Brake switch assembly on 76 midget

[Tipsy]

Well it's finally getting nicer here in Central Illinois so I'm getting out my '76 Midget. I have a brake fluid leak at the switch assembly(Moss #141-710)where the switch(Moss #181-955)is threaded into the body of it. I tried snugging up the switch but it seems to still be leaking. Does anyone have any experience with this? If I remove the switch is there a gasket? Or can I just remove the switch and wrap some teflon tape around the threads? The switch is nylon and the assembly body is brass.
I'm also wondering if brakes need to be bled? Is this loose fitting letting air into the lines or not?
Thanks everybody! Happy Spring!
Jeff

 

[Billm]

You have leakage in that assembly- there should be no fluid in the area of the nylon switch.
You need to get the rebuild kit (it is just two o-rings) from Moss and rebuild it.
BillM

 

[RichBall]

That valve has a shuttle inside that travels forward or back depending on which circuit has lost pressure. Travel is away from the side with pressure. This movement triggers the switch and illuminates the warning light.

The shuttle has O-rings on it to keep brake fluid out of the switch. Your O-rings could be worn out and leaking in which case you'll need to replace them. I got my rebuild kit from Peter at World Wide Auto Parts https://www.nosimport.com/

 

[Tipsy]

Thanks BillM. I thought the switch was a pressure type of switch that would be measuring the pressure of the brake fluid through the assebly block, looking for a pressure failure to signal with the switch. But if it's a repair with o-rings to the assembly I will do that. And of course if I have to rebuild that then I'm going to have to bleed the system, right?
Thanks!

 

[Tipsy]

Thanks to you too Rich!

 

[Billm]

Yes- you will have to rebleed and you will have a huge mess of fluid! Before you break the fittings loose open the cap to the master res, put a cheap plastic bag over the opening and then put the cap back on tight. This will minimize the fluid leakage but it will still be a mess!
Bill

 

[Tipsy]

OK!
Thanks again everyone!

 

[Tipsy]

So now I've rebuilt the switch assembly and am trying to bleed the system. I put on speedbleeders so I can do it myself. But I'm now discovering no fluid is being pushed out the back half of the master. Is this due to air being allowed into the master? (Moss has a video about bench bleeding the master because you can never get air out of the master) Or did I just not realize that the rear brakes were never working in the first place?
Thanks!

 

[Billm]

I have found that the fluid doesn't like to drop from the reservoir into the cylinder so I wiggle the peddle a bunch (VERY small movements, maybe 1/2" at the peddle) and watch the bubbles rise in the reservoir for a while. THEN I try to bleed it.
BillM

 

[JPSmit]

Did you clean the master while it was apart? I was amazed how much crud there was in it

 

[Tipsy]

Did not have master apart. I've ordered the rebuild kit and will attempt that this weekend. There is no fluid coming from the back half of of the master at all. So either the master is clogged or that part of the piston inside the master is not working. I do get good pressure from the front section of the master.