RADIUS ARMS It should be noted that different radius arms are used on 'wet' and 'dry' suspension models. The Hydrolastic arm is most easily identified by the bump stop platform on the top side of the arm and the unthreaded spigot opposite the stub axle for the helper spring attachment. The 'dry' arm has a threaded spigot for mounting the lower end of the shock absorber and no bump stop is fitted. The brake pipe attachment bracket is on the top of the 'dry' arm, and on the bottom on Hydrolastic models. The strut foot housing is also in a different position, being set further forward on the arm on hydrolastic models, but this will be less obvious.
1. Jack up the rear of the car and support on stands beneath the sub-frame side members. Remove the road wheel.
2. On 'dry' suspension models, support the radius arm and remove the shock absorber as detailed previously.
3. On Hydrolastic models, depressurise the Hydrolastic system as detailed under the appropriate heading in this section. Support the radius arm and detach the helper spring from its mounting spigot on the radius arm.
4. Remove the clevis pin and disconnect the handbrake cable from the lever at the brake backplate. Also detach the cable from the abutment bracket at the backplate.
5. At the handbrake cable sector on the underside of the radius arm, lever back the flange at the sector corners where it retains the cable and release the cable from the sector.
6. Disconnect the brake pipe from the brake hose, then release the brake hose from the abutment bracket on the radius arm. Plug the hose and pipe ends to prevent loss of fluid and the ingress of dirt. Ideally, the brake hose should be sealed using a brake hose clamp.
7. Remove the support from under the radius arm and depress the arm sufficiently to allow the connecting strut to be extracted from the spring unit or displacer. Pull the strut rearwards to disengage its ball end from the seat in the radius arm.
8. Remove the nut and spring washer securing the inner end of the arm pivot shaft to the sub-frame.
9. Remove the end finisher panel from the sill panel, where fitted. Remove the nut and spring washer securing the outer end of the pivot shaft to the support bracket. Remove the four bolts securing the support bracket to the sub-frame and detach the bracket.
10. Withdraw the radius arm assembly from the subframe. Retain the thrust washers and rubber seals fitted at either end of the arm pivot shaft.
Installation Installation is basically a reversal of the removal procedure, but special attention should be paid to the following points:
a) Invariably, the reason for removing the radius arm is to renew the pivot shaft and bearings and in this case ensure that both the pivot shaft and bearings are liberally lubricated with grease before installing the shaft in the arm.
b) Assemble the thrust washers on the ends of the pivot shaft with the lubrication grooves towards the radius arm. The large washer is fitted at the inner end of the shaft, and the small washer at the outer end. Fit the rubber sealing ring over the thrust washer and the spigot at each end of the arm. Ensure that neither the thrust washers or sealing rings are displaced during installation of the arm.
c) Tighten the pivot shaft nuts to 53 lb ft (7.3 kg m).
d) Lubricate the strut ball end and the nylon cup in the radius arm with a suitable grease, such as Detragrease Super G.P., before installing the strut. Ensure that the rubber dust cover at the ball end is located correctly around the lip of the nylon cup.
e) When raising the radius arm to reconnect the shock absorber or helper spring, ensure that the strut is correctly engaged at both the spring or displacer unit and the radius arm seat.
f) Bleed the brake hydraulic system as detailed in the BRAKES section.
g) On Hydrolastic models, repressurise the Hydrolastic system as detailed later in this section.
Pivot Shaft Bearings As mentioned previously, the radius arm pivot shaft runs in a bronze bush at its outer end and a needle roller bearing at its inner end. These bearings are a press fit in the radius arm and require special tools to remove and install them. The bronze bush must be fitted first and linereamed to size before installing the needle bearing. A lubrication tube is fitted between the two bearings and must be installed with its small diameter towards the bush.
Because of the work involved and the need for special tools, it is recommended that this job be left to a Specialist Machine Shop who will have the necessary equipment and knowledge to carry out the work successfully.
The pivot shaft and bearings are normally supplied as a complete kit containing all the parts necessary for overhaul.