Mark_Series3

Mark_Series3

New Member
Hi all, i've just replaced the master cylinder on my swb truck cab and after a LOT of messing about i got them bled up but the pedal is very very hard but the brakes do work however after about 4 or 5 miles of driving the brakes are virtually seized if you crack the bleed nipples off it squirts fluid out with some force as though someone is pressing the pedal (even though they aren't) then it's ok for another 4/5 miles. I've tried all the adjusters but to no avail, any other ideas?
I'm meant to be going off roading tomorrow.

Thanks
Mark
 
There is a threaded rod by the master cylinder, it sound as though that needs adjustment, not sure which way. It sounds like its not letting the fluid back into cylinder as its acting like a non return valve...
 
There should be a small amount of play, I think about 1.5 mm, on the push rod to the master cylinder, this will give a small amount of play on the pedal.
If you have adjusted all the play out of the pedal you will get the symptoms you describe!
 
It sounds like the threaded rod in your master cylinder is badly adjusted, this could have also caused you to have problems bleeding the system. When adjusted correctly as said the rod should have a little free play before connecting with the master cylinder. You can see and adjust this through the pedal box top cover.
Use the PDF file 5, page 46 NONE SERVO BRAKES
 

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Still no joy:mad:
So i've replaced the rear flexi as it was on it's way out and clamped it off with a pair of mole grips just to see if it was the master cylinder and the front brakes don't bind up.
Any ideas?

Cheers
Mark
 
Assuming it’s a single line system, I would start looking at a seized slave cylinder or as said shoe return spring problem.
 
Hi,
I have a similar issue with my 1970 SIIa. When I adjust my pedal high properly and 1.5 mm freeplay in the rod then the pedal goes down to the floor, if I slightly preload the pedal then it's OK but the brakes will bind after a couple of brakings. The excentrics are all correctly adjusted and the system bled, I have also changed both front flesible.
Anybody experience similar probelm, I would like to have advise before I get myself into a gruelling piston change operation!
 
jyt said:
Hi,
I have a similar issue with my 1970 SIIa. When I adjust my pedal high properly and 1.5 mm freeplay in the rod then the pedal goes down to the floor, if I slightly preload the pedal then it's OK but the brakes will bind after a couple of brakings. The excentrics are all correctly adjusted and the system bled, I have also changed both front flesible.
Anybody experience similar probelm, I would like to have advise before I get myself into a gruelling piston change operation!
Click to expand...

Sounds like you have the springs incorrectly fitted (on one or all wheels) and the reason that it binds when you set the pedal wrong is that the one way valve in the master cylinder isint realeasing.

On a 10" single leading shoe set up.
Top spring = Leading shoe (the one with the cam) to post on back plate
Bottem spring = shoe to shoe.
 
Thanks, I really thought it was the master cylinder but on inspection all looks OK, apart from the fact that I thought that there might have been 2 springs in the cylinder?? anybody's got a layout of CV type master Cyl?

I guess it may be like you say the springs although i think that all wheels are locking...
 
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