work well in some instances.

    Let's be safe out there & if in doubt ask an expert.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
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  2. #2
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    7th September 2009 - 09:47
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    Don’t use ally bolts anywhere near brakes. Levers, disc, and calliper mounts should have good quality steel bolts (or titanium if yer a wanker).


    Hey dave, I had Ti bolts on old blue and I am no more a wanker than you...

  3. #3
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    25th March 2004 - 17:22
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    My 500 is covered with them. What's your point?
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  4. #4
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    18th June 2006 - 00:14
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    Good thread... just been looking at the brakes on my FXR and the rear discs is well scored as the muppet who owned it had continiued to use it with no rear pad... looks terrible.

    I was planning to sand it and put some new pads on... it is the back after all ......!!
    One for the road...
    Kat1230 (81), GSXR1100 (86), RG500 (86)
    The 80`s - Back in the days when men looked like women, women dressed like whores and the music F@#KING ROCKED!

  5. #5
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    24th July 2008 - 18:01
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    All good stuff Dave . I got gsx wheels for my FXR and they came with discs but they are smaller dia about 10mm I think not wanting to buy new ones I removed the bottom bolt on the caliper and swung it down untill it was 3mm away from touching I then marked through the caliper bolt hole and drilled and tapped a new hole ,Not being sure if this would work was very carfull in practice but it has been great I was lifting the back wheel at the weekend .

  6. #6
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    I keep a syringe with a piece of rubber hose, I find it far easier to "back bleed" brakes than using the master cylinder. Make sure you flush it after using with brake fluid or it will be rooted next time you need it.

    Another tip is if you are struggling to get air out, cable tie the lever against the grip and as long as the master cylinder is the highest point it "can" self bleed the air bubble out.

    This is all good stuff Dave, thanks for sharing.


    Its harder to lose weight than gain horsepower.

  7. #7
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    30th November 2005 - 18:27
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    Quote Originally Posted by Rick 52 View Post
    All good stuff Dave . I got gsx wheels for my FXR and they came with discs but they are smaller dia about 10mm I think not wanting to buy new ones I removed the bottom bolt on the caliper and swung it down untill it was 3mm away from touching I then marked through the caliper bolt hole and drilled and tapped a new hole ,Not being sure if this would work was very carfull in practice but it has been great I was lifting the back wheel at the weekend .
    Hahaha, i got around that by fitting the complete front end.


    Its harder to lose weight than gain horsepower.

  8. #8
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    Quote Originally Posted by F5 Dave View Post


    A big disc is nice, but weight is a consideration. A more modern calliper with decent pads is worthwhile. I found a decentish calliper off an RG150, but turned out to be a rear & the pads available were all rubbish.
    An interesting point worth noting is that the front caliper is the same, however some brake pad manufacterrereers sell different pads for front and rear. Sometimes the 'rear' pads have heaps less friction material on too.
    Heinz Varieties

  9. #9
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    25th March 2004 - 17:22
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    Well I'm not a 150 expert, but the calliper appeared identical but (from faded memory) inversed & a search didn't find pads, they were just slightly different to everything else. Oh well, the problem went away with some excellent CBR 250 brakes of TM, think I still have the other side too.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  10. #10
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    12th February 2004 - 10:29
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    In Auckland check Darren Morgan's RG50 for an excellent example of how to do it. mmmmmmmm . . . billet bits

  11. #11
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    6th August 2008 - 09:18
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    You saw a muppet at buckets with bad brakes...? It wasn't my bike was it? My brakes work really well and haven't come loose at the caliper mount, despite the use of a few spacing washers. Or was it that bike Adrian was borrowing..? That thing looked like it might take some time to slow down haha

  12. #12
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    No it wasn't yours. & the A100 falls into the tiny drum brake category, - only really suitable for maneuvering off a trailer.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  13. #13
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    5th June 2005 - 18:35
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    Muppet at buckets with bad brakes... are you some sort of poet?

    Someone there was having trouble with their front brakes and problems became obvious when we were looking at them.
    Then I noticed the rear brakes

    The present owner didn't build the bike and was under the impression it was a good runner.
    He's had quite a few issues with it since he bought it.

    Goes to show that the idea of buying a ready to ride bucket, already built up, doesn't always work as well as it could.
    Life is a lesson-if I bother to listen

  14. #14
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    4th August 2007 - 17:55
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    Anyone got a recommendation for replacing standard front pads on a FXR?

    Brand etc.

    I haven't had to change them till now.

    Cheers

  15. #15
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    Quote Originally Posted by richban View Post
    Anyone got a recommendation for replacing standard front pads on a FXR?

    Brand etc.

    I haven't had to change them till now.

    Cheers
    MDF are really good try mitre 10
    It's not what you ride but how you ride it!!

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