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A A A A Author Topic: 650 Euro Rear Brake Problems  (Read 324 times)

muzza

650 Euro Rear Brake Problems
« Started on: 13-Dec-20, 08:52 »
I have rebuilt my rear caliper and fitted a new  braided brake line , stripped and cleaned the master cylinder and ensured the tiny return hole is open - yet can not get any sort of pressure , or even fluid movement . I have back filled the caliper and hose via a large syringe , had fluid into the reservoir , topped up the reservoir but to no avail.

Its got me stumped? Any suggestions please ?

Onetrack

Re: 650 Euro Rear Brake Problems
« Reply #1 on: 13-Dec-20, 09:29 »
These things are difficult to bleed and in my opinion the brake itself does not work as well as a drum.  Persistence with the bleed technique of pumping the pedal and holding it down whilst releasing the nipple at the caliper will eventually work, may take some time.  Close the nipple before lifting the pedal.  All this assumes the master cylinder is correctly assembled.  Look for any fluid leakage at each joint in the hose path.

"Young" Les F

muzza

Re: 650 Euro Rear Brake Problems
« Reply #2 on: 13-Dec-20, 10:05 »
The M/C  is reassembled as per how it came apart. Only reason I pulled it apart to begin with was the new brake pads I fitted dragged because the caliper piston werent returning enough to allow clearance , so I thought I might as well overhaul everything while I waited for parts.

This really is a pain in the rear end .... zero resistance at the pedal - it just does full travel . I am stumped

doddsy1000

Re: 650 Euro Rear Brake Problems
« Reply #3 on: 13-Dec-20, 10:12 »
If you're not getting any fluid movement mate,  then the most likely culprit is the master cylinder plunger isn't going back far enough to let more fluid in.

A faulty rubber seal or an extra washer behind the circlip perhaps?


muzza

Re: 650 Euro Rear Brake Problems
« Reply #4 on: 13-Dec-20, 10:37 »
I imagine I will have to pull it apart again. That might be this afternoons task. Damn

muzza

Re: 650 Euro Rear Brake Problems
« Reply #5 on: 13-Dec-20, 12:36 »
I have pulled the M/C off the bike and stripped it to its bare components. I would happily post a pic but I have not managed to do that in the last half hour of stuffing about and now I actually cant be bother trying any more. What happened to the tutorial that there used to be ?

Every thing looks fine and clean inside -the bleed hole - the small one at the very rear of the orifice - has a hole that just accepts a 0.4mm wire probe right through into the piston bore. Is that the correct size? Is it possible to enlarge that hole or will it make matters worse?

And I have thrown all the M/C parts in the ultrasonic cleaner to see what some heat and Simple Green can do.

Seagrass

Re: 650 Euro Rear Brake Problems
« Reply #6 on: 13-Dec-20, 14:52 »
Muzza I suspect you have the large rubber inner seal (in the master cylinder) on backwards. If it is on backwards you get no pressure when pumping the rear brake pedal and, bleeding the system is difficult (do not ask me how I know this)

Seagrass

muzza

Re: 650 Euro Rear Brake Problems
« Reply #7 on: 13-Dec-20, 15:16 »
   well - if I could post a pic we would be able to see , but I am not having any luck there . Why must it be so difficult?

and why is there now a pic when I have not been able to post one before ? Damn I hate technology

WTF does this mean "650MC.jpg: Your attachment has failed security checks and cannot be uploaded. Please consult the forum administrator."

muzza

Re: 650 Euro Rear Brake Problems
« Reply #8 on: 13-Dec-20, 15:22 »
  [ You are not allowed to view this attachment ]  

muzza

Re: 650 Euro Rear Brake Problems
« Reply #9 on: 13-Dec-20, 15:23 »
Forgive me whilst I go out side and bash my head against the brick wall of the house .....

Seagrass

Re: 650 Euro Rear Brake Problems
« Reply #10 on: 13-Dec-20, 17:34 »
Muzza the assembly looks correct in the pictures (I referenced two manuals and a parts list to confirm). I remember when I did the last one or the second last one that I could not get any pedal pressure and when I took the master cylinder apart I had one of the rubbers in the wrong way. Looking at your pictures I think I had the spring with the rubber end the wrong way around (rubber end in first).

The large hole in the first picture takes brake fluid from the reservoir and the small hole is to allow for the pads to back off so both need to be clean. I normally wash the whole thing in water and then use compressed air to ensure all holes are not blocked.

When you put it back together, try forcing some brake fluid from the caliper bleeder nipple back through the braided line BEFORE you tighten the banjo bolt onto the master cylinder. This will prime the line from the caliper ready for new fluid from the master cylinder. Hopefully you will then have "pedal feel" when you start bleeding from the master cylinder to the caliper.

Seagrass

muzza

Re: 650 Euro Rear Brake Problems
« Reply #11 on: 13-Dec-20, 17:55 »
Thanks man . I had backfilled from the caliper but was planning to manually fill the M/C before I tightened everything down.

Have given the M/C two 60 minute runs through the ultrasonic cleaner then flushed with brake cleaner and blown out with air. Just dont see why it should be so difficult  to get fluid through it all.

Will report back in due course.

Onetrack

Re: 650 Euro Rear Brake Problems
« Reply #12 on: 13-Dec-20, 18:32 »
This brake is not one of Hondas' best designs, even when bled properly the rear brake does not work well.  I have spent hours in the past attempting to get this brake to work at its best.  All of a sudden it works.  Given that the front is very similar(same caliper and pads, similar disk) no wonder there are two of them, takes two to make a good brake.
"Young" Les F

Dragonstaff

Re: 650 Euro Rear Brake Problems
« Reply #13 on: 13-Dec-20, 20:30 »
I had the same problem after re-kitting the Goldwing at the rear (and currently with the clutch), and found that I had nothing...nothing...nothing...Oh,look, I have brakes now. I don't know what fixed it, but I had it off and apart several times, bleeding the master on the bench and getting pressure, then nothing on the bike again, then it worked. I don't know why, nothing changed, but it decided to work.

Must be a quirk of mid-'80s Hondas.

Seagrass

Re: 650 Euro Rear Brake Problems
« Reply #14 on: 13-Dec-20, 21:10 »
It can take a long time and numerous pumps of the brake pedal to get any response. I think I pumped the brake pedal well over 100 times when I did my Euro a few months ago.

Seagrass

muzza

Re: 650 Euro Rear Brake Problems
« Reply #15 on: 19-Dec-20, 09:47 »
Finally this morning - after much faffing about - I have sorted the brake issue .

I fitted a big syringe filled with brake fluid to the open bleed nipple , topped up the reservoir , pumped the pedal a few times and then left it to sit for a couple of hours. Returned and pumped some more untill the air stopped rising in the syringe , tightened the bleeder and -voila - we have brakes again. This has been a mission to say the least.......

But now they work , test ran it around the back yard a bunch of times and called it a good 'un.

Thanks for the help , guys , much appreciated .

Have a great Xmas if you arent all in lock down again.

Seagrass

Re: 650 Euro Rear Brake Problems
« Reply #16 on: 19-Dec-20, 09:53 »
That is a different method but it obviously worked well and is one to remember for those times when nothing else seems to work.

Good to hear it is all working now.

Seagrass

muzza

Re: 650 Euro Rear Brake Problems
« Reply #17 on: 19-Dec-20, 10:30 »
I think it allowed air to ecsape at both master cylinder and caliper. I Backfilled the system first then mounted the syringe on the side grab rail to get it up high like the master cylinder . That way the fluid should have leveled out equally at both sides .

Anyway - it worked and I can put it all back together again ;-)

 


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