will 89 crx si seats fit in a 90 civic hatch?

 

if you are asking if it is a direct swap with no modification necessary, the answer is no.

they will "fit", but you will have to swap the pans/rails off of your hatchback seats onto the 89 crx si seats. it's not that bad, i swapped pans/rails from my 91 CRX Si seats to JDM CRX seats. took about 2 hours i think... we had to trim some of the foam off of the underside of the seat bottom to get the pans on. you can't even tell once they are installed. save your hog rings and re-use them. needle-nose pliers work nice for prying them open, and closing them again when you put them back on. if you need to, use a small screwdriver to make holes in the seat vinyl where necessary for the hog rings to attach the seat cover to the pan.

NOTE: it is MUCH easier to do if you take your seats apart. by that i mean detach the back of the seat from the seat bottom.