Drivers side floor support repair

The drivers side floor support is split where it transitions from the rear of the frame rail to the firewall. I suspect this is due to the fact that the entire area seems to have been patched at some point in the cars past. It also looks twisted, presumably as a result of torque causing the chassis to twist (this may also explain the crack in the windscreen). On close investigation the floor support is not correctly welded to the floor and it appears the frame rail does not correctly sit against the firewall either.

Solution? – Replace the floor support!

I ordered a set (in case I need to do the passenger side later) from CJ’s before starting to remove the old support. It’s going to be difficult as its (presumably) welded to the tunnel support plus its plug welded in dozens of places on the frame rail (queue the purchase of a weld cutter tool). I also have to work out how to do the inside edge, especially as the fuel & brake lines run right behind it.

To start with I used a stiff scraper to remove as much of the flaking paint, dirt and underseal (Liberally applied, I suspect to hide the disaster lurking beneath!!). This revealed that it wasn’t attached to the floor support on the outside edge. It looks like the welds have given way or they were non existent to start with (It looks like a portion of the floor pan has been replaced in the past). I then used a sanding disk so that I could see the welds connecting it to the frame rail.

I was pleased with how the spot weld removal tool worked (although the drill I was using was under powered). I then used the appropriate tools (screw driver and a hammer!) to peel back the steel before moving on to the next spot weld. You have to be careful not to cut the steel behind, which I managed to do twice however I’m going to need to patch the rail so I’ll be cutting a lot of this out.

The frame rail itself looks ‘ok’ which is a relief, however you can see that the bottom of the rail doesn’t seem to be connected to the side. The underside is pretty bad with a hole towards the front of the above picture.

A bit more hammering and prying and I was able to remove the outside of the old floor support from the frame rail. This has shown that the bottom of the rail is not welded to the sides (old repair??). What’s worse though is the inner side is blown through with rust, as is the bottom side. All this will need to be cut out and patched.

I can’t do any more work until I move the fuel line, rear brake line & hand brake cable, all of which connect and run right by the frame rail. I was able to move the brake lines reasonably easily without disconnecting/draining. The front portion of the fuel line was a pain but is now removed.

I then started cutting which was really satisfying. Most of the mangled rusty steel is now out. I then cut the patch panel (from CJ’s) to roughly fit. I’ll be working on tidying up all the cuts and getting this to fit as best as possible whilst I learn to weld!

I have been working on how best to patch the drivers side frame rail. I’ve decided upon a blend of plug & seam welding to ensure the strongest possible fix. You can see the patch panel pushed up inside the frame rail below. I’m going to trim to ensure the front is below the flanges which will be welded to the toe board, drill holes for plug welds and then seam weld the heck out of it. Once that’s done I’ll be able to add the floor support which I’ve test fit as you can see in the last few photos below.

19th December 2021 – Well, today was a long time coming. I decided to attach the floor support to the patch panel which meant I didn’t need to do that welding when it was on the car. I started by drilling a load of holes for plug welds, grinding them flat and then clamping it all together before welding.

I finished the plug welds on both sides and the bottom of the floor support, waited for it to cool down and then ground them down before spraying a coat of weld thru primer to protect the metal. I’m really pleased with how it came out. I now have to work on fitting it so I can move on to the torque box install.

I marked and then cut all the holes I could using the spot weld cutter in my drill. I have a clearance problem on the transmission side so have to figure out what I can do. I have a right angle drill bit somewhere….

I managed to cut the remaining holes using a drill bit and a slightly smaller drill. The fit with the transmission brace is ok and the new floor pan sits on the support flanges. Now I need to drill the holes in the bottom of the support so I can spot weld it to the transmission support flange.

After cutting the final spot weld holes I started welding. I started with the transmission flange and then completed the outside before crawling under the car (not the easiest place to weld!) to complete the engine side. It looks messy but most of this will be hidden by the torque box when I get around to installing it.

It’s very sturdy but I will grind down the welds and redo a couple of spots but I’m calling this done.

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