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Independent front suspensions |
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By the 1950’s the Austin beam axle was an old design with limitations even when modified into a lowered sports shape. Independent suspension units were fashionable in the ‘50’s both on new cars and as something to add to your special. Unfortunately they work best on a very rigid chassis, not something the Austin 7 chassis is renown for. However if you wanted your car to reflect the ethos of the time, this was the thing to have. |
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A wider steering cross tube is used with the wider axle. SPEEDEX and Bowden track rods were threaded to take Ford 10 track rod ends to cope with the articulation of each separate side—the A7 ones won’t work with this set up. Steering arms had to be taper bored to take the tapered fixing. They can fit in either side, the correct way is with them inclined downwards and pointing in towards the chassis, the track rod end tapers then enter from the bottom all of which lowers the cross tube so it doesn’t foul on the chassis. You’ll probably notice that the IFS cross tube has less of a down sweep in the centre for this reason. You can tell if they’re on the right way round from the little square ‘stop’ on each arm, it should butt up against the axle behind the king pin. Arms should be very tight in the stub axles, the offset of the track rod end can tend to rotate the steering arm in the stub axle. If necessary drill and tap through the stub axle just catching into the steering arm and fit a grub screw. Austin’s had a similar problem with their Sports models, these had lowered steering arms to match the lowered axle. However this produced a turning moment on them. Their solution was to cut small keyways in the stub axle with keys in the steering arms.
New Ford track rod ends can be obtained from Small Ford Spares
The Cambridge IFS has a straight cross tube with a different (and as yet unidentified) set of track rod ends, the steering arms are also cranked like the sports ones and the drop arm reshaped to clear the suspension—see the picture above. |
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The most popular type was the Bowden twin spring type with two springs one above the other, the axle ends clamped between the ends. SPEEDEX like all the tuning firms produced their own version of the suspension unit. Their version only had one spring with two tubular arms forming the bottom joints, this followed a similar theme to an earlier Dante design. A Cambridge version was more complex and had a bottom spring and tubular arms as the top joints with special articulating radius arms back to the chassis side members near the rear of the engine. Note the neat front shocker arrangement, it fits unobtrusively on the ‘conventional’ type A7 special. Those shockers are quite short! This set up has the advantage of not needing radius arms but does involve drilling the side of the chassis members—getting the nuts in isn’t easy if the chassis has been boxed!
SPEEDEX IFS’s were available in two widths, standard 3’ 5” to fit underneath the wings of a standard car and a wider 3’ 10” to improve road holding on a special and giver a wider stance matching the width of a later back axle.
They all bolt onto the standard chassis in the same way with two U bolts but everything gets more complicated from there on. One thing to watch out for with the SPEEDEX type is the alignment of the bottom part to the top spring with the central bracket. They’re not a close fit together and you can end up with positive camber on one side and negative on the other. Slacken the U bolts and wiggle about until they’re the same both sides then retighten. |
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Bowden IFS with twin springs |
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SPEEDEX IFS with top (red) spring and bottom links. Note the frame to mount shockers and the water pump |
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Cambridge IFS with bottom spring and short articulating radius arms. Note the chassis bracket to mount the top of the shockers and the radius arm brackets mounted on the side of the chassis rails. |
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IFS axles don’t have the holes for the Austin friction dampers so you have an alternative arrangement. It was normal to fit telescopic shock absorbers, Mini front ones make good replacements of the bulky Woodhead Munroe originals. These have rubber bushed eyes, the bushes should have a steel tube down the centre, the bore of this can be 1/2” or 3/8” to match the fixing bolt that should nip it and slightly compress the rubbers. A frame is needed to firmly anchor the shocker tops. I can help with a SPEEDEX type frame as in the picture above if you need one, one of the owners has sent me a dimensioned sketch. The Bowden type frame is shown to the right. An alternative may be one of the twin friction brackets that are popular with A7 racers. |
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Radius arms will fit straight on for the standard width but the wider track one, which most seem to be, need two mounting balls spaced 4” apart, 2” either side of the centre of the cross member. However the rigid fixing between the radius arm and axle acts as a very stiff anti roll bar giving difficult steering characteristics. It’s better to have radius arms that articulate at both ends. |
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Telescopic shockers are sized on the stroke between fully open to fully shut measuring between the centre of the eyes.
Cambridge Woodhead Munroe 8 1/2” to 11” Bowden Woodhead Munroe 11 1/2” to 18 1/2” Speedex ? ? Mini fronts Various makes 8 1/2” to 11”
Vauxhall Viva shockers are also said to be quite short so may be useful.
Some good news; although the king pins probably have a harder life in an IFS unit they’ve probably also had less years of abuse and tend to have more metal around the eye compared the A7 beam. I’ve never found one with a stretched axle eye as is so common on the standard axle beams. On the ones I’ve done, new pins are a good fit, maybe testimony to good accurate manufacture as well. |
