G'day guys,

Doing a brake master cylinder upgrade for a 1600 and had a couple of questions.

The original brake master cylinder had no booster and a single line going straight to a junction box. So I thought I'd upgrade to a 180b combo (pretty common upgrade).

So the new one is a 180b booster, complete with spacer plate and twin brake line (thanks beeb_86!). Before we go breaking things, had a couple of queries...

Firstly - It's a 4-way junction box. I'm guessing I need to blank one port off so it's just used as a 3-way for the front brakes, and the rear line gets plumbed straight up to the port on the master cylinder?

Secondly - There are four tapped holes in the fire wall used for mounting the old cylinder. But the new one comes with four fixed studs. Do I need to file away the thread in the four firewall holes to fit the studs through?

Thirdly - The cylinder looks like it comes pretty close to the strut tower. Is it likely to clash? Do I need to knock the side of the tower back a bit?

Any help would be great!

Thanks -Tom

1. You will need to use the 180B 4 way block. Plumb to fronts up to it and the rears up to it. The block has a proportiong valve in it for the rear brakes. So make sure you plumb it up right.

2. The original master bolts on to a plate. The plate bolts on the the firewall. Remove the plate and the 180B master will blot stright on. You need the get to the back of the fire wall to do the nuts up. Use the alloy spacer that came from the 180B

3. No need to knock the tower or wheel well around. It will fit in with no hammer mods.

You will also need to hook up a vacume from the inlet manifold to the booster. Depending on what engine you are running there will be a port on the manifold. You will then need to source a 1 way vac booster valve. This is a MUST! Otherwise no brakes for you. Make sure you use fuel hose of the coreect diameter. If you use water hose it will most probably fail over time and then no brakes for you.

It's any easy conversion. Just make sure you get the plumbing right. I't is highly likley you will need to make up a few new brake line to get the pluming right.

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1928 Model A CC Pickup

Thanks mydato.

With the original system (see attached) there was one line going from the master cylinder to the junction box (presumably containing a proportioning valve). This had three outlets, two going to the front brakes, another heading to the rear.
The new master cylinder I have now has two outlets. so I'm guessing you need to run BOTH lines into a new 180b junction box (which I haven't got yet)?

-ta

Whilst I agree with all MYDATO has posted, the one area I differ in is using the 180B valve.
Its a sh*t of a thing, more difficult to plumb in & generally they are seized up or full of gunk.
Connect it up like you described & if you later have bias problems fit a wilwood bias valve.

We have done many conversions, blocking of the original T with no problems what so ever.

_________________
A little knowledge is a dangerous thing.
www.datsport.com

"R.I.P. Baz. 29 April 2022. Thank you for all your contributions to the Datsun community over the years. You will be missed." - OZDAT

Good point Baz. The datto God has spoken : )

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1928 Model A CC Pickup

Thanks for the advise guys, much appreciated. I'll try the original plan then - blanking off one of the ports in the stock 1600 proportioning valve. Any problems and I'll look at the sticking a bias valve from datsport.

Baz - you guys sell blanking plugs? btw, bought a master/slave clutch cylinder combo from datsport couple a weeks back. thanks - worked a treat!

Further to the "threaded holes" in the firewall that I mentioned... I'm guessing that's incorrect. Made the assumption they were screwed through the firewall, but instead I think the previous owner has just locktite'd the four bolts from the inside... They're basically just four bolts pushed through from the inside above the brake pedal (absolute prick to get to from inside the cabin!) Will investigate next weekend.

-Tom

Is it possible to go from the two 180b master outlets into a T, and then the single outlet of the T straight into the 1600 juction box?

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Sam-U-El/Racer135
1973 B110 - http://ozdat.com/forum/viewtopic.php?f=60&t=21539
1972 B110
1978 120Y sdn
1973 B120 - dead
1971 VB110 4dr - sold
Others:
1995 Proton Wira - daily sh#tbox

yes it is possible. but defeats the purpose of the tandem MC.
You would also need disc rears to make this work.
Why do this ? It is just as easy the correct way.

_________________
A little knowledge is a dangerous thing.
www.datsport.com

"R.I.P. Baz. 29 April 2022. Thank you for all your contributions to the Datsun community over the years. You will be missed." - OZDAT

Just wondered if it was possible to do it.

How does it defeat the purpose of the tandem? I have no idea of exactly how the twin master works, but with some assumption, say you hooked front outlet to front brakes, rear outlet to rear, the front of the master sh*ts itself, then you have no brakes in the front, and the rears do f*ck all anyway (and acts unsafely like a handbrake), whereas if you hook both sides of the master up to the one inlet of the 1600 1-into-4 distributor, if one side of the master sh8ts itself then all the brakes come on evenly. Plus having both joined together they share the load so the front side of the master doesn't have to do so much work.

_________________
Sam-U-El/Racer135
1973 B110 - http://ozdat.com/forum/viewtopic.php?f=60&t=21539
1972 B110
1978 120Y sdn
1973 B120 - dead
1971 VB110 4dr - sold
Others:
1995 Proton Wira - daily sh#tbox

I've got one of these for my 180B SSS project, still in a box in the shed and will be a while before I plumb it up, but I'm hoping it will look neat as well as doing the job.

http://www.jegs.com/i/Wilwood/950/260-11179/10002/-1

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

Your method will work but, you have assumed that the master cylinder is the part that will fail. Plumbing the system your way will provide full braking if a outlet happens to fail. The system is essentially a single circuit. However if a hose failed or a break line got damaged then you will have no brakes at all . This is the very reason for a dual circuit system. The dual circuit system provides some form of safety net in case sh*t goes wrong. It would not matter where the fault was in a dual circuit system the other would still work and provide some form of braking.

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1928 Model A CC Pickup