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inline one-way brake valve?
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Author:  monkey [ Thu Feb 26, 2009 8:09 am ]
Post subject:  inline one-way brake valve?
hey,
still having a problem with my brakes :x

I have to pump my brakes to get any peddle.. 1st pump goes straight to the floor then 2nd picks up half way and 3rd gets a full peddle. I dont loose pressure when i hold my foot on the peddle but once i take it off, after a minute or so i have to pump the brakes to get pressure in them agen.

I have had the M/C rebuilt and all new cylinders..
the only thing that i think it can be is this one-way valve? any other suggestions of what could be causing this?
where these standard?
and where would be the best place to get a new one from?

heres a pic of the valve..
Image

cheers James
Author:  albino235 [ Thu Feb 26, 2009 8:12 am ]
Post subject: 
A one way valve is only used on a system with a booster, and I'm pretty sure it's not supposed to be straight after the MC.

Have you checked the usual suspects, air in the lines, brake hoses, leaks in the system...
Author:  monkey [ Thu Feb 26, 2009 8:16 am ]
Post subject: 
thanks for the quick reply albino :)
Sorry forgot to mention that i've bleed the lines about 4 times, cant find any leaks, brakes have all been adjusted..Drums all round and no booster.

yeh i was looking thru other people pics of there engine bay and couldn't see any one else with a valve...so is it needed??
Author:  TheMiniMan [ Thu Feb 26, 2009 8:24 am ]
Post subject: 
There is no need for that one way valve (if in fact it is a one way valve) because the master cyl "Should" have a "Slow return Valve" fitted inside it,,, but even if it didn`t then that still isn`t your problem,,, & the fact that you`re able to pump up a pedal means that there is in fact a "Slow Return Valve" fitted either in the master cyl or that thing you`re showing the pic of

Now all that said,,, """IF""" your brakes were all adjusted correctly,,, then the first press of the peddle should be high & hard,,, so it`s still an adjustment problem in my books

That is unless the pedal you get is spongey,,, then it`s probably both air & adjustment :-)
Author:  monkey [ Thu Feb 26, 2009 8:42 am ]
Post subject: 
yeh i thought the same thing so i adjusted all the brakes untill i couldn't move the wheels at all, the peddle did pick up earlyer but still had the same problem of loosing pressure..
Author:  mollymoke [ Thu Feb 26, 2009 8:47 am ]
Post subject: 
I'm not really sure about the one way valve external to the MC.
But inside the brake MC there should be a minimum pressure valve / slow return valve as mini man said, but I think even without this valve you can pump up some pressure? The Clutch MC kit does not have this valve, you may have a clutch MC instead?

One of mine was a bitch, took ages then I gave up took it to a mini shop, they told me they de-adjusted all the shoes, then bleed (which lets the slaves all shrink back to zero) and then adjusted them up.... Sweet! Only cost me 70.00 but good piece of mind, solid brake pedal.
Author:  peterw [ Thu Feb 26, 2009 12:06 pm ]
Post subject: 
If you can pump the pedal up it is most likely air still in the system. If bleeding isn't getting rid of the air it's gotta be getting trapped somewhere.

See if you can borrow a vacuum bleeder from someone, they are brilliant.

Pete
Author:  drmini in aust [ Thu Feb 26, 2009 12:32 pm ]
Post subject: 
I had this problem on Barney (tandem MC) after it got air in the rear circuit due to a leak.
After putting over 500mL of fluid through it I admitted defeat, and took it to B&R brakes for a pressure bleed. $45 well spent, the pedal was then rock solid. :D
<edit> this thing has the `FAM' brake bias/limiting valve on the firewall, I reckon the air was in there somewhere.
Author:  pristic [ Thu Feb 26, 2009 1:16 pm ]
Post subject: 
I had a brake prob for over a year. New everything lines, MC, etc etc and still didnt help. Bleeding about 7 million times and still didnt help.

Pulled off the rear bias valve inder rear subframe and found no pison in there... fitted on after cleaning it all up, BANG brakes are SUPER!!!

Have a looksee at your rear bias valve

Pete
Author:  monkey [ Thu Feb 26, 2009 1:45 pm ]
Post subject: 
peterw, doc - I'll get my brother to bring home his pressure bleeder from work and give it a go..

Pristic - a couple of weeks ago i had the rear bias valve off b'cos the rears were locking up and staying locked.. i didn't pull it apart - just soaked it in metho over nite and it worked fine after that. but if pressure bleeding dosn't work i'll pull it off again and check it out.

and if all that dosnt work - off to a brake specialist :wink:

thanks :!:
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