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Y'all got me wondering about the Mavens and down a rabbit hole I went. Couple things stood out to me in the MC's architecture. 1. The diaphragm for the reservoir has a lotta 90deg angles. Fluids (of which air is one) don't like moving smoothly around right angles. This might be making a proper purge of the system difficult, whether by cup or syringe. 2. They use a single timing port hole to allow fluid passage between the MC bore and the res. Might this create a choke point that is in turn causing a slight bit of cavitation during use? With the larger caliper pistons, there's more fluid moving to n fro. Can that timing port allow it to move smoothly in all brake actuation scenarios? This of course leads to the compression and banjo fittings. Are their diameters large enough to allow for smooth fluid movement in all actuation scenarios?
I’ve had good luck in the past with the Jagwire ones. They will bend to nearly flat without much issue if you need them to.
In all my messing with them, I’m pretty much convinced that the inconsistency comes from the caliper.
My personal theory is that something about the caliper causes the pads to roll back too slowly. It’s either the seal material is too soft, or there’s some sort of flow restriction. If you pull the lever multiple times quickly, you’re pulling the lever again before the pistons have retracted and that’s why they pump up.
I’ve been considering a couple of possible fixes to test:
1. Try to align the holes in the banjo bolt with the hole in the fitting for the hose. (This could explain why some people have zero issues with them, they just get lucky and all the holes line up nicely)
2. Try deburring, chamfering, or making the banjo bolt holes larger.
3. Try deburring or “porting” the transfer ports between the caliper halves. I’ve had to split the caliper a couple of times because I got a little impatient with my umpteenth piston massage and noticed that the ports looked kinda messy on the edges.
Anyone have issues with their Hope V4 pads rattling front-to-back in the caliper? The pads in my E4 calipers seem perfectly sized (T4 E4 and XCR E4), but there's some free play with the pads in the V4 allowing them to rock or rattle. I'm struggling to think of a solution besides a strip of mastic tape on either end of the caliper (which I think would melt?)
Yes, and these better bolts after market pins retaining pins eliminated it for me. From their website: “For Hope V4 brake pad axles the center shaft has been machined larger than stock to eliminate pad rattle”
I used small strips of hockey tape on the edge/back of the pads and they seemed to work well, but I don't push my brakes to super high temperatures. You can also try to open the retaining springs absurdly wide.
Dig the idea of the banjo bolt. I haven't seen one for the Mavens yet, however I have improved performance on other brakes by cross drilling and dilating the ports. There's not a lot of material there to work with, so a smidge bigger is better than way bigger. Def worth a shot since banjo bolts are relatively cheap and inexpensive.
Update on some Maven bleeding:
Tried the pinner cups/overnight bleed/dangling caliper with bleed blocks in on 3 sets of mavens and the improvement is dramatic. At this point I'm fairly convinced that the mineral oil formula that SRAM is using holds onto air a bit more than some other formulas (like magura/shimano), and that degassing the mineral oil is a very important step.
Also, the more aggressive the piston massage the better. I've also noticed that I need to do it a 3-4 times for things to really improve, and I repeat the process until the pistons move evenly and very freely (both coming out and being pushed back by a spacer). The manual does say give'r the beans on the piston massage and I really think they mean it.
Nice! That's awesome to hear. Thanks for reporting back.
I was wondering about that! Any reason I couldn’t just use shrink wrap?
Genius! I shrink wrap the shit out of everything I can, but this application didn't cross my mind.
I’ll give it a go and let you guys know the results!!
Anyone in the US have any luck on getting a set of the new Hopes now that they’re out?
I have some that I’ve been testing for a few weeks now. Review will drop in due time, but I can answer some questions here as a forum bonus 😃 (E4 on trail bike, also have V4 still to mount on the big bike…).
My number one complaint with the T4V4’s was a soft bite point.
Have they firmed up the bite point with the new lever?
it doesn’t feel vastly different to the previous Tech 4. The main difference is that the new cam design shortens the free stroke quite a bit, which for me makes the brake feel more direct when you activate it. It’s SUPER easy to feel what it’s doing and when the power comes on. I had to change where I run my levers in the starting position because they bite and ramp up sooner. That overall softness you speak of is still there once you get into the power band more, but I’d say their claim of 6-7% increased power holds true. Also the new lever shape with the smooth hook is an improvement in my opinion. I have yet to test the different lever blade options (power and control), so far only been running the standard.
Biggest question is, do they still squeal all the time or with a stiffer caliper it’s gone?
If you’re talking about that signature little high-pitched squeal as the pads engage, yep, still there…
How is the bleed process in comparison to the old process? Does the new bleed port help?
You feel like power is about the same?
i was hoping they addressed that, while riding i don't even care anymore, but sometimes i take some 3rd view or pov videos and it's pretty annoying
i'm Considering selling my T4V4 and either, Get the Evo GR4, or the Radic Kahas, there's no info out there about either at the moment, for the kahas all i see is the previous generation with different seals and no bite point control.
The lever feel of the kahas is pretty insane, i just wonder how close do the pads stay to the rotor?
Does anyone here have the latest Kahas? i hated that about the MT7, how close the pads were to the rotor and how painful they were to keep drag free, the Hopes on the other hand have been easy as.
I am Torn between the 2, i can get them at the same cost, For the Hopes i don't like too much the noise, The Kahas i wonder how they are noise and to generally live with, any imput is appreciated
I never felt like the old, open-lever bleed process was that much of a hassle to begin with, apart from the little puddle of brake fluid that invariably ends up on the floor, but yes the new bleed port makes the whole thing much cleaner for sure. I've always been able to get really good bleeds without any trouble with Hope brakes, so the port is just more convenient and less messy (the process itself doesn't change, you still do a top-down bleed by pushing fluid through the system from the lever and out of the caliper end). The bleed cup they supply is really well made and works perfectly.
As for the power, it seems to be up a tiny bit, a feeling that is further accentuated by the shorter free stroke and more instant pad engagement.
Unfortunately it doesn’t help you right now but I think I’m going to order a set of the new Kahas and have him add the tool free reach and bite on them as well and also get a set of 612s for my other bike.
Have Code RSCs on both my trail bike and DH bike and time to change it up and get better for both!
Thanks, that's good info. I'm considering trying these at some point.
Do they actually include a bleed cup now or is it still a secondary part?
is there a tool free reach adjust version?
I believe so but you have to ask for it. That was my understanding the last time I spoke with Taylor. It is not a given because I believe it is located in a spot that can interfere with grips so to avoid issues, he only puts it on upon request.
that would be Trickstuff style i assume, but yeah it could be cool, curious give us some feedback here about it all when you get them
The bleed cup is part of the bleed kit, purchased separately. It's a very nicely made part (cup and plunger). Here it is in action:
They include the bleed cup now??? Oh man, that's quality!
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