Front Brakes Upgrade
During the year that my Cortina provided me with daily transport it became apparent that the brakes are actualy not that bad and it was quite possible to lock up both front wheels. However, what I did find was that the brakes quickly overheated causing the inevitable brake fade.
The picture above shows the standard front brake set up comprising of a twin pot calliper and a solid disc. You'll notice that unlike modern cars the disc is mounted on the back of the hub as oposed to being sandwiched between the hub and the wheel. Modern cars brakes dissapate a lot of there heat by transfering it to the large alloy wheel bolted against the disc, effectively using it as a heat sink. On older cars such as this the disc has only the iron hub to spread it's heat to and iron doen't make nearly as good a heat sink as alloy. The other problem is the lack of airflow to alow heat to escape. The disc is solid and theres a debri gaurd located against it's inner face obstructing the airflow.
The ideal soloution would be to fit modern vented discs that locate on the outboard end of the hub and use modern single piston sliding calipers. However, in order to do that you would need to reduce the outer diameter of the hub to allow the disc to slide over it and you would end up with your front wheels been spaced out giving a slightly wider track. You will also need to fit longer wheel studs. This is all very do-able but there is an alternative easier option for a road car.
As already stated, the ideal soloution is to use a completely modern set up and move the discs to the outboard face of the hub against the road wheel. However, this requires a lot of work and alters the track of the car. But that doesn't mean we can't improve things whilst retaining the discs in there original position. As I stated at the start, the brakes are actualy not that bad when working properly, they just overheat quickly producing brake fade. Therefore we need to improve the cooling to them. There are two things we can do to achieve this, remove the debri gaurds to allow some airflow over the brakes and upgrade the solid discs to vented discs.
No model of Cortina was ever fitted with vented discs so you'll have to find some from somewhere else. The mk2 Granada uses a very similar set-up to the Cortina and the bigger models did use vented discs but they use 5 stud hubs and as a result the discs are also mounted with 5 retaining bolts as oposed to the Cortina's 4. But all is not lost as the Capri 2.8i has vented discs of the correct size and shape and is also of 4 stud hub design. You will have to raid a mk2 Granada 2.8i of it's callipers though as your originals won't fit around the thicker vented discs and the Capri callipers are of a different design.
Capri/Granada - Original Cortina
So to recap, you will need:
- Capri 2.8i vented front discs
- Granada mk2 2.8 front calipers (ensure spaced for vented discs)
- Caliper rebuild kit
- Granada mk2 2.8 front brake pads
- Brake fluid
- Wheel bearing grease (and wheel bearings if you want to replace them)
First job is to remove the old stuff. Your maintenance manual will show you how but just in case, follow the pics.
Remove the old caliper remembering to catch the brake fluid as you do so. Don't re-use it as it' be old and water logged by now.
Next the hub needs to come off, remove the dust cap as shown to reveal the hub nut. This is locked in place by a spit pin and castlated nut cover.
Here you can see the three retaining bolts that hold the debri gaurd in place. Soak them in penetrating oil first before trying to remove them. All of mine came out but you may end up grinding yours off.
The bare upright. This now needs cleaning up and a lick of paint.
Next the hub needs seperating from the old disc and cleaning up itself. You' need one of the wheels for this bit.
This is the inboard side of the hub showing clearly the 4 retaining bolts. These 4 bolts are secured in place by locking tab washers that you might just be able to make out in the above picture. Flatten the bent tabs down away from the heads of the bolts. Now here's were your wheel comes into pay. Bolt the wheel back onto the hub and place the road wheel on the floor face down (preferably onto something soft to avoid damage to your wheel) so that you can access the hub. You or your assistant can now grip the tyre whilst you try to loosen the disc retaining bolts without the hub spinning round.
The disc and hub seperated. It's a bit of bad practice but if the locking tab washers are still in good condition and not showing signs of spliting/cracking then you might get away with reusing them. If not then use them as patterns to make your own.
The hub was attacked with a wire 'twist knot' brush in an angle grinder and taken back to clean metal as was the face of the upright.
Each was then painted in good old black Hammerite! Whilst it was all apart I took the oppourtunity to replace the wheel bearings. Be sure to spread a thin film of bearing grease around the inside of the hub to prevent future corrosion that may leave deposits to be injested into the bearings.
Be sure not to get any paint on the spindle. This must not be allowed to corrode so if it's going to be exposed for any length of time give it a coating of grease.
The calipers have also been stripped, cleaned, rebuilt with all new seals and painted.
On competion of this upgrade and refitting the wheel it was discovered that the wheel was fouing on a cast in lump on the caliper. This lump serves no purpose and so needs to be ground back smooth as shown above. It was then repainted.
Here's a picture of the old and new calipers for comparison.
Time to put it all together! Start with the new discs first, you'll need that wheel again for tightening the disc retaining bolts.
Here you can see I've been a little bit naughty and re-used my locking tab washers. I gave them a thorough examination first and all was well. Note also the new bearings and seal in place. The red grease visible in the picture is actualy aircraft spec wheel bearing grease!
That's the hub complete, it can now be refitted.
That's the first bit done. Note the graphite grease smeared across the face of the hub to prevent the wheel from corroding onto the hub.
Next up is the calliper. This is where the fiddle factor comes into play, the caliper will bolt straight onto the upright but it won't be central about the disc. The caliper needs spacing out by approx 7mm to achieve this which also requires longer mounting bolts.
Thick alloy washers have been used in the above picture purely to get the correct spacing. These are replaced by a steel plate of the correct thickness.
The new pads can now be fitted and the brake system bled.