Quantcast

Calliper leak check

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
I recently goofed and pumped one of the pistons too far out of my calliper.

I was in the middle of a bleed, so kinda just panicked and slipped it straight back in.

I sprayed everything down with alcohol and wiped it down and finished up the bleed.

Cleaned everything (I thought) before I went for a test ride and bedded in the pads to the new rotor.

Things seemed good on 2 rides, but on my latest ride, the brake isn’t locking up.

I’ve since removed the pads and hung the brake vertically with some paper towel in place of the pads to check for leakage.

No signs of leaks, but there’s no pressure in the line, and the fluid is likely being help up in the vacuum.

Suggestion for how to check for leaks?

I’m hoping for a clever idea that will save me trial and error and ruining expensive sets of pads in the process...

Cheerio.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
You likely need to do hell lot more thorough bleeding than you think you do at this point.
Oh, that I did. It was a bitch +1. Lever feel is good.

I’m not too familiar with the anatomy of the calliper, so a bit fearful...

I am a cowardly bike mechanic...

I’m thinking @Nick is probably right, but wish @johnbryanpeters is right.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
And what was the result?
Inconclusive. Hard to tell if my shop towel was “polished” by the piston or got oil on it.

I’ve set it up more tidily and will take a closer look again after work today.

I’m thinking the rear set of pistons are the culprit.

Times like this make me less glad I run quad piston brakes.
 

canadmos

Cake Tease
May 29, 2011
20,197
19,162
Canaderp
Is it possible something just got on the rotor to make them feel like poo? How long was the period between the first two rides and that third one where it all went to crap?

Maybe try cleaning everything really well and baking the zonked pads in the oven and then try it now?
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Is it possible something just got on the rotor to make them feel like poo? How long was the period between the first two rides and that third one where it all went to crap?

Maybe try cleaning everything really well and baking the zonked pads in the oven and then try it now?
Well,

I’ve still not ruled out a leak, but I’ve tidied up the checking arrangements a bit.

522320EF-7D3B-4514-8456-ADEB425EEAEA.jpeg


I’ve also baked my pads and given them a gentle sand just to give it a try
78F72017-612F-4364-AFB6-7C3D955B693C.jpeg


And I cleaned the rotor with alcohol, burnt it down, then wiped it down with alcohol again.

While I wait for my leak detectors, I’ve got the lever applying pressure to the pistons, but with the bleed blocks in. Not sure if the leak might only occur when the pistons have travelled out a bit more.
9401F068-8E29-484B-AD73-07217C30C7AD.jpeg
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Alright,

Soakers appear to be dry after the loaded bleed block test.
20802FD4-039E-4D45-A038-5F1564B49284.jpeg


I think I’ll just re-assemble and hope I don’t have a leak.

If I don’t get gains ferda braking bro, I’ll clean the pistons/seals and start over.
 

Westy

the teste
Nov 22, 2002
54,241
20,025
Sleazattle
Inconclusive. Hard to tell if my shop towel was “polished” by the piston or got oil on it.

I’ve set it up more tidily and will take a closer look again after work today.

I’m thinking the rear set of pistons are the culprit.

Times like this make me less glad I run quad piston brakes.

Your TRPs would have been fine.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Your TRPs would have been fine.
Ha, I’m sure they still suffer from a certain level of non-idiot-proofness.

This has all stemmed from my casual-IPA-induced drive to put an 8” rotor out back on my bike.

This was exacerbated by my extended storage and subsequent installation of a damaged brake adapter off my 2006 Kona Stab Primo Garbanzo, which sent me into a failed attempt to align/center my calliper, which l, of course, led to an ill-advised effort to balance the action of my pistons, which led to my blasting of a piston out of my calliper.

I bet there’s no label on the TRPs to not do that.

Part of me still thinks I just had shitty pads in those TRPs.

I like the levers better on my Maguras, and I got a great bro deal on them, so I’m still happy.

Come up and ride here so I can try yours out.

It’s a crime against mountain biking that you haven’t been here yet.

Especially if you’re entertaining moving for work.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Id think pull the piston back out, remove the seals, install piston, then seals, fill bleed try nao repeat profit etc.
Install pistons THEN seals?

Hmm. I’m hoping I don’t need to, but I had visualized seals first, then inserting pistons back in.
 

Westy

the teste
Nov 22, 2002
54,241
20,025
Sleazattle
Ha, I’m sure they still suffer from a certain level of non-idiot-proofness.

This has all stemmed from my casual-IPA-induced drive to put an 8” rotor out back on my bike.

This was exacerbated by my extended storage and subsequent installation of a damaged brake adapter off my 2006 Kona Stab Primo Garbanzo, which sent me into a failed attempt to align/center my calliper, which l, of course, led to an ill-advised effort to balance the action of my pistons, which led to my blasting of a piston out of my calliper.

I bet there’s no label on the TRPs to not do that.

Part of me still thinks I just had shitty pads in those TRPs.

I like the levers better on my Maguras, and I got a great bro deal on them, so I’m still happy.

Come up and ride here so I can try yours out.

It’s a crime against mountain biking that you haven’t been here yet.

Especially if you’re entertaining moving for work.

Fuck socialized health care, you need socialized bike repair.

I hope to get up North at some point. But with not be able to ride most of my time out here I haven't exactly been motivated to drive into foreign countries when I haven't even been to Bellingham in over two years. It helps that a friend of mine has surrendered his 'Merikun lifestyle to live in Squammish.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Fuck socialized health care, you need socialized bike repair.

I hope to get up North at some point. But with not be able to ride most of my time out here I haven't exactly been motivated to drive into foreign countries when I haven't even been to Bellingham in over two years. It helps that a friend of mine has surrendered his 'Merikun lifestyle to live in Squammish.
Always good to have an anchor friend in far off lands!

I bet you have awesome insurance. Get a Nexus card and get northward.

Bellingham is awesome, and I’m sure there’s a ton of riding there I haven’t even seen which is even better.

I’ve got some goods up here that is different, and also awesome.
 
Last edited:

englertracing

you owe me a sandwich
Mar 5, 2012
1,573
1,069
La Verne
Install pistons THEN seals?

Hmm. I’m hoping I don’t need to, but I had visualized seals first, then inserting pistons back in.
I think hes got that backwards....
But yeah i think your over worried, you assembled the piston into the caliper just the way they did to assemble it in the first place, well maybe not as clean but, close enough
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
13,681
4,904
North Van
Looks as though the caliper is ok. Unfortunately, I think I wasted a set of pads. The ones I suspected of contamination and baked/sanded just never performed. I swapped them out for some cheapo chinese ones, but sintered. MUCH better bite and they seem to be ever so slightly thicker than the stock Maguras, so my lever throw is shorter, which I like.

I was dreading having to perform surgery on the calipers. I don't think I have the tool to get at the pistons...

edit: nope, I definitely don't have one of these:

https://www.bikeonlineshop.net/shop_catalogue/magurar-mt-brake-piston-dis-assembly-tool