brake vac woes

[lobster]

Hi mud manics.  having a little prob with the brakes on my SIII.  when i first press the brake pedal the vacuum doesnt seem to work and the pedal goes right down (with not much braking!), but after a second quick 'pump' of the brakes it becomes stiff again (resistance as normal) and the brakes work fine.

is my manifold pressure low, or is there a simpler fix? i have recently bled the brake system (accientaly cut through a brake line with a grinder - whoops!) so i dont think it would be that.

am just slightly fed up of having to jump up and down every time i brake!!!! your help would be most grateful

zander

[Reaper]

Did you bleed the master cylinder ? only I had the same problem for 2 years before a friend of mine took 2 mins to solve it. he just cracked open the outlet pipe and let a few bubbles out! job jobbed

[lobster]

cheers.  call me prat but how do you bleed the master cylinder (as opposed to the normal way of brake lines)????????

im on one of those 'self learning' landie mechanics courses...

[Reaper]

Well my s3 has no servo but it should be the same, push down on the brake gently while just loosening the outlet pipe/s you should get a few bubbles out then tighten back up and hopefully hey presto!  just the same as bleeding the cylinders.
I put all new cylinders and shoes front and rear and a new master cylinder
but it was the same had to pump the pedal a couple of time to get good brakes, my friend said have you bled the master cylinder out?  "eer umm err no", two minuets later perfect brakes!

[Dr Neil]

failing that it might be worth adjusting up the brakes.
when you bled the brakes did you back the adjusters of completely first?
when i changed the brake shoes and cylinders on mine i bled it bowt three times but the peddle was soft on the first application,then took one drum off at a time and manually forced the cylinders back witha screwdriver as the adjuster doesn't allow the shoe to push the wheel cylinder all the way in thus trapping a small amount of air in each cylinder, done this on all four corners then adjusted up the brake shoes and "hey presto" A VERY GOOD PEDAL ON FIRST APPLICATION :D  :D
Hope this helps, regards Neil...

[lobster]

thanks for all your help guys.ive tried bleeding the M.C. but no change.ill try adjustting the brakes and then squezing the shoes closed etc.ill let you know how the stopping gets on!!!!!!!
cheers,
  zander