The brake light being on has been a nuisance ever sine I bought my 77".  I Replaced the master cylinder and relay under the front seat last spring and the light went away They were both bad.  After getting the car back from welding this summer, there it was again.  So now I'm going to go through the rest of the system.  Pads, shoes, wheel cylinders(leaking) done. I just replaced the brake booster and found this thread.  I've already disassembled and cleaned the Brake Proportioning Valve as per Chas's great photos.  Now I'm working on the Brake Switch Valve.

 

The question I have is how to remove the shuttle? The switch itself is out but the shuttle does not move. Is it supposed to slide out by itself or is it attached to the end in some way?

I've tried tapping the housing on the workbench hoping it would slip out with no luck.  There is probably a better way and as usual I have to go the long way around to figure it out.  Better to ask before I go Neanderthal on a part that is hard to get.

Can you plug some of the ports and blow it down onto the bench? You could probably even connect the end circuit back to it and push it out with fluid. Messy, but it would probably work. Are you sure there is nothing holding it in the middle where the electrical plug goes?

 

I googled "Datsun brake switch valve" looked at images. They may help but I am not sure which one you have...

If you have everything out of the ports I would say corrosion is holding it in...

This is the piece I am referring to.  You are probably right about corrosion. Seems like I could just probably hook and pull it out.  According to this drawing it is more like a fitting. I was thinking that it was attached to the shuttle on the end. 

 

After removing the big plug nut on the end, the part you circled is a snug fit and should fall out with a couple of firm taps on a block of wood.

 

Mine wasn't being very friendly and I used a little heat (hot air gun) on the aluminium to help it. Don't heat it too much, just enough so you can still hold it with your hands. The aluminium expands enough at that temperature to help it come free.

 

It will be full of gunk and sludge and that will be holding the sliding piston so it won't come out easily. Leaving it soak in some brake cleaner over night would also help loosen it up.

 

I used a piece of rubber sheet to clamped it in a bench vice and block to (rear brake) two ports and brake switch port. The switch port needed an extra layer of rubber because there is a little height difference. It came out with a little air pressure on the front two ports.

 

Since you have been experiencing problems with the brake witch, you might not get it out so easily. My next step, if the air didn't work, was going to be a zerk fittng and the grease gun to push it out.

 

Here are some extra phots. Hope that helps you.

 

As an FYI to anyone reading this thread, Motorsport Auto now offers a rebuild kit for the S30's brake proportioning valve...

 

sorry - double-post

Edited December 19, 20159 yr by Namerow

Zerk fitting and grease is a good idea

Thanks Folks, the heat worked.

How does the bore look inside? Mine was corroded with light pitting. I cleaned it with a homemade hone. Made it from bic pen with a slot in one end so I could slide a piece 400 grit paper in it and wrap it around the pen.

These switch doesn't need to be perfect like the other cylinders in the brake system. The piston does't move very much, if any at all during normal service. The o-rings will settle and seal it mild pitting.

The bore doesn't look too bad. It was gunky and dirty but I really can't see any pitting.  I'm just going to clean and maybe lightly run a Dremel with a wire brush in it.  I did wire brush the outside already.  That aluminum shines up bright!

 IMO, a ScotchBrite pad is easier on the bore and cleans very well.

I know you can get scotch brite tips for a dremel and that would work well. Probably should ask for one for Chrissy. I ended up using a cordless drill and a small container with kerosine and not forgetting my hi-tech bic pen hone.

 

I tried scotch bright, but didn't have much sucess. The diameter is so small and it kept getting cought up on the ports. 

The emery paper wears down very quick because its such a small circumferance. Within a minute it felt like 1200 grit. 

 

Its been almost two years now and I had the switch out in September just to check. The cavity was still dry (cotton bud test) so the o-rings are holding up nicely.

 

The method used to restore aside, its good to see you dismantle, clean it and refresh the o-rings. After all it is a safety device with its sole purpose to warn you of inbalances within the brake system.