There are a lot of parts to assemble in order to complete the rear suspension:

DeDion tube: The ‘Ears’, Rear Hubs, Discs, Drop-link brackets Speed Sensor and Rear Brake calipers all mount to the DeDion Tube. Before installing I gave the inside of the tube a liberal coating of ‘waxoyl’ anti-corrosion spray.

The rigid copper brake lines have to be attached to the DeDion tube using P-clips riveted to the tube itself.

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Radius Arms: The radius arms control the rotational movement of DeDion tube and affect the ride and handling. One end of the radius arm mounts on the chassis and the other directly to the DeDion tube. There are two mounting points on chassis, we used the lower one as this is an ‘R’ spec car (the upper mount is used in ‘S’ spec cars and give a slightly softer ride).

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A-frame: The A-frame controls the lateral movement of the rear suspension. The apex of the A-frame mounts onto the centre point of the DeDion tube and must be carefully spaced so that the distance between the face of the DeDion Tube and the chassis rail is equal on both sides. This required a lot of careful measuring and the use of spacer washers between the A-frame and chassis mounts. Whilst the spacing has to be equal there must also be no play between the A-frame bushing and the chassis rail.

By this time in the build Michael & I were getting used to using pin-punches and the nylon dead blow hammer to install tight fitting washer / spacer packs.

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DeDion Ears: These are nicely machined aluminium mounting brackets that attach to each end of the DeDion tube. The hubs and one half of the brake caliper assembly mount onto the DeDion Ears. The only way to adjust rear toe in / out on a Caterham with rear DeDion suspension is to fit shims between the main tube and the ‘ears’.

After about 500miles all the suspension parts should have settled in and I will get the suspension professionally setup (toe-in, bump-steer, ride height). Chances are that rear-shims will not be needed but in case they are I chose not use silicone sealant between the Ears and the DeDion tube as illustrated in the manual as this would need to be scraped off and could interfere with the shim spacing.

In the main picture above the two DeDion Ears are on the bench by Michael’s left hand with one of the hubs just above them, a rear brake caliper and rear disk are further to the left.

Rear Dampers: The bottom damper bolts to the DeDion tube and the top is bolted to the chassis directly underneath the track-day rollbar fixing bolt (the track-day rollbar has to be fitted before the rear dampers)

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Rear anti-rollbar: The rear anti-rollbar is a torsion bar that is connected to the DeDion tube via drop-links. Installation is a little tricky as the orange flexible bushing needs to be threaded onto the tube which involves passing it over a rectangular flat bar section and a 90 degree bend. Silicone lubricant and a flat bladed screw driver helped to persuade it into place. The two part aluminium chassis mounts have a nice ‘7’ machined into them.

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Drive shafts: One end simply pushes into the differential and the other goes into the hub bearing. The drive shafts are handed so it is important to get them the right way round.

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Assembly: There are a lot of bolts and washers involved in this part of the build so it is really worth laying them all out on the bench before starting to make sure the right length bolt is used in the right place.

Flexible Brake Hose: A braided flexible brake hose runs from the chassis to the T-piece on the DeDion tube. IVA regulations stipulate that this hose must have additional protection and so a piece of rubber fuel hose is split longitudinally, passed over the hose and cable tied in place.

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Rear Brake Calipers: These come in two parts as it is a floating caliper design. The floating part of the caliper goes over the brake disk and is located with two dowel pins on the fixed part of the brake assembly which control the movement. Interestingly the rigid copper brake pipe connects to the floating part so there will always be a little movement in the brake pipe.

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Speed sensor: The speed sensor is a tiny threaded rod with a cable attached to it. The speed sensors goes inside a nylon ‘top-hat’ spacer that mounts onto the right hand side drop-link bracket. The right hand drive shaft has a toothed ring mounted on it and the sensor ‘senses’ each tooth as it spins past. The gap between the speed sensor and the high points must be between 0.8mm and 0.9mm.

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This was quite fiddly to setup but I was able to check it later in build when I connected up the electrical system. There is a tiny LED in the base of the sensor that lights up as a tooth passes underneath, it worked as I rotated the wheel by hand, let’s hope it works on the road.

Hand-brake cable: The hand-brake cable is one of the most awkward parts to fit. Each end hooks over a claw on the caliper body and the only way I could do this was to slacken the adjuster off as much as I could and use a pair of locking jaw pliers to wrestle the terminal eye over the claw.

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The second difficulty is in finding a secure route for the cable that avoids fouling the driveshafts, brake and fuel lines and any moving parts of the suspension. I eventually used a P-clip on the boot floor rail as a guide and then had the cable loop underneath the drive-shaft and round to the caliper. I secured the handbrake cable to the chassis rail with cable ties and hope that this arrangement passes the IVA inspection.

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