Thanks for the massive compliment! Don't feel demoralised though, everything I am doing though really shouldn't be beyond the reach of a home mechanic with a workshop manual. I am lucky that I have a nice heated workshop attached to the house though!
I'm going to start today with some good newwwws as Jeremy Clarkson would say. Something arrived in the post today that we all thought was lost, can you guess what it is?
Yep, you guessed it its my NOS master cylinder!
Needs a slight clean but that's a huge weight off my mind. Sorry Alun, I wont be buying a club one now! Do you want the old one for reconditioning?
Back to the LSV, all external components have been bead blasted, the only problem is that if I just left the casting as it was it would have just rusted so I have given it a light dust of my favourite silver enamel, I say favourite because the colour is an exact match for the bead blasted finish.
This now needs reassembling with the club seal kit pictured with it. I cant do this until the spring assembly comes back from the other blasters. Or well I hope that's where it is because I cant find it.
Seriously though I think it's in the blasting box, I remember seeing it last week when I was organising boxes.
So I have moved on to the final part of the braking system that needs looking at, this....
This is your standard PDWA (pressure differential warning actuator) valve. You will have one of these if you have a dual circuit braking system. Note that this is not a brake proportioning valve, this is a device that senses a pressure difference between the front and rear lines and then causes the warning light on the dash to be illuminated by the use of a switch if a difference exists.
Opened up it is simply a brass H valve with each leg providing a link to various parts of the braking system. On my car, the master cylinder enters from the top, the rear brakes exit from the left hand leg and the front brakes exit from the right hand hex plug and bottom leg.
A small piston rides in the cross piece and two rubber o rings prevent fluid flowing between the two sides and maintaining the dual circuit nature of the braking system.
The idea is that if the pressure is the same across all outlets then the piston will not move, if the pressure in one outlet drops then the piston will move towards that lower pressure side triggering the switch which then illumines the brake warning light on the dash. So really, this is a part which most people overlook and could one day save your life.
You can get these new, they are used on series Land Rovers that have dual brakes, only problem is that I think they have metric unions, so if you needed a new one you'd need to change your brake hoses. They also cost around £150 whereas a repair kit only costs £15 from Rimmers, they are so simple it makes sense to just refurbish them.
They are simple to get apart, I cleaned mine up first then removed the plastic switch and large hex nut. Then with a fine pick and WD40 I pulled the piston assembly out, this is where I think it's important to check these out. On mine the piston was quite gummed up and really wedged in there and it was only after a good soak with WD40 could I get it out so I wonder if it would actually work if one of the brake lines failed.
I will end this post here to avoid any confusion and pick it up when I have received the repair kit in the post. By then I should have got the rest of the blasting back so I can get the LSV back together as well.
Have a good week everyone!
James
EDIT: I have edited the union locations because I didn't look at my reference photo and diagram properly!