Archive for the ‘Brakes’ Category

Brake Saga Part 3

Posted on April 11th, 2012 in Brakes | 5 Comments »

The Master Cylinder

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Having successfully replaced the rear wheel cylinders and front callipers I was now confident that the brakes would be approaching the standard that Henry Ford designed them to be back in the 1970’s. The new brake pipes and hoses further reinforced my confidence that, if I needed to stop in a hurry, I would be able to without the fear of a hose or pipe splitting. With age, rubber hoses can deteriorate and, even if they do not split, they are more likely to bulge under heavy braking thus reducing the amount of effort we transfer from the brake pedal to the brakes. Put simply, we are putting our effort into expanding the hose rather than putting the brake on. This is why rally cars, high performance cars and a lot of motorbikes now use steel braided hoses.

Master Cyl (1)I now turned my attention to the master cylinder. When I first checked the car over I noted the brake fluid in the reservoir appeared to be dirty with what looked like sediment in it. As I did not wish any of this fluid to go into the new callipers or cylinders I had already disconnected the two pipes connected to the master cylinder and drained the system.

IMG_0025 (2)The master cylinder and reservoir are secured to the servo with two nuts and a simple matter to remove. Once on the bench it was clear that the cylinder bore was badly deteriorated. An attempt to dismantle it further was thwarted when the plastic reservoir steadfastly refused to detach itself from the metal cylinder. Although, only a push fit, the plastic appeared to have bonded itself to the seal and, despite careful prising and pulling, the reservoir eventually cracked. According to the internet this is not an unusual problem.

I now needed a new master cylinder and reservoir. Research had already informed me that master cylinders for mark 3 Cortina’s were like gold dust and fetching ridiculously high prices. A used one had recently been sold on e-bay for almost £200, and I wanted a new one. I didn’t want to chance second-hand. Internet forums referred to using Land Rover parts on some Ford Capri’s and Ford based kit cars but nothing specific to Cortinas.

More research confirmed that a pre 1980 series 3 Land Rover master cylinder had the same external dimensions, but that the piston diameter was bigger. My knowledge of hydraulics told me that the bigger piston would move more fluid in the system for the same amount of brake pedal travel. Simply, if the brake pedal travel was originally 50mm, with a piston that is twice the area the pedal travel would be 25mm. Would this be a problem, only one way to find out, buy one and try it.

IMG_0018 (2)

I ordered a cylinder (part number 90577520) from Paddock Spares at a cost of £53.94. This was delivered promptly and I set to work. The first difference was the reservoir, on the Cortina the master cylinder slopes up towards the front and the reservoir is shaped so the top of it is level. I guess not all Land Rover cylinders slope, and, despite the picture on the supplier’s website showing the shaped reservoir, the one they IMG_0020 (2)sent had a reservoir that was intended to be fitted level. Undeterred I attached it to the Cortina servo and, using a spirit level, I could see that, despite the reservoir not being level, the amount of fluid could still reach the maximum mark. So far so good.

 

IMG_0028 (2)Next to fit the two brake pipes, Cortina’s have metric brake pipe unions and, as I discovered, Land Rovers have UNF. Hence the brake pipes would not screw into the ports on the master cylinder. A quick look under the front of the car revealed that both the brake pipes terminate at unions under the front of the car so removal was quite easy. My initial thought was to ask my local garage to cut the metric unions off and fit appropriate size UNF ones, but we decided it was best to have new pipes made up with metric threads at the lower end and UNF at the top. This way the original pipes could be archived and reused if it was subsequently found the Land Rover master cylinder was not suitable. This, of course, would still be dependent on locating a Cortina cylinder.

The pipes were made up and fitted without any problems and the reservoir filled with new fluid. Before fitting the master cylinder to the car I “bench bled” it. This process requires you to pour fluid into the master cylinder outlet ports and reservoir and gently work the piston in and out with a clean non-metallic object. The idea is to ensure the seals are lubricated with fresh fluid and that no air is trapped in the bores. This is particularly important with the Cortina as the master cylinder is mounted on an angle. Having completed the “bench bleed” I used two plastic bungs to seal the outlet ports whilst I fitted the cylinder onto the car. A quick removal of the bung followed by a quick fitting of the pipe ensured only a small amount of fluid leaked out. Be quick but careful when fitting the pipes and do not use a spanner until you are certain that they are not cross-threaded. A damaged thread could cost you another master cylinder.

There are some good videos on YouTube on bench bleeding master cylinders, but I found the above process works well.

IMG_0049

And so to bleeding the system. I had purchased a Gunson Eezibleed pressure bleed bottle from Halfords for £19.99 and I would recommend this as a worthwhile purchase. There are cheaper alternatives but they are little more than a pipe with a one way valve and, in my opinion, are of limited use.

With the Gunson kit fitted and pressurised and, starting at the wheel furthest from the master cylinder, I opened the bleed screw and bled the rear brakes. I then bled the front brakes and, full of confidence, pressed the brake pedal down. Yes, it felt like a good brake, I pressed a bit harder and the pedal went slowly to the floor. There must still be air trapped in the system. I bled the brakes a second time, then a third, the pedal always went to the floor. Give up for the day!

The following day, after much thought, I removed the master cylinder and repeated the “bench bleed” again. Refit the master cylinder and bleed the brakes again. Exactly the same. At this point I noticed that as the pedal went down the level in the reservoir went up. It appeared that the master cylinder was in fact allowing the fluid back into the reservoir rather than feeding it out to the brakes. Time to contact Paddock Spares, I explained the situation and was given a returns number. They said that the cylinder would be examined, and if faulty, I would receive a refund. As I still needed a master cylinder I had to order and pay another £48.94, however I was not charged postage and it was sent express delivery and arrived by 11.00 am the next morning. Within half an hour it was bled, fitted and worked perfectly. Time to put the wheels on, clip the brake pipes neatly in place, and go for a road test.

Westwood  (3)A gentle drive and application of the brake gave me a good feeling, the pedal was firm and the car came to a halt with a significant dip of the front end. A longer road test and I was happy and confident with the cars ability to stop. Conclusion, Land Rover master cylinders, whilst not being a direct replacement, are an acceptable alternative and preferable to putting new seals in a worn master cylinder or buying a used one of unknown condition. With new callipers, wheel cylinders, master cylinder, pipes and hoses my overhaul of the brakes was complete.

The Brake Saga – Part 2

Posted on March 16th, 2012 in Brakes | No Comments »

Front & Rear Brakes

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On removing the Cortina’s rear drums I discovered that the brake shoes were serviceable but one of the wheel cylinders was partially seized. I am not a believer in fitting new seals to 40-year-old hydraulics, so I decided to replace the wheel cylinders on both sides. As it was unlikely that brake pipes would oblige and unscrew easily the best plan was to replace the pipes as well. Wheel cylinders were bought from Firstline via eBay for £9.00 each and brake pipes made to pattern by a local garage.

Different wheel cylinders were used on the Mark 3 Cortina during it’s production dependent upon year, model and engine size. Significant changes were made to the rear brakes from 1973 onwards and little will interchange with earlier cars. The wheel cylinders supplied by Firstline were exact replacements and fitted, together with the new pipes, with a minimum of fuss. The handbrake cables and  linkages, pivots and self adjusting mechanism were all in good order so the brake drums were replaced awaiting bleeding.

Brake Cyl NSR Inner3

Rear Wheel Cyl (1)

The front brake strip-down showed the pads and discs to be ok; however I decided to remove the pads to check the calliper pistons. Having removed them and gently pressing the brake pedal down there was no movement, more force and the pistons moved enough to close the gap and stop me putting the pads back in. An hour later, and the use of large crow-bar, I had managed to push the pistons back sufficient to insert the pads. Having changed many sets of pads over the years experience told me that gentle force with a short bar moves the piston back into the calliper. Substitute laying on the drive with both feet on the hub and pulling wildly on a crow bar! Clearly something was not as it should be.

Front Brakes  (4)The callipers looked original equipment and the ten years of dry storage had done them no favours. Brake fluid, although it is oil, has the ability to absorb water from the atmosphere. Modern service schedules require brake fluid changes every few years but this was uncommon thirty or forty years ago. Possibly the frequency with which seals leaked back then resulted in brake fluid being replaced quite often anyway. As a point of interest most garages can check the water content of brake fluid quite easily. A small sample of the fluid is taken from the reservoir and heated until it boils, the lower the boiling point the greater the water content. Pure water boils at 100⁰C, brake fluid with no absorbed water may be double this. High water content in the brake fluid can not only cause metal parts to corrode but, under heavy braking, the heat generated may cause the fluid to boil or vaporise causing brake failure.

Back to the Cortina: It’s my guess that the lack of use and old brake fluid had caused the pistons to corrode and seize. The brake fluid in the reservoir was cloudy and not at all as it should be. Replacements were required. Most replacements these days are refurbished units and there are a number of companies that provide quality products. When ordering, a surcharge is payable against the return of your old units. I sourced two refurbished callipers from  Brakes International for £139.40 including the surcharge of £36.00.

This £36.00 was dented somewhat by the cost of posting them back. Weighing just over 10 kg postage cost nearly £16.00. The old returned parts must be complete with no broken lugs etc.They will be inspected before the surcharge is repaid. The company websites generally list what is and what isn’t acceptable. Despite postage costs it is important that old units are returned, as these provide the basis for future refurbished units. Without them we would struggle to obtain quality spares.

The new callipers arrived promptly and fitting commenced. The mounting bolts also hold the Tab Washer Templatebrake hose bracket in place. This bracket has tabs that fold over onto the flats of the securing bolts to prevent them from coming undone. One of the nearside tabs broke off. A spot of fabrication was now required. Using a scrap piece of metal a new locking tab was sawed, filed and drilled until a functional, if not particularly pretty, component emerged. This fitted between the brake hose bracket and the bolt heads. Prior to fitting I placed it on a sheet of paper and sprayed black paint over it. I now had a painted bracket and a paper template for future use.

Fluid is fed into the callipers by a short length of intricately shaped brake pipe; this snapped off when I undid the unions. Another trip to the local garage for new brake pipes to be made. Whilst waiting for the callipers I ordered two new front brake hoses to replace the aging ones fitted. Three of the four nuts, which hold the two brake hoses to their brackets, came undone with the application of WD40 and Herculean strength, the fourth one had to be sawn off, but at last all parts were removed and new ones were ready to fit.

IMG_0042Fitting the new ones proved less stressful than removing the old one. The only snag was that the new brake hoses were supplied without the securing nuts so another trip to the local garage was required to raid his useful bits and bobs selection of nuts and bolts. At last two new callipers, brake pipes and hoses were fitted and I was ready for the next stage. The master cylinder.

To be continued!

Click to go to Part 3

The Brake Saga – Part 1

Posted on February 29th, 2012 in Brakes | No Comments »

Within a few minutes of setting off towards home with my newly purchased Mark 3 Cortina I met a car coming towards me on a narrow section of road. It was at this point that I discovered the joy of forty-year-old brakes. Apart from a short trip to the MOT station the car had covered little mileage since being put into storage in the late 90’s. Whilst meeting the MOT standards the brake performance not only fell short of modern standards but also of my memories of these cars when they were new.

NGX 87L 5

Driving steadily, with a heightened awareness of stopping distance, the next few days saw the brakes improve to a more acceptable level. It was however clear that an inspection of the brakes was high on the priority list. Before I could get around to any significant work I came to an unscheduled stop when the brakes locked on. For a few miles I had been aware that the brake pedal travel was getting less each time I pressed it and eventually the brakes were on without pressing the pedal at all. I pulled off the road to the accompaniment of smoke from the front brakes and a nasty hot smell.

Master Cyl (1)

Having owned a 1965 Beatle many years ago, which had a similar problem, I was aware of a ‘quick fix’ to get me home. This took the form of slackening off the front brake pipe union where it screws into the master cylinder, at the same time recruiting a passenger to gently press the brake pedal down about half way then tightening up the union while the pedal is held at the half way point. This was then repeated for rear brakes by slackening the rear brake pipe union. Checking that the brake pedal travel was normal, I made my way cautiously home. (If you ever have to do this yourself make sure the brakes are working correctly before rejoining the traffic and clear up any lost fluid from the road surface). Serious brake overhaul required.

More to follow

Click for Part 2