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Frankenbrakes and brake improvement discussion

konifere

Monkey
Dec 20, 2021
513
634
Many people have pistons that slowly weep oil and this ends up on the pads someway. I've never had this happen, but I used to clean my pads and rotors with isopropyl alcohol almost weekly and removed my pads in the off season. Then I'd clean my calipers before putting them back in to ake sure they were clean as. Maybe that's helped.

Now running Magura and TRP brakes though :nerd:
 

Jm_

sled dog's bollocks
Jan 14, 2002
18,850
9,556
AK
Many people have pistons that slowly weep oil and this ends up on the pads someway. I've never had this happen, but I used to clean my pads and rotors with isopropyl alcohol almost weekly and removed my pads in the off season. Then I'd clean my calipers before putting them back in to ake sure they were clean as. Maybe that's helped.
Probably not, soaking the pads in IPA wouldn't remove the contamination.. Good for cleaning rotors, but I've never had it remove pad contamination as in oil.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
This is like a pressure preload from what I understand. It will also put pressure on the reservoir's seal which is probably not designed/tested for that.
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
That thing is just an adjustable in line reservoir that works the same way over filling a brakes does. If worn down pads cause a brake to lose power due to too little fluid, that's a design flaw of the pump. Are there still any such brakes?
What a scam.
 

Nick

My name is Nick
Sep 21, 2001
23,926
14,438
where the trails are
OK help me here. Does that work like the old Hope C2 closed brake system? I remember decades ago they had a brake that you could manually adjust in a similar way.
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
OK help me here. Does that work like the old Hope C2 closed brake system? I remember decades ago they had a brake that you could manually adjust in a similar way.
Not quite, but in a kind. In a closed hydraulic system you have to adjust the reservoir volume to compensate for the higher volume behind the slave pistons in the caliper due to pad consumption on the one hand and for the volume expansion of the hot fluid during long descents on the other hand.

This is an in line adjustable reservoir, which can serve as an additional adjustable volume, when the intended one in the brake lever is too small to compensate for the higher volume and therefore fluid need in the calipers due to pad wear. But this is risky, as @Happymtb.fr noted. The seal in the lever res is not designed for a lot of pressure. And if the pads are worn and somebody dials the funny boosters volume out the fluid is sucked out of the levers res even more and the lever may go all the way to the bar.

What a BS product
 
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konifere

Monkey
Dec 20, 2021
513
634
Probably not, soaking the pads in IPA wouldn't remove the contamination.. Good for cleaning rotors, but I've never had it remove pad contamination as in oil.
I said that in the sense that oil didn't have time to migrate to the pads if it was weeping from behind since I was so meticulous on cleaning the brakes to keep them dry. But you're totally right, IPA never got rid or oil when they got on the pads.

I used to have good results using a torch to brun-decontaminate pads for customers back way back when I was wrenching at a shop. It's pretty much the only thing that works to get rid of it in my experience. The only time I had contaminated pads is when my Marzocchi 66 leaked oil from the footnut right onto my rotors and they were so filled up with oil that I just threw them away.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Welp, I've got my first issue with my Dominions. I noticed a lazy piston when I changed my pads, so cleaned and lubricated them with a eensy bit of silicone grease. Worked a treat for the rear, and it feels amazing.

Since I was in "play bikes" mode, I had a look at the front pads, and noticed I had a REALLY lazy piston on the front, caliper, so tried the same. Got it gliding pretty well. Not perfect, but better. As I put in the new pads and went to pump up the brake again, it feels like total mush. I fear I make have stroked the pistons out a little too far, but it sure didn't look like it.

So, now I need to bleed my front brake again, probably just the caliper.

Given BOTH of my SFL levers have arrived, I'll be fiddling much this week...

Stay tuned!
 

konifere

Monkey
Dec 20, 2021
513
634
Speaking of bleeding brakes, how important is it to have all 4 pistons at the same depth when bleeding Magura mt5s ? I did it yesterday and finished quite late, but I forgot to check where the pistons were and they were not at the same depth. Should I do it again, or will they feel fine and self-adjust? (I haven't put the pads or wheels in yet).
 

canadmos

Cake Tease
May 29, 2011
20,188
19,155
Canaderp
Welp, I've got my first issue with my Dominions. I noticed a lazy piston when I changed my pads, so cleaned and lubricated them with a eensy bit of silicone grease. Worked a treat for the rear, and it feels amazing.

Since I was in "play bikes" mode, I had a look at the front pads, and noticed I had a REALLY lazy piston on the front, caliper, so tried the same. Got it gliding pretty well. Not perfect, but better. As I put in the new pads and went to pump up the brake again, it feels like total mush. I fear I make have stroked the pistons out a little too far, but it sure didn't look like it.

So, now I need to bleed my front brake again, probably just the caliper.

Given BOTH of my SFL levers have arrived, I'll be fiddling much this week...

Stay tuned!
Did you use the fancy one sided bleed block thing they come with? Actually, I'm not sure if they do come with it, but I have a set with the Hayes bleed kit I picked up. I might have an extra...

I have to do this as well. I think one or more of the pistons on my front brake isn't retracting enough.

I'll adjust the brake in the stand and the rotor makes zero noise while spinning. But when I go to use it, it'll start rubbing.

So then I adjust it again, usually have to pull the caliper the other way. Zero noise. Go out on the trail and it'll rub again. Adjust it again, in the other direction....rinse and repeat. Friggin' annoying.

Maybe it'd be fine if I had the Hayes rotors, but I'm using slightly thicker (2.05mm vs 1.95mm) Trickstuff ones. :confused:

 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Speaking of bleeding brakes, how important is it to have all 4 pistons at the same depth when bleeding Magura mt5s ? I did it yesterday and finished quite late, but I forgot to check where the pistons were and they were not at the same depth. Should I do it again, or will they feel fine and self-adjust? (I haven't put the pads or wheels in yet).
Not sure. I always used my bleed block when doing my MT7s, so I went with the "all the way in" approach.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Did you use the fancy one sided bleed block thing they come with? Actually, I'm not sure if they do come with it, but I have a set with the Hayes bleed kit I picked up. I might have an extra...
Nah, I didn't have it handy. I used my old pads and a 3mm allen key in the "groove" shimano style.

I will do so now that I'm back home....
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Ok all sorted.

Did a bleed and sorted things out. That dual bleed port is ingenious.

No test ride yet, but the SFL levers feel a lot closer in shape to Shimano.

They’re shorter and thinner.

IMG_0676.jpeg
IMG_0677.jpeg
IMG_0675.jpeg
 

konifere

Monkey
Dec 20, 2021
513
634
Follow-up on the MT5 bleed for science. I pushed the pistons as flush as evenly as possible, installed the yellow blocks, and ended up with the same uneven piston positions afterwards. We'll see if they even out when I install them on the bike.
 

Balgaroth

Chimp
Oct 22, 2021
45
29
Alsace (FR)
Any news and feedbacks about DB8 levers ? I am tempted to try it on a set of MT7 as opposed to go with Shimano 3 finger levers.

Also, isn't silicon incompatible with mineral oil seals ? I thought silicon was only used to lub DOT seals.
 

canadmos

Cake Tease
May 29, 2011
20,188
19,155
Canaderp
Ok all sorted.

Did a bleed and sorted things out. That dual bleed port is ingenious.

No test ride yet, but the SFL levers feel a lot closer in shape to Shimano.

They’re shorter and thinner.

View attachment 195594View attachment 195595View attachment 195596
They're so cute :wub:

For some reason I thought they'd be longer too...

I fixed my dragging brake. Went through the whole rigmarole of cleaning the pistons, but upon close inspection I think it was caused by a lip of material on the brake pads.

I didn't look closely when I installed these Trickstuff rotors, but they have an aggressive chamfer on the outside edge - I guess to help with put your wheel back on? Anyways, the Hayes pads overhang that part of the rotor and don't get worn down, eventually making that awful noise.



Also, isn't silicon incompatible with mineral oil seals ? I thought silicon was only used to lub DOT seals.
Is this in reference to Da Peach lubing his brakes? The Dominions use DOT5.1 fluid..
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
2 test rides in with some fairly hairy descending and I’m very pleased.

The metallic (semi), pads work great. SFL levers feel more similar to Shimano (when they’re working).
 

Boozzz

Chimp
Sep 12, 2019
80
84
Amsterdayummm
Any news and feedbacks about DB8 levers ? I am tempted to try it on a set of MT7 as opposed to go with Shimano 3 finger levers.

Also, isn't silicon incompatible with mineral oil seals ? I thought silicon was only used to lub DOT seals.
Someone tried the DB8 on Magura a few months back, reported somewhere in this thread. I recall he wasn't that impressed.

Re silicone: perfectly safe to use. Even better, if you completely flush a system, you could use silicone based oil (e.g. DOT 5) in both mineral and DOT brakes, for the ultimate Frankencombo.
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
I didn't look closely when I installed these Trickstuff rotors, but they have an aggressive chamfer on the outside edge - I guess to help with put your wheel back on? Anyways, the Hayes pads overhang that part of the rotor and don't get worn down, eventually making that awful noise.
Yeah, that's what this chamfer is made for, easier insertion of the wheel/rotor into the caliper.
The second aspect could get dangerous. Should your pads make contact above the rotor your brake force will be significantly reduced! Are you sure it's only been a tiny, tiny lip?
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
15,825
13,054
Yeah, that's what this chamfer is made for, easier insertion of the wheel/rotor into the caliper.
The second aspect could get dangerous. Should your pads make contact above the rotor your brake force will be significantly reduced! Are you sure it's only been a tiny, tiny lip?
I have a problem with my wife's road bike Colnago where the pads sit above the level of the rotor so I have to keep a really close eye on their wear level...

Never did manage to solve why :/
 

toodles

ridiculously corgi proportioned
Aug 24, 2004
5,479
4,719
Australia
Any news and feedbacks about DB8 levers ? I am tempted to try it on a set of MT7 as opposed to go with Shimano 3 finger levers.

Also, isn't silicon incompatible with mineral oil seals ? I thought silicon was only used to lub DOT seals.
New mineral oil Codes rumoured to be released soon according to Vital. Could make for some interesting mix/match combos.
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
I have a problem with my wife's road bike Colnago where the pads sit above the level of the rotor so I have to keep a really close eye on their wear level...

Never did manage to solve why :/
Missing at least 57 standards?

Seriously though the whole rotor to pads to calipers distances and locations to each other are not very well defined and leave a lot of room for errors.

Keep watching!
 

Balgaroth

Chimp
Oct 22, 2021
45
29
Alsace (FR)
Someone tried the DB8 on Magura a few months back, reported somewhere in this thread. I recall he wasn't that impressed.

Re silicone: perfectly safe to use. Even better, if you completely flush a system, you could use silicone based oil (e.g. DOT 5) in both mineral and DOT brakes, for the ultimate Frankencombo.
My bad I was convinced the Dominions were Mineral and not DOT, tho still good to know that silicon based lubricants are compatible with mineral systems.

As for the DB8 yes I did my research and found that someone here tested this combination. But The only feedback he gave was after his first test-ride and no update since, which is why I was if anyone had news or update on that front. Thoeretically the DB8 is a great candidate with 9.5mm MC piston, long lever blade and no weird cam systems. Main question being, is there enough fluid in the MC or will you need to change pads at mid life ? Is the lever adjustement reliable or does it unwind on its own like many brake systems ? Is the bite point consistent ? I guess the last 2 questions can be answered by anyone using a set of DB8s and the first one only by those who attempted a Shimano or MT7 based Frankenbrake.
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
15,825
13,054
Weird adapter/rotor size?
Flat mount 160 front and 140 rear. Appropriate adapter in the correct orientation up front, but the pads sit a couple of mm above the height of the rotor on both ends of the bike. The rear can only take a 140 rotor so no adapter even required...

I even hunted down the SRAM spec docs that outline mounting heights and distances from the dropout etc and all seemed correct. I've not been able to work out why, so I just have to keep a really close eye on pad wear.

I bought the frame new off ebay, so no real ability to chase Colnago for a solution and I never got around to taking it to a local Colnago shop to see what they say.

There's probably an "italian" flat mount standard that Colnago build to...
 

sethimus

neu bizutch
Feb 5, 2006
4,881
2,132
not in Whistler anymore :/
Flat mount 160 front and 140 rear. Appropriate adapter in the correct orientation up front, but the pads sit a couple of mm above the height of the rotor on both ends of the bike. The rear can only take a 140 rotor so no adapter even required...

I even hunted down the SRAM spec docs that outline mounting heights and distances from the dropout etc and all seemed correct. I've not been able to work out why, so I just have to keep a really close eye on pad wear.

I bought the frame new off ebay, so no real ability to chase Colnago for a solution and I never got around to taking it to a local Colnago shop to see what they say.

There's probably an "italian" flat mount standard that Colnago build to...
colleague bought a tout terrain tourer frame w/ flat mount. turns out, they only tested it for shimano. he wanted to put on force brakes, needed to file the mounts down for proper fit…
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
15,825
13,054
colleague bought a tout terrain tourer frame w/ flat mount. turns out, they only tested it for shimano. he wanted to put on force brakes, needed to file the mounts down for proper fit…
These are SRAM Force, only other flat mount in our house are my older Red's and I've never tried to bend those across to test fit as internal routing makes that nearly impossible to attempt.

I think the complete builds with that frame were Shimano, so that's interesting to hear of your colleague's woes, thanks.
 
Flat mount 160 front and 140 rear. Appropriate adapter in the correct orientation up front, but the pads sit a couple of mm above the height of the rotor on both ends of the bike. The rear can only take a 140 rotor so no adapter even required...

I even hunted down the SRAM spec docs that outline mounting heights and distances from the dropout etc and all seemed correct. I've not been able to work out why, so I just have to keep a really close eye on pad wear.

I bought the frame new off ebay, so no real ability to chase Colnago for a solution and I never got around to taking it to a local Colnago shop to see what they say.

There's probably an "italian" flat mount standard that Colnago build to...
Machine the adapter down?
 

Sandro

Terrified of Cucumbers
Nov 12, 2006
3,224
2,537
The old world
No one is more surprised than me that I managed to assemble a Shigura in one go without a single hiccup. Didn’t even need to bleed it after filling the system.
Works a charm right out of the box, so hopefully it will get even better during tomorrow’s maiden ride.

I’ll do the rear brake some other time as the internal cable routing promises to make that one a lot more frustrating.