Fitting new car floor pan Advice

[duffman]

I am process of fitting chassis legs into my project car, but floor isn't great in places. So I've bought a new replacement boot floor. So I've been thinking of only using half the floor and butt welding the old half where the fuel tank mounts to the new floor section reason being this floor is to suit a later model and therefore won't fit the original fuel tank I have. I could buy a new tank but talking additional £600.

I have only some experience doing plug welds and wondering if I am going to butt weld these panels together it would be a series of stop/start beads as panels are 0.8mm and warp easily. I've included photos of other people doing the same job of cutting new floor and butt welding to suit older model fuel tank.

Any help appreciated

 

[Nomad]

I recently finished putting new floors in a classic.
For plug welding, overlap the panels, drill holes in one piece then weld though the holes.
For but welding, yes - weld in short beads with a gap between. I ended up welding beads a couple of inches long then leaving a gap for 2+ more beads, then next bead ( hit one, skip 2 or more). Avoid getting too much heat into the panel (not a problem for me - by the time I finished a run of beads the the first ones were stone cold)...

Whichever way you do it, get the panel located, tacked, and make sure both panels are tight together before you weld - it's a lot easier than trying to close up a gap between panels once it's all welded up.

Have fun !

 

[duffman]

I recently finished putting new floors in a classic.
For plug welding, overlap the panels, drill holes in one piece then weld though the holes.
For but welding, yes - weld in short beads with a gap between. I ended up welding beads a couple of inches long then leaving a gap for 2+ more beads, then next bead ( hit one, skip 2 or more). Avoid getting too much heat into the panel (not a problem for me - by the time I finished a run of beads the the first ones were stone cold)...

Whichever way you do it, get the panel located, tacked, and make sure both panels are tight together before you weld - it's a lot easier than trying to close up a gap between panels once it's all welded up.

Have fun !

For the new panel I'm going to have to drill all the holes again along the sides and for the chassis legs. I'll have to scribe the legs and then have to take the floor out and drill everything as I want to weld from inside the boot.

You think leave no gap between floor panels or small gap. I'm going to weld the seam from the bottom side and dress the top side. It will never be seen as it is underneath the middle crossmember of the chassis

 

[Blobber]

It's a shame to loose so much of the new panel but if you have to so be it, leave a gap between the new panel and old, take your time leaving nice big gaps between the welds to try and minimise distortion

 

[duffman]

It's a shame to loose so much of the new panel but if you have to so be it, leave a gap between the new panel and old, take your time leaving nice big gaps between the welds to try and minimise distortion

Yeah I know its not ideal. The only other thing I could do is buy the bigger fuel tank which will cost another 600-700. It will allow the rest of the floor to be fitted though. It's really a toss of a coin which way you do it.

Be a great job though tbf

 

[ajlelectronics]

Yeah I know its not ideal. The only other thing I could do is buy the bigger fuel tank which will cost another 600-700. It will allow the rest of the floor to be fitted though. It's really a toss of a coin which way you do it.

Be a great job though tbf

I solved that with a custom made alloy fuel tank. It also allowed me to use a tank in pump arrangement, rather than having it strung along the chassis a la Middlebridge.

 

[Keithmac]

I solved that with a custom made alloy fuel tank. It also allowed me to use a tank in pump arrangement, rather than having it strung along the chassis a la Middlebridge.

View attachment 483787

I converted my Golf to put the main fuel pump in the tank, instead of the plastic pump housing under the car it left the factory with.

Looks like money well spent on your fuel tank.

 

[duffman]

Small update decided to buy new fuel tank to fit floor pan. Floor now removed and new floor being prepped to be installed. Long road ahead. But I'll get there