Announcement

Collapse
No announcement yet.

Disk Brake Heating Up

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • SanJoseUnicyclist
    replied
    Finspin, I love your solution! Simple and like you said, it did not take a lot of time. I'm a product designer. So, I do this type of stuff for a living. I just could not help going overboard on this design (just wish I had the time and machining capabilities to put a little industrial design into it)... Also, like you said, I don't need to remove this extra bracket to take off the wheel.

    I agree about not being able to tell the difference with the different brake pad materials. I was very surprised that after spending ~$300 on this (somewhat) top of the line disk brake that I could hardly tell the difference when compared to the original $100 brake from UDC. The only difference being that this nicer brake does not overheat. If I was not riding steeper hills, I'd be very happy with the $100 brake.

    Leave a comment:


  • finnspin
    replied
    Originally posted by JimT View Post
    An interesting fix for the poorly desiged D' Brake Adapter. I think a welded bracket on the frame would have been better and it would be a lot easier to remove the wheel when needed. A good tig welder could add a bracket on the frame for a clean solution to the problem.
    That costs a decent amount of money though, unless you have a TIG welder friend, which I'm still looking for, unfortunately. My brace on my oracle cost me about 5Ä, and doesn't add any time to remove the wheel. It's a bent piece of aluminum as a bracket on the frame, and a piece of tube "hinged" at the bracket by a bolt, and attached to the top of the brake caliper with it's mounting bolt. If I want to take the wheel of, I can swing it out of the way, and only need to remove the two usual bolts of the bearing holder/Dbrake adapter.

    Click image for larger version

Name:	IMG_20180410_191608928-468x832-210x374.jpg
Views:	1
Size:	18.7 KB
ID:	2461739

    Not as pretty as SanJoseUnicyclists solution though, but it has worked well so far. My next unicycle will get a frame with a proper mounting tab though.

    Does anyone have first-hand experience comparing the difference between ceramic and steel pads on a uni?
    I've only had metallic, semi-metallic, and resin/organic. To be quite honest, I didn't feel as much of a difference as many people would say, neither in performance, modulation, noise or wear. From the tests in magazines I've read, they often find that the presumed characteristics of materials often are not reflected in the test results, there are organic pads that last longer than some metal ones, really quiet metal pads, etc. So it's not just a question of material, but the specific compound any manufacturer uses.

    Leave a comment:


  • JimT
    replied
    An interesting fix for the poorly desiged D' Brake Adapter. I think a welded bracket on the frame would have been better and it would be a lot easier to remove the wheel when needed. A good tig welder could add a bracket on the frame for a clean solution to the problem.

    Leave a comment:


  • kunstrasen
    replied
    Wow. Looks like you spend a lot of work and time. Maybe buying a disc frame (e.g. Oracle frames are not too expensive, at least here in Germany) would have been easier. But that is just a boring stock solution.

    Good luck with your latest version. Looks pretty solid to me.

    Leave a comment:


  • SanJoseUnicyclist
    replied
    Well, I've been on a journey dealing with brake chatter from this 203 mm disk. Before I get into it, I'd like to thank kunstrasen again for sharing the design to stiffen the D'brake adapter's large cantilever arm.

    I copied Kunstrasen's basic design, but since my son has a 3D printer, I thought I'd design a nice (plastic) bracket to clamp onto the KH frame. Also, I noticed that one of the M6 threaded mounting holes on TRP's "disk brake adapter" (a.k.a., the standard mountain bike bracket that fastens to Unicycle.com's D' Brake Adapter to position the brake caliper at the correct location for the 203mm disk, phew...) was nicely pointed in the direction of the KH frame.
    Click image for larger version

Name:	IMG_7180 (digimizer) (low res).jpg
Views:	1
Size:	144.2 KB
ID:	2461731

    So, I though I could easily lengthen the M6 screw and then hold the extended screw with the 3D printed bracket mounted to the KH frame. The design worked sort of nice. Check out the pic below:
    Click image for larger version

Name:	IMG_7549 (low res).jpg
Views:	1
Size:	134.7 KB
ID:	2461725

    The problem was that I did not buy a longer M6 screw. I tried to wedge a rod between the 3D printed bracket and the "disk brake adapter". (Figuring that the rod would always be in compression.) After a few rides, the relatively flimsy 3D printed bracket became lose and the rod fell off.

    So, for the 2nd design attempt, I still used a relatively weak 3D printed bracket, but this time I got rid of the original M6 socket head cap screw and bought a 4" long M6 threaded rod. I then used the threaded rod to mount the Slate T4 caliper while the 3D printed bracket held the other end of the threaded rod (still just used compression between the 3D printed bracket and the threaded rod). Two pics below:
    Click image for larger version

Name:	IMG_8629 (low res).jpg
Views:	1
Size:	158.7 KB
ID:	2461726
    Click image for larger version

Name:	IMG_8635 (low res).jpg
Views:	1
Size:	145.1 KB
ID:	2461727

    This worked great for several weeks. But, I've been braking pretty hard and either from yielding the plastic bracket, or creep, or low cycle fatigue, the 3D printed bracket started to twist on the frame and under really extreme conditions I could hear the brakes start to make noise (I believe this is the precursor to chatter once the bracket became even looser).

    So, I bit the bullet and redesigned the bracket out of aluminum. I know that the bracket is huge, but this 3rd try has got to work! Also, I've threaded the M6 rod into the aluminum bracket. Super stiff... Below is my final design. if this does not work, I'm biting the bullet and buying a 180 mm disk and the Shimano Saint caliper...
    Click image for larger version

Name:	IMG_8824 (low res).jpg
Views:	1
Size:	159.0 KB
ID:	2461728
    Click image for larger version

Name:	IMG_8829 (low res).jpg
Views:	1
Size:	116.3 KB
ID:	2461729

    Look at how little clearance there is between the disk and the bracket. Hope this is OK. It was Ok for ~6 weeks of riding with the plastic bracket (and that bracket had even less clearance because of thicker walls).
    Click image for larger version

Name:	IMG_8828 (low res).jpg
Views:	1
Size:	104.1 KB
ID:	2461730

    In a few weeks, I'll let you know how this works. My guess is that it's going to be super solid and I'll be able to brake hard and fast with no chatter!

    Leave a comment:


  • kunstrasen
    replied
    On mtb in the past I did compare the original organic vs metal pads on a shimano XT. My feeling was that the modulation is a bit better on organic. The braking power is lower on them. In case of vibration the organic can help, they tend to be quiter. However, I did not have noice with the metal pads as well. As braking power is higher and the wear is much lower on metal, I stayed with them.

    There are other pad makers as well. One of the best tested (high power) were always the trickstuff brake pads (available for most current brakes). I have no first hand experience here.

    On the Muni I never changed the original Saint metal pads.
    Attached Files

    Leave a comment:


  • SanJoseUnicyclist
    replied
    Yeah, I sort of wish I bought the Saint!

    Does anyone have first-hand experience comparing the difference between ceramic and steel pads on a uni? I'm curious how big of a difference you actually feel on a muni.

    Also, as mentioned above, I have the T4 caliper with steel pads. I was concerned that the steel pads would be too aggressive and cause me to stop too quickly (low modulation). Not the case. I feel I could still use more braking power. I believe the reviews for the T4 caliper say that it does not have as much braking force as other calipers. So, I'm wondering how much of the lack of braking power/force that I feel is due to a single brake on a 29" unicycle while going down a 25% grade, or how much is due to the T4 not having as good of braking force as the Shimano Saint.

    Leave a comment:


  • kunstrasen
    replied
    If it comes to 4 piston brakes I can recomment the Shimano Saint. It has excellent braking power and great modulation. Very easy to control. Due to he solid caliper design plus ceramic pistons it has also no overheating issues at all.

    Leave a comment:


  • SanJoseUnicyclist
    replied
    Thanks for pointing that out, Finnspin!!!! (I did not take the time to re-read the entire string before posting and missed your post. Sorry about that.)

    You should read the reviews on the T4. If I remember correctly, they talk a lot about how great the modulation is. I thought modulation would be important because with my old brake I would have to be very careful about not over-breaking when first engaging the brake. With the T4, I can brake hard even when first engaging the brake because it is so forgiving.

    BUT!! I'm guessing that the T4 gives up braking force in order to have improved modulation. The reviews say that the T4 does not have good braking force. (I read the reviews a long time ago, hope I'm remembering correctly...)

    I have to admit that I wonder what the best Shimano four-cylinder caliper would be like! My understanding is that it has great force, but who knows about the modulation.

    I find this topic all very interesting, but frustrating because there is such little data/experience out there with these brakes on unicycles. Thus my motivation for posting about my T4 experience.

    Leave a comment:


  • finnspin
    replied
    Good to hear the overheating is solved!

    Originally posted by SanJoseUnicyclist View Post

    But, there is one huge caveat! The brake chatter that Kunstrasen and others mentioned is very real with the 203-mm rotor. If I had to do it all over, Iíd stick with the smaller rotor. The brake chatter that I experienced with the 203-mm rotor was severe and I could not ride a couple of feet down the steep grades without being tossed. The only solution was to use Kunstrasenís support bracket design. THANK YOU for the design tip!!!!!!!! Iíd be out of luck without that bracket.
    As I mentioned, I had that brake chatter with a 180mm rotor, so I'm not sure it depends on brake disk size alone, but probably more on pad compound, frame stiffness etc. The support bracket will also help the Adapter not break (which they sometimes do), so it's definetely worth it for anyone.

    I'm in the market for a good 4 piston brake (well, that's when I have some money to spend), so I can add the slate t4 to the list of candidates now. How far away from the seat does the brake lever end up?

    Leave a comment:


  • SanJoseUnicyclist
    replied
    Ok, I finally have my new brake and have put a couple hundred miles on it.

    Here is what I purchased:
    - 4-Piston Caliper: TRP Slate T4 Four Piston Caliper (front) for $120 US
    - 203-mm Rotor: SHIMANO XT SM-RT86 6 BOLT ICE-TECH ROTOR for $57 US
    - Metal brake pads with cooling fins: Shimano H03C Metal Brake Pads with Cooling Fins for $30 US

    Total was $210 + tax and $60 for install.

    Am I happy? Yes and no. First, I figured that with 1) a 203-mm rotor, 2) a four-piston downhill mountain bike caliper, and 3) metal brake pads, that Iíd notice a huge difference in braking power (by this I mean less force on the brake lever with my finger for more braking force). However, the braking power of this relatively expensive setup is very similar to my original Shimano BL-M445/7L Disc Brake from Unicycle.Com. As a matter of fact, after this first-hand comparison Iíd highly recommend the Shimano BL-M445/7L Disc Brake from UDC for most riders.

    The big difference is that my TRP/Shimano-Ice setup does not overheat at all. I have ridden these steep/rocky hills (>20% grades) 3 to 5 times per ride about 3 times a week with no overheating issues.

    But, there is one huge caveat! The brake chatter that Kunstrasen and others mentioned is very real with the 203-mm rotor. If I had to do it all over, Iíd stick with the smaller rotor. The brake chatter that I experienced with the 203-mm rotor was severe and I could not ride a couple of feet down the steep grades without being tossed. The only solution was to use Kunstrasenís support bracket design. THANK YOU for the design tip!!!!!!!! Iíd be out of luck without that bracket.

    My big takeaways:
    1) Donít get a 203-mm rotor

    2) The TRP Slate T4 has incredible modulation. So good that I can switch hands during the steepest parts of these declines. I feel modulation is extremely important for muni.

    3) Donít hesitate to get metal brake pads. I donít think they are overly aggressive! Iím amazed that I canít tell the difference between the original Unicycle.com brakes and these expensive brakes (other than the fact that the expensive brakes do not over heat!).

    Leave a comment:


  • finnspin
    replied
    It's too little torque for most torque wrenches. So the KH instructions are the best guide there is. You should also make sure the D-Brake adapter is installed correctly. (Tighten the back bolt all the way down first, then snug up the front.)

    With the amount of instruction you'll have to do for the uni specific parts, I'd just have them install the disk on the wheel, and shorten the lines, then do the rest myself.

    Leave a comment:


  • JimT
    replied
    Originally posted by SanJoseUnicyclist View Post
    Does anyone know of a good torque requirement when tightening the bearing housing screws on the KH frame? On the KH website, the only guidance given is:

    "... tighten the bolts with slight hand pressure. To test whether the bearing housing bolts are too tight, give the wheel a spin. The wheel should spin freely. If it does not turn perfectly freely, the bearing housings are too tight, and should be loosened slightly. Overly tight bearing housings will damage the bearings, and will not be covered by warranty."

    Since I'm going to have a bike shop install the disk brake, I know that most of the mountain bike components provide torque requirements and the tech's are used to tightening screws to a required torque. Without a torque requirement, I could imagine the tech being ignorant about uni's and cranking on the screw to the point of damaging the bearing.

    (I searched the forum, but could not find a discussion about torque requirements.)

    Thank you!!
    I think the spin free method is the best. Just direct anyone messing with it not to over tighten.
    Unless you do like I did, then you can torque to the limit of the fastener.

    Leave a comment:


  • SanJoseUnicyclist
    replied
    Does anyone know of a good torque requirement when tightening the bearing housing screws on the KH frame? On the KH website, the only guidance given is:

    "... tighten the bolts with slight hand pressure. To test whether the bearing housing bolts are too tight, give the wheel a spin. The wheel should spin freely. If it does not turn perfectly freely, the bearing housings are too tight, and should be loosened slightly. Overly tight bearing housings will damage the bearings, and will not be covered by warranty."

    Since I'm going to have a bike shop install the disk brake, I know that most of the mountain bike components provide torque requirements and the tech's are used to tightening screws to a required torque. Without a torque requirement, I could imagine the tech being ignorant about uni's and cranking on the screw to the point of damaging the bearing.

    (I searched the forum, but could not find a discussion about torque requirements.)

    Thank you!!

    Leave a comment:


  • finnspin
    replied
    From my experience, "noise" isn't the best description for what can happen with a flexing D-Brake. Massive vibration under my butt, and not in a pleasant way is what I had, before I made up a "Hugo strut" as kunstrasen linked to. But not everyone has that problem, it's highly dependant on your brakes, pad material, frame stiffness, riding technique etc.

    Leave a comment:

Working...
X