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Sid Goble Farina Magnette IFS |  |
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Many of you will have travelled in a London Taxi of the 1950-1970 vintage. Few of you will have realised that the car is running on the very same front suspension as fitted to the MG Farina Magnette and its sister Farina models. A few of you will have been treated to a run in an Austin Healey 100, or even a 3000. Again, those front wheels are being kept on the road by the very same front suspension. Like Morris, Austin used common components where they could. The suspension of the MG Farina Magnettes, that Austin/ Carbodies London Taxi, and the Austin Healey sports car share the suspension with the large late 1950's Wolseley and Austin six cylinder saloons (as well as every Austin 1947 A40, 1952 A50 1956 A55 and BMC variations.) These big saloons, the Taxi, and the Healey have disc brakes, so it is not difficult to fit a Farina Magnette with disc brakes. If you do fit them, you have to obtain a set of MGB steel disc wheels, as the standard ones do not clear the caliper. Who was Sid Goble? Well, Gerald Palmer designed the 'Z' series of Magnettes, and whilst Pinin Farina styled the BMC mid-range saloons, it was Sid Goble of BMC who put the badges onto each model. Sid did not design the Austin IFS system, that was a corporate job by the Austin Design Office at Longbridge for the 1947-48 Austin Devon, Dorset, Somerset, Hampshire and Hereford. Rebuilding the front suspension of a Farina Magnette is not fraught with the problems of the older 'Z' Magnette. Spares are reasonably priced and plentiful. Whilst the inner lower wishbone used silent-bloc bushes, the outer end used hardened steel cups running on a threaded fulcrum shaft. These cups are located in the suspension arms by cotter pins, just like a bicycle pedal arm. The threaded fulcrum is itself located in the bottom of the king pin by a smaller cotter pin. ( A cotter pin is a tapered steel rod with a thread one end. When tightened up it pulls up and locks the two items together.) The king pin is a simple affair running in sintered bronze lined steel bushes. These are easy to fit, but require in-line reaming. In true ' Austin' fashion, they are different sizes top and bottom, so a stepped reamer is required. You can get ready reamed stub axles and new king pins as an exchange kit. The top of the king pin ( also called a swivel pin, ) is held in place by an Armstrong lever-arm damper. This is single acting on the Mk3 and double acting on the Mk4. They look very similar to the one on the MGB. Beware though, Mk3 damper arms are one-inch shorter than Mk4. This is true of the lower suspension arms as well. BMC widened the front track of the Mk4 by two inches by lengthening these arms. Whilst the top trunion is locked to the top of the kingpin, it has a silentbloc bush between it and the damper. This bush has a special bolt holding it in, that also locks into a grove in the king pin top. The Farina king pin looks very like that of the MGB, but not quite as it is thinner and longer.
Faults are that the suspension is a bit over engineered in some places, and under engineered in others. When it was first seen on the 1947 Austin A40, Austin's had a great number of warranty claims. Workers who did not understand how rubber bushes worked, were tightening up the suspension with it hanging down unladen on the production line. To correctly fit silentbloc bushes they must only be tightened up once the suspension is laden, but at rest, ie when the car is parked on the level. A40 bushes were breaking up after only a few miles being almost twisted fully one way under a normal load, strained. The bolts that hold the damper to the cross member can work loose, and dampers are infamous for leaking. Exchange ones are not expensive. If not greased, king pins wear very quickly. This is due to water getting into the bottom bush very easily. Only a felt seal stops it. If you do not grease the suspension every thousand miles, it will soon seize up. If the incorrect shims are placed under the top trunion, you can either lock up the king pin, or give far too much up and down end-play. This will fail the Mot, and let water in. King pin end play is often diagnosed as a worn wheel bearing so check carefully. The two steel cups and the threaded pin wear very quickly if not greased. And if the cotter pins are not tight things will move and become sloppy. Again the cups are not expensive, but can be fiddly to fit. It is not unknown for the rubber silentbloc bushes on the inner lower ends of the lower wishbone to have completely disintegrated. Alas, engine oil is not kind to them, and they live right under the sump of one of Britains best oil leaks, the 'B' Series. On the Mk4 there is an anti-roll-bar. This is rather thin for so heavy a car and can be swapped for a much thicker late Marina/Ital one with a bit of modification. The rubber blocks are often cracked and ready to fall to bits. They cost pence to replace. The under engineered bit is lower pressed steel spring pan. Like its 'Z' counterpart, it rusts away. But unlike the 'Z' which has a steel forging running underneath it, the coil spring just bursts through the bottom and the car collapses onto the road. On the Mk4 the pan is extended forward to take the lower end of the anti-roll-bar. This bends the pan back and forth as you corner hard, eventually breaking away. Because the Mk4 is one inch lower that the Mk3, it has half-inch spacers between the lower suspension arms and the spring pan. This lets even more dirt and salty water into the centre of the pan, assisting further corrosion. A good item to replace and treat to a thick layer of 'waxoyl' is the lower spring pan. As the suspension literally bristles with grease nipples, there is no excuse to not lubricate it all, and often. The service schedule says every 1000 miles. Looked after it will last for years. Neglected it will all soon seize up. Neil Cairns
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