Brakes aaaagh

[Jamesreabrookes]

Hi

Anyone local to Cannock know anything about bleeding front brakes

I rebuilt my calipers with new seals as they were shot and now for the life of me can't fat them to bleed

Still got the rear to do as well :confused::confused:

Thanks james

[Fen Tiger]

I haven't tried other systems but I can recommend using a Mityvac vacuum system to bleed the brakes. The kit for home use is about £35 to £40 and lasts well. Should make short work of getting the air out. Great for flushing the system every year too.

[Craig380]

I've used two methods to bleed up stubborn brakes, both are successful but one takes longer, and is less toxic:

1) Cover the fuel tank, plastics etc in cling film to keep off any stray brake fluid. Get a long section of clear plastic tube (about 4 or 5 feet, the aquarium stuff from pet shops is good). Push one end over the bleed nipple. Take the other end up over the handlebars and fully submerge it in the brake fluid in the master cylinder. Use a couple of wire twist ties from plastic bags to hold it firmly in place.

Open the bleed nipple half a turn, squeeze brake lever SLOWLY and STOP when the lever is at the twistgrip. Tighten nipple. Release brake lever. Then open nipple, squeeze brake lever slowly again until the lever is at the grip, and close nipple. Repeat these steps until you've got brake fluid filling about a foot of the clear hose above the nipple. Then you can just leave the nipple open, and keep on squeezing the lever gently. Keep an eye on the level in the master cylinder and keep topping it up.

You've now got a closed loop where air cannot get in, and any trapped air has to rise up the tube to be expelled into the master cylinder.. When no more bubbles come (and you can leave it overnight with the tubes attached and bleed nipples open), close the nipples, remove the tubes carefully to avoid splashing fluid, and it's done.


2) Attach 3-foot length of new, CLEAN, clear tube to brake nipple. Put other end in mouth. Open nipple half turn, squeeze brake lever gently, and stop when the lever is at the grip. Then start sucking on the tube, and gently release brake lever. Then squeeze brake lever gently (don't close the nipple) and keep sucking. Obviously stop sucking before the brake fluid reaches your mouth. You'll look and feel stupid, but it works.

[Jamesreabrookes]

ok thanks wil ltry and see what happens - better get shopping!!

[Red Herring]

If you do a search on here under brakes and bleeding you will find this has been discussed several times. Investing money in a vacuum kit is fine if you're going to be doing it regularly but is a bit extravagant for a one off in my view.

The problem when filling a dry system and bleeding it conventionally is you are trying to get the air to go down faster than physics wants it to go up. Using method one above is a way of helping it out a bit but.... If far easier to push the air out of the top and keep physics on your side.

Either get a syringe or a reasonable length of bleed pipe, fill it with brake fluid and attach it to the open bleed nipple. Then gently force the fluid into the system either with the syringe or pressurising the end of the pipe with your mouth. If just using a pipe you may need to refill it a couple of times by dipping it in a bottle of fluid and sucking some up (tip, make sure you put the same end in your mouth each time) and don't forget to close the nipple when you remove the pipe. Start with an empty master cylinder, by the time it's about half full you should be able to stop and bleed the brakes in the conventional way.

Just remember air rises. If you have any loops or joints in your system try and position them so the rising air doesn't get trapped.

[Fen Tiger]

Re 2). Above, be aware that brake fluid is poisonous and will damage vital organs if ingested.

[Jamesreabrookes]

THanks I have ordered a vacuum pump system so no fliud sucking required

[Craig380]

Re 2). Above, be aware that brake fluid is poisonous and will damage vital organs if ingested.

I forgot to add that as a warning, but it's good advice. I've titrated worse stuff by mouth, though :clown:

Discount shops often have big plastic syringes for use in cooking, and those are great for brake bleeding too.

[Tamsen Cooper]

Hey, I am down in Cornwall so too far for me to travel, however, I did cover calliper rebuild and brake bleeding in my youtube videos if that helps. I used a combination of vacuum pump and lever. I found the pump was great at drawing the fluid through, but that by pumping the brake lever gave me a much better and more solid feel with all the air expelled. I hope it helps

Bleeding part starts at about 9:05 through this video.

MlOGPUlD78s

Good luck, looking forward to hearing how you get on.

[AlexAdams]

At last a brakes not breaks thread!

[Davemurphy007]

Alex - blame tablet autocorrect. I tried to edit the post title I put up recently about breaks/brakes and it let me edit the title of the post, but that didn't then display in the list of threads on the forum. As a fellow grammar/spelling Nazi I winced every time I opened my own thread.

[Dunn-y]

Just get a large syringe. Fill with fluid and force the fluid up the system via the bleed nipple. Or suck the fluid down via the bleed nipple using the syringe. You can get a syringe for less than £1 and does basically the same job as these £30 - £40 vacuum pump things.

[Jamesreabrookes]

Ok so done reverse bleed on one side and sucking down on the other starting to get some feel in the lever now so a bit longer and I should done hopefully

[Tamsen Cooper]

I found finishing off with the lever pumping gave a better feel than just using suction, Using suction is great to pull the fluid through. I also tied off the brake lever overnight so the last of any air would get removed.

[Jamesreabrookes]

yep had loads of air and didnt even realise - tied lever up and now have brakes again :)

[Fen Tiger]

Excellent, good to hear you got it sorted.

[Craig380]

Changed the fluid on mine at the weekend, the lever was soft immediately after but left it on the side stand with the bars at left full lock overnight (so the master cylinder is level, allowing any air to rise into the reservoir), gave the brake lever a gentle waggle in the morning, and it's spot on and rock solid now.

Time is often the key!