1999 Hyundai Elantra Strut Replacement brief guide

to remove back struts the back seat has to be removed starting with the bottom cushion

then the back cushion

now the strut mounts can be seen and the cap over the spring nut

broad view of rear driver side strut mount

side view of rear strut mount

view of spring nut. make sure to loosen this nut while the strut is mounted  and before removal  otherwise it'll be really difficult to remove the spring safely once the strut is removed 

Once you've loosened the spring nut then proceed to detach strut from rear wheel

broad view of rear wheel

remove break mount and remove breakline from the rear strut

Once strut is removed, compress spring using the special spring compressors.  The two spring compressors should be compressed gradually and carefully to maintain balanced spring compression.

strut on the left is the old one! No longer working . The right one is the new one. Its easily compressed by  hand and it'll return to original form once no longer compressed.

The rear strut: the spring, the mounting bracket, and the mud  guard.

OEM spring  rubber cushions/pads. Good idea to replace them since the old ones are most likely  hard  and worn out.

Use a bottle jack to help mount strut into place by keeping the wheel  in position.