The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: AlfromNH on March 06, 2014, 06:43:43 AM
-
I'm starting with a completely dry front brake system. Using the normal "squeeze the lever, crack the bleed screw, close the bleed screw, release the lever" method, I have fluid into the caliper. But it seems like I'm not getting any further than that. Still no feel at the lever, but no more air coming out the bleed screw.
I also have a fair amount of fluid drooling out the threads of the bleed screw every time I open it. :(
Should I buy one of the vacuum bleeder devices? Harbor Freight? Is there a sealant for the bleed screw threads?
I've bled brakes and clutches, but this might be my first time starting from dry...
-
Starting from an empty system I always fill from the bottom upwards using a large syringe on the bleed nipple. That gets most of the air out before you start having to use the usual bleeding methods.
I use PTFE tape on the bleed nipple threads to stop leakage. Just make sure not to contaminate the hydraulic system with bits of tape by keeping it towards the top of the threads and away from the pointy end.
-
Vacuum bleeders are nice, but from my experience perform poorly if the system has much air in it. The containers they come with are also awful. I ended up making a reservoir for one (in a pinch) using steel brake line, super glue, and an old mason jar. It hasn't failed me yet.
+1 on the syringe. Get one from your local drug store with a "luer lock" tip. It will thread over the clear plastic tubing
If you have an "uphill dead end" at the splitter it will trap air there. Try turning the handlebars to change the angle of the splitter. Or try putting fluid in one bleeder and out the other, so you get a nice cross flow through the splitter.
Or try the old way, whereby brake bleeding got its name. Fill the reservoir and open up both bleeders. Let it sit overnight.
One last thing you can do is tie the lever back to the handlebars and let it sit overnight to help improve the feel.
-
I started using speed bleeders a few years ago and haven't had a problem yet. I fill the reservoir, leaving the top off. Crack both speed bleeders with a length of clear tubing attached, going into a mason jar. Slowly pump the brake lever and keep topping off the reservoir. Before using all of a small container of brake fluid I am usually good.
-
I love those speed bleeders. Got 'em on the Airheads and the Trophy.
-
I had good success with a Mighty-Vac vacuum pump device. I just filled the resevoir and left the top off, fastened the brake lever back by wrapping a strip of velcro around it, hooking up the vac to the bleeder, and opening up the bleeder and keep pumping the vacuum to draw the fluid. I kept an eye on the resevoir, and when it started to get low I just closed the bleeder, topped of the resevoir, and continued the bleeding process. The results were good, and the feeling is nice and firm.
k_enn
-
I saw something about speed bleeders, are they bleed screws with a built-in one way valve? Where can I get one, and how do I know which version fits my ATE caliper?
-
Got my speedy bleeders here. http://www.speedbleeder.com/
Tell 'em your bike specs and what brakes you have.
-
Yep, they have a check valve in them so you can just keep them open the whole time you are bleeding. They come in varying thread sizes and pitches. Can't recall what size the ATE screw is, but you could just check it with a known bolt or nut. Bike Bandit carries them.
If your problem is air in the line, however, they won't fix it by themselves. Either you can try running a lot of fluid through the system or you have to find a place where the air could be hanging up and get the air out of there. Tapping gently on the brake hoses can help get the air bubbles moving.
-
I guess I wasn't being patient enough :( I have it bled, good solid feel at the lever. I wish there was some provision for adjusting the lever travel, it pulls back to within an inch or so of the grip.
-
There are adjustable levers for clutch and brake application .
Problem is, trying to find one that will work on your bike, usually not applicable to older bikes .
Been looking for adjustsable levers for my Guzzi, I've got small hands and have to grip the levers at it's base, losing the mechanical advantage of the lever .
-
Al, that amount of lever travel could be related to your master cylinder bore size. You can change the feel and amount of lever travel by changing the MC... but I'm sure you'd want to wait until you have the bike on the road to start messing with that ;)
-
I've used a vacuum bleeder from Harbor Freight for years now .
One thing to do when using a vacuum bleeder, is to put a wrap of teflon tape on the bleeder screws, just on the threads only, the conical point of the screw, is the sealing surface on the caliper seat, so you don't want any tape near this surface .
If you don't do this, you will draw air from around the threads and it looks like you never get all of the air out of the brake system .
Don't ask me how found this out on my own !!!! :D :D
-
If the master cylinder was dry too, it helps to bleed that first by taking off the brake line at the cylinder. Covering everything with towels, fill the master with fluid while holding a thumb over the outlet.
Slowly squeeze the brake lever with the other hand while feeling the pressure build against your thumb. While holding the pressure let it burp by slightly uncovering the outlet then covering it again with the thumb. It should bleed the master quickly and then all that air won't have to go through the system.
Have the brake line ready to reconnect as soon as you remove your thumb when it's done. It's not as messy as it sounds.
-
thank you very much for the tip of putting some tape on the bleeder screws!
I have been fiddling around for 2 weeks now trying to get the pressure on the handle up and no success. Which means my pressure is up on the second pull of the lever, first pull is still feeling flimsy. And I can see that on one bleeder screw the tiniest air bubbles just keep on coming and never end (yes, I purchased brand new bleed screws).
Now I can get some tape and hopefully that sorts the brake build-up I have done. I changed everything except the calipers themselves.
I've used a vacuum bleeder from Harbor Freight for years now .
One thing to do when using a vacuum bleeder, is to put a wrap of teflon tape on the bleeder screws, just on the threads only, the conical point of the screw, is the sealing surface on the caliper seat, so you don't want any tape near this surface .
If you don't do this, you will draw air from around the threads and it looks like you never get all of the air out of the brake system .
Don't ask me how found this out on my own !!!! :D :D
-
I have been fiddling around for 2 weeks now trying to get the pressure on the handle up and no success.
I removed the caliper from the fork leg and suspended it above the height of the master cylinder(with the lines still connected) hoping to get any air to rise and settle in the caliper. I left it like that overnight.
Not sure how much that helped, if at all, but I was struggling getting a solid feel at the lever and eventually got it solved.
-
I removed the caliper from the fork leg and suspended it above the height of the master cylinder(with the lines still connected) hoping to get any air to rise and settle in the caliper. I left it like that overnight
Thanks for the tip. I am waiting for the wrap tape from the mail, wrap it around the bleeder and bleed it like then. But getting all the tiniest air bubbles to rise to the highest point is a good idea. I will try to bleed the hoses while having the caliper higher than MC to see if that solves that last final sloppiness of my lever ( it is rather ok but might prove not sufficient for MOT test).
-
I re-piped my brakes on the R100 yesterday. Single pipe from master cylinder down to right hand caliper and then a second pipe running from the right hand caliper to the left. Banjo bolts required. Pipe between calipers loops over front mudguard, just behind the fork leg.
What I found that works well, in the traditional way, is to fill the master cylinder and then lightly feather the brake lever - i.e. tickle it until air bubbles stop finding their way up through the master cylinder into the reservoir. Once the master cylinder is properly primed, it will efficiently push fluid down the pipes. Air will still work its way to the top, and should be dealt with the same way by tickling the lever.
Took us less than half an hour to bleed the system from dry. nice and firm now.
Rev Light