Brakes - Front Brake Discs

The front brake discs came out from the States and hadn't arrived at Juniors Kustom Rides at the time we were down there picking up the chassis. Just a week or so later though and they turned up at work. 

They are what are known as cross drilled. You can see the surface of the disc has holes drilled in it. This lets air flow through the disc to better dissipate heat build up. 

Before the disc can be mounted on the stub axle I need to fit these bearings so that the disc and ultimately the wheel can turn freely. The rings at the top of this next picture are what are known as the bearing "race". These are machined to a very tight tolerance and have to be driven into place in the Brake Disc hub either using a big press or as I did, using a drift made from a soft metal so as not to damage the hardened race. You do this by slowly hammering the race, down into the hub, a bit at a time, going round the race evenly. With a bit of patience they are finally driven home. If you look carefully you can see the race in the top picture.

The bearings then sit in the race like this. The one on the left is the inside bearing and the one on the right is the outer.

Here you can see the bearing in place and ready for the brake disc to be mounted on the stub axle.

Voila! The big nut sticking out the end is what holds it all in place. It is just nipped up, so that the bearings can turn freely. Once finally fitted it will have a pin that slides side ways through a hole drilled in the axle and a notch in the nut. This is to stop it coming undone.

Looking down on top now you can see the disc has little vanes around the circumference. This is what is known as a vented disc. This is also to help dissipate heat. Couple this venting and the cross drilling mentioned above, with some decent brake calipers and this car should stop nicely!

At this point I ran into a couple of problems. One problem is that the seal that goes in the back of the hub to protect the bearing from dirt and grime, wouldn't fit. I had to get the hub machined on a lathe so these will fit in place (Thanks to Peter Farrant). You can see in the next picture what the seals look like (the round black things that look like washers) and then the next picture shows one of them sitting in place. They are a tight fit so will need to be carefully tapped into place with a drift once the discs are fitted up properly. I will have them finished in HPC before we do this though.

The second issue is that the steering arm has to bolt onto the back of the hub. This is held in place with nut and bolt, but as you can see there is no room for the head of the bolt, once I fit the brake discs, it will rub on the back of the disc, which just won't work.

This will be a fairly easy fix though. I will will drill and tap the stub axle backing plate. This will mean there is a thread in the hole, so the backing plate of the stub axle effectively becomes a nut. So now I can put the bolt through the steering arm and tighten it into the stub axle. The bolt no longer needs to go right through. No more clearance problems.

You can see here the bolt going through the steering arm and into the stub axle flange.

And here is a view from the other side. As I mentioned before the flange is threaded so the bolt screws into it now and there is no need for a nut on this end. This of course means there is now plenty of room for the brake disc to be fitted without binding on anything.

So thats about it for now.....well at least until I pop all the pieces apart for finishing. I will probably use HPC to do this at a later date.