soft brakes

[necromonger]

what to check next. driving the other day ( t25 caravelle 1.9 water cooled ) had to do an emergency stop that was fine, ever since brake pedal goes all the way down when braking slowly. checked the brakes out and found had popped one of the rear wheel cylinders, replaced it and bleed the system, brake pedal still the same. replaced slightly worn servo pipe on the manifold and checked the one way valve that it was only sucking not blowing that was fine. brake pedal still the same, when braking while apporaching a junction the pedal is just going all the way down, the van is still stopping but the pedal feels "pooh" and a bit nerve racking as the pedal has no where else to go. have tried emergence stop and the van pulls up pretty good, but slow stopping crap. re-bleed the brakes got a couple of small bubbles out but still no improvement. what next ? any help would be great.

[Fritz]

This static test may help you decide on you next plan of action :::Provided you have bled the brakes system properly...

Using brake pipe clamps,,,clamp front and rear flexy brake hoses then press brake pedal a few times, it should be at the top of its travel and also be solid if it is working properly.

If you still get pedal travel to the floor it may be safe to say the master cylinder is at fault.

Regards


Fritz,,,,,,,,,

[dugwiththevwbug]

when you fitted the rear wheel cylinder did you adjust the brakes shoes up so they just touch the brake drum as if you didnt, the travel on the brake pedal will be all the movement needed to move the brake shoes out and your automatic adjuster may not completly work at that sort of travel if at all
good luck if not keep bleeding
doug

[Cafnod]

To expand on what Fritz said; clamp all flexis, if pedal good then try taking front clamps off, if pedal still good then problem very likely rear brakes, although you could take the back clamps off and clamp the fronts again to check. When you know where the problem is (I suspect back end) one of several is things happening;
Excessive movement of shoes.
The other cylinder not operating properly (I always change them in pairs).
Air still in the system, or possibly a pinholed back flexi.
If after adjustment and visual inspection it is air then I wonder if there are any tricks to bleeding to avoid an airlock situation, perhaps another member may know this. Series I land rovers had to be lifted up at the front, minis could be absolute horrors whatever one did.
If it is master cylinder gone, and it can happen under heavy breaking then its replace or service, I dont know if they are servicable or not. If so I would kit it as it has gone under heavy breaking not due to corrosion or an oval bore from wearing out.

[necromonger]

thanks guys, that information saved a lot of time and pin pointed the fault straight away, master cyclinder shot.
I bleed the brakes again first to check no air, clamped the hoses and pump the brakes hard but pedal slowly hitting the deck. jacked up the back end spun the wheels and applied the brakes, rear wheels stop but then the brakes release and you can spin the wheels again with the brakes fully on. So yes the master cyclinder at fault fluid going passed the seal, new one on order should have it fitted tomorrow, and fingers crossed will be back up and running, and stopping.