Knuckle joint replacement
When you replace a knuckle joint plastic cup, make sure that you check the bottom of the hole in the suspension arm.
It is fairly common to find that, at sometime in the past, the knuckle ball has worn right through the plastic cup, and has re-shaped the bottom of the hole in the arm. If this is no longer a conical shape, but has evidence of rounding (see diagrams), then just renewing the cup will result in premature collapse of the new cup, and a consequent lowering of the car’s ride height.
The only correct solution is to replace the affected arm (but please note that this damaged item will not be allowable for reconditioning). However, if the wear is only minor, here is a trick that might work.
Clean out the hole carefully, ensuring that the little drain hole at the bottom is clear. Mix up some epoxy glue (Araldite or similar), and fill the bottom of the hole. Press in the new plastic cup. The excess adhesive will squeeze out through the drain hole. Leave to set (24 hours?), then reinstall on the car.
Hopefully the epoxy will be strong enough to support the new cup and stop it distorting into the worn area.
Please note that we have not actually tried this ourselves, and would welcome feedback from anyone who decides to give it a go.
It is worth stressing that this is only applicable when the wear in the arm is minimal. We have seen suspension arms where the knuckle joint has worn right through, resulting in complete suspension collapse. This tip will not help those arms!