2004 Elantra 2.0 HVT XD Brakes
 

Hi, I am currently replacing the brake discs and have done the front with no problem. So far I have only tried to do the rear R/H but am unable to push the piston back in while using a piston tool. Any advice would be appreciated. Regards

The piston on many (but not all) rear calipers must be turned when pressing it back in. Generally this is the case where the emergency/parking brake is part of the caliper and not a separate drum brake inside the rotor hat. The Elantra does use the caliper as the parking brake and it must be turned to be compressed back in. You need a tool that looks like this:
https://www.alltools.com.au/shop/images/sz/2447.jpg
It goes on the end of an extension on a ratchet and it twists the piston back in (clockwise). Find the side of the tool where the studs best match the grooves in the piston.

See here:
http://www.youtube.com/watch?v=QuLEx...eature=related

2004 Elantra 2.0 HVT XD Brakes
 

Many thanks for your advice and the link to yjre video. Now I know the procedure I am confident I will be able to fit the new pads. Thanks again
Regards Alan