Why the faff bleeding brakes?

Greggors

After a trail side repai/adjusment (bike upside down), Ive ended up with some air in my front brakes.

They are tektro augiras and Ive found the manual on the website and located a lbs with the service kit with the syringes, tubes etc.

But why cant they be bled like car hydraulic brakes? As long as the nipple is the highest point on the caliper and the brake line doesnt loop back down anywhere, can you not just use the lever to pump the fluid through the system from the top.

Is there something different about the master cylinder that doesnt allow this. Sorry if this has been explained a million times before, I did a search but there was just a load of threads on how to bleed a certain type of brake.

Thanks

Chris

nicklouse

No real reason other than is does not always work.

I have always found that following the makers instructions the easiest and fastest and most trouble free way of sorting ally brakes.

Even the cars.

allen.coulson

Because you have servo assist in the car and not on the bike.

Greggors

Nick, I guess they are the tried and tested that work best for each manufacturer. Just wondered if there was a reason why normal bleeding doesn't seem to work.

Allen, do you mean that with servo assisted brakes the brakes don't need to be bled as well? When bleeding the brake system on a car without a servo you still bleed them in the same way.

Chris

sniper68

Hope brakes
No syringes just a bit of tube a bottle and crack open the bleed nipple etc.That said I've not had to touch mine in 2 years 8)

The Rookie

allen.coulson wrote:

Because you have servo assist in the car and not on the bike.

No its because a car uses a large open resevoir and a bike does not, in a car you just fill the resevoir and then pump the air through using the master cylinder topping up as needed, Shimano can be done like this using the attachable large resevoir, most others use syringes, perhaps because keeping the bike dead upright isn't so easy!

Simon

Greggors

Ok so because one stroke of the brake lever is enough to empty the reservoir. Makes sense now.

nicklouse

Greggors wrote:

Ok so because one stroke of the brake lever is enough to empty the reservoir. Makes sense now.

nope.

The Rookie

Hmm I'd have said 'sort of' one stroke won't empty it, but you don't have a large enough resevoir to bleed it.

As a system designed to be sealed you would soon empty the resevoir and be pumping more air into the system though...

Simon

hobbitsharley

i bleed my brakes all the same way - large syringe on the nipple full of fluid and squeeze it up to the cylinder be careful not to just squeeze as brake fluid can be corrosive when it squirts out all over the shop with practice you can just slowly fill the reservoir and once there is fluid in there just top it up - works on my MC's and my MTB's - its sorta reverse of a mity vac which sucks the fluid thru

Greggors

nicklouse wrote:

nope.

Ok maybe not one stroke but why the reason they can't be bled in the standard way? Apart from because you once tried it and it didn't work.

gtd.

Greggors wrote:

nicklouse wrote:

nope.

Ok maybe not one stroke but why the reason they can't be bled in the standard way? Apart from because you once tried it and it didn't work.

Hope are bled the same as a car. just make sure the fluid doest drop to the level of the deflector plate in the master cyl/lever res

nicklouse

Greggors wrote:

nicklouse wrote:

nope.

Ok maybe not one stroke but why the reason they can't be bled in the standard way? Apart from because you once tried it and it didn't work.

no reason why you cant give it ago.
like I said

No real reason other than is does not always work.

I have always found that following the makers instructions the easiest and fastest and most trouble free way of sorting all brakes.

Even the cars.

Even hope bleed better with a big fluid holder clamped to the top of the lever assy.

But again i will repeat

I have always found that following the makers instructions the easiest and fastest and most trouble free way of sorting all brakes.

mrmonkfinger

funny that, its almost like they know how the brake works or something

Greggors

mrmonkfinger wrote:

funny that, its almost like they know how the brake works or something

Or they want to sell you a service kit?

Anyway, turns out my LBS didnt have the right service kit and I couldnt find a syringe at work with the right size nozzle. So cut the head off an M6 bolt, drilled it through, threaded this into the reservoir filling hole, attached 6in of hose to this, filled the hose with fluid, then another bit of hose to the bleed nipple, opened the nipple and pumped the fluid through. Job done!

I did try it without the hose on the reservoir but was a real pain to keep it topped up as gravity drew the fluid through on its own.

Thanks for the help and suggestions, now to get out and ride!

mrmonkfinger

which is usually overpriced if you're inventive you can make "suitable" hardware... like you already have

nicklouse

mrmonkfinger wrote:

which is usually overpriced if you're inventive you can make "suitable" hardware... like you already have

see the FAQs.

Northwind

Incidentally, you don't need the Tektro kit- instead of using the syring and wee hole, take the back cover off the brake (obviously point it downwards first) and it's basically exactly what you want,an open reservoir brake. Watch the screws, tehy're quite delicate.