RobinTR6 Posted July 1, 2014 Report Share Posted July 1, 2014 Now I can drive my reassembled car I have noted that the brakes feel a bit dead and lack bite. I discovered that although the rear brakes were all new, shoes, springs, cylinder, pipework....after some use started leaking. I'm assuming as the car had been sitting round for 10 years that the seals had gone weak. Anyway they have been replaced with new cylinders and shoes etc. SO why are the brakes so weak, you need a real shove on them to get them to slow down and the do stop the car....but I have yet to get them to lock at any speed.....so whats up FYI New master cylinder new servo all new copper pipework stainless flexible hoses all round new discs new pads (just bought them) new shoes new rear wheel cylinders and shoes yes, silicone brake fluid....I couldnt face stripping my new paintwork(again) so.... new (but been on the car for 10 yrs) calipers, no they dont leak All of the above should mean good brakes but .... Quote Link to post Share on other sites
mike3739 Posted July 1, 2014 Report Share Posted July 1, 2014 Hi Robin Sorry to hear your woes Whats the betting Silicone fluid gets the blame?? I have no issues with it for over 8 years now after a full rebuild with complete new braking system. Given past threads on Master Cyclinders that would be my first port of call. I am sure others with far more knowledge will offer other suggestions. Let us all know how you fair! Cheers Mike Quote Link to post Share on other sites
peejay4A Posted July 1, 2014 Report Share Posted July 1, 2014 Linings not bedded in? Quote Link to post Share on other sites
Peter Cobbold Posted July 1, 2014 Report Share Posted July 1, 2014 Peejay +1 Drive it! I bed the linings in with left foot braking at low speed on an empty road ! Get them hot. Once bedded in you should definitely then be able to lock up the fronts with heavy pedal pressure. I can..... even with silicone fluid. Peter Quote Link to post Share on other sites
simonjrwinter Posted July 1, 2014 Report Share Posted July 1, 2014 Are the pistons free in the calipers? After sitting for ten years there could be an issue there unless they've been looked at? Simon Quote Link to post Share on other sites
RobinTR6 Posted July 1, 2014 Author Report Share Posted July 1, 2014 Pistons seemed free, ill double check. How many miles to bed in the pads and shoes ? Quote Link to post Share on other sites
Peter Cobbold Posted July 1, 2014 Report Share Posted July 1, 2014 Pistons seemed free, ill double check. How many miles to bed in the pads and shoes ? Until they feel right. Brake pad materials differ. A handful of hard stops from medium speed should be enough. If its braking straight it unlikely to be sticking hydraulics or oil/grease contamination. The hydraulic lines are connected to the m/cyl correctly? - front to the big chamber. Peter Quote Link to post Share on other sites
peter.goreham Posted July 1, 2014 Report Share Posted July 1, 2014 What type of pads have you fitted? Peter Quote Link to post Share on other sites
Denis Posted July 1, 2014 Report Share Posted July 1, 2014 A few years ago I completely renew my standard brakes, front and rear, changed everything except the metal brake lines...it passes the MOT ok...but you could hardly compare them to brakes on modern cars! So the answer is keep your distance and plan your braking! It's a 45 year old car! Quote Link to post Share on other sites
Alec Pringle Posted July 1, 2014 Report Share Posted July 1, 2014 Bedding in . . . . accelerate to 60, brake firmly down to 10, repeat and again maybe a dozen times in quick succession. That will achieve most of the necessary. The fronts do most of the work, check the calipers, and then that the servo is working . . . . In the 1970s it was not difficult to lock all 4 wheels at 100mph on the track, using road pads and shoes and XAS tyres. By classic standards that was about as good as it got for road useage. Even by modern standards that's a pretty reasonable rate of retardation . . . . Sorry, but I don't buy in to the idea that TR brakes are inadequate compared to modern cars - that's just another way of saying the system isn't functioning at its full efficiency, for whatever reason. SBF should not affect braking performance at road speeds, other than possibly making the speed of reaction a fraction slower - it's only under track conditions that the limitations become apparent. Unless of course the fluid is contaminated with water, in which case the water will drop to the lowest point (as in calipers) and then boil . . . . bingo, no brakes. Cheers Alec Quote Link to post Share on other sites
RobinTR6 Posted July 2, 2014 Author Report Share Posted July 2, 2014 Pads are from a well known specialists and are Borg and Beck branded. I'll check the calipers, but they eased back easy enough when I cahnged the pads. How best to check servo and would this stop the brakes working effectively, thought that if it wasnt doing its job it would just take more pedal effort.? As I've said pipework and fluids etc are all new so cant be any water in there, and no leaks. Quote Link to post Share on other sites
peejay4A Posted July 2, 2014 Report Share Posted July 2, 2014 One check of the servo is thus: With the engine off pump the brakes until the pedal is very firm. Hold the pedal down and start the engine. The pedal should move down perceptibly. If it doesn't, suspect the servo. Quote Link to post Share on other sites
harrytr5 Posted July 2, 2014 Report Share Posted July 2, 2014 My experience with after market servo,s are not good.Borrowed an original one from a mate that we knew worked and harmony was restored.I have just had my original servo rebuilt and hope it is worth it when I put it on my TR. With no servo the pedal is very firm and takes a lot of foot pressure to stop.I have forgotten what it was like as I drove many cars in the 60,s with out servo,s. Regards Harry Quote Link to post Share on other sites
duncan Posted July 2, 2014 Report Share Posted July 2, 2014 I agree with Alec, even towing the unbraked trailer with boat, I tend to watch what is behind me as the 6 will still stop quickly enough to give drivers behind a surprise. They don't expect trailers to stop that quickly, especially with an old car. Quote Link to post Share on other sites
Andy Moltu Posted July 2, 2014 Report Share Posted July 2, 2014 Is your pedal soft? If it is bleed the brakes - preferably when you've warmed them up with some repeated braking to expand the air and help the bubble float to the top of the caliper. - the usual culprit is the n/s front. If the pedal is hard then it may be the servo isn't working or it may be crappy pads. This has been my experience thus far with the greenshite pads or maybe I'm comparing them to the Hawk pads I had before. Quote Link to post Share on other sites
Denis Posted July 2, 2014 Report Share Posted July 2, 2014 So Alec & Duncan, you don't believe brakes have improved on cars in the last 45 years! Quote Link to post Share on other sites
Andy Moltu Posted July 2, 2014 Report Share Posted July 2, 2014 The basics of brakes haven't changed much. if you can lock the wheels then you have brakes that exceed the grip of the tyres. Have brakes got better in the last 45 years? Bigger tyres with more grip have allowed bigger brakes to be used. Multi piston calipers in themselves don't do more than just allow larger pads to be used. They have become more efficient in dissipating heat on repeated braking with vented discs and materials capable of running at higher temperatures. ABS has allowed steering when braking and mechanised cadence braking but they don't make braking more powerful. We've all got used to more powerful servos but that gives the impression of more powerful brakes. The loss of asbestos pads did challenge brake manufacturers to achieve the same level of bite without locking up too easily, at least for a while. Quote Link to post Share on other sites
RobinTR6 Posted July 10, 2014 Author Report Share Posted July 10, 2014 Update, I have discovered to my horror that the rear drums although they bite when pedal is depressed DONT LOCKUP. No air in the pipework and new wheel cylinders and barke shoes. I can see the cylinder moving when pedal depressed more than enough to engage with the drum and the handbrake locks the drums but NOT the pedal. Pedal is firm etc. Could it be that the drums are worn or out of shape ? Quote Link to post Share on other sites
Peter Cobbold Posted July 10, 2014 Report Share Posted July 10, 2014 Its essential the brake cylinder body slides in the back plate to equalise the force on each shoe, especially when using the adjuster. Quote Link to post Share on other sites
RobinTR6 Posted July 10, 2014 Author Report Share Posted July 10, 2014 Peter, thanks, and yes it slides as it should and the adjusted is working so why not locking drum.Could wear on drums be the cause. Quote Link to post Share on other sites
Peter Cobbold Posted July 10, 2014 Report Share Posted July 10, 2014 Can you lock the drum against turning by hand, on the adjuster? Quote Link to post Share on other sites
Alec Pringle Posted July 10, 2014 Report Share Posted July 10, 2014 " So Alec . . . . . . you don't believe brakes have improved on cars in the last 45 years! " Now that's a fairly breathtaking extrapolation, even by the standards of a New Labour politician . . . . As Andy points out, tyres are the defining factor in the equation as discussed. Cheers Alec Quote Link to post Share on other sites
RobinTR6 Posted July 10, 2014 Author Report Share Posted July 10, 2014 I'll check the adjusters, all I need is the likely candidate for why my drums won't lock ? Quote Link to post Share on other sites
John L Posted July 11, 2014 Report Share Posted July 11, 2014 PDA valve perhaps not allowing any pressure to the rear system? John Quote Link to post Share on other sites
RobinTR6 Posted July 11, 2014 Author Report Share Posted July 11, 2014 John, nope no PDA valve its a 68 CP UK car, but thanks anyway. Quote Link to post Share on other sites
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