DISCS AND CALIPERS
1
Although just the front end of our MG needed to be lifted clear of the deck to fit the new discs and calipers, axle stands were placed beneath the spring pans before the front wheels were removed.
2
Next job was to test the state of the brake fluid as it’s hygroscopic and absorbs water. This handy tool shows the condition with a series of lights – our was green and OK.
3
Before replacing the cap on the brake fluid reservoir, a sheet of plastic was put underneath it to stop air being drawn into the system when the flexible hoses were slackened off.
4
The nut securing the braided brake hose to the caliper was rounded off, so it was undone at the first junction. This wasn’t a problem, as clamps don’t work too well on braided hoses.
5
The condition of the left-hand side caliper and pads didn’t look too bad but we decided to replace it anyway as the offside caliper had a sticking caliper and it’s always best to renew these components in pairs.
6
Once the old caliper was off the car, it was evident that someone had used a clamp on this braided hose as it had partly collapsed. New rubber flexible hoses were fitted when fitting the new calipers.
7
It was obvious from the amount of corrosion in the bore of the offside caliper why our MG pulled to the left when braking as the piston was partly seized. Note how the friction material on one pad was starting to delaminate.
8
With the hub off the car, the old disc was gripped in a vice while all the recessed securing bolts were undone. We fitted new spring washers when the new disc was bolted to the hub.
9
The outer seal was prised out of the hub with a screwdriver. Next out was the inner bearing, followed by the cone shaped spacer, taking care to retrieve any shims found in the grease.
10
Next, the inner and outer bearing races were drifted out of the hub using a suitable flat-tipped punch. Races should be struck equally on both sides otherwise they’ll jam.
11
Note the two small cut-outs on the inside of the wheel hub casting. These allow the punch to make firm contact with the base of the old race while it’s being drifted out.
12
While new races can be pushed in using a suitable sized socket, we did it properly with a 15-ton press. One hub was scrapped, as the surface where the race sat was worn.
13
Before fitting the new bearings they were given a generous coating of grease. There’s no need to lubricate the spacer but make sure grease is worked into all the rollers.
14
The hub was temporarily fitted to the stub axle along with a selection of shims before the castellated nut was tightened up so the end float could be measured with a dial gauge.
15
The new disc was bolted to the hub and carefully fitted to the stub axle with the correct number of shims before the outer bearing, washer, castellated nut and new split pin were fitted.
16
Annoyingly, the new nearside caliper was far too close to the disc and it took some fiddling before we could get an acceptable installation.
17
It was even worse on the offside as the caliper wasn’t square to the disc. The problem was due to a bent stub axle on the recently fitted reconditioned kingpin assembly.
18
When the new calipers, pads and flexible hoses had been all been fitted, the discs were given a final spray of brake cleaner to remove any oily fingerprints.
19
To purge all the air out of our MG’s braking system, we used an EasyBleed kit attached to a partly deflated tyre rather than have someone sitting in the car pumping the pedal.
Despite pressurising the system, it took a while to bleed the brakes as the servo had been fitted upside down in the front of the engine bay rather than the back and it needed several firm thumps to dislodge all the air bubbles.
20
It took quite a while to get a firm pedal as the new calipers had to be bled several times. While we were at it, the back brakes were bled too just to be on the safe side.
21
Job done and time to go home at last! Once the front wheels were back on the car, Steve checked the tyre pressures and found them slightly over inflated. There should be 24psi in the fronts.