| Author | Message | ||
     davide frada Yet to post message Username: davidef Post Number: 1 Registered: 11-2008 |
hi chaps, i've recently purchased a 1970 shadow relatively cheaply on account of a total lack of brakes. in addition to the obviously weepy rear calipers (and broken bleeder screws), in filling and pressurising the system, i found a few other leaks, namely the top of the right level valve, the unassisted master cylinder, and a couple of weeping hoses. i also found the rear brake pump to be faulty. removal quickly revealed the source of the problem - a stuck plunger. PBR were able to supply replacement pistons, hoses, and seals, as well as sleeving the master cylinder. i seem to be on top of everything with the exception of the brake pump - has anyone a detailed exploded diagram? the components of the inlet valve fell out when i was messing around with the pump, and i want to be certain i'm assembling it correctly. thanks in advance davide | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1033 Registered: 4-2003 |
Davide/ First thank you for rescuing the car from the wreckers' yards. Rather than recite the workshop manual can I refer you to the Tech Library which will give you all the detail you require. If you want more detailed accounts of working on these areas of the car can I refer you to Tee One topics which is at the same site. The web address is http://rrtechnical.info/. For a car in the condition you describe the general summary of work required is to open and clean out the reservoir particularly the sight glasses and filters, remove and overhaul the pumps check that the push rods are not broken, remove and overhaul the accumulators and recharge them with nitrogen, overhaul the 'G' valve in the rattrap, replace the master cylinder (usually cheaper and simpler than resleeving it) removal and clean all callipers and fitting with new seals, replace all hoses, overhaul the levelling valves and re-seal the rams. While you are in a constructive mood check that the handbrake cable hasn't frayed or stretched and that the adjacent starter solenoid in the engine compartment has secure rubber covers on the terminals since it would be a pity to do all that work and have it make like a Roman Candle! I suggest when all the work is done you pump a couple of reservoirs full of blue DOT3 brake fluid through all the bleed nipples then flush that out with RR363 which is almost clear! | ||
| Paul Yorke Prolific User Username: paul_yorke Post Number: 248 Registered: 6-2006 |
Follow Bill's plan and you should be good to go. The only thing I'd add is if you are buying a new master cylinder - I'd recommend fitting the next bore size up. S 1 Landrover amongst lots of other cars of that era. You may have to use your threaded rod depending on what you get with the new one. I haven't got the numbers in front of me, but the casting number is the same, a brake shop should be able to search on that. It will make bleeding easier and will give you a bit less pedal travel, which most people find excessive on the early cars. | ||
| davide frada New User Username: davidef Post Number: 2 Registered: 11-2008 |
Bill and Paul, many thanks for the advice. the car is actually not as bad as it sounds - for instance, the air conditioning still works very well, along with all other accessories. it seems it was a case of the car being parked following brake failure. the reservoir and sight glasses were clean, and half the hoses had been replaced, along with recently rebuilt level valves. in doing this, though, it would seem someone snapped the lower rear bleed nipples, and didn't bother to attend to them. the car sat for one year before i acquired it. its an australian delivery car and very solid, though the leather is showing signs of age, which doesn't really bother me as i enjoy the patina of an original car. anyway, i thought as a starting point, i'd attend to the obvious issues and reassess once its on the road. upon delivery i was able to get the front-most calipers to function, which was sufficient to confirm the condition of the suspension and drive line. i'm very much enjoying working on the car - the engineering is thoroughly fascinating (and in some ways quaint - the unassisted master cylinder, for instance). overall it seems no more difficult to deal with than a jaguar. anyway, the workshop manual only breaks the pumps down into a few sections (as i recall, body/valve/plunger/sleeve), and does not give an exploded diagram of the valve assembly. the accumulator on the circuit with a working pump seemed to hold pressure, but i'm not sure of the other - the wire was pulled off the pressure switch to disable the light. this may have been on account of the faulty pump rather than the accumulator itself. in any case, if required, before i rebuild the accumulators, i'd like to try having them charged up. i have read that citroen specialists are able to do this with the units in situ... is this the case, and does anyone know of such a person in adelaide? regards davide | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1034 Registered: 4-2003 |
I think that the information on page 958 of Issue 68 of Tee One Topics will be what you are looking for. I recharge accumulators to bring them up to speed. You need a cylinder of Nitrogen a $1000 regulator an appropriate hose and connector. You will also need a couple of plastic sealant balls and probably a small 'O' ring for the sealing cap. Remove the stay bracket under the accumulators and remove the charging caps. Prise out the sealing ball. You then need to unbolt the accumulators but leave all the pipes etc on which will allow you to screw on the hose. Next step is to completely exhaust the accumulators, then slowly pipe in the nitrogen until your gauge shows a bit over 1000 psi. Unscrew the hose quickly wack in the selaing ball and 'O' ring and pop the cap on quickly. lastly the quickest way to overcome low pressure in the accumulators is to disconnect the pressure switch wire then that annoying light stays off. Alternatively the more imaginative fixers simply remove the warning light globe! | ||
| davide frada New User Username: davidef Post Number: 3 Registered: 11-2008 |
Bill, thanks very much for passing on the procedure. for the moment, fortunately, at least one accumulator appears to be doing its job. this morning i bled the brakes, starting with the low pressure circuit. when i attempted to bleed this circuit a few days ago, i was astonished to note the ease with which it was all happening - i have read the horror stories. unfortunately, once under braking pressure, it became clear the right nipple wasn't seating correctly. the caliper was removed and the thread/seat was repaired. once installed, i was still getting a reasonable quantity of fluid, and the brakes do work, but the pedal is not at all firm. with the engine running, i primed the pumps. i was delighted to note the rear pump seemed to be working quite well, and though it was certainly providing some pressure at the accumulator, it was not nearly as much as the front pump. it should be noted the front fluid, though free of large bubbles, was slightly aerated. the rear pump was providing a clear stream. the calipers all bled easily and appeared to work, turning the wheel by hand then applying the brake. i could get no fluid from the height control nipples despite disconnecting and raising the valve levers. living in a rural area, i thought i might take the car for a drive. it actually feels delightful on the road, with no real issues of note, aside from the brakes, which, while capable of slowing the car down at speed, are simply not right. when accelerating in second gear up a hill, however, a loud clacking noise appeared. at slow speed, with the brake applied, the noise is barely audible. a very slight pulsing of the pedal coincides with the clack. the noise is not really audible outside the car, only inside. perhaps the reasons behind the clack will uncover the reasons for the poor braking performance? regards davide | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1037 Registered: 4-2003 |
OK - In para order As it happens I have a '72 Corniche in my care at the moment and the next job is to bleed all three systems! The low pressure will not give you a hard pedal - simply a firm one. Its function is to provide feel for the pedal rather than provide any braking potential. If you have got fluid and cleared the bubbles that is great. Sorry what wheel are you turning? To bleed the high pressure system you need the engine running at a fast idle and lots and lots of fluid. Jam a piece of wood between the front of the driver's seat and the brake pedal then bleed each system. Have someone at the reservoir continulaly topping up the reservoir as it goes down quickly. For the moment use DOT 4 as it is cheaper. Do not re-use fluid. It really doesn't matter the order although you should start with the shortest run and finish with the last. When the bubbles cease let the fluid run for another 15 seconds to flush and make sure all air is out. As to nipples I always replace them if they show the slightest bit of damage or corrosion. Note that there are three different sizes which I need to put in Topics pronto as I have only just found this out. As to the front pump, aeration=bubbles=air! What are the warning lights doing? If as I suspect the nitrogen is lost the only braking pressure you will have is when the engine is running. There will be no reserve. The only solution is to overhaul the accumulators. The clacking noise is most likely a worn universal on the back wheel or drive shaft or a rear axle bearing. Applying the brake holds the worn bits together temporarially and stops the noise. Can we have the chassis number pls? Hang in there. | ||
| davide frada New User Username: davidef Post Number: 4 Registered: 11-2008 |
hi Bill, thanks for your help - much appreciated. the low pressure system does bleed up, but the pedal still goes more or less to the floor before it is at all firm.... the clacking seems to be a brake pump or accumulator - the fluid from the accumulator bleeder relevant to the rear pump is now pulsing in time with the clack. i had the rear pump apart as it had seized at the top of its stroke from sitting. the front accumulator holds some pressure - the car will brake quite well with the engine stopped. i don't know why there is aeration at the accumulator though (the calipers seem to run clean). so close yet so far! i'll have a chassis number for you tomorrow. | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1039 Registered: 4-2003 |
Sounds as though you have not yet got all the air out of the low pressure system. Keep pumping! Sorry about the clacking I associated it from your description with driving. I would certainly check the push rod lift on the back pump I suspect it may be broken but there is enough there to give the pump a bit of a lift. If you get a strong magnet you should be able to pull the rod out and inspect it. They always break at the bottom - by design! Sounds like air is getting into the accumulator from the pump. Try exhausting the system disconnect the delivery pipe on top of the pump put some clear hose onto it and run the engine. Keep the hose vertical near the pump to build up a head. If there is air coming out it should show there. I suppose it could get in past the seals on the outer casing but then there would be a noticable leak. One other thing remnember if you open the bleed screws too wide the fluid coming out will suck air in around the threads and come out with the fluid. Many a bottle has been wasted with this trick. Open the screws slowly and sufficient to get the flow you want. | ||
| davide frada New User Username: davidef Post Number: 5 Registered: 11-2008 |
This makes sense - i will try the hose trick on both pumps and see what happens - perhaps there is a fault in the rear accumulator valve? a broken push rod makes some sense, as the noise did commence at high rpm... but this morning, having sat overnight, the noise wasn't there for quite some time. i ran the car for several minutes in an attempt to bleed it, and only started making the noise after a km of driving. nonetheless, when i was attempting to bleed it, the fluid was pulsing causing the whole pipe to shake considerably. more work to do! oh, the chassis number is SRH 8810 |
