75 series brake problems...

[Buggerific]

Howdy...

Just replaced all the pads on my 75 and now I seem to have no pedal pressure... The car stops and everything but when you apply pressure to the pedal it goes to the floor. if you pump it up a few times and hold it, the pedal still slowly goes to the floor.

I don't seem to be losing fluid. Question is, is it possible i somehow got air in the line or is my booster screwed?

[joel HJ60]

Did you undo any lines to change the pads?

Give the brakes a bleed, see if it goes away.

There is a test to see if the booster is working ok, has to do with pumping the pedal a few times then starting the engine and seeing if the pedal goes down. I'll have a think.

[howesy]

Sounds like a master cylinder problem if it slowly sinks.
With the worn pads the cylinder piston may have been sealing on a slightly different part of the unit or maybe by pushing the old fluid back up the line when you compressed the pistons at the pads it pushed some s*@t up there.
Either way what you describe generally means that it is not holding pressure and you should try a good bleed right through and if that fails seek an opinion from an expert and expect to replace it.

[Buggerific]

Yeah prett much the pedal does sink slowly... and yes... if i pump it while its off there is pressure there then i turn it on and the pedal goes down slowly all the way to the floor...

That's what makes me think its the booster or master cylender or whatever. And i guess that makes sens about either pushing some crap back up the line or sealing in a different position. First step will be bleeding ths system and then yes, seeking expert advice. I kind of already am expecting to replace it :(

Any ideas on cost of replacememnet?

[Bezman]

Seen this a couple times over the years just after replacing pads and it was either the load valve in the rear or a T valve or piece some where in the line, Changing pressure in the system while replacing pads seems to stuff it. Sorry cant be more descriptive as one the other boys did the work. They just sent it down to the brake specialist and they solved it I think by bypassing that T piece I think. Maybe worhtwhile taking it to a brake specialist before replacing master cylinder booster etc.

[smiggs50]

yeah mate i also had the same problems, try first by bleeding from the point farthest from the master cylinder and workning back, also make sure you bleed the proportioning valve which if you follow the lines from the rear wheels you wil find it, i would have done wheel cylinders when changing pads as they are only 20 to 30 bucks each, also the master cyl is only 110 bucks, to eliminate if the prob is the back brakes you can crimp off the flexible line with vice grips and a rag, this should make the pedal hard, cya mate

[Buggerific]

yeah im undecided... the brakes kinda seem ok, car stops with no probs but the pedal still doesnt have as much pressure as i would have hoped for

[hulsty]

Sounds like a master cylinder problem if it slowly sinks.
With the worn pads the cylinder piston may have been sealing on a slightly different part of the unit or maybe by pushing the old fluid back up the line when you compressed the pistons at the pads it pushed some s*@t up there.
Either way what you describe generally means that it is not holding pressure and you should try a good bleed right through and if that fails seek an opinion from an expert and expect to replace it.

Spot on, the master cylinder is my tip. When you bleed the brakes you push the cylinder and pedal outside its normal operating range. When you do that the piston moves to an area in the bore that never normally gets wiped over, this area is normally dirty and crusty and this shit damages the deals on the piston. Which slowly leaks pressure back.

[Buggerific]

Well that kinda sucks huh...

I'll look into it, first i think i need a new clutch, ha ha