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How to disassemble a master cylinder

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1492300 by mcoomey Thanks, Barry and Randall. Now I've got more info on brake fluid than I would have guessed existed and I'm sold on the DOT 5 Silicone. It's strange about the brake switch, though. I wonder if anyone is looking into that.
I've looked at it a little bit, on my cars. Not sure exactly how, but it seems that somehow, a tiny amount of silicone is working it's way past the diaphragm inside the switch, and fouling the contacts. I've heard that it doesn't happen with some switches; but all of the ones I have tried (including the original switch on my previous TR3A and a replacement for a Ford truck) have failed. The failure is kind of insidious too; seems like it just keeps taking more and more pressure to operate them.

I finally solved the problem by converting to a mechanical switch. On the 3A, I mounted the switch to the pedal box, ala TR4. That car was strictly daily driver, so I didn't worry about what the engine compartment looked like


With my current TR3, I wanted a more stealthy approach (plus I wanted to keep the original adjustment screws on the pedals), so I made up a bracket to fit a switch under the dash. (Obviously still not a show car, but it might be someday.)




Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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KingstonO Avatar
KingstonO Simon Oliver
Vancouver, BC, Canada   CAN
Michael .. I've used Dot 5 silicone fluid in both my lbc's for many years, with excellent results. The pressure brake light switches are another matter however, (sometimes lasting a few months, and once only one day!), so I followed a tip (Randall's, I think), and installed an updated mechanical switch - Moss part #542-371, listed at $14.99. So far, so very good! It was an easy job, involving: re-routing the two wires from the original switch - through the firewall, behind the heater, and through the firewall again; enlarging the hole in the box just a little to accept the new switch, and then fiddling a little to work out the exact placement. I'm very happy with the result .. and just a little less nervous about being rear-ended drinking smiley

Cheers! Simon.


Attachments:
TR3 brake light switch 001.JPG    43.6 KB
TR3 brake light switch 001.JPG

TR3 brake light switch 002.JPG    38.7 KB
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Jacad Avatar
Jacad Gold Member Barry Shefner
Montreal, QC, Canada   CAN
1959 Triumph TR3A "Loose Wheels"
1976 Triumph TR6 "The Tweetster"
Has anyone tried the SW-32 pressure switch? Supposed to be "silicone compatible" http://www.ronfrancis.com/prodinfo.asp?number=SW-32

ATTENTION: THIS updated version of this trusty switch is D.O.T. compliant which includes silicone fluid compatibility and it is capable of 200 -300% more cycles



Barry
59 TR3A 0TS57675LO - "Loose Wheels"
76 TR6 CF54266U - "The Tweetster"
Website: Triumph TR2-TR3-TR4 www.trtriumph.com/ (sorry for not keeping it current for the past couple of years)



Edited 1 time(s). Last edit at 2017-10-17 03:09 PM by Jacad.

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mcoomey Avatar
mcoomey Silver Member Michael Coomey
Paxton, MA, USA   USA
Well, I've already purchased a new pressure switch from Moss, but will be prepared for it to fail. I'm not sure if I'll go with the silicone-compatible or mechanical option though, but thanks for the information and pictures. I'm actually kind of looking forward to its failure so I can try to figure out why!



Michael Coomey
Paxton, MA

'57 TR3

Jacad Avatar
Jacad Gold Member Barry Shefner
Montreal, QC, Canada   CAN
1959 Triumph TR3A "Loose Wheels"
1976 Triumph TR6 "The Tweetster"
Great Michael,

If you can figure out why they fail you can update everyone who has a 1/8 NPT pressure switch As you can see from these threads below this is not a problem unique to TR's ...plenty have gone before you in trying to understand the problem and possible solutions
https://www.minimania.com/msgThread/109490/1/1/Hydraulic_brake_switch
https://www.jalopyjournal.com/forum/threads/whats-the-negative-of-silicone-dot-5-brake-fluid.185724/
https://www.fordbarn.com/forum/showthread.php?t=160945&showall=1
http://www.sw-em.com/hydraulic%20brake%20light%20switches%20notes.htm https://porsche356registry.org/article/159



Barry
59 TR3A 0TS57675LO - "Loose Wheels"
76 TR6 CF54266U - "The Tweetster"
Website: Triumph TR2-TR3-TR4 www.trtriumph.com/ (sorry for not keeping it current for the past couple of years)

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