I found lots of rust under the crossmember that also supports the back seat. The rust is severe on the passenger side. I was looking at a post last week that showed how one member repaired and reinforced this area but can no longer find it. If anyone has any links to a post that shows how this area has been repaired, please post them. Also, how do the guys that race Spider beef up this location or is it best to go back to stock metal thickness? If there is a better way than back to stock to improve this area, now is the time to do it! After looking for a good link with photos showing how to repair rust in this location, I decided to just jump in and fix it as best I can. I will add photos as I go along.

not the best pic but it gives you the idea. cut out everything that's rusty, weld in new sheet metal, 1.2mm thick or simmilar.
http://i43.tinypic.com/eqwitk.jpg
keep in mind that on he underside that's where rear suspension mounting point is

you'll find this very usefull although it's for sedan
http://postimg.org/image/9cvkiptl1/

Thanks for the links! I would like to find some photos of how others boxed or reinforced the mounting points for lower control arm mounts and if the used the factory crossmember/seat support or fabricated a new one.

It looks like the rest of the metal is in great shape, could you simply cut out the bad metal and weld in new pieces?,,,,bare in mind I am not a welder!! Can you reuse the cross brace or did it get to damaged during removal?

If I can't find any information on beefing up the area then I will just cut out the bad sections, lap weld in new metal and put the old crossmember back in. I just wish I could make it stronger while it is open, I am thinking of adding a smaller crossbrace under the factory one on each side that goes from the inner rocker to the transmission tunnel hump.

no need for that really

After looking for posts showing how others repaired this area, I jumped in and started cutting out rust. It took 4 hours to get to this point. The floor pan is going to be replaced next but now it's needed to locate the bottom of my patch panel.


The hard part was getting the location/angle/height correct for the lower control arm mount and the curve of the panel correct. The repair panel was held in place with sheet metal screws until it was tack welded in position. I lap jointed the top 3/4" and tack welded the seam on each side and plug welded the seam in the center. The screws are removed one at a time and the hole filled (I still have a few screws to remove).

Looking good so far

I now have the patch panel welded in, so on to the passenger floor.


My car is a '79 but I am removing the catalytic converter hump and going with a flat floor on the passenger side. Also all the repair panels I am fabricating are 16 gauge (.063") material and I'm using a 5/8" overlap where possible for all joints.


The floor panel in position but not tacked in yet.