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The Restoration
Other CX19s

Bulletin 17 - 16th April - 30th April 2006

We've been turning our attention to the rear brakes and hubs. Again we found the linings to be in good condition, but like the front axle the taper roller bearings were showing signs of wear. Further dismantling revealed that the nearside oil seal was starting to break up. This is made of felt and had attached itself to the ring that the hub butts on to. It looked as though the cage had been rotating but the seal hadn't and both needed replacement. Spares weren't readily available in the UK and although David had offered to send a pair of seals from Turramurra stores, the time factor was critical. We decided to do away with the old felt seals and their cages and replace with new modern lip seals.

But this can lead to its own problems. The hub is designed to rotate against the abutment ring with the felt seals in between. However, the new lip seals need a little bit of clearance otherwise the friction created would soon wreck them. To get the required clearance we had to shim the hub out just enough to get a feeler gauge in between the ring and the new seal. It then followed that the hub clamping bolt would not screw up far enough to allow the lock screw to line up with the hole in the axle tube. The manual says you can drill and tap a new hole in the axle tube, but we were reluctant to do that. The problem was solved by adjusting shims and that did the business.

A final check on all the grease points revealed that two of the four points which lubricate the brake cam spindles were not taking grease. Each cam spindle is located by two tubular castings with brass bush inserts. Both spindles were removed and it was discovered that two of the four brass bushes had turned by about 90 degrees, thereby effectively blanking off their greasing points. The offside bush was removed and re-inserted so that it was correctly orientated with the grease nipple. But the other bush refused to budge and it was clear that it was not going to come out without damaging it. A new hole was drilled in the bush through the grease nipple aperture and this resolved the problem.

When we refitted the half shafts we noticed that the bolt holes in the nearside driving flange were elongated. At some point the bus had been running with these bolts not fully tightened and this had caused the wear in the driving flange. Additionally one of the driving flange bolts was missing altogether and an HD replacement would not tighten because the thread in the hub was stripped. The hub was taken to a bench where a Helicoil thread repair insert was fitted. Finally a replacement driving flange was sourced from Davies donor HD lorry. With this fitted, the overhaul of the rear brakes and hubs was complete.

During the last few weeks Jasper has fitted six new tyres, tubes and flaps onto our newly shotblasted and painted wheels. Having finished the brake overhaul we worked late that evening to get the wheels fitted as the bus may soon require to be moved to get more headroom for repanelling the roof..


The rear brake and hub overhaul begins. John removes the clamping
bolt from the hub

And then the brake shoes.

John examines the felt oil seal. It's split and cannot be reused.

Left: The hub is placed in the press and a new lip type seal sits in its recess ready to be eased into place. Right: The plate goes in and the seal gets pressed snugly into place.

  One of the threads for retaining a driving flange bolt is found to be stripped, so a new Helicoil insert is fitted.

The hub, complete with Helicoil insert and new seal, awaits fitment. With the new type of seal fitted, the hub will now require a few thou clearance to the abutment ring which is visible between the brake shoes.

The hub goes back on and the driving flange now has a full set of bolts.

The wheels go back on with their new 10.00 x 20 tyres.

And meanwhile the panelling is proceeding apace.