advice needed on chassis weld.

[dandare]

hey peeps, firstly hello. this is my first post.
i'm new to mig welding, i've had a few trials and errors on my transit van, mainly errors but it's getting better, with alot of help from the tutorials and forums.
i have, for me, a big job to do on the van. it has to be done asap as if the van gets a pull it'll be taken off the road.
my girlfriends dad, is letting me use the garage he works at on saturday, so i should have all the equip needed at hand and her dad to keep my right.
here's the damage:

it's where the rear mud flap attaches. the wood floor( white stuff in image) has been cut away to give acces to the hole in the floor pan.
i've made up a half box section for the chassis hole and have panels for the floor and the inner body.
i'd like to know what you think is the best way the do it, easiest?
which order to do the sections in as they attach to each other?
or should i just leave it to her da until i get better?
i like the idea of learning by doing so i'm happy to give it a bash.
ta
dan

 

[peterd51]

Hi,

it depends...

I'd attach the chassis first as it's heavier and it'd give something to support the other bits as I placed them.

However it's difficult to see from one photo if that chassis position is fixed in any way or if it has a 'floating' end, ie, you're not sure of the exact position it needs to be in.

If this is the case then you may want to tack everything together and make sure it all fits before running continuous weld.

It's easier to grind off a tack than a full weld!

I'd also be tempted to chop the bottom section off and put a new 'full' box section in with a couple of larger pieces of new metal plating...multiple pieces as it's easier to get around corners, etc.

You need to ensure you get rid of all the rusty bits and weld onto clean metal.

Can you get a couple more photos from different angles?

I bought a Tranny once with a couple of holes in the floor. After cutting out all the dodgy stuff I had to use 18 square feet of plate to sort it!

Regards
Peter

 

[dandare]

thanks for the speedy reply.
i was thinking of doing the box first, then the floor but i can't get my head round once those two are done how i pull the inner body panel on the left into meet the end of the box section, i was thinking of a flange similar to the one that's still? attached and using a couple of rivets to pull them together then filling the drilled out rivets?
when you say to chop off the bottom box and put a full section. do you mean the full U? shaped section with flanges the lot?
dan
oh here's another picture, maybe help a little,

i've also cleaned up most of the metal. the half cleaned up piece in the above pic seems ok, thats what made me think to weld onto that, bend at the corner and then up to the floor pan. i suppose doing the full bit is the right way to do it. i should be able to make it up in work tomorrow so it's no great hassle.

 

[Towing and trailers]

first of all get some clean 1.2mm plate this will be easy to weld do not buy .8 galvanised sheet from your car spares shop.
Treat each face as a seperate plate.
I wold go for the one at the side of the chassis member first get a grinder and clean the edges spot less if you gring through the crap and see any trace of rust move out until you are getting clean metal. if you find a bit of rust and try and gring it out you are making the metal thinner making the steel thinner meaning in a year it will rust again.at the side of your plate.
then cut all the rusty bits out these are not going to do you any good they will promote more rust.
remove the end of the crossmember out so that you can get your tirch around the corner inside then slide the plate up the side of the cross member and tack it in. then work round it making sure the edges are touching by tapping it with a hammer. if you have not remmoved all the rust the hammer will.
then weld it do runs of about 3 inch a time and move 6 inch away from the last weld so that you are not welding continiously as this will reduce schrinkage once you have been all the way round ie got 3 inch miss 6inch all the way round then check that you have not got any gaps between your plate and the parent metal. then tack in the middle of the 6 inch gaps then repeate the process doing more 3 inch runs then repeat and fill in the last gaps.

then repeat with the nearest side of the chassis to (one with big hole) when you make this plate bend the edges at 90deg to lap on tho the other faces so that you can get a goog joint weld in the same process as above.

do this on any rust I can not see.

give it a good coat of stone chip then underseal.

waxoil onside if there are any inspection holes.

then watch it out last the rest of the vehicle.

Pete