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Lachlan's 1972 Datsun 1200 Sedan


Lachlan

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Today I made a start on the non-functioning brakes. I'm anticipating every important part (master / wheel cylinders, pads, shoes, misc) will need replacing.

 

From previous inspections, I knew the master cylinder had one empty reservoir and a lot of corrosion-like substance on the metal case. The unit is a PBR master cylinder that I've learned many Australian delivered/built 1200s came with, not the more common Tokico / Nabco units that most USA and Japanese models came with.

 

Unfortunately, this means that if I can't get this one to play nice I've got a potential parts sourcing headache.

 

Dual Reservoir (rubber lid removed, both drained)

 

IMG20211025111408%20-%20Copy.jpg?dl=1

 

Master Cylinder

 

IMG20211025112221%20-%20Copy.jpg?dl=1

 

I concluded that the white corrosion-like substance was the evaporated brake fluid that had leaked out of the rear reservoir. Given my inexperience with brakes, I would read later that now would've been a great time to bleed the master cylinder. I've not done this before, thinking this would happen automatically when bleeding the whole system from the wheel cylinders.

 

After cleaning it up as best I could, I refitted the reservoirs and topped them up and moved onto the rear drums.

 

Left Rear Drum

 

IMG20211025131440%20-%20Copy.jpg?dl=1

 

The drum itself took me a long time to separate from the drum brake assembly. I think the rear drums are rubbing a lot as they were the only things holding it on.

 

Under the Drum

 

IMG20211025132048%20-%20Left.jpg?dl=1

 

Looks pretty scungy and rusty. After taking heaps of photos, I was surprised that everything came apart fairly easily.

 

Close shot of Wheel Cylinder

 

IMG20211025145229%20-%20Copy.jpg?dl=1

 

It looked jammed up and rusty, and given it's an affordable off-the-shelf item, I'll be replacing these on both sides. It's another PBR item that I'm hoping will be much more straightforward to replace. Note more white substance towards the centre of the drum assembly.

 

Everything laid out in order

 

IMG20211025150609%20-%20Copy.jpg?dl=1

 

For someone who's always been mystified by the dark magic that is braking systems, this was quite enlightening for me.

 

Brake Line and Bleed Screw

 

IMG20211025153114%20-%20Copy.jpg?dl=1

 

I was ever hopeful that all I had to do was fill the master cylinder reservoir, bleed the brakes at each corner and voilà - instant brakes. No such luck. After seeing the shabby state of the wheel cylinder, I suspected they needed replacing. I put some homebrew penetrating oil on the brake line screw, gave it some percolating time, and ... rusted solid. The flare nut wrench wouldn't get it to budge, rather it was gently rounding the nut. This is a potential problem for future Lachlan.

 

At the end of the day, I tried doing a quick brake bleed to no avail. There's a slim chance that the master cylinder still works and I got air in it. Next time, I'll bleed it properly and have another shot.

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