I need to bleed my 705 brakes. I bought what is supposed to be a Shimano compatible MTB bleed bowl with adapters, but none of them seem to fit. The narrow one looks about right but a bit short, and the threads don't engage. Anyone any ideas what adapters or bleed kits I need to get?
Wisper 705 brake bleed adapter
- Thread starter PaulM
- Start date
I measured the port screw and the plastic adapter that came with EZmtb base kit. They are both M5 and the thread pitch looks the same. I can only assume that the plastic adapter is slightly undersized. I notice in the Wisper how to video, the mechanic uses a bleed bowl with a metal adapter.
My wife needed to adjust the reach on her 705 ?
www.pedelecs.co.uk
Wisper 705
Hi all I've just bought a Wisper 705 - very pleased with it but noticed that after my first ride (only around 10k) there was more play on the rear brake lever and I'm having to press it further down to activate the hydraulic pads. I thought I could adjust this myself but immediately discovered...
www.pedelecs.co.uk
The metal bleed cup fitted perfectly, so both brakes bled at the lever and the sponginess has gone. I also increased the lever reach.
Where does the air come out? Do you take the lid off the master cylinder reservoir?
There's no need to take the lid off the reservoir because the volume in the system doesn't change; however, what I've noticed is that the more air is in the reservoir, the higher the chance of air going into the hose when you invert the bike. On the other hand, if you fill the rervoir to the top, then start riding your bike, the heat from the brake expands the oil, and it can make your brake jam on permanently until you let some oil out. That's why cars and motorbikes have that rubber bellows thing in there, but I haven't seen one in a bike brake, though it doesn't mean they're all like that.
Please forgive my thickness but where does the air come out then, when you pump the lever? Do you open the bleed screw on the caliper? Or does it rise to the surface inside the reservoir?
No air can get into the system, except when you turn the bike upside dow, in which case a bubble gets into the hose and makes the brakes spongy. When you turn the bike up the other way, you pull the lever about ten times, and you feel it gradually becoming firmer as the air bubbles back into the reservoir and sits above the surface until the lever is firm again. I have had a couple of times when the air couldn't easily get back out because it was trapped further down the hose. In that case, I just tilted the bike so that it was uphill all the way up the hose. Air always tries to go upwards.
Good to know, thanks.
So I guess the only time one would need a bleed kit would be if you wanted to replace all the fluid or build a brake from scratch from separate components.
Apologies for the thread hijack OP.
Air space in the reservoir increases as the brake pad wear increases, unless one lays a bike on it's side or upturns it then air shouldn't be an issue.
You don't need a bleed kit at all for most bicycle hydraulic brakes. I've replaced calipers and hoses, and I never needed one. Air always tries to go up in oil, so just hold everything so that the only way is up.
You never need to replace the brake fluid either. That's a scam when they do it to your car or motorbike. They tell you that the oil can absorb moisture, but the system is completely sealed. There's nowhere for the moisture to come from unless you open the reservoir every day to check something. My motorbike was 20 years old with 40, 000 miles and never had anything done to the coolant or brake fluid. Everything worked perfectly, especially the brakes. It had only done 1100 miles when I bought it, so all servicing was done by me. All it ever needed was engine oil and filter change, brake pads, occasional light bulb, tyres and occasional lube on the choke cable.
I learn something new every day on this forum.
I remember years ago, me and my mate fitted a complete new front brake on his Suzuki GSX600 . All the components were dry and needed filling with hydraulic fluid.
We naturally assumed we'd just have to fill the reservoir, open the bleed screw on the caliper and pump it through.
But it didn't work, the fluid refused to budge no matter how much we pumped the lever.
A quick trip to our local motorbike shop and had a chat with a mechanic. He said we were filling it from the wrong end, he suggested we get a big syringe and pump the fluid into the brake from the caliper bleed hole and up into the reservoir until you got to the right level. It worked, once the brake components are filled with fluid you can bleed it to your heart's content.
Of course with pushbikes one simply buys the complete brake system pre-filled with fluid, just shove it on the bike, tighten three screws, job done.
This is of course complete boolocks. Brakes need bled if they become spongy, and turning a bike upside down does not introduce air into the system.
Really Saneagle, you do come up with the most bizarre notions sometimes.
I've bled brakes for decades, people i know have bled brakes for decades, watched dozens of bike mechanics at races bleeding brakes. All pro's, all working for big companies.
Are you trying to say all of them have been hoodwinked and dont know what they're doing.
System is sealed. but its not sealed 100% air can get drawn in and can affect the fluid by Adsorption, rather than absorption.
And ive also serviced brakes that have been lying for years. - used to buy old bike brakes, strip and service and resell. and the fluid on old brakes can be manky and emulsified
Ebike ones don't. They're nearly all self- bleeding. Yes you have been hoodwinked. I have installed many hydraulic brakes, and I've serviced many, both for myself and when I worked as an ebike mechanic for 2 1/2 years. I've never had to bleed any yet.
The brake fluid should never go emulsified because the fluid system is completely sealed. No air can get in unless you've done something wrong. The only time you'd get problems is when people mess about with it when they don't know what they're doing.
When you turn the bike upside down, any air in the reservoir will go into the hose unless the reservoir has a rubber bellows. That's why brakes can go spongy afterwards until you pump the lever a few times to operate the self-bleeding. The bellows separates the air from the fluid.
Many people have asked about their spongy brakes on this forum during the 14 years I've been on it. I always explain how to self-bleed them, then they come back and say thanks, it worked. Not one has ever come back and said it didn't.
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