Dingy, still brake trouble?

[bkuhr]

Had Ford Ranger front flexable brake line rubber had deteriorated and swelled. Allowed pressure from master to caliper, but caliper would not fully release pressure back toward master keeping brakes partially applied. Looked at brake line. It had swelled completely closed. Looked like big O-ring with very small center hole.

 

Got me thinking. If your O-ring between Reservior and master was plugged due to? (pinch, swell, dirt, master pistons doesn,t fully retract...) would cause simular problem. You can force fliud thru restriction with Mity-vac, but it will not gravity feed into master chamber.

 

If you can confirm problem is with master, I suspect 1 of 3 things

1. trapped air

2. restriction as above

3. fluid blowby around master piston

 

Just my thoughts

 

Brian

[dingy]

I am slowly getting pressure built up in front lever.

 

Every so often I bleed at top banjo bolt.

 

Every thing is new in front brake system, rebuilt calipers, master cyl., new S.S. lines. Speed bleeders. De linked brakes, Electric anti dives,

Here is an update on what I have tried.

 

I have the new (to me) MKII master that has been rebuilt. I took it apart yesterday and checked for proper assembly. It looked good. I also looked at seal mating surface with a magnifying glass and saw no nicks. Small seal in master (one toward banjo bolt) also looked OK. Bore looked good.

 

I have three masters here for the front brake. I have had all three on with same results.

 

I just within thew last hour put the rebuilt MKII master back on, bled it at top banjo and pulled a couple of reservoirs of fluid through each caliper.

 

It did produce 'slight' brake lever pull. This pull does not increase with rapid pumping.

 

I have also at one point pulled the speed bleeders off and did it the normal way with regular bleeders, no difference.

I have the screw in the end of the brake lever set to just contacting piston when lever is released.

No leaks in system.

 

Also yesterday, tried removing both calipers and holding up as far as lines would permit with bleeder at top and bled, no difference.

 

Bleeders are at top.

 

At no point does master lever become hard.

 

Pistons do come out and cause pads to contact rotors.

 

Most of time when I am bleeding, I use mighty vac attached to speed bleeders with vacuum applied, If speed bleeders where leaking I would see a rapid loss of vacuum. I also am using clear tubing to bleed with, and I do not see fluid be pulled back into caliper.

 

I have also checked both holes in bottom of master & both are open.

 

I see some fluid squirting out of the bottom large hole in master when lever is depressed. This seems to be where problem is coming from.

 

But I would have thought one of the other masters would correct this, one of them came off of this bike, prior to upgrades, and was functioning correctly.

 

 

 

Gary

[Yammer Dan]

Have you tried pulling brake lever and tying it in place leave sit overnight with brake on? Sometimes this lets trapped air sneak out of there.

[dingy]

Have you tried pulling brake lever and tying it in place leave sit overnight with brake on? Sometimes this lets trapped air sneak out of there.

 

I will try this tonight.

 

Gary

[capn eddie]

I will try this tonight.

 

Gary

gary when i did the brake mod i had the same problem bleedind ,it would do the same as you have , it felt like it was working but not a firm lever. i then tied the lever back over night and the next day i had a firmer lever and reblead the front brakes and all is good now:dancefool:

[Yammer Dan]

Gary leave lid loose so air can get out. If you leave it tight this don't work very well.

[Squeeze]

Sounds like there's still Air trapped inside the Line.

 

I guess you did all this work with the Master mounted in it stock Place ?

 

I recommend mounting the Master temporary to a Tube or spare Handle Bar and secure this to the Bike in a Way which directs all Lines going straight upwards. At stock Position the Banjop Bolt End of the Master is facing upwards and creates an Air Sack right inside the Banjo Bolt.

 

I had this happen often, especially with Clutch Masters and empty Lines. I mount the Master to a spare Handle Bar, bleed everything with a Mighty Vac or my compressed Air Tool and then pull the Lever to the Handle Bar over Night. It doesn't matter much if you have the Lid on or not. But you need to have some Pressure in the Line, this Pressure is the Force which drives the Air Bubbles upwards into the Reservoir over Time. No pressure, no Force.

[Yammer Dan]

How is it Gary? Any improvement??

[dingy]

It got a little better when I tied handle back Monday night.

 

I did it again last night (Tuesday) I haven't messed with it yet.

 

I can squeeze handle to the point where metal lever will touch throttle grip.

 

Is this normal on these MKII brakes?

 

I can pump lever till I am blue in the face and no change.

 

It has always been my experience that if there was air in system, pumping them would increase the pedal (lever)

 

Gary

[Squeeze]

You need to position the Master in a Way that the Banjo Bolt End isn't facing upwards.

[Venturous Randy]

It sounds like you have been thru everything, but one of the things that has worked for me is I take the banjo fitting off at the master and use my finger as a check valve. This way, it seems to do a better job of filling the void in the master. After I do it a couple of times, I will get better fluid with each movement of the lever, then I put the banjo fitting back on.

RandyA

[dingy]

I have gotten fairly decent lever pull now.

 

I have tied the lever back to the throttle grip with a zip tie for several days now. Released it in morning and retied at night.

 

But, I can still pull the lever all the way back to the throttle rubber, but with decent pressure.

 

Is this normal with the MKII brakes. I had MKI brakes prior, and I really don't recall how far back the lever came.

 

Could someone check theirs for me please?

 

It's just frustrating with the front brakes, the rear brake & clutch were also rebuilt and they bled first time.

 

Gary

[Squeeze]

Gary, with the Lenght of the VR Lever, you should be able to pull them back until they hit the Grip, but there should be a tight Pressure Builtup while you pull the Lever. Most likely the front Wheel will be all locked up before the Lever is that far in. Maybe it's Time to have another Test Drive.