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lowmass

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  1. btw does anyone kno Brembo master and caliper piston diameters? And yes I understand theres another LR at the lever itself, just curious about piston size
  2. I agree this is a good point however I have bran new rotor hangers and pins. Also when I measured the flex it was caliper off bike and removed from hanger , caliper alone. That makes sense
  3. Not sure what your tryin to say here? Do you mean that the caliper does not flex?
  4. Yea as I said I suspect the problem was far more the angled wear than the flex. Once the parallel was milled back in the breaks worked good again. Nothing like the Brembos however. Anyone know how to post a vid from an I phone. I will show ya way more than .005" on my "real life " test
  5. yes if you read a few posts back it wasn't .030 it was actually .017". That plus the angled wear made the pressure on the pads so uneven that you could actually see from the marks on the rotor that only 1/2 the pad was in play ( was obvious in mud). A lot of people are surprised at how much mechanical structures flex. We think things are more rigid. This is an area I deal with quite a bit in the design of high precision measurement equipment used in physics labs. In that community there is a saying, " everything is putty" Once we were designing a "measurement bench". The "bench" was a granite beam that was 24 inches wide by 30 inches deep and about 10 feet long. You could actually take your finger and push down on it and see a section about a foot away actually hump up a few microns. As far as the aluminum caliper goes, I modeled up a similar structure in our CAD program and did a flex analysis on it. It didn't take much force at all to get it to open up enough to cause non parallel surfaces.
  6. Anyhooo…. Looks like the keyboard warriors are going the way of CNN We will shut it down from here. Problem solved
  7. that's right, I have failed every spelling test I've ever taken yet there are satellites over your head right now with my fingerprints on them . Go figure
  8. No my friend it is flexing and flexing a lot. You need to take a materials property class if you think that aluminum is not flexing from hydrolic force, or set things up as I have and see it for yourself. I don't mean to sound rude BUT I am a mechanical engineer with over 30 years experience designing equipment for physics labs all over the planet . Equipment that needs to understand flex well as the measurements are often in microns and even a 2 foot thick steel beam will flex that much just by setting your lunch on it. This one is is pretty simple, As far as your thinking it would "flex other way" The caliper is like a C clamp. Tighten the screw and the C shape flexes open. Wich does seem opposite of wear but think on it some more. Even the wear marks on the rotor tell same story. You may have a point about the wear from moving around, Im not sure yet BUT eather way the wear resulted in only half or less of pad being clamped. No again. I wish I could load the vid. The caliper removed from bike and the guide pins, and with a medium pull on lever the caliper flexes open about 17 thousands of inch. That plus the angled non parallel wear between the piston faces and the other side of caliper add up to more than enough to be an issue. I suspect the wear is more of the issue than the flex in this case however. not likely but I admit when I get on my friends KTM it takes a few laps before I get used to not having to pull that lever hard, Now for some evidence. Took caliper to our machine shop at work. Remeasured to be sure and yes it wayyy out of parallel. So we milled it back to parallel. Went home and rode. YAY!! the power is now back! its not KTM power BUT even with a shinny rotor it now doesn't give me arm pump in a few laps, AND the lever now feels hard again, not mushy . Much better. Again not KTM level but at least it back to how I remember when new.
  9. Ok so investigating this further has revealed something I have been wondering about for a while. Is the caliper wearing at an angle? I know from measurement that the caliper is quite flexy, and if it is flexing then the two surfaces that squeez the pads will no longer be parallel. And if that's happening it should over time wear at an angle. Well sure enough,the surface where the back side of inner brake pad pushes against the caliper is far from parallel with the pistons surface. In this case I put two flat straight pieces of plate against each surface with a spacer in between and tightensd up with brake lever just enough so that there are no spaces. First photo shows distance between piston surface and caliper surface at point where outer diameter of brake pad would contact, and second photo shows measure where inner diameter of brake pad would contact. The measurement shows a farly large difference of about .035" over width of brake pad. This means the caliper is squeezing unevenly on brake pads and not spreading force out evenly. This btw would make the brake feel spungy even with no air in lines and yes that is what mine fells like. Last pic is just showing the surface of caliper that pads sit against that is wore at an angle. Even before I put the measuring calipers on it , it was obvious to the eye! Also I did a video of the caliper actually flexing apart as you squeez the brake lever. I did this with I Phone BUT It would not load for some reason. Anyway done this way with caliper removed from bike it flexes open about .017" with two finger pull. Not the .030" I clamed earlyer In the end its clear that the caliper is rather flexy AND over time as grit is mashed in there and squeezed, it wears the pad clamping surface at an open angle with respect to the piston surface. My plan now is to mill the surface back to parallel and see what happens. Maybe even machine it so that its at an angle a few degrees past parallel so that at a two finger medium pull on lever the flex in caliper makes the surfaces parallel and pressure even across pad surfaces.
  10. I'll see what I can do
  11. done that. same issue with stock. Back when I was 120 pounds soaking wet and 30 years younger thes brakes were enough. There are reasons why the pros use a billet caliper and when I ride my friends KTM I dont have an issue.
  12. more like .030" , more if pull hard Yes your getting the force BUT once the caliper spreads open a bit you no longer have parallel even pressure over brake pad. this means that the force of pad against rotor is not even across pad surface.
  13. Dont mean to sound punchy BUT this simply isn't so. Both visually and in measurement the caliper is flexing and flexing a lot. I put a large measurement caliper on the break calipers of both the Brembos and the Nissin and with even a small pull on lever ( used a force gauge to do it equally) we see quite a bit of flex. However the Brembo flexed less. Cast aluminum can be flexed. These systems are not taken past yeald point of materials BUT they are flexing as ALL materials will due under a load. The trick to making Aluminum last in flexy situations ( within reason of course) is all in the SHAPE of the structure. Get the shape right and the stress can be evenly distributed enough to avoid the stress risers that can fatigue aluminum very quickly. As far as your comment on epoxy goes... This was a response to someones statement that there may be trouble welding on that cast aluminum. The idea was to mill out some C shaped pieces of aluminum that fit snug around caliper then epoxy them in place. The epoxy is not being used to stiffen the caliper, its simply used to glue the stiffeners in place. As far as finger strength goes I am at a big disadvantage and putting all effort there has dimishing returns. Im closing in on 60 yrs AND have small hands and forearms. I can still hang with the young guys in expert class BUT arm pump in right arm/ hand from front break weakness limits me to about two laps at that pace.
  14. lowmass

    The Hand

    did some comparisons this summer between the old MX3S ( famous for cracked knobs) and the new MX33 ( supposed to be more durable than the MX3S) On the front... Yes the MX33 held up better than the old MX3S. The knob cracking seems to have been solved or at least usefully reduced. Couldn't tell if there was a drop in performance. On the rear... didn't see any obvious change BUT the new MX33 did seemed to wear faster than the old MX3S. Not absolutely sure on this one though. Then went through some of the Bridgestone Battlecross tires. X30 front , X40 rear. These wear noticeably less than the Dunlops. And yes the Dunlops did perform to a higher standard than the Bridgstones BUT only in the conditions that the Dunlops excelled in. IN the wide variety of conditions I would actually give the Bridgstones the nod simply because they were at least "good" everywhere AND beat the Dunlops in hard pack. The best trate of the Bridgstones is their consistently good perf everywhere. More predictable than the Dunlops that may out shine them only in specific condition. As well in our area we get these deep narrow groved rolled over ruts at turn entrance. The Dunlops seem to more easily catch the sides of these ruts and climb out. This was most noticed at choppy turn entrance. The Bridgstones did not have as much issue here.
  15. lowmass

    super vet

    https://motocrossactionmag.com/80-year-old-grandpa-earl-shreds-on-a-dirt-bike/
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