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Do you have access to a 3d printer? If so I would really recommend printing out some of the tools that they have designed for piston massaging and caliper centering. Maybe if there is enough interest I can print some of these parts and sell them to cover the cost of the resin and shipping. They are worth it in my opinion. Forgive me if they are already available from a retail source.
I installed my t4v4’s after a piston message and use the caliper centering tool and have not had a single issue with rub.
I recently set up some Evo GR4 brakes and used the piston massage tool and got the bleed perfect and they feel pretty stellar so far. I also have a Bambu 3d printer if anyone needs help getting some tools printed out. Have not encountered any caliper rub issues using TRP RS05E race rotors. Once I get my DH bike back together I'm going to try pairing the new Lewis AX lever with my maven expert calipers and see how those play along. Already tried Lewvens with the LHP lever and it felt pretty damn great but AX should push a little more fluid and hopefully result in a more consistent lever feel. Intend trinity is probably my favorite lever feel to date, I just wish it had a bigger pad layout as it definitely feels like it lacks a little top end power with the code pad shape compared to something like a maven or Hope
Photos from some testing recently. Made some rotor guards on my 3d printer, going to make the new ones BYB released recently once I get more black filament.
Regarding mechanics/causes of the pump-out sensation, it has always seemed to me to most likely be due to a mismatch in the speed at which the fluid can flow back through the hose and fittings when the lever is released, and the "demand" for fluid to take up the expanding space in the M/C as the lever returns to the starting position. In other words, the fluid is moving too slowly, and so the return spring in the lever creates a partial vacuum in the M/C, which causes it to then draw in extra fluid from the reservoir when the piston seal exposes the timing port. Once the fluid coming back from the caliper "catches up" and then you quickly squeeze the lever again, you essentially have an overfilled system.
Things that could potentially slow the fluid return include (working from bottom to top):
1. Relatively weak caliper seal return force. As someone pointed out earlier in the thread, assuming the same seals, the 18mm pistons will push back harder relative to the fluid moved 2. Really gunky caliper seal/bore/piston interfaces, such that drag is being exerted on the pistons as the seal tries to retract them. All else being equal, the smaller pistons will have less surface area where gunk could exert drag. 3. Pinched/restrictive hose ID or fittings 4. Overly viscous fluid relative to the hose and fittings.
If the sum of those factors leads to a slower fluid flow than the pull of the master cylinder piston return spring, you have a potential problem. It seems to me that putting a weaker spring in the M/C could be one way to restore balance to the force (as well as reduce finger fatigue) but for some reason that doesn't seem to be a thing.🤷♂️ Anyway, if one were to assume that the stock configurations are designed in such a way that the forces are balanced, with these DIY mashup combos it seems like you have greater potential for there to be a mismatch. Having a mismatch where the fluid is returning faster than required wouldn't create a problem so, if you have a choice, it seems like a safer bet to choose the individual parts that will supply more oil back to the lever rather than less. For example, if we knew what the flow rate under a given pressure was on Maven vs. Shimano hose and fittings, or the viscosity of their respective fluids, pick fastest flowing hose/fittings and thinnest fluid.
I agree with the 'pick the fastest fluid.' I know users have put low-viscosity fluid in Shimano brakes for a while now to resolve their issues and they don't seem to leak more than Shimano calipers already leak.
I'm suprised we don't see more small brake companies putting out videos/marketing about how their brakes solves the Shimano pump up/wandering bite point issue. Advertising a solution to your competitor's design flaw is pretty common, why not in brakes?
Cause better brakes than Shimano is the answer, there’s not much to do there to fix those issues
I imagine that some companies could be scared of the repercussions if your brakes fail because of your (the company’s) recommendation. It’s all fun and games if you tinker around but if someone goes off a cliff with your „hack“…
That’s just what would concern me, if I was offering „braketuning“
what should i use instead of the silicone lube for piston massage?
Nothing
I apologize that this is a double post! Most folks only look at this thread in regards to brakes info but figured I would put it over here too and hope you may go over to the thread I just created and leave some feedback. Thanks!
"Alright I know this one has been hit hard and in pieces and in different places over time. Trying to consolidate to one spot and get feedback. I have someone that isn't a part of the Vital Forums asking me questions and advice so figured I would just lay this one out for feedback to forward to them directly for helping make a decision.
Simply put a T4V4 with bearing mod vs GR4. For the folks that have actual experience with both/ possibly own both... would greatly value your feedback.
Notes they have heard
- GR4 significantly easier/cleaner to bleed
-T4V4 has slightly lighter lever throw
-GR4 with power levers can allow for best use of close to bar set up
-GR4 might have improved the classic Hope noises?
I will edit and add if I remember more for them. But in the meantime... appreciate the feedback!"
https://www.vitalmtb.com/forums/hub/hope-t4v4-bearing-mod-vs-gr4
Also.... for myself now
Anyone have any inside info on release date ballpark for Brembos. Brembo keeps on teasin and sure am excited to learn more about em finally
Knowing Brembo I'm sure they will come with a premium price tag, I wouldn't be surprised if a set would cost $999. I was lucky enough to run into a Specialized athlete at Whistler last season and got to feel the brakes myself. They feel pretty good and have a firm bite point but curious how that will translate on trail along with power/piston size layout.
Are they built for comfort or speed?
Hopefully they release along side the new demo. Id love to try a set. But going way back to when specialized first brought the ohlins shock in on the demo, you couldnt buy the shock alone for good while. It was oem only for however long. At least thats how I remember it could be wrong.
I use SRAM dot grease, but as others have reported in this thread whether any lube is needed is questionable.
If you didn't already, then centering the rotor and pads is also important. There was a hope video that showed using a small screwdriver behind the pad that needs to be moved closer to the disc whilst pumping the brake. I find this works really well and makes sure that the pads contact the rotor at the same time on both sides.
seeing them in the wild had to have been rad! glad they felt like a nice firm bite point.
I think they should be some of the most powerful yet and very adjustable
No doubt the price will hurt but all we can hope for is performance more than making up for it
I am with you and hope that release is soon. And they can be bought separately right away
You know they work great!!
They slowed Loic down enough that Jackson went flying by, unable to stop with his barely functional Shimano prototypes!!!
Serious question: how is everyone putting the pistons back in place after extending them during a piston massage?
I'm using an old yellow plastic tire lever and doing the pistons one at a time (more or less), just like SRAM recommends, but that feels barbaric and incredibly imprecise, and seems like a great way to sideload or accidentally angle a piston into the caliper seal. Is anyone messing around with a piston reset tool like one of these. And yes, I recognize that two out of these three tools would not work in a Maven because there's no access to the top of the caliper:
This birzman getup seems cool.
https://www.tradeinn.com/bikeinn/en/birzman-double-disc-brake-piston-pusher/138156761/p
Its still sitting in the 'I probably don't need that, but I want it basket'
In my mt7 I was using a 5mm Allen to push from top and bottom
Mavens are a pain due to the design which is very close, and like codes and all sram stuff they go sideways badly if not carefully handled also because they hardly move
Trp and hope I use my fingers to push them back as they go so smooth but I use a Schwalbe Tyre lever occasionally to be quicker as it’s wider and flat
Shimano, the less I touch them the better, those pistons give up incredibly easy no matter what, so I don’t touch them if not pushing them back with some old pads or veeeery carefully
Oh yeah, that thing is sweet. Didn't know it existed but now I need to have it.
Check this out first: https://escapecollective.com/new-tools-day-2-its-a-good-time-to-be-a-to…
3/3 of those don't work on Mavens. I tried the Birzman version of the bottom one and it just bent, plus it had a hard time getting the rear pistons due to the notch in caliper.
I start by pushing the pistons back (pads in) with the fat side of the pad spacer, then remove pads and use the red plastic SRAM double slider tool (with rounded end) to fully seat them back. It's too thick to fit without that initial nudge, but it ultimately does fully push back the pistons.
This does it for me but working from the bottom is always a challenge no matter what.
If I'm worried about alignment I throw the pads back in before pressing them out. I use the Birzman piston press (just the lever one) and haven't run into issues. If I'm doing one piston at a time, I choke up on the grip and push flat instead of levering the pistons out.
https://www.birzman.com/products_2.php?uID=2&cID=4&Key=135
Beaut Bike Mini Bicycle Disc Brake Piston Press – Beaut Bike Australia
Finally got some mavens! They came with resin pads.
How much truth is there to the "don't mix pad compounds on the same rotor" theory.
I know Sram even posts that on their site regarding Mavens. I'd like to try these bad boys as is but will likely switch to metallic when I can get a pair of pads.
I mixed it up many times. Never had any problems going from organic to metal.
Depends on the brand. I have tried going from trp organic (blue pad backers) to shimano metallic pads and that did not work so well. I have had good luck going from sram organic to sram metallic, but not 100% success on that process over the years and did have one rotor that would brake fine, but never stopped making noise.
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