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Chassis

A 1931 TK 12/60 chassis frame after restoration

Alvis chassis are all inherently strong except for some of the very early side valve cars which can suffer chassis breakages. On the pre-war cars serious chassis rust is very rare indeed even on grossly neglected examples. Surface rust is inevitable but usually trivial. The ones to watch are the 12/70 and Silver Crest where the ends of the chassis are boxed and can harbour rust-inducing muck. This applies more strongly to the TA 14 where the boxing was extended further along the side members. The Three Litre models need much more care, with their completely box section side members devoid of lightening (and ventilating) holes.

Speed 25 SC front suspension and brake - from the Instruction BookThese chassis are also made of much thinner gauge material than the Forth Bridge type pre-war stuff. The bottom closing plate is spot welded on and moisture accumulates within, congregating at the lowest point just behind the cross member before the frame sweeps up over the axle. This is the commonest area for corruption, but holes can appear almost anywhere, usually on the side members just above the bottom closing plate flange. A favourite place for this is on the inner nearside member. One of the exhaust silencers sits very close to this and the heat loosens the paint and underseal here. The corrosion can run all the way along from the front to the back and is very effectively concealed by the silencer. It is difficult to check the straightness of the chassis without much time and energy, and many if not most cars have suffered accident damage at some point. Check visually for obvious damage and whether the car tracks straight and true on the road test as an Alvis should.

Front axle and backplate of 1932 Silver Eagle TD 16.95 - from the Instruction Book.Suspension and brake components are robust and availability good. There are several firms who can make new leaf springs to pattern, and most of the moving parts such as king pins, bushes and so on are available or simple to make. Some of the '30s ifs models used needle roller bearings on the wishbones, but these are available, as are more robust bronze bush substitutes. Wishbones on the Three Litre are pressed steel and rot prone, but available. It should be noted that suspension work on these cars needs care: the threaded pins on which the outer joints articulate wear rapidly if not generously lubricated. The whole king pin assembly must be dismantled to replace them, and this can involve oxy-acetylene and strong language. Conventional methods of cramping the springs are useless as the springs are very strong indeed and cannot be jacked (the whole car will ascend). The proper extra strong spring compressor must be borrowed, made or hired. On the pre-war models and the TA 14, the condition of the king pins and steering components can be checked by jacking up the front, brakes off and suitable chocks in place.

Front chassis of 1932 TD 16.96 Silver Eagle - from the Instruction BookAny movement here indicates wear in king pins or hub bearings, more than about an eighth of an inch is not good and likely to lead to MOT failure. Sometimes thick grease pumped in will disguise the problems sufficiently to fool the MOT tester. These days they are seldom familiar with older cars and their ways. Now grip the wheel at 3 and 9 o'clock and rock again to see the wear in the track rod ends, drag link and steering box, noting how much rock there is before the steering wheel moves. There should be no play at all in the ball joints, but a bit of play in the box is normal after years of hard use, say half an inch at the steering wheel rim. Nil play can be achieved if all is perfect. Pre-war models (mostly) used track rod and drag link joints with lignum vitæ inserts which are self adjusting to a degree.

The pre-war independent front suspension using the single transverse leaf spring has merited articles to itself. Models using this system can develop a tendency to front wheel tramp, and cure may be difficult: there is no single certain cause and a combination of slight wear in a variety of components seems to set it off under certain conditions. On the other hand cars with well worn parts may not exhibit the fault at all. Overhaul of king pins, suspension and steering joints, steering box, springs, shock absorbers and the chassis frame may be needed to effect a cure. The rear springs must be included in this since their camber affects the castor angle at the front. Loose chassis rivets seem to be a factor and must be dealt with.

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