Brake bleeding issue, Pedal still spongy

toopy

Club Member
When ever I've disconnected a caliper brake line in the past, i have sealed the end of the pipe with a bleed nipple rubber cover, and then when bleeding the brakes later, minimal fluid is required.

Recently i replaced the calipers, and i hadn't noticed that one of the pipes was slowly leaking while everything was apart, as a result the reservoir on the master cylinder ran dry.

I topped it up and used the bleed screw on the master cylinder first, strangely nothing came out initially at all, i actually completely removed the bleed nipple at one point, just to check it wasn't blocked!
Any way once fluid came through, the air cleared, so i moved on.

Moving to the calipers, nothing but air at first, as you would expect with brand new ones, then fluid, some air, more fluid.
Pedal still soft, so more bleeding, a few bubbles but nothing major air wise, pedal better but still spongy for first half of travel!

Also tried the pedal with the engine running, and i noticed when i released the pedal, the engine revs go up slightly and then drop, never noticed that before, coincidence or yet another problem?

How much fluid would you expect to have to bleed through the front lines to clear any air? the bore of the pipe is quite small, but am i assuming I've flushed it through when in fact any air is probably only half way through?

So far i think approx 500ml of new fluid has gone through the front lines, seems a lot, but maybe its not, no idea! :oops:
 

jonbills

Membership Secretary
Site Administrator
A few weeks ago I managed to empty my front circuit on the M6 and refilling it was only a few hundred ml. You’ve probably got a pocket of air trapped somewhere.
 

toopy

Club Member
Am i right in thinking that the Toyota calipers having a bigger volume of fluid in them, will make the pedal feel slightly less firm any way on initial application?

though obviously not as much as i have at the moment!
 

toopy

Club Member
Some one told me today at a meeting with my local classic car club, to wedge the pedal down as far as possible, and leave over night, and that might help.

No one seemed to know quite why it would work, but apparently it can!
 
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