Tandem brake mastercylinder directions....

[shaunroche]

Having fitted a tandem master cylinder from a single, I cannot find which port goes to the front brakes and which to the rear, via the bulkhead valve....any one have any diagrams or pictures please?

From all the pics I've seen, I just can't quite see which goes to where....there's always something in the way........

[Flyfisherman]

Shaun

There are five exit points from the brake balance valve two top exits / two bottom exits and a side exit and according to the parts manual June 76. The side exit should be on the driver side or off side of the car and feeds the off side front brake, then working in a clockwise direction the top two exits are feed from the master brake cylinder, bottom right exit feeds the rear of the car annd the bottom left feeds the near side front.

Second post down from Martin shows layout.
viewtopic.php?f=4&t=27210

Hope this helps

paul

[Carledo]

Right, the front circuit of the master (big metric union) goes to the inboard top fitting on the PDWA and the rear circuit of the master (standard metric union) goes to the outboard top fitting on the PDWA.
From the PDWA the outboard lower fitting goes to the rear brakes, the inboard lower fitting goes to the o/s/f wheel and the central inboard fitting goes to the n/s/f wheel. That do you?

Steve

EDIT!, I have the same issue parts manual as Paul and it's WRONG! This has been discussed in other treads on here before!

The reason the pic is wrong is because, in 1976, tandem brakes were only fitted to selected export market cars and, because they were LHD, the fittings are reversed!

Checkout the pics in James467s resto thread, most of the pipe runs can be deduced from that!

[PaulB]

Hi Shaun,
You are welcome to come over and inspect EFR if that is any help.

Regards, Paul.

[shaunroche]

Cheers PaulB, but I think I've bottomed out the directions and had a good chat with Paul (flyfisherman) re which port goes where on the valve, but haven't quite sorted which port on the master cylinder goes to what port on the brake valve.....it seems pretty obvious on the diagram, but agree it is back to front: if it was plumbed with the big central nut on the left (nearside) I think this would almost clash with the clutch master cylinder.

As the right hand side of the valve goes to the front brakes, I intend for the front port of the master cylinder to go to the front (right) portion of the valve, and likewise, the rear port to the remaining left hand smaller port on the left (nearside)......does this make sense?

[Carledo]

As the right hand side of the valve goes to the front brakes, I intend for the front port of the master cylinder to go to the front (right) portion of the valve, and likewise, the rear port to the remaining left hand smaller port on the left (nearside)......does this make sense?

Thats what I said!

Steve

PS, Do you have the oddball unions for the 3 front circuit ports on the PDWA? If so where did you get them? my factors couldn't match them at all!

[Flyfisherman]

Shaun

Great to talk to you and thanks for your comment - this my be of use to you last two pictures

viewtopic.php?f=19&t=17826&start=165#p253172

Looks like the brake pipe nearest to the servo feed the connection for the rear brakes and the brake pipe furthest away from the servo feed the front brakes

Paul

[shaunroche]

As the right hand side of the valve goes to the front brakes, I intend for the front port of the master cylinder to go to the front (right) portion of the valve, and likewise, the rear port to the remaining left hand smaller port on the left (nearside)......does this make sense?

Thats what I said!

Steve

PS, Do you have the oddball unions for the 3 front circuit ports on the PDWA? If so where did you get them? my factors couldn't match them at all!

Yep....but I'm not very bright so I have to work it out for myself sometimes!

No unions as yet....I'm waiting to see what my mate has in his tool box when he comes round to plumb everything up on Monday. ..

[Flyfisherman]

As discussed with Shaun yesterday this balance valve could be fitted either way - but the brake pipes must be fitted / routed in the correct manner and as shaun stated in a previous thread note the pipe feed the nearside brake could foul the clutch master cylinder - see attached picture.

Front brake pipes + reservoir pipe to be fitted in the red circled area.



and in reverse




Is it the case that at the time of fitting this assembly on the production line as per the drawing the guy's found that the balance valve fouled the clutch master cylinder and rotated the valve through 180* but forgot to inform the drawing office to ammend the drawing - we have all probably done this - especially me (as I work in engineering) not working to a procedure because we find a better way of doing things than what the procedure of specification states.
Paul

[Carledo]

All the RHD drive tandem braked cars I have seen (quite a few over the years) have the valve fitted with the mounting hole at the bottom and the 3 ports for the front brakes on the inboard side. I'm sticking to my guns, the drawing is that way round in the parts list because it is meant for LHD applications.

Steve

[PaulB]

The PDWA is mounted as in the second picture, with the mounting bolt at the bottom, the large threaded nut on the right.

The top left connection goes to the first section of the tandem master cylinder, closest to the servo. The one below this goes to the rear brakes.

The top right goes to the second part of the master cylinder. The one below goes to the offside front brake caliper. The large threaded silver nut connection goes to the front nearside brake caliper.

Clear as mud?

[James467]

Shaun, while you have it off the car strip it and replace the seals.

viewtopic.php?f=19&t=27969&start=255

Nice to see my pictures are of use!!

[Flyfisherman]

Hi Shaun,
You are welcome to come over and inspect EFR if that is any help
Regards, Paul.

Clear as mud?

Probably - when you one to reference against Shaun doesn't have that luxury.

Paul

[Carledo]

Ive just been looking again at the parts list drawing again and it clearly states RHS, so its not for LHD!
However it shows the PDWA with the front brake ports (3) on the left and the mounting hole at the bottom - which is physically impossible!

My conclusion is the drawing is just plain WRONG!

Steve

[shaunroche]

For whatever reason, the drg is wrong, but it's all a bit acedemic now as the job's almost done....



Cheers James, Paul (s) et al....after taking it apart and cleaning it, the O Rings etc. looked to be in decent condition so I just cleaned it and put it back together thanks.

Having converted this car from a single line to a double with the tandem master cylinder coming from the club, we were very surprised to learn that the master cylinder has metric ports.....that caused a bit of chew I can tell you! What's all that about then? There's not much else on the car that's metric....

Anyhoo, thank you one and all for your input and lively debate!