ferny
Club Retro Rides Member
Posts: 983
Club RR Member Number: 13
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Braking strangeness ferny
@ferny
Club Retro Rides Member 13
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Triumph Herald single circuit system. MX5 turbo engine. Off-the-shelf generic servo.
Before Christmas I was taking a spirited drive through an area with lots of american traffic circles and found myself with very soft brakes. Normally they're nice and firm.
I've been away climbing Kilimanjaro (yes, I'm blowing my own trumpet) and decided to look at them today. All was fine and firm. Until I came into a roundabout and they were soft again.
Any ideas? I originally used the Mazda non-return valve and it didn't work - can't remember why - so it currently doesn't have one fitted. I've tested with the vacuum hose removed and it feels the same. The brakes have been fine since the servo was fitted 6 months (?) ago.
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Is it possible to pump the pedal up and get it firm again? Ooerrr!
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have you not just boiled the fluid?
get some ate200 and bleed the whole lot...
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sonus
Europe
Posts: 1,386
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Common problem on TVRs that use Herald uprights. Scary until you know to double pump the brakes before panicking 😅
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Current 1968 TVR VIXEN S1 V8 Prototype 2004 TVR T350C 2017 BMW 340i
Previous BMW 325d E91LCI - sold Alfa Romeo GTV - sold Citroen AX GT - at the breakers Ford Puma 1.7 - sold Volvo V50 2.0d - sold MGB GT - wrecked by fire MG ZT 1.8T - sold VW E-golf Electric - sold Mini Countryman 1.6D -sold Land Rover Discovery TD5 - sold
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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Braking strangeness Phil H
@philhoward
Club Retro Rides Member 133
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Common problem on TVRs that use Herald uprights. Scary until you know to double pump the brakes before panicking 😅 Hence why I mentioned it - have experienced it on cars with the “big” Triumph versions too 😂
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even without knowing the intricacies of the hubs I'd suggest pad knock back too!
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Check wheel bearings first. Given Triumph's weird budget arrangement at the back you should check those too.
Nick
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1967 Triumph Vitesse convertible (old friend) 1996 Audi A6 2.5 TDI Avant (still durability testing) 1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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ferny
Club Retro Rides Member
Posts: 983
Club RR Member Number: 13
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Braking strangeness ferny
@ferny
Club Retro Rides Member 13
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Deffo not pad knock. I've had it in the past and pressing the pedal doesn't return the brakes. The only thing which fixed them was leaving the car stationary. For the same reason it can't be air or boiled fluid. Rear brakes should be fine as I replaced the adjusters the other week and again the brakes felt perfect after left standing.
Thinking about it, I suspect master cylinder seals. I'll report back when I have time to strip it all down.
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ferny
Club Retro Rides Member
Posts: 983
Club RR Member Number: 13
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Braking strangeness ferny
@ferny
Club Retro Rides Member 13
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Jan 10, 2020 18:00:50 GMT
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Quick update for future searches.
Just replaced the brake master cylinder and the brakes are now firm and how they should be. I haven't stripped the original master cylinder for damages reports, but it appears to have fixed it.... so far.
Nice 30 min fix. 🙂
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