Brake bleeding hassles

[Jim DrewMember]

Your problem is simple hydraulics,you are trying to shift a large quantity of air with a small capacity master-cylinder. What you find that is happening is that the air is just moving back and forth as you attempt to bleed it ,I think what will need to do is to block the flexible hose as close as you can to the bit you are fitting (vice grips or brake hose clamp should do but don’t crush it just apply enough pressure to stop the fluid from moving, you will feel this by applying the back brake pedal pressure). After you have done this you will need to undo the bleed nipple(you could put clear hose onto the bleed nipple then into a jar to allow the fluid air to go into the jar,this not only stops the mess but also allows you to watch the fluid flow to make shaw that all the air is out).
The process 1 With the clamp applied, release the bleed nipple as described above, then apply brake pressure(the pedal should be hard) release the clamp, the pedal will go down, before you let the pedal up again apply the clamp again. This will allow the air to move, after doing this you will need this process about a dozen times to be shaw that all the air is gone. Be shaw to keep a check on the fluid level in the reservoir.

The main cause of brake fad is riding the brakes, you find it less a problem if you go up a gear before you go down the hill and apply light pressure to both brakes at the same time, take a bit of getting use to but it does work. The actual cause is fluid boil caused by overheating and the only way to fix the problem is to. 1 Fit a bigger caliper and disc. 2 Use better brake fluid non boil type and better pads. 3 Or change your riding style. Hope this helps.
Jimbo
PS Reverse bleeding has no affect on the seals in the system, but if you are going to do it the procedure is correct you will need at least double the volume in the system of brake fluid in the system. Your brake fluid should be change at least every couple of years as it beaks down with age.

[RoyMember]

Thanks Jimbo.

I’m pretty sure I fall into the option 3 category. Need to improve my riding style.

I have trouble finding a pedal height where it is low enough that I’m not accidently riding it but high enough so that it doesn’t feel like my ankle is pivoting through 90 degrees to get the brake on. Hence I’m pretty sure I drag the rear brakes a lot.

[TheBossMember]

Those that have had posts deleted from this thread please note the “Tech help” thread is the only thread that must have helpful sensible answers

Rules of the Tech Thread Here

[Aaron WildeMember]

I did the new front braided brake braided line thing once and I never got the lever to feel as solid as it was before I started. The brake still works but always feels that little bit spongy. I started the old fashion way but then tried the big ass syringe at the caliper end and it did help but I can’t help but think there is still some air hiding in there somewhere. I am not game to replace the fluid on my newer YZ for fear of stuffing it up because I like it just as it is.. sad but true. It would be cool if you could prime the brake line with something that would work like surfactant does with weed spraying.So the fluid would not bead on the sides of the line and stick to it instead. I watched a show once about how people in South America using all sorts of things dodgy to get their old cars going with stuff that was not designed to be used that way. They used shampoo mixed with something else for brake fluid. Shampoo is sort of a surfactant They could have been on to something. Or not…. :unsure:

[AlexMember]

Hey Roy, how about you look into some way to keep your foot away from the brake such as bending the tip toward the bike or cable tie a chunk of plastic say 5mm to the frame to keep your boot out more. Most of us tall blokes end up pointing toes out naturally and conciously twist in to brake.

[Dwayne OMember]

I like to remove the lever & perch assembly from the bars once I have filled & bled the system, tie it up somwhere high above the bars as vertical as possible (piece of string from garage roof trusses etc), lightly tap the whole length of the line starting from the Caliper working up to the perch assembly & leave for a few hours if possible.
This gives a chance for any minute bubbles of air to rise thru the fluid to the reservoir, then reattach the perch & off ya go;)

I found it made a difference for me anyway

Cheers

[DavidMember]

Hello Roy,
I don’t know how you finished up with this problem but i thought i would give you some feedback on my similar brake issue.
I have a KTM450exc and on the last few rides i have experienced the rear brake fluid boiling.
I thought about getting a brake reservoir extension and even went to Suttos to get one.
The price scared me off a bit, so in desperation i went to the owners manual.:unsure:
The manual says that you need to adjust the pedal height with the adjuster under the pedal stop to your desired height and then you need 5mm freeplay on the push rod in the master cylinder.
The 5mm freeplay is between the adjusting rod and the piston, so when you push the pedal up and down there is freeply before the piston starts to move.
I did this adjustment before the Birthday pre-run and i had absolutely no problems the brake worked as it should all the way through the ride.
I now have confidence in my rear brake, there were a couple of good hills and in the past the fluid would have boiled.
I didn’t change my riding position as i have had other bikes and not had the same problem.
I am not saying that this is your issue i am just pointing out something that worked for me.
I thought that i had enogh clearance but it says in the manual if you don’t have the freeplay then the heat tranfers from the pads as they expand.
Probably could have saved some time and brake fluid if i had read my owners manual in the first place. :pinch: :whistle:

Rebore.

[dennis da menaceMember]

Bundyroy wrote:

This was what I am trying to fit.

http://slavensracing.com/products/brakes/brake-caliper-cooler-ktm-husaberg

you legend Roy, i have been looking for one of those. i showed Tisco from suttos one and he couldnt source it..

it will defo be air in the banjo.
go to the chemist or vet and get a massive syringe and connect it to squirt from the caliper end. it will prolly help if you put the caliper on the ground too.
then pump the whole syringe through as fast as you can, letting it spill out onto a rag from the master cyl.
make sure you nip the nipple up before getting to the end of the syringy.
refill and repeat as necessary.

piece of piss mate…..

thanks for the Slavens find

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