TR6 Pressure differential warning assembly PDWA valve

[mallard]

All the brake fluid has leaked out of the large reservoir on the back side of the master cylinder. It came out of the top of the brass PDWA switch. I can't see that TRF sells a repair kit but Moss has two styles. It looks like mine has the lip seals so I'll have to convert to the O-ring style kit. Two questions

Can I get the correct lip style seals, and who has them?

Do I need to get a new switch because it leaked out through the top of it, should the switch also have a seal in it? My thinking is that the switch is fine and was never designed to hold back fluid, that's the lip seals, or O-rings job.

 

[TR3driver]

AFAIK the lip type seals have been NLA for a long time. There was a nice article on how to make a replacement shuttle to take common O-rings, but I think the author asked to have it taken down due to potential liability.

The switch doesn't seal. As long as it still works electrically, no need to replace it.

 

[mallard]

Thank you Randall, the switch still works fine. The kit Moss sells includes a new shuttle for the O-rings.

 

[dklawson]

I believe the article Randall mentioned is on the Buckeye Triumph web site. Take a look at the two links below.

https://web.archive.org/web/2003050...yetriumphs.org/technical/Brakes/MCPDWA/MC.htm

https://web.archive.org/web/2003050...yetriumphs.org/technical/Brakes/PDWA/PDWA.htm

If you cannot get the o-rings from a local supplier, you can order them from McMaster-Carr (www.mcmaster.com). Just make sure you order EPDM, not Buna or Viton.

EDIT: I forgot to mention that if you do start having trouble with the PDWA switch, one for a '67-'69 Ford Mustang is the common replacement (Ford # C8AZ-2B264-A). See the related thread linked below.
https://www.britishcarforum.com/bcf...-TR6-pressure-switch-(pdwa)-rebuild-kit/page2

 

[mallard]

Thanks Doug interesting articles, I'll check McMaster