I removed the drivers seat from my 1998 XK8 convertible for refurb. Upon reinstalling it I found what appeared to be some kind of rubber shield that had torn in two. I had to remove the passenger seat to see if I could see the same thing and determine where it came from on the drivers side. The picture is the passenger seat. Is this a primary seat foam support or can I leave it out. I don't know how I could have damaged it by removing the seat so I assume it has been torn in two for some time. Sorry about the big picture I don't know how to shrink it.

1998 XK8 seat base

 

Do you mean the big grey bit under the cushion? If so, that's what supports the cushion and stops you sinking into the frame.

 

That piece is the main support for the seat bottom. I believe it is a common failure point of the older XK8 seats.

At some point Jaguar got smart and replaced that bad idea with a wire frame that will age better.

Not sure what year it changed but my 2004 had the wire version. Looks like this, and does appear to be a swap fit into the older cars. That frame was not sold separately, only as part of the (now unavailable) lower seat frame assembly. It does look simple enough to fabricate one from scratch though.

Seems risky to leave it out and rely on the foam cushion to handle all the weight. A simple foot or knee in the middle of the seat could be disastrous.

 

I wrapped some sling chair fabric around the end support and stitched it to both pieces to reattach the two pieces. I zigzagged the stiches and spaced them out as far as I could so the needle holes would not act like perforations to tear apart the rubber again. So far so good. Going forward I will probably forget about it and won't know if it broke again until the seat bottom falls out. I have to think it had been that way for some time though. If I do find it broke again I will try to fabricate something like yours using some heavy wire and springs. The picture is how I found it. I neglected to take an "after" picture before the seat was reinstalled. Thanks for the updated part info. Still haven't figured out how to shrink pictures.