40 years working in the motor industry, mainly on cars but also some spent on bikes (including my own) has taught me a last-resort method that has ALWAYS worked for me. When the problem actually is difficulty in bleeding (as opposed to seized/sticking caliper pistons), the real cause is always trapped air somewhere. Remove the caliper/s without disturbing the hose connections; hold/suspend the caliper/s up in the air so they are higher than all other hydraulic components with bleed nipple/s AT THE TOP; make sure there are no up-and-down loops on any hoses; insert spacer to substitute for pads; thoroughly bleed brakes again; if all is now OK, re-fit caliper/s again without disturbing hose connections. If necessary, pump brake lever/s and bungee tightly on overnight. If a hose really can’t be removed without disturbing tbe hydraulics, get as close to the above ideal as possible, maybe leaning a bike right over. Another solution can also be to first try carefully releasing the master cylinder hose union to bleed the system at that point, which is usually the highest.
When refitting calipers I always push the pistons as far into the caliper as they go and hold them there while bleeding.
It might not be much but it minimises the amount of air in the system I have to bleed out
I also find that for the initial bleeding of an empty system or to remove trapped air it helps to open the bleed nipples 2 full turns rather than the 1/4 turn you would normally use.
Oh yes that works.Use plenty of rag around it though.
As described Soooo many times before, the older Brembo brake calipers do have a tendency to trap air behind the piston and rather than faff about undoung calipers and all that … Drain old fluid …get a big syringe Open bleed nipple and slowly force the fluid UP into the master cyl, take precautions so fluid does NOT squirt out onto components it takes 30 secs to do…
Used this method front and back ever since I was told about it.
IF your brakes DO NOT bleed then
Look for leaks check all joints
IF you used new nipples check they have seated, old npples can sometimes get crap under them
Finally suspect Master cyl, Me I get a refurb kit and pay local shop to fit £5-£10 depending where you are BUT job done for less than a set of circlip pliers.
By all means if you want to undo calipers and lift them, and such go ahead it IS sound practice, I used to do all that. …
I did the syringe method for the first time this year and was surprised at how simple and effective it was. For all “normal” conditions it’s my future method.Regards,John
looking at trying the method after the new rebuild kits come for calipers and master cyls, whats the best way to bleed the linked front left and back brakes? front then back or back then front???
I don’t think it matters.
When bleeding brakes on most vehicles it is best to start with the one furthest away from the master cylinder, then move in closer.
When I replaced the steel pipe on my Le Mans 2 with Kunifer, I used a vacuum bleeder, and it was an easy two mins job!
don’t forget to inspect the link brake manifold / splitter… many days spend on my old t5’s brakes only to find the manifold had dried brake fluid blocking it
Ive serviced the calipers and replaced copper washers, renewed feed pipes from reservoir and cleaned it. tried a vacuum bleeder still no luck. going for the master cyl service kit as I can hear hiss then suck while bleeding.
seems like its ok below master but not charging it as lines are empty but don’t fill. probably invest in a set of Hel lines while I at it. .
I just (to day) bled my empty brake system, on my 1979 V50.
It was VERY difficult to get the “system started” - even if I had installed new seals etc.
Maybe my experience can help?
I took the bled plastic pipe in my mouth and sucked, at the same time pumping the brakes.
Slowly by slowly the master cylinder(s)started to take brake fluid inside the cylinders . took a considerable time - much air in the system - so be PATIENT!
Suddenly, the airbubbles stopped to come (and I got a dreadfful taste in my mouth) - but, anyway, I guess its a question of raw patience, provided the seals are OK.
Empty master cylinders are very reluctant to “start”!
But now, I have a hard pedal, and a hard brake grip - took me meny hours…
Empty master cylinders are very reluctant to “start”!I think this is the problem most have, but I would prefer not to taste brake fluid.
I tend to fill a new master cylinder up and pump it a few times and the leave it pref over night and start next day with the full bleed
You should have read the whole thread and how to reverse bleed yer brakes buddy 30 secs job done easy …
The brake system is Hydraulic…there is the clue, they need fluid in them…the front brake is especially difficult as air travels UP as you are attempting to pump fluid DOWN hence the above trick to push fluid up feom the caliper, gets rid of the air bubble behind the caliper that is almost always there on the Brembo (Altered from a mispelling due to imbibing…ho ho ho) calipersguzzibear2013-12-29 21:15:49
“Bosch” Calipers, Teddybear - mine are original “Brembos”…
No timbers were bent by this message, but many leaves fell to the ground.
OOOps that’ll be the Christmas Spirit then …hohoho Both START with a B
Tastes alot better than Brake Fluid tho’ guzzibear2013-12-29 21:17:11
vacuum bleeder, manual bleeder, reverse bleed, normal bleed, priming, new seals new copper washers, new bleed screws and still cant get the damn things to pressure up.
next stop take the master cylinders off again and check the pre assembled pistons just replaced!!
I found my brand new master cylinder piston was not able to move because it was jammed with machining swarf. Removing the piston, cleaning out the swarf, replacing the piston with new seals meant it bled immediately.
All the best.