Brake problem (Mx5)
clairetoo - 19/8/12 at 11:06 AM
I'm having a fairly major brake problem with my project Mx5 - the final job before MOT and some V6 fun......
Everything was working fine when I refitted the front callipers and bled the brakes - then I had to remove and weld the pedal bracket . On re-fitting
, the pedal was further forward than before , and near solid (about 1/2 and inch of travel)
I've just removed the servo - seems to move fine , refitted without the M/cylinder and it still has full movement .
As soon as I fit the M/cylinder - it goes solid ?
I've driven it round the block , and the brakes simply dont work ........... this is realy bugging me 
maccmike - 19/8/12 at 11:52 AM
If everything was working before removing the pedal and welding it, Id look at that again, take it off and assess for movement. Try levering the m cyl
when the pedal off, might help locate the fault
britishtrident - 19/8/12 at 02:49 PM
What happens when you crackopen a bleed nipple ?
clairetoo - 19/8/12 at 02:55 PM
quote:
Originally posted by britishtrident
What happens when you crackopen a bleed nipple ?
Nothing unexpected - fluid dribbles out , pump the pedal and it bleeds normally . Tighten it up , and the pedal goes back to solid , with slightly
less movement with the engine running (which suggests the servo is working ?)
rusty nuts - 19/8/12 at 03:27 PM
Either the pushrod is now "overadjusted" due to something not right with the rewelded pedal box , or the servo isn't working correctly?
Check for a decent vacuum to the servo and that the one way valve is working , when working, if the brake pedal is pumped to evacuate the servo
without the engine running, the pedal held down and the engine started the pedal should creep down a bit . The fact that the brakes can be bleed would
seem to indicate the the pedal has full travel without interference and the brake pipes and hoses are allowing fluid through OK . You'd be
suprised how often things like brake hose clamps are forgotten. Is it worth getting a S/H pedal box?
clairetoo - 19/8/12 at 03:48 PM
The weld repair was to the throttle pedal mount - but the brake pedal mount is on the same bracket . I just disconnected the push-rod , and
removed/replaced the bracket without adjusting anything .
I'll try working the pedal and starting the engine (right after Moto GP.....)
britishtrident - 19/8/12 at 03:54 PM
quote:
Originally posted by rusty nuts
Either the pushrod is now "overadjusted" due to something not right with the rewelded pedal box , or the servo isn't working correctly?
Check for a decent vacuum to the servo and that the one way valve is working , when working, if the brake pedal is pumped to evacuate the servo
without the engine running, the pedal held down and the engine started the pedal should creep down a bit . The fact that the brakes can be bleed would
seem to indicate the the pedal has full travel without interference and the brake pipes and hoses are allowing fluid through OK . You'd be
suprised how often things like brake hose clamps are forgotten. Is it worth getting a S/H pedal box?
+1
clairetoo - 19/8/12 at 08:08 PM
Sorted........................non-return valve in backwards 
I'd cut down the stock pipe , which is sort of `u' shaped - and cut the wrong side of the valve.......so when fitted looking right , it was
wrong 
rusty nuts - 19/8/12 at 08:23 PM
Glad you have it sorted