Hi, I'm Matt, from IntroCar, we are going to start doing some video blogs, showing you some of the parts we do, hopefully answering some questions, maybe giving some technical advice, I am definitely not an expert(!) but I know a little bit and we can certainly find out things, so, if you have any questions then please feel free to comment.
We will talk a little bit about brake pumps. For Silver Shadows, Spirits and Turbos, the whole hydraulic system is run from two brake pumps. Obviously Shadows are run on RR363 brake fluid and anything 1980 onward is on LHM+ mineral, you have to be very careful not to mix the two because you can cause a lot of damage to all the rubber components.
So, I've got some parts here to look at, this is a brake pump, this is from a late Shadow with a big top, the earlier ones have a smaller top. To try to give an explanation of how they work, the camshaft on the engine, which is the shaft that gets turned by the crankshaft, usually pushes the valve lifters up and opens the valve... it has an extra lobe at each end which pushes another little tappet, which pushes this push rod, this push rod comes up through the middle of the engine, through the tappet cover, which is where the brake pump is screwed onto. And as the camshaft pushes this, this internally pushes the plunger, and as the plunger goes up it pushes fluid out the top, as the plunger comes down it draws in fluid through these holes and builds up a pressure. The pressure is regulated to 2500 PSI but there is nothing that would stop that. It could go a lot higher.
Inside the pump this is the plunger, this is, if you look underneath here this is the end of that, this is the plunger and barrel; these are match ground to a very, very fine tolerance, a couple of microns. When they wear obviously you are going to lose efficiency in the pump, they could also seize if you've got moisture in the brake fluid, and it rusts up a lot, quite normal if you've got old pumps they can seize. This is obviously pushed up by the push rod, and there is a spring inside it that pushes it back down, that spring can break, if that spring is broken off, you will see this just up inside the pump, you can undo the circlip, take the plunger out and replace the spring.
If you've got a leak from the pump it could be that these O-rings here have got old and failed, you will have to undo the top pipe, undo the ciprclip here which holds down these shrouds, the shrouds sit down over the pump and the feed pipe from the reservoir goes in this side of the shroud, this obviously sits around there, it fill up here with fluid....... and as the pump comes down it draws in the fluid from around the shroud. Two different types of shrouds, early and late shadow, The early shadows have a flair fitting on the feed pipe that....... I think they proved to leak so they modified it......it's got like a shoulder in there which takes an O-ring on the pipe, on the feed pipe, they both do the same thing.
This is a little shim that you use to set the height of the pumps on the tappet cover, the tappet covers haven't got a gasket because obviously that would affect the height of the pump depending on how much you tighten down the gasket. So, they usually put a piece of cotton, but now you just use well seal or gasket paste or something like that. But to set up - If you have noisy brake pump it could be that the height is incorrect and there is a gap between the push rod and the pump causing it not to knock.
The other thing is the push rods can break. This is a wasted push rod you can see it narrows down here, it gives it a place to break, the earlier ones were straight, but I think you can get wasted ones even for the earlier cars; you have to check the length.
This is the spanner that you use to take off the pump, so, that sits over the pump there, locks into the castellations at the bottom, don't try to use anything else to undo it because you will probably just damage the pump and they can be very tight.
There are two different types of pumps, different size tops, the early ones had a smaller top. This is the late old shadow one with the big top, then they go over to mineral oil, then they go back to a smaller top, not the same just a third size.
One on the front of the engine, one at the back, the front pump feeds number one system I believe, and the rear pump feeds number two system.
The hydraulic system is very complicated, there is a lot to discuss in it, maybe we go further down the system in the next video? If you have any suggestions or questions please comment.. apart from that see you next time!
Check the RR - Technical Video Library for more.]]>