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  • Disc brakes

    It's always easier to modify something instead of designing and building it from scratch, and today Amazon were selling an Artek MTB disc brake setup for just under 14, including stainless 160mm rotor. Sod it I thought, and got one to play with.

    Intention is to park the existing fairly chunky steel drum brake mechanism and drum, mounting the rotor onto the wheel via a cotton-bobbin flanged spacer, and the cable disc caliper on a couple of tabs on the fork leg. Should save at least a kilo.

    First, does anyone know what the proper name is for the flat tab headed bolts that are typically used on kingposts to take the outer cable at the top? Two would make ideal mounts for the caliper in the fork leg.

    Second, an MTB weighs maybe fifteen kilos with a rider of 82kg, and has two brakes, I'm proposing stopping around 220 kilos with just one, think the pads will just disappear?

    If so, at least the disc and experience fitting it will not be wasted, anyone know of a beefier caliper?

    Cheers
    Kev

    Ps

    http://www.apse.com.tw/E/body.php?web=11&SNo=02&FNo=101

    The manufacturer is APSE Enterprise Co. Ltd. and is Tawainese.

    APSE ENTERPRISE CO. LTD.
    No.54, Jhangma St., Sioushuei Township, Changhua County 504, Taiwan (R.O.C.)
    Tel:886-4-7612127 Fax:886-4-7613428
    Website:http://www.apse.com.tw/
    E-mail Box: apse.artek@msa.hinet.net
    G-KEVA
    BMAA 5696

    "If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls."

    R.J. Mitchell :- Designer of the Supermarine Spitfire

  • #2
    Disc brakes

    If it's any help, some while ago I had been playing with a few different set ups.

    1 problem I found was that manufacturers would not disclose technical details such as temp build up per joule input, max pad temp allowed, average pad wear etc.etc

    I think you may be pushing it a bit with only 1 brake, although they would not be subject to semi continuous, or such prolonged operation as on a bike.

    Most cable systems work out at about 0.8Kg per pair inc rotor and cable about 0.65kg

    You can get "racing" pads for many systems, which help to obviate brake fade, but generally are not so suitable when used with cable operation due to the harder compound

    Cable types
    The Avid "bb7" type has found favour with a number of PPG types, although it is "single acting" and appears to suffer from needing continual adjustment with a system which I do not like.
    Many of the single pot types, seem to suffer in the same way.....
    Single pot systems can suffer from "stiction" in the caliper slide which could be "offputting" if used in an independant heel/toe set up.!

    The IRD "Dual banger" is a better cable operated bet and tends to keep it's settings as is the Gusset Chute Mechanical Disc Brake.

    Hydraulic

    1 thing to watch is that some are "closed system" and although can be operated with the "master cylinder" in any orientation, can suffer from gradual self application in hot weather (no problem here as it's always BB^^%$$*& cold[IMG]/emoticons/smile.gif[/IMG]
    Others can only operate with the master cylinder in the normal "bike" position, otherwise they cannot recouperate.

    The Shimano M596 hydraulic 2 pot seems a good performer at a reasonable price and I believe the Kid uses the Hope Mono 4 which is a 4 pot hydraulic system and rather expensive..
    The Magura Julie HP (High Pressure) seems to have better stopping power for less effort

    Although they have not yet been tried in anger, I have currently settled for the Quad QHD 4 "Axis" dual pot hydraulic as an ecconomical set up with self adjusting pads.. although a sealed system. (partly because I got them VERY cheap[IMG]/emoticons/smile.gif[/IMG]
    .

    As an afterthought and not being a trike pilot, I wonder if it is a good idea to use a single brake on the front wheel?
    I can imagine all sorts of nasties when braking with the front wheel miss aligned.

    Comment


    • #3
      Disc brakes

      Front brake is actually more efficient on trikes.
      Rear wheels tend to unload and lock up, mostly on grass.
      I can't imagine brake fade is ever likely to be an issue on a landing.
      Unlike a motor vehicle, you only have a finite amount of energy to dissipate.
      Also on a trike, you have a good aerodynamic brake in the wing (bar hard into chest...)
      Dave

      Comment


      • #4
        Disc brakes

        I did look at using Pit Bike brakes, but the calipers themselves weight about 0.6Kg and use a heafty rotor although some do use a 160 mm dia rotor, but as you are aware,the larger diameter the rotor the better:-).
        There are a number of MTB 160 rotors available with different claims to "efficiency". However, there are 3 different "standard" rotor thicknesses used and of course thicker ones may not fit your calipers.

        Comment


        • #5
          Disc brakes

          Interesting .. my two recent 'steeds' (GT450 and MF) have front-wheel disc brakes, but no way I would think to be able to run up the motor against them. Handy for bringing the craft to a stop at the end of taxiing, but really would not think of using them at any other time.

          Mike

          Comment


          • #6
            Disc brakes

            Kev.. I knew I had seen a front wheel set up similar to the one you are proposing, although on PPGs.

            http://www.believeaviation.com/Home_Page.html

            Also

            http://www.skysthelimitusa.com/index.html

            Comment


            • #7
              Disc brakes

              > GT450 has two main wheel brakes Mike, no brake on the front wheel.

              Indeed. Typo --- I wrote just about the MF at first, then realised it was also true for the 450, added that and forgot to delete 'front'. Sorry.

              Also true for the Ikarus: could never do a mags check at 3000 rpm unless on rough ground/grass.

              Mike

              Comment


              • #8
                Disc brakes

                Loads of disc brake units on http:/ulmtechnologie.e.catalogues.info/ page 74

                Comment


                • #9
                  Disc brakes

                  Kev Armstrong wrote: Brilliant input

                  I tend to use the brake to run the motor up against it, having a 750 metre home strip means it isn't used a lot otherwise. At that price I am happy to bung it on and see what happens, after all, the mounting for the caliper is a DIN or similar standard, so it can be slung for a better one if required.

                  The ideal would have been the little cable disc on my lad's Derby Dirt Kid 12 mini motocrosser, but he would have objected to that being pinched.

                  Lots of scooter brakes around but it is finding someone who sells them as a kit, I'd have been happier locating something designed to stop a motorised vehicle, the stand-off spacer will have to be designed to accept other sizes of disc rotor, so if this packs in I can hunt out a beefier one, or just refit the original drum brake rig.

                  There are lots of lovely billet alloy parts on the Magic trike, but the brake drum is a lump of steel plate, on a slower machine I'd have slung the thing altogether, but mine's too quick to feel happy with no brake at all.

                  All hints and tips welcome, this will fit on any SSDR after all

                  Kev
                  hmmm not absolutely true Kev. I got quite excited until I read the rotor diameter was 160mm. The wheel not including tyre on the Dragonfly is just 115mm.
                  bummer
                  Mike

                  Comment


                  • #10
                    Disc brakes

                    If you are not aware, Pocket Bike rotors generally are 160,140 and 120mm dia, but the 120 mm ones are generally 3mm thick, instead of 1.75/2mm and so ensure any caliper you buy can accommodate the extra thickness.

                    Obviously the larger the diameter rotor the better the braking effort for any given set up, but you mentioned 2.5" ground clearance, I imagine the rotor will be close to the tyre sidewall, by it's very nature. May I suggest you consider the case when the tyre gets a puncture, especially if coupled simultaneously with a heavy nosewheel landing, I think there is the possibly of the tyre "bulging" out enough to distort the rotor, also if operating from grass with little ground clearance, grass can easily get "picked up" by the rotor, in both cases causing a partial/full "jam" in the caliper causing uncommanded partial/full braking effort:-(..
                    I would suggest that the rotor should not be significantly larger in diameter than the wheel rim.

                    Comment


                    • #11
                      Disc brakes

                      Kev. with all that fresh air above the tyre, you could fit a complete Pit Bike/pocket bike wheel and brake systems and still have space for an "airbag" for additional safety:-)

                      Comment


                      • #12
                        Disc brakes

                        Kev, Wally,

                        Judging by the cost of pocket bike wheels and tyres, fitting the complete wheel, tyre, and brake unit might be the most economical way to do it. You also get a really cool looking three or four spoke alloy wheel instead of a converted wheelbarrow wheel, and if weight allows you could fit them on all three axles, perhaps unbraked at the back.

                        Best regards,

                        Bob Hood
                        XL's forever! Well, one of them anyway. It's all I can afford, not to mention the Raven and the Mini-Max. Oh, and I almost forgot the Spectrum as well :-)

                        Comment


                        • #13
                          Disc brakes

                          Thanks for the info Kev. If Mike C is right though it sounds like Ben has already incorporated a disk brake on the latest dragonfly/motorfloaters. Mine's definitely a drum brake (and pretty useless)
                          By the way the wheels on the Flylight stuff are definitely not converted wheelbarrow wheels - they are from the Mountain Board world made by Scrub, albeit at the budget end. It's possible to buy full carbon fibre rims and I would have done, but my drum brake wouldn't have fitted and I'm not practical enough to make it do so.
                          Mike

                          Comment


                          • #14
                            Disc brakes

                            [quote=Bob Hood BMAA 3300]Kev, Wally,

                            Judging by the cost of pocket bike wheels and tyres, fitting the complete wheel, tyre, and brake unit might be the most economical way to do it. You also get a really cool looking three or four spoke alloy wheel instead of a converted wheelbarrow wheel, and if weight allows you could fit them on all three axles, perhaps unbraked at the back.

                            *oi Hood! converted wheelbarrow wheel? ;-)

                            John makes his own wheels, cast alloy with proper bearings inside, rather pretty too. Main gain is they are split rim, so a puncture in the field is easy to sort out with a couple of spanners, no heaving and tyre levers.

                            They do have 8mm bolts holding them together which is over the top, I swapped thebolts for 6mm with hard nylon pneumatic tube sleeves over to knock a few hundred grams off, it works well.

                            One item that could do with being in the handbook is NOT to just tighten up the wheel retaining nuts, to save weight the bearings don't have spacer sleeves between, so the nut is merely spun up to touch then split- pinned.

                            Kicking ideas around like this is great for advancing everyone's safety, thanks

                            Cheers

                            Kev
                            G-KEVA
                            BMAA 5696

                            "If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls."

                            R.J. Mitchell :- Designer of the Supermarine Spitfire

                            Comment


                            • #15
                              Disc brakes

                              Kev,

                              Please apologise to John for me, I was of course thinking more of our older trike designs when I wrote about the wheels. For instance, I hadn't noticed that the wheels on your trike are ally, and made the assumption (it is bad to assume anything!) that they would be plastic like mine.

                              Sorry!

                              Bob Hood
                              XL's forever! Well, one of them anyway. It's all I can afford, not to mention the Raven and the Mini-Max. Oh, and I almost forgot the Spectrum as well :-)

                              Comment

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