Leaf Springs
for AC's post-war 2 Litre Saloon
Rear springs were part number A336C made by Jonas Woodhead & Sons Ltd. The data shown here comes from one of their drawings dated 25th June 1946. I've heard that there was a later design of spring, and my own AC was fitted with a variation on the A336C spring. It is described further down this page.
Free Camber - important note
The specification on free camber of this spring was changed on 16th May 1949. This followed the addition of a flat rebound plate to the top of the spring (specified from 17th March 1948). Originally the free camber was 6.25 inches, but this changed to 5.75 inches. With the rebound plate removed, the camber increases to 6.25 inches. Unfortunately, all the AC handbooks simply quote "6.25 inches".
So, 5.75 inches is the figure you want, which will reduce bottoming of the axle against the chassis. This is measured to the top of the main leaf and not the top leaf.
Camber under static load = 0.875 inch (tolerance of +0 / -0.25 inch)
Length when flat = 42 inches (between pivot centres).
Leaves are 1.75 inches wide and 7swg (0.18 inch) thick. 11 leaves in total including 3 dampers above the main leaf.
Spring rate = 16.10 inches per ton.
Static deflection = 4.89 inches with 680lbs load.
Silentbloc bushes fitted to both ends, type E2073: Outside diameter = 1.00 inch. Inside diameter = 7/16 inch. Length of outer tube = 2.00 inches. Length of inner tube = 2.125 inches.
Later rear springs: The springs fitted new to my AC in 1960, differ in design slightly from that in the Woodhead drawing that I have. The difference concerns the bottom two leaves. On this later spring, the bottom two leaves are the same length, and have a long taper at each end. The bottom leaf is also much thicker (2/0swg / 0.348" / 8.8mm) and completely straight. The extra thickness would have slightly increased the axle-to-chassis clearance. Being straight and stiff, it would have increased the spring rate on a severe bump before the axle hits its stop.
The front springs were by Jonas Woodhead & Sons Ltd and were fitted from 1947, possibly up to 1952. The data shown here comes from one of their drawings dated 12th June 1945. Many ACs will have had the later type 535C springs fitted during overhaul.
You can identify the early type by the presence of shorter leaves above the main leaf, and there are 5 clips.
Measuring the camber is not straight forward, because only the front end has a conventional pivot-eye. The rear end slides in a slipper arrangment, and thus has a plain end. The reference line for measuring camber must be drawn from the front eye, to a point 1.5 inches from the rear end.
Free camber = 3.875 inches, measured to the top of the main leaf (not the top leaf).
Camber under static load = 0.875 inch.
Length when flat = 36 9/16 inches (from eye centre to rear end).
Length from eye centre to centre bolt = 18 1/32 inches.
Leaves are 2.00 inches wide and 7swg (0.18 inch) thick. 9 leaves in total including 2 dampers above the main leaf.
Spring rate = 9.95 inches per ton.
Static deflection = 3.02 inches with 679lbs load.
Bushes: Outside diameter = 11/16 inch. Inside diameter = 1/2 inch (tolerance of +0.0005 to +0.0015 inch). Material is labelled as "G.M." (which I presume is gun metal?).
Front Springs - Later Type
The later front springs were also by Jonas Woodhead & Sons Ltd, part number 535C. The data shown here comes from one of their drawings dated 27th August 1952.
You can identify the later type of front spring by the absence of any short leaves above the main leaf, and also there are only 4 clips (rather than 5).
Free camber = 3.50 inches.
Camber under static load = 0.50 inch.
Length when flat = 36 9/16 inches (from eye centre to rear end).
Length from eye centre to centre bolt = 18 1/32 inches.
Leaves are 2.00 inches wide and 7swg (0.18 inch) thick. 9 leaves in total.
Spring rate = 9.95 inches per ton.
Static deflection = 3.02 inches with 679lbs load.
Bushes: Outside diameter = 11/16 inch. Inside diameter = 1/2 inch (tolerance of +0.0005 to +0.0015 inch). Material is labelled as "G.M." (which I presume is gun metal?).
