New Zealand Datsun Club

Yeah!!

Electrics are all sorted and I'm happy with the work just not happy about the cost.. but don't want to get into that at the moment. So was driving it home from work yesterday and about halfway home the brakes start locking up again great!!!! I pulled over for a bit this time so I didn't cook the brakes again but didn't wait long enough as they just got worse! I wasn't far from my house and I pulled over again but this time I couldn't get the car to move at all! The tyres were smoking up abit as well but the car just wouldn't move! I called my girlfriend who was at my place to come down and wait with the car while I ran down to get some tools, had to bleed pressure out of the m/c so it could move the damn thing which worked so I was able to drive it the rest of the way home. I'm so frustrated and angry as to why this has happened again this is not what I want just before cert! I'm going to be spending quite a bit time this weekend working on it if anyone feels like helping I'd greatly appreciate it!

Change master cylinder out dude - you got a listing at work?

wasnt it re -conned? does it have a pcb valve thing, if so is it possible its in back to front? have you tried dis connecting the booster, like brock suggested, if they work fine without it then thats the problem if it still does it after disconnection then master cylinder be the fault ,could be an easy way to narrow things down.

If its doing it when it heats up it could be slave cylinders if you haven't already been there?

Greg was saying when he released the pressure at the master Cyl the brakes came free, so sounds like an issue at that end. May be Booster, push rod or Master cyl.

classicdat wrote:Greg was saying when he released the pressure at the master Cyl the brakes came free, so sounds like an issue at that end. May be Booster, push rod or Master cyl.

Are but don't they have a cheek valve in the master to stop all the fluid going back so it doesn't take a lot of pressure in the line to make sticky slave cylinders stick?

I think we got it sorted yesterday but the residual check valves is a good point, did 720s have front discs?

It's a 260c master Bart and I removed the rpv from the rear resoivor as they drums as stock. Pretty sure they run disc on the front as 180bs and 120ys of that era did. I've got one last thing to check today which is pump the pedal heaps with car running then go for another decent drive as that's what Bart did yesterday to get them to lock up again. So we've machined down the push rod quite short now so that there is no effort required to fit master to the booster as even when I changed it to the shorter rod there was still a bit of a gap that needed a small amount of force to close

So it would seem to me that pressure is building in the system and since I'm only driving short distances at this stage it doesn't lock up until I drive again after sitting for a while (within that same day) at the chamberlains when the wheel alignment was getting done they put a tool on the brake pedal to lock up the brakes on the hoist so me driving it home after that meant pressure had already been built up and the short period between chamberlains and home made the brakes lock up as I used them.... make any sense??? So HOPEFULLY! With this shorter push rod I should be sweeet...

Also after it locked up we jacked the rear end up and could only just turn the wheels, jacked the front and both sides were jammed on faaaaarking tight and only released when djz unbolted the master from the booster. Jeez I'm going to be brake expert by the end of this. After chatting to Shane from Safe R Brakes on Friday about my situation he bloody offered me a job hahaha