From Issue 57 (Dec. 93), Spanner goes down to the GCW and takes a look at the braking system - oh, and FoFToCs, fellow Spannerman fans...
STOP HERE! A LOOK AT BRAKES
FOFTOCS. ISN'T IT funny how touchy some people can be! I said last month that no, I was not being rude. But you try telling that to her. They were discussing my use of the phrase down at the Chequered Flag, and everything was o.k. until that nosey old barmaid got wind of it. She just had to go and tell her indoors all about it. All manner of commotion broke out after that. I've tried explaining that it's just my way of remembering to Follow the Fluid To Check the System. But she insists I mustn't use language like that in public. So whilst I'm down here in the GCW (Garage-cum-Workshop), FoFToCS! FoFToCS! FoFToCS!
Anyway, now I've got that out of my system, it's time to think about the system we had a look at last month - the braking system. We are going to look at the overhaul of specific brake components, starting with the brake master cylinder. As discussed last month, any slight flaw in the cylinder will impair the efficiency of the brakes. If the safety check procedures have shown that there is cause for concern with the master cylinder, then an overhaul is required. Although there are differences in operation between the two main types of hydraulic master cylinder - the Lockheed and the Girling - the basic principles are the same. In order to be aware of any special requirements which may apply to your particular classic, it is essential that you have your vehicle's workshop manual to hand.
Once the cylinder is removed from the car, carefully clean the exterior so that there is no dirt which can find its way into the internal workings of the cylinder. Remove the dust cover which sits over the end of the cylinder bore. The pushrod will most likely be held in place by a circlip. Push the rod a little way inside the bore, then remove the circlip. The pushrod can now be withdrawn and the rest of the internal components can also be pulled out. It's at this point that most workshop manuals I read seem to get a little silly. They always tell you to clean all components next. What utter bunkum! If the master cylinder bore is scored, the whole unit is scrap and will need to be replaced. So I always carefully clean and inspect the master cylinder body first. If, and only if, this is o.k., I then go on to clean the rest of the components. Makes a lot more sense if you ask me! Just a pity that not many people do. I wonder why....
Anyway, back to the job in hand. I normally use methylated spirit for the cleaning. Don't forget to check that all the holes and fluid passageways in the cylinder are clear. A small piece of wire will act as a probe for this job, but don't forget that if you cut a piece of wire for this, do make sure to rub the end of the wire with emery cloth before using it. It's surprising how sharp the cut end can be. Once everything is clean, check the replacement seals you have bought to fit into the cylinder are a match for the old ones. Then lubricate all the parts to be refitted in clean brake fluid. And now the phrase I've been waiting to say : Reassembly is the reverse of the removal procedure! Or at least it usually is. Your workshop manual will be an invaluable guide to any special procedures on your car. When the unit is reassembled, it should be refitted to the car paying particular attention to the hydraulic unions and the clevis pin attachment to the pushrod. We'll have look at bleeding the master cylinder later, once we've considered other components in the braking system.
And how do we know what to look at next? Of course, it's FoFToCs! Since you all know that I think that the servo is a modern invention, I'll use the excuse that not all our classics have them fitted and so we'll look at them later! Instead we'll now think about the metal brake pipes. If, during our safety check, we found any pipes which were in need of replacement, now is the time to do the job. If the pipe is being replaced as part of a major overhaul of the braking system, then the master cylinder will probably already be empty. If however it's not, then don't forget the old trick of placing a piece of plastic under the fluid reservoir cap. This will help prevent excessive loss of fluid from the system. I always find it best to do one pipe at a time. The first thing to do is to remove any supports that the pipes might have fitted. These could be the metal "P" clips, metal band clips to secure the pipes to axles, or perhaps the later plastic snap-in clips. Next unscrew the unions on each end of the pipes, being very careful not to allow any brake fluid to get onto the paintwork. I'll guarantee there'll be regrets if it does. The pipe can then be removed from the car. If any pipes are very badly corroded and snap into two or more pieces, do make a note of how they came off the car. The reason for doing this will become obvious when you do the next job - measuring and specifying the pipe for replacement. Of course it may be that you are doing the job of replacing the full set of pipes, in which case you will have probably bought one of the readily available kits which contains all the pipes you need for the car. These kits are generally supplied with each pipe labelled as to where it goes. If however you are only replacing one pipe, or have not been able to obtain a replacement kit, then a trip along to your local supplier of made up brake pipes is called for. I normally pop along to see my old mate Herbert down at the local garage. He makes up the pipes for me using his very expensive flaring tool. I pay him for the materials of course, but the cost of the labour is usually met down at the Chequered Flag! (Mr Editor - I hope you don't let any Income Tax people see the paper. I'd hate to get Herbert into trouble.) After my visit to Herbert, I take the coiled up pipe and working alongside the old pipe, I carefully reproduce the shape of the original pipe. When the pipe is more or less made to the right shape, I offer the pipe up to the car and start to loosely secure the pipe using the pipe clips I removed earlier.
When the pipe is in place on the car, I connect the unions at each end. Once these are firmly secured, I go along the length of the pipe and tighten up all the pipe clips. I learnt to follow that procedure when replacing brake pipes after that famous incident back in the other long hot summer of 1976. I remember that I'd dashed over to get an MOT on a Mini I used to own. After the tester had the temerity to fail the car because of a speck of rust on one of the brake pipes, I hurried over to the local accessory shop and bought one of the "off the shelf" ready made up pipes. Of course, it was four inches too long, but I only realised that after I'd attached the front union, tightened up all the clips along the length of the pipe, and finally came to put the final bend into the pipe. Where on earth could I lose four inches? So I had to loosen off all the clips and make each of the bends a little more generous. Still, it was a lesson learned.
After the metal pipes, the fluid will pass through the flexible brake hoses. If inspection has shown that any of these need replacing, then it's generally a simple job; but do pay particular attention to the position of the pipe when refitting. Any unnecessary twisting in the pipe could lead to premature failure.
Next month we'll continue our look at the overhaul of the specific brake components, going on to consider the callipers and the wheel cylinders. (And yes, I suppose I might even mention the servo!).
Got a technical query for Spannerman? E-mail your problem to the old boy here and we'll try sort you out! He might even ask his old pal, Klaxon...after he's sorted out just what IS e-mail!
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