Frankenbrakes and brake improvement discussion
- Thread starter Udi
- Start date
Goddamnit, I found a flaw with Dominions. I was building up my new frame, and discovered I didn't have any spare hose barbs/compression fittings. I've got some on order now, but the problem with using smaller brands like this is that there's no shops in the area that carry their small parts. So now I have to stare at my new bike sitting in the stand with the rear brake hose disconnected.
Took those 1gen Code calipers apart. Dirty goo inside... no wonder pistons didnt want to retract.
I've ordered new seals compatible with mineral oil, so I can use mineral oil and shimano levers. Will report later next month probably. If not, something went horribly wrong, and you should consider me dead.
I've ordered new seals compatible with mineral oil, so I can use mineral oil and shimano levers. Will report later next month probably. If not, something went horribly wrong, and you should consider me dead.
Question for all you Dominion A4/T4 guys. How have you managed to keep the pad spreader clips from rattling in the calipers? I got a fresh set of brakes installed and set up this weekend took them for a ride, and they are excellent. But the spreader clip rattling through tough terrain is driving me nuts.
I gently bend them apart (in the center, where the bolt goes through) with a flathead screwdriver when I first install the brakes.
I haven’t run into that problem. Stuff a little chunk of neoprene in under the retention bolt?
Mine aren't rattling? Probably just try to bend the spring for more tension?
I was gonna try that, but I reached out to Hayes and asked them about it. They told me to carefully pry the spring apart a little bit and put it back, that seems to help in most cases. Gonna give it a shot and see how it goes.
They feel fantastic, but during the ride I thought maybe it was the cables rattling against each other or I was hearing/feeling something that wasn't really there. Finally I stopped and felt all around the hub/wheel/brake caliper and sure enough I could easily move that retention spring around and that was the sound.
My buddy who got them first had a rattle with the sintered pads when he fit them, but not the organics. Wonder if it was just the spring causing it. My sintereds didn't rattle so I'd put it down to a bad fitting set of pads.
Blob of thick grease on the bolt area will soon stop you worrying about the noise from the pads rattling.
I found a nerdy mechanic (Brad Kelly) on insta sharing some tricks to improve braking
Pads' squareness
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New pads prep
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Shaving Sram brake pads
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Straighten rotor
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Bleed port at the highest for the caliper too
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Facing brake mounts
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Caliper maintenance
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Shimano pad spring
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Pads' squareness
BK on Instagram: "It's pretty obvious the majority of riders like their brakes "tight" with as little "free stroke" as possible. This can also enable you to run your lever reach a bit closer which can help with finger strength/power on the brake lever and can also help reduce forearm strain and arm pump. To get your brake pads as close to the rotor without rubbing requires a solid hub/frame interface with minimal flex/movement, an aligned/square disc mount, a straight rotor and square pads. It's only natural that brake pads trying to grab/stop a spinning rotor causes the leading edge of the pad to want to rotate inwards. This is even more noticeable on brakes such as the Magura MTs that run 4 smaller individual pads, as the shorter pads don't have the length that helps them resist rotating. Having 4 leading edges of pad as opposed to 2 is one of the ways Magura is able to increase brake power. As the pads "wedge" it decreases the ability to have a tight bite point as the trailing edge of the pad will contact the rotor but will then require more lever movement until pads hit flat reaching the bite point. If this becomes annoying enough (rotor rub/too much free stroke), there are really only 2 things you can do. Replace the pads or square them up. Replacing the pads would be my recommendation for maximum performance. If this happens quite quickly and you still have more than half your pads left, you can (like I have done on my own bike) mount pads in a vice and file them square, checking vertically and horizontally with some vernier calipers. On customers bikes, I do not file pads, it's too much of a stuff around and time consuming. I usually just advance pads and get brakes as tight as possible without rotors rubbing. I do however recommend new pads on the earlier side of things (at approximately 1/3 left). One, to fit pads that are nice and flat and get that nice tight bite point and two, because customers in general don't usually keep an eye on things and don't want to need to go to their LBS more often than needed. For reference, these pads had a 0.4mm difference in width between the leading and trailing edges. Continued in comments.."
1,666 likes, 36 comments - bee_kay77 on March 13, 2023: "It's pretty obvious the majority of riders like their brakes "tight" with as little "free stroke" as possible. This can also enable you to run your lever reach a bit closer which can help with finger strength/power on the brake lever and...
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New pads prep
BK on Instagram: "Bedding in new brake pads Aim: To get brakes as powerful as possible and as quick as possible after fitting new brake pads. Before fitting new pads, I highly recommend measuring your rotor wear. This is one of the most overlooked components on the bike, and plays a huge part in brake performance and safety. Depending on pad compounds, you can need to replace rotors as often as every 2nd set of pads. Be sure that when measuring rotor wear, vernier caliper measures the centre of the braking surface and doesn't foul on parts of the rotor where pads do not contact. Step 1. Wet new pads with water, rub braking surfaces together, rinse and repeat until black gunk stops coming out (usually 2-3 times). You're going to be surprised how much gunk you remove from (most) manufacturers new pads.. Step 2. Fit pads, wet rotor and brake caliper thoroughly, use an easy gear so you can pedal through some hard braking. Do not lock the brake up. (This process will be noisy due to the brake being wet) Rinse black gunk from rotor and repeat until you can see (on the rotor) that all of the pad has contacted the rotor. This will vary depending on rotor wear, as rotors generally wear to a concave profile due to less material in the centre around the holes/slots. Step 3. Remove pads, and repeat step 1. Be sure to keep pad orientation the same as previously fitted. Recap: 1. Cleaning new pads 2. Deep cleaning rotors (with clean pads) and accelerating pad wear with water to get brake pad to meet rotor profile. 3. (The most important step for power increase) Removing gunk from pads that has come out of the rotor during the bed in process (the rotor is not coarse enough to clean pads effectively) I generally don't sand pads or rotor unless removing rust or minor damage from a rotor and have found this process to be far more effective and superior. The faster you can stop, the faster you can go.. Caution, brakes may be lethal. #driftbikes #builtbybk #mtb #bike #bikemechanic #bikelife #techtips #tunedbybk #bikehacks #performance #freespeed @weratoolrebels @bsc_tools @beautbike @toolboxwars"
2,787 likes, 87 comments - bee_kay77 on August 19, 2022: "Bedding in new brake pads Aim: To get brakes as powerful as possible and as quick as possible after fitting new brake pads. Before fitting new pads, I highly recommend measuring your rotor wear. This is one of the most overlooked...
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Shaving Sram brake pads
BK on Instagram: "Shaved down a couple more sets of Sram brake pads this week. Pretty crazy this is a thing, and no wonder why people have problems setting up and keeping their brakes running well and drag free when you have problems like this added to an already high maintenance component such as brakes. I also installed for the first time in a long time, some after market brake pads (due to ongoing supply issues) into some Sram calipers with the exact same tolerance issues (was hoping they would have uncoverd this problem and rectified it) but more than likely, they just replicated factory pad dimensions (their painted backing plates for compound identification possibly didn't help either). I'm not 100% sure where the inconsistency is coming from and I haven't looked too far into it, manly because I'd rather just modify a brake pad (wearing component) than the harder to access steel pressure plate that is sandwiched between the two caliper halves, which would obviously be much more work too, including caliper disassembly and a bleed. Problem is still there however when it's time to replace pads and this isn't picked up and the new pads aren't shaved down.. These pads actually needed a fair bit of material removed too, and I opted to shave both sides a couple of times (remove a minimal amount and retest several times) to make sure the sides of the pads were flat, because there was actually some high points (see marks in second pic) that needed to be "faced", to be sure tolerance was still as tight as possible, to minimise excess movement, but ensure pads could move with the pistons without any restrictions. #driftbikes #beforeandafter #tunedbybk #builtbybk #mtb #bike #mechanic #mechaniclife #bikesforlife #dirtcycle #ridefixrepeat #brakes #mountainbikes #brakeperformance #mods #techtips #dialled #padslap #zerodrag #freespeed #soundupforthirdpic #rageagainstthemachine"
1,600 likes, 92 comments - bee_kay77 on April 30, 2022: "Shaved down a couple more sets of Sram brake pads this week. Pretty crazy this is a thing, and no wonder why people have problems setting up and keeping their brakes running well and drag free when you have problems like this added to an...
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Straighten rotor
BK on Instagram: "My preferred and most accurate method for straightening rotors: Whether it's a new build or adjusting a used brake within a service, in both these cases the brake will benefit from having the pistons pushed all the way back into the caliper (after cleaning pistons if they're dirty). This will also give you the clearest view of which way the rotor needs correcting to straighten. It's one thing to have your brakes drag free, but it's another to have your rotors running as straight as possible. I recommend connecting a bleed syringe half filled with fluid to the brake lever before you push caliper pistons back (especially with Magura or Shimano systems), unless you're 100% confident or know the system was either bled with the manufacturers bleed block or the system was closed with the caliper pistons retracted all the way back in the caliper, to prevent any risk of damage to the master cylinder if the system has been bled incorrectly with too much fluid (unfortunately pretty common). With pistons retracted back for a clear veiw, I then run the caliper bolts just loose enough to be able to move the caliper to make the rotor rub intermittently (just like a truing stand) so you can see AND hear where the rotor rubs the pad. I mark the start of the bend with my finger on the TOP of the rotor (to not touch braking surface) then stop the wheel at the end of the rub, so I can visually see how long the bend is. I can then determine how many fingers I use (1 to 4) depending on the length of the bend and aim to pull or push in the middle of the bend. Once rub free, I then move the caliper in slightly to get an intermittent rub again and repeat until dead straight! You are better off doing small adjustments and repeating, rather than bending too far and going back and forth with it. (Picture of Knipex on rotor for attention) Although I have used this method on a repair when the request was "just get it going" and the rotor was too bent to be straightened by hand, in which case I would usually just replace the rotor. Although I think the Knipex would do a better job than a rotor tool anyway which is another good space saver for the toolbox."
1,244 likes, 56 comments - bee_kay77 on May 14, 2022: "My preferred and most accurate method for straightening rotors: Whether it's a new build or adjusting a used brake within a service, in both these cases the brake will benefit from having the pistons pushed all the way back into the...
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Bleed port at the highest for the caliper too
BK on Instagram: "I see a lot of people tilting brake levers during the bleeding process to insure bleed port is at the highest point to help aid in the removal of air, but it doesn't seem many people understand the importance of removing calipers and tilting so that the hose connection/bleed nipple is at the highest point. It's super important as oil flow during a bleed isn't fast or strong enough to pull bubbles trapped at the highest point in a caliper. It can be a little awkward trying to juggle the caliper, syringe and bleed nipple tool, but what's the point in bleeding if you're leaving air trapped in the caliper? I always do a small reverse bleed first (first pic), to remove any air created while connecting the syringe, any air/dirt stuck in a bleed nipple or any bubbles in the caliper first, rather than having to push these through the whole system and out the lever. You definitely don't want dirt or contaminants obstructing your lever ports that have been pushed through from a bleed nipple. Position bleed port at the highest point for the reverse bleed and removing air from caliper first, then rotate caliper so that brake hose connection is at the highest point when pushing fluid upwards through the system (second pic). I also see a lot of brakes overfilled which can cause huge problems including master cylinder and bladder failure. This has no effect on making brakes "tighter" as many people seem to think. Use manufacturers bleed block to ensure fluid level is correct, and know that adjusting lever throw is all done by retracting or advancing pistons. #driftbikes #builtbybk #tunedbybk #mtb #bikes #bikemechanic #techtips #cycling #magura #bleeding #performance #bikeservice #bikemaintenance #mechaniclife"
1,263 likes, 80 comments - bee_kay77 on April 15, 2022: "I see a lot of people tilting brake levers during the bleeding process to insure bleed port is at the highest point to help aid in the removal of air, but it doesn't seem many people understand the importance of removing calipers and...
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Facing brake mounts
BK on Instagram: "Face it Friday. For ultimate brake performance it all starts at the brake mounts and having them perfectly aligned. They never are from the factory before facing them (especially if painted over) . Not only does it get the new pads hitting a new rotor perfectly flat increasing performance and pad life, it also reduces piston friction by ensuring they advance and retract perfectly aligned in the bore. Tips is to always use cutting fluid, it enhances tool life and cutting performance. #driftbikes #builtbybk #bicycle #mechanic #bikemechanic #mechaniclife #precision #performance #probuild #doitright #martiniracing #doodoomobile #bikelife #mtb #facing #cutting #brakeperformance #inspires #confidence"
1,624 likes, 49 comments - bee_kay77 on April 1, 2022: "Face it Friday. For ultimate brake performance it all starts at the brake mounts and having them perfectly aligned. They never are from the factory before facing them (especially if painted over) . Not only does it get the new pads...
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Caliper maintenance
BK on Instagram: "Caliper maintenance. I hear the term "sticky pistons" a fair bit. 99.9% of the time, it's from not performing regular caliper maintenance and from pushing dirty pistons back into your caliper seals! Of course your caliper pistons will become sticky and won't retract or advance as freely if you don't regularly clean your pistons. Maintenance Tips: If you have an air compressor, constantly blast dirt and brake dust that sits on your pistons out of your calipers from the top and underneath. If you don't have a compressor, using a hose will flush most of the dirt/dust out. Never push pistons back into a caliper without cleaning the pistons first! This is the biggest culprit! Using old pads to push pistons back before replacing pads is a good method to avoid damaging pistons, just be sure to remove pads, clean pistons and re fit pads before pushing the pistons in! I have a cut down toothbrush, bristles and shaved down head for maximum clearance and simply wet the pistons and brush with brake cleaner (I use Wurth in pump action spray bottle) and scrub a few times until clean before retracting and resetting. You can also remove caliper and submerge in bike wash/soapy water if you want to be super thorough and don't mind having to re adjust your caliper. I find if you do this often enough, you don't need to put any potentially contaminating products (lube/grease) anywhere near your brakes. As an absolute last resort, I have in the past used a silicon based product "fork juice" by Juice Lubes and had good results. It is designed to lubricate rubber seals and is the best lubricant I have used for this application. Spray clean advanced pistons, retract, then run a rag through the calliper to remove any excess. Also, when removing the pads, if pads are symmetrical (not left or right specific), be sure to reinstall pads in the same side/order! This is very important for alignment, piston advancement and pad wear. #driftbikes #mtb #bikes #performance #bikemaintenance #techtips #builtbybk #tunedbybk #protips #toolboxwars #lookafteryourbike #enjoytheride #brakeperformance #workshop #bikelife #bikemechanic"
1,123 likes, 33 comments - bee_kay77 on January 28, 2022: "Caliper maintenance. I hear the term "sticky pistons" a fair bit. 99.9% of the time, it's from not performing regular caliper maintenance and from pushing dirty pistons back into your caliper seals! Of course your caliper pistons will...
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Shimano pad spring
BK on Instagram: "Tweaking Shimano pad springs. (the only springs that I adjust) It's definitely better when pad springs can't move and contact the rotor. Pics of pad spring before and after adjusting. The main problem with the factory bent springs, is that the section of spring that contacts the pad is on a pretty big angle and only contacts the pad at the bottom of the spring, therefore the spring can pivot and move from side to side fairly easily which can then contact rotor or just be a pain in the ass and block your line of sight for adjusting and centring pads. I first open them up slightly at the top, then straighten out the little bend at the top that contacts rotor, then I straighten out the arms that contact the pad so that they're almost parallel (will be parallel once closed slightly when installed) Also pad springs only hold pads back against pistons and aren't strong enough to have any affect on lever stroke. I have heard people mention this in the past. After adjusting, spring has much more clearance and doesn't move from side to side. Another plus for the Maguras that I've been running for many years that have Magnetic pistons and don't require any pad springs which make adjusting and viewing pad wear much easier. #driftbikes #bikemechanic #tunedbybk #mtb #bikes #bikelife #techtips #cycling #betterthannew #brakes #performance #mods #builtbybk #seethingmakebetter"
1,140 likes, 78 comments - bee_kay77 on February 13, 2021: "Tweaking Shimano pad springs. (the only springs that I adjust) It's definitely better when pad springs can't move and contact the rotor. Pics of pad spring before and after adjusting. The main problem with the factory bent springs...
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initial run of 50 already sold out..... any lucky monkeys here snag a set?
I've watched Cornelius' video explaining a lot of features and how they decided to implement them, and I have to admit now I admire him.
^^^ me too, although the subtitles switched between English and German for me..
Anyone see the purple Hayes? Those look spiffy.
Anyone see the purple Hayes? Those look spiffy.
Yup, I too suffered a bit of subanempujenestrujenbajen in some parts. I guess not even Google can completely understand Zee Germanz.
JensonUSA had the purple version on its website a few days ago but they're gone now.
Anyone ever have leak issues with a MT5 caliper? Finally got out for the first ride of the season and noticed some noise and lack of power from the front. When I got back, I noticed that the whole caliper/pads are covered in an oily grime. I've cleaned everything up and confirmed that the fitting and bleed port are tight. No obvious damage. Going to try bleeding it tonight to see if anything shows up...I don't recall there being an o-ring on the bleed port screw that could have been pinched, so struggling to come up with an explanation.
A friend of mine was complaining about an oily MT5 caliper, contaminated pads, etc.
I cleaned everything up, and sat with a magnifying glass looking at those pistons, searching for the leak... nothing!
So I cleaned everything again, and covered the whole caliper in climbing chalk, then applied pressure to lever, and behold, a leak became visible through the wetting of the chalk. It was a leak in the aluminium crimped banjo. Good luck finding that leak!
SMRT
Cleaned everything, threw in a bleed block, dusted with chalk and clamped the lever to the bar for a few hours. No sign of anything. Guess it's possible that not enough pressure is being generated for the leak to show up, so I'll go ahead and bleed and repeat.
Fortunately if I need a new caliper they're essentially the same cost as a new brakeset, so I might as well just do that and have a spare lever and hose (if it turns out there's an issue with the caliper and I can't get Magura to cover it).
Fortunately if I need a new caliper they're essentially the same cost as a new brakeset, so I might as well just do that and have a spare lever and hose (if it turns out there's an issue with the caliper and I can't get Magura to cover it).
Need to replace at least one piston on an SLX 7120 4-pot caliper. (Cracked and leaking.) These are the ceramic pistons that seem pretty fragile, and I'm seeing some aftermarket options, including resin, like these, supposedly an upgrade:
Any thoughts or suggestions on this (aside from tossing in the bin and getting trickstuff)? These have been surprisingly consistent and I prefer to repair rather than replace. Thanks!
Any thoughts or suggestions on this (aside from tossing in the bin and getting trickstuff)? These have been surprisingly consistent and I prefer to repair rather than replace. Thanks!
@kidwoo shot his old cracked pistons across the street a couple years ago by blowing them off the caliper with an air compressor. He then replaced them with Chinesium metallic ones, which leaked straight from brand new IIRC...
EDIT: Seems like my ceramic pistons/metallic master cylinder theory as causing the dreaded wandering bite point in mid-pack-and-upper Shimano brakes still holds!
Has anyone got some tips for giving the servowave piston / camshaft area a good clean and lubing to make the lever feel nice and smooth again? or any good style brushes for getting in there and scrubbing the dirt away? bit of an awkward area
Well I successfully installed two new pistons in that SLX caliper. The new ones are made of delrin or some other resin and they came with new seals and o-rings. Wasn't too much of a hassle and seem sto work ok, at least in the stand and after a short ride (no leaks or other weirdness so far). It remains to be seen if they can handle the heat of a long sustained descent and how they survive over time. Reviews seem mixed in that regard so guess we'll see how it goes...
Man, need to vent my frustration with these Hope Tech 4 V4 brakes again. Those calipers with their oh-so-grear new and improved stainless steel pistons, they keep leaking past the piston seals, all of them. Even after Hope and myself replacing a bunch of seals and pistons.
Micro leaks, after a few rides, the brakes start to squeak slightly. Dark dirty oily rings visible around the pistons.
Just now, as a final test, I cleaned them up for the umpteenth time, sprinkled them with climbing chalk, threw in a bleed block and squeezed the lever 50 times. Sure enough, very obvious dark rings appear around the pistons, a big wet blob even on the side of one of them. What the hell, brakes are supposed to stay dry right?
Micro leaks, after a few rides, the brakes start to squeak slightly. Dark dirty oily rings visible around the pistons.
Just now, as a final test, I cleaned them up for the umpteenth time, sprinkled them with climbing chalk, threw in a bleed block and squeezed the lever 50 times. Sure enough, very obvious dark rings appear around the pistons, a big wet blob even on the side of one of them. What the hell, brakes are supposed to stay dry right?
Should've done the same. Still have my old V4s here as well, but figured I might as well get the 'new and improved' caliper while I was at it. Will be putting the T4 levers on my old calipers for now (no issues save for one single piston seal replacement in 7 years).
In the meantime waiting on Hope to come up with a proper solution. I mean, both calipers having pretty sweaty piston/seal interfaces, with one of the smaller pistons especially bad, must point to something more than just bad luck.
ditched the idea. Had problems with the seals, as they made them with wrong geometry. Bought MT Trail Sports, slapped Trickstuff Power pads and rotors onto them. Gonna try them this season.
@Udi if you are around, you can update the values for the viscosity of the Bionol oil
Viskosität unseres Bionol:
bei 40°C: 8,56 mm2/s
bei 100°C: 2,80 mm2/s
from trickstuff themself: Viskositäten von Bremsölen? | Seite 2 | MTB-News.de | IBC Mountainbike Forum
Viskosität unseres Bionol:
bei 40°C: 8,56 mm2/s
bei 100°C: 2,80 mm2/s
from trickstuff themself: Viskositäten von Bremsölen? | Seite 2 | MTB-News.de | IBC Mountainbike Forum