Rust in the floor and boot rubber channel

[Philby]

Hi All,

Well I’ve been too busy over the past couple of months to do pretty much anything and now I have some time to tackle a few jobs on my FC (daily driver). 

Firstly, I’ve cut out a rust spot in the Left Rear floor pan and I’m ready to weld in a plate. I’d like to do this myself, however I’ve only got about 10 hours welding experience after doing a course and this would be my first actual job. If anyone can provide guidance on how to weld the plate in it would be greatly appreciated. The section cut out is about 15cm x 40cm and I’m now unsure if the plate should go on the underside or top side? Do I weld the entire plate or leave some gaps and fill them? Etc…etc..

Secondly the boot rubber channel has a few spots of rust and I’m wondering what the easiest fix is for this.  I’ll need to replace at least 20cm of the channel where it’s badly rusted.
I’m grateful for any and all advice.

Cheers,
Phil

[mcl1959]

it's far easier to put the plate on top and weld around the top. Don't leave gaps. Are you using a mig or Oxy?
A mig is OK using this method but I prefer Oxy. You need to use a seam sealer underneath once the welding is completed, then paint.
By far the neatest results are obtained by butt welding the new plate to the old floor using an Oxy welder and a hammer and dolly. You can achieve a finish which looks as if a repair has never been made.

Ken

[waynos]

ken,
what are your thoughts on tig over oxy?
theoretically they are much alike( but argon produces a better weld in my eyes because the weld is shielded from impurities unlike oxy welding.
i love oxy and anything old school but i lean towards tig cause there is much less heat involved hence less warpage.

[Johns]

Welding plates over holes does not produce a good result. So called butt welding is the best option, the lower the heat the less distortion and the better the finished job. We used a pulse welder for Nevs floor pans, low distortion and a very neat result.

Here are the details http://fefcholden.org.au/forum/index.php/topic,10350.0.html

If you are not an experienced welder the results may not be very satisfactory.

Cheers
John

[mcl1959]

I am answering Phil's question firstly - I agree that plating over holes is not the best but with only 10 hours experience and your first job, this is what I would recommend. I like Tig as well but the arc still bursts through thin metal easily. I guess 20 odd years of experience with Oxy over maybe only 2 with Tig makes me lean personally towards Oxy because I can do it better.
But everyone has different experience and preferences so each story will be different. For anything other than sheet metal, I would use Tig everytime.


Ken

[pedro]

G'day Phil, all of the above are good suggestions, but as you haven't had much welding experience you would be better going with the overlap method, it gives you a bit of thickness to weld to and even if it's not done really well it can't fall through, i usually leave 10mm or so, then weld the top and the bottom, the most important thing is to make sure you remove all the paint etc. so you are welding bare metal, oxy, mig or tig are all good depends on what you can get your hands on, don't do long welds or you can put too much heat in and warp it, tack all the way around first and slowly fill in the gaps swapping from a hot area to a colder area, if you start having trouble with warpage have a bucket of water and a rag ready, weld a few mm then hit with the soaking wet rag, repeat until finished, have fun.
                                                      Pedro F4+

[JB]

Plenty of great ideas here Phil,

What i was shown when i first started was to place the plate over the hole, and the to screw top to the bottom with metal thread screws. Then with the 1mm cut off wheel, cut along one side of the new piece so the the old bit falls away i.e the underside, then push the new piece down a litle to create a butt weld. Tack this into place with a mig, and then conitinue this process until all four sides are tacked into place. When you have done this remove the screws and you should have the new piece totally tacked into place ready to continue to weld up. It won't be as clean as kens suggestion (Oxy and hammer finish), but will finish better than just placing the new over the old and welding up. The best part is that you are starting on a floor piece which doesn't really get seen anyway.

Hope this helps a little,
Cheers
Jason.

[Philby]

Hi all,

Thanks very much for all the advice.  I'll let you know how I go with it all.

Cheers,

Phil