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Triumph TR6 - Brakes, Master Cylinder and servo's

Happy Thanksgiving to all my domestic neighbors, well I seem to have developed a leak in my braking system in the area of the master cylinder/servo unit. My question is, the leak seems to be at the rear of the master where it enters the servo. There is no evidence of fluid on the interior floor panels or rugs (footwell area) but rather a dripping from the area immediately below the master at the servo. In looking at the TRF catalog(blue page 238)the 2 units are separate my servo is a little beaten up at the bottom edges facing the nose of the beast. Would a leaky seal at the back of my master cause the fluid loss at the face of the servo and does the servo contain fluid or just air pressure. If the master is to blame I assume the proper course is to replace with new not rebuild since I like to stop when I need to. Prior to discovering the leak and even now my brake system has performed quite well with just a slight loss of pedal pressure at a full stop while at idle. Just trying to figure out how deep into the brake system and my wallet this repair will go.
Best Regards and thanks in advance,
Keith
1972 TR6
K.B.Dixon

If your master cyl is original (and yes, that is where it leaks), try 'Apple Hydraulics' Price is fare, exchange for a resleeved and rebuilt master. A quick changeout too. Peter G
PS I may be new to Triumph - have learned a lot tearing mine down - impressed w/ the construction - but no stranger to Brit cars. Are you aware of 'Hemmings Motor News', has all kinds of resources, available at any decent bookstore.
Peter G

Keith
It sounds like you may be in need of a rebuilt of the master. It may only be that u need to replace the rubber components. Only a disassemble will tell that. The inside walls obviously must be as smooth as the proverbial babies u know what. The inside bore is "stepped" so look way in at the back brake piston area. If it is scored or pitted then do the rebuild as Peter said. Make sure they use the better quality rebuild kit...there are 2 qualities available.
Rick C
Rick Crawford

KB--I'm surprised your PDWA didn't trip as mine did. I just fixed the exact problem with my MC. If you are lucky (I wasn't), the condition of the bore around the primary piston seal will be OK after a mild honing. I had another used MC in the pile that I honed up OK. Not a bad job to do, the hardest part being getting the thimble off the secondary piston. Use Reidel's instructions from the Buckeye site (and a generous application of that red rubber grease). Also, bench bleed the MC and you won't have to bleed through the wheel cylinders. Time for DOT5?

I believe the leaking fluid will also get sucked into the servo via the vent that's behind the MC.

Rick O.
Rick Orthen

Thanks for the comments, Peter I checked out Apple they were a little pricey but their work is good. Rick C, I think I will go with new as the one I am looking at seems to be original and needs attention any way (reservoir etc.) Rick O it already had dot 5 lucky in that respect so I will stay with it and I think it was Bill who talked about bench bleeding in a previous thread so I will do the same.
Regards,
Keith
K.B.Dixon

Rick O., you mentioned that your pdwa had tripped what are the symptoms of this in case it has happened and I am unaware. The only thing amiss with my pdwa is the electrical connection on the top has popped off and will not refitt. I assume this is just a warning light on the dash that is now inop. As I mentioned my brakes are working fine I just check the brake fluid and top up if necessary before I roll.
Thanks For the Help,
Keith
K.B.Dixon

Keith
The pdVa does pretty much what it says. The symptoms ( cause for it to activate)are a difference in the pressure either side of the valve. In other words, if you loose brake fluid to either the front or back brake systems the valve will slide inside the brass piece and push up a pin "making" a circuit which turns your warning light ON at the dash. Also what happens is that as this brass valve slides towards the low pressure side ( the failed side) it shuts that side off and all pressure goes to the other brake system. Actually, a very important piece in the brake system.
Normally ( this has been mentioned in other threads) when doing a brake bleed you have to make sure the pdva is centered. Keith you should check to see that it is centered but probably still is since it does not sound like you had a major leak/loss of pressure.
Rick C
Rick Crawford

Keith--My PDWA "tripped" (went off-center) because the seal area around the MC primary piston was pitted enough to force brake fluid past the piston into the servo area. As Rick C. explained, the PDWA serves a vital function and you must make sure it's operational. BTW--if your 'BRAKE' lamp circuit is inop, your 'OIL' lamp in the tach won't work either. These warning systems are wired together. Until you get that arrangement fixed, keep a close eye on your oil pressure gauge.

Rick O.
Rick Orthen

That should have been "IGN" lamp, not "OIL" in the previous post. So watch your ammeter/voltmeter instead.

Rick O.
Rick Orthen

Rick O, Thanks the ign. lamp is inop at this time I will attempt to refit the plug during my master install the pdwa seems to be fine at this time.
Thanks, Keith
K.B.Dixon

Rick O
You where right the first time. It is the oil light and brake light that are wired together. But as u said there is still the oil pressure gauge.
Keith if the plastic top piece is the part broken, I recall my son changing the exact same part in his brake system of a GMC S10 early 90s. It was identical to mine in the 6.
Rick C
Rick Crawford

Rick C. my oil light works fine maybe I am mis wired in this area but thanks for the tip on the s10 I will check that out too.
Regards, Keith
K.B.Dixon

Keith
It is true they are wired together. It is when the bulb (only)of the brake failure system is bad, missing, or not connected that you will not get oil pressure warning light. The PDWA light will work regardless of the oil pressure light/switch in or out of circuit. I will be talking to my son this weekend and will post back the exact year.
Rick C
Rick Crawford

Keith
If this was a baseball game, I would be out. It was a Ford, F150, 1985...Ok I was only off a little bit:) I can not keep up with the vehicles he owns anyway. I was out in the garage and actually have the piece in hand ( the thread part had snapped off). It is identical. VB shows it available. Probably from their LMC division. Or there is always the scrap yard. Maybe it was used in later trucks also. Anyway, hope this helps.
Rick C
Rick Crawford

Rick, Thanks I will check that out this week.
Regards, keith
K.B.Dixon

This thread was discussed between 20/11/2002 and 24/11/2002

Triumph TR6 index

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