The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Oconner on June 28, 2016, 10:37:51 AM
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Yesterday tried my first brake bleed. Its never been done in the 1.5yr I have owned the bike and I doubt the PO did anything either. I read and watched every tutorial and seemed like a simple process. I have a vacuum pump from Harbor Freight. I tied a rag around the MC had other rags and a bucket of soapy water handy for spills. Took off the MC cap. Removed the bleeder valve cap. Hooked up the pump. Pumped to 10-15(lbs?) cracked the valve and about an inch of fluid came out, no flow, and when I kept pumping not much more at all. I then tried it with out the pump using the crack the bleeder in combo with the brake hand lever this actually got a bit more into the line but nowhere near flushing the system to the point I need to refill the MC. After a few cycles I can no longer move the lever more that a half inch and no pumping action occurs. Cant figure out what I am doing wrong or if the line is clogged. Any thoughts?
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It does sound like there may be a blockage. There are two small holes at the bottom of the master cylinder reservoir which might need clearing with a stiff wire.
Another possibility is you have used too much vacuum and collapsed the brake hose internal liner. I would crack the bleed nipple and then apply a little vacuum. It shouldn't need much.
Yet another possible issue with vacuum bleeding is that as soon as you open the bleed nipple the vacuum sucks air in around the threads. If that happens you will see the bubbles. I remove the nipple and put some ptfe tape on the threads.
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With no pumping action at the brake lever it is possible that the plunger on the master cylinder is catching on its mount and not returning. Remove the brake line from the master cylinder and unbolt the master cylinder from its mount.
Try pressing on the MC plunger with your fingers and see if its moving freely. It should return easily if the MC has been removed from the line.
You could also try this!
*Remove the reservoir cap and suck the remaining brake fluid out of the reservoir with a syringe.
*Next, fill a large syringe full of brake fluid and attach a length of clear plastic hose to the end of the syringe. Make sure it is completely depleted of air.
*Once that's done, connect the clear plastic hose on the syringe at the bleeding nipple. Open the nipple and slowly empty the syringe. When the syringe is almost empty, close the bleeding nipple to ensure that air does not enter the system. This process is known as a reverse bleed. Be sure to keep an eye on the reservoir as it fills. It is easy to overfill it.
If there are no blockages in the brake line, the fluid from the syringe should quickly begin to fill the reservoir from the bottom. If the brake fluid does not enter the reservoir it is evident that there is a blockage somewhere in the line or the master cylinder.
If a blockage is evident, it maybe at the bottom of the system in the slave cylinders inside the callipers. When I resurrected my bike I found it was blocked inside the callipers. With your hand covering the slave cylinder piston (so that it doesn't fly across the room) blow compressed air into the passages. If those passages are clean, the pistons should easily come out. If they don't move the passages will be blocked. Clean them out with pipe cleaners if that is the case.
*Do not touch the faces of the disk pads when you dismantle the callipers. Even the slightest amount of brake fluid on your fingers will be absorbed into the pads and cause you even more grief.
The hydraulic brake system should be replenished with new brake fluid every 12 months. DOT 4 fluid attracts moisture and therefore must be replaced before too much moisture enters the system.
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This is great advice, thanks guys. I think I am going to just bite the bullet and get new lines after all they are nearly 35 years old!
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I put a new stainless hose on mine for just the opposite reason you had
I new I had all the air out but it was still spongee until I replaced the hose.
I could squeeze the lever almost all the way back to the grip.
Like warbucks said back bleeding my get it but what if the blockage reoccurs when you need the brakes
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You make like to check for any bulges in the lines. If they are the same manufacturer as the K series then I would bin them after 20 years and fit new stainless lines.
Sometimes it is easier to just replace things instead of trying to repair and have the fault reoccur later on. As brakes are a bit of a safety issue, I would not hesitate to replace the lines.
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I found a product on line called a speed bleeder. it looks just like the OEM nipple, but it has a one way valve inside just like a backflow preventer. To work it, you simply crack it open a 1/4 turn and pump the front brake lever. Nice to be able to bleed the fluid single handed. I attach a tube to the nipple feeding into a jar. I remove the existing fluid from the MC, and pump fresh DOT 4 through the system 3 or 4 times to be sure all the old fluid has been evacuated, close the bleeder, top up the MC and I am good to go for another year.
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What a good idea.
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Maybe of some value for something like a car, nut really, this is a solution to a non-problem for our motorcycles.
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Maybe of some value for something like a car, nut really, this is a solution to a non-problem for our motorcycles.
less bending over, less shaking of the front end while the MC reservoir is open, less work altogether...
Are speedbleeders necessary? No. But they sure make the job easier.
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Maybe of some value for something like a car, nut really, this is a solution to a non-problem for our motorcycles.
less bending over, less shaking of the front end while the MC reservoir is open, less work altogether...
Are speedbleeders necessary? No. But they sure make the job easier.
Speed bleeders on ALL my motorcycles. Cleaner. Easier. Faster.
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less bending over, less shaking of the front end while the MC reservoir is open, less work altogether...
Are speedbleeders necessary? No. But they sure make the job easier.
Speed bleeders on ALL my motorcycles. Cleaner. Easier. Faster.[/quote]
Additional and un-needed potential failure point in a critical system, time saving and convenience factor trivial.
Right up there with chrome plated grease nipples and twin overhead foxtails IMHO.
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I thought they were good until i saw the cost to get them here.
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Additional and un-needed potential failure point in a critical system, time saving and convenience factor trivial.
Right up there with chrome plated grease nipples and twin overhead foxtails IMHO.
Speed bleeders are not a failure point. The check valve is built into the banjo-style bleeding orifice. When the bleeder is closed, it is the taper on the end of the screw that does the sealing. Because check valve is built into a regular bleeder orifice and only sees hydraulic pressure when the bleeder screw is opened, the operational failure modes of a speedbleeder are identical to a conventional bleeder screw.
They are a bit pricey, and I'll confess that I don't own any myself. However, if you do annual bleeding they will eventually become a minimal cost, and they are a great convenience. Now that I've got Hagons and the optional digital clock, they are on my short list.
I'd further add that while bleeding brakes is a pretty straightforward process and that most folks have been able to bleed brakes just fine for the last century, speedbleeders should reduce the possibility of sucking air in from the slave end of the brake system.
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Speed bleeders are not a failure point. The check valve is built into the banjo-style bleeding orifice.
Luca, you are of course 100% correct -brain fade on my part when not thinking about how bleed nipples work.
I'd still put the money into LED tail/brake lights though as even though I am nearly 60 I can still bend down and use a spanner on a conventional bleed nipple, pump the lever and monitor fluid level without any difficulty.
I also find that a length of clear plastic tube over the nipple not only gives a 1st class indication of when the system is purged of air, in the event that I become uncoordinated, no air will be sucked in.
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I need to repair a sidecar brake. My arm cannot reach from the rear mc to the sidecar wheel to work the bleeder so this might be nice.
Tony give it a decade plus and tell me how easy it is to bend over. I always say I must be getting taller, it's getting harder to get back up after squatting down.
Bob
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These are my cheap take on speed bleeders