hi all. Does anyone know which is the harder material out of the rear shocker shoulder or the top mount?

I have a Hawk with knocking rear top mounts and it's driving me mad on the daily commute. I'm wondering if I replace just the top mounts themselves if it will fix problem. Looking at the top mounts they have worn slightly but it's difficult to see if the shoulder of the shock has worn also.... Overall to me the design seems a bit flawed as the the shoulder only has about 1.5mm of engagement inside the top mount, at best.

I'm looking at these parts on amazon http://www.amazon.co.uk/dp/B00CEFF53...I2RA54XXX37YKG


Cheers!

 

Euro car parts does the lemforder bushes and they are very good.