I have bought this shock off ebay and it needs rebuilding how do i do this

 

I'm not sure what you mean by rebuilding but I know a 300EX shock rebuild is limited to replacing the spring, damper or the bushings where you bolt it to the bike. You can't take the hydraulic damper apart. You just replace it. So, you keep the spring and buy a new damper or keep the damper and buy a new spring.

 

im sorry i guess i shuld have went in to more detail but its the bushings that are shot

 

Ok. It should be pretty easy and not too expensive.. Go here and look up your parts.

http://www.dgy.com/fiche_section_detail.asp

 

Some shocks are rebuildable and some are not. Call WorksPerformance, if it is they will know, and can do it for a reasonable price.