Replacing the Front Brake Discs
In order to replace the brake discs the callipers must be removed and the hub withdrawn from the stub axle.
Save the tab strip from the calliper bolts, they are not available and you will need them as patterns to make replacements.
For details of hub removal and replacement see the FRONT HUB BEARING REPLACEMENT page.
Whatever work you do to the brakes on one side of the car,
you must also do to the other side to maintain a balance of breaking effort. This is essential.
As soon as the hub has been removed stick tape over the openings to stop muck getting into the hub bearings.
The discs are held to the inner flange of the hub with five "V" quality bolts, 5/16 inch diam 1 inch long,
threaded for ½ inch, tightened to 30 foot pounds. Under no circumstances should these be replaced with normal bolts.
Although the discs can corrode terribly, the bolts seem to fare well.
Undo All 5 working diagonally. Since the disc is scrap it can be held in the vice to do this.
Knock the disc off the hub, keeping it straight as you go. Click on the pictures for bigger versions.
Here is a comparison of a knackered original disc and a new one. Nice isn't it.
Who would believe discs like this actually stopped the car! The original discs had a soft iron band round the perimeter.
This was supposed to prevent brake squeal by resonating at a different frequency to the rest of the disc.
The new discs do not have this, neither am I using anti-squeal shims, yet don't squeal, so it's a bit of a mystery.
When you have got the old disc off you can clean up the hub and bolts ready for fitting the new disc.
Place it on the hub and spin it while pressing it in place to make sure there are no high spots or muck trapped.
Insert the bolts and tighten in stages diagonally to 30 foot pounds.
Re-fit the hubs to the car as described in the FRONT HUB BEARING REPLACEMENT section.
Note the trick for measuring run-out without using the special tool,
then re-fit the callipers using new tab strips which you will have to make.
Click here to see a pattern for them. One large square = 1cm.
It is advisable to rebuild the callipers before re-fitting them.
The new disc is 14.5mm thick and each new pad is 19mm thick so the calliper pistons will
be further retracted than they have been for years.
An accumulation of muck on the pistons may cause sealing problems.
Incidentally although the workshop manual says that a maximum of 3.8mm can be skimmed off a disc,
it fails to mention how thick they were to start with!
If the replacement discs that I bought are the same thickness as the originals,
this gives a minimum allowable disc thickness of 10.7mm.
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Here is a comparison of a knackered original disc and a new one. Nice isn't it.
Who would believe discs like this actually stopped the car! The original discs had a soft iron band round the perimeter.
This was supposed to prevent brake squeal by resonating at a different frequency to the rest of the disc.
The new discs do not have this, neither am I using anti-squeal shims, yet don't squeal, so it's a bit of a mystery.