SILL REPAIR

S

sawdustcaeser

New Member
I'm not sure where to start. This is my first restoration, I've just bought a MIG welder, and i'm ready to rock! I've looked at past threads which have been invaluable, but i'd just like to pick your brains before I start.

I think what i need to do is drill out the spot welds on the underneath where the flange from the centre sill attatches to the floorpan and then cut the inner sill off with an angle grinder about 1 inch from the bottom.
http://i153.photobucket.com/albums/s229/sawdustcaeser/PICT0147.jpg

this is where the floorpan rot extends into the spot welded flange.

I planned to cut around the box section below the B post as it seems solid, rather than remove it, but again there is a little bit of rot where the centre sill is spot welded to the floor pan.

i have attatched some photographs of the main areas of concern. sorry it is such a long post. :)

http://i153.photobucket.com/albums/s229/sawdustcaeser/PICT0162.jpg

this view is from underneath where the box section folds over and is spot welded to the flange of the centre sill.

how easy is it to reve this section by drilling out the spot welds and re- using?

http://i153.photobucket.com/albums/s229/sawdustcaeser/boxsection.jpg

hope that all makes sense!
 
Hi Sawdust,

I'm doing my P6's sills at the moment (& have done several others).

I often wonder about the relative merits of removing whole sills rather than carefully cutting rot out & then welding in new metal. It can be a bit difficult in places, but unless a car is really shot, I would do the repairs rather than replace every time. 'New sills' sound good but do not always produce an invisible job.

Take your time, practice on spare metal using the lowest setting first (& wire speed about 1/2 way) and work up. Weld relatively slowly using small circular motions on the joint as you move the torch slowly forward. You'll soon find the point when you get the speed & current right for good penetration & no holes! Always clean the rusty metal back to good with a grinder or cup wire-brush, etc. The only other thing would be to use large gas cylinders (unless your welder is gas-free) rather than the small disposables - it improves your welding ten-fold in one go! You'll soon be grinning to yourself when you see what you can acheive.

Good luck!

Phil.
 
Just been looking at your photos, do you have any shots from a bit further away, so we can see more of the whole sill ?
 
Thank you for the replies. i think the sills are better patched than replaced, as you say. i am starting with the rear off side. i have cut away the centre sill and drilled out the spot welds underneath. i think i will seam weld to the remaining inner sill, and plug weld underneath. there is some work to do around the jackingpoint before i weld in the repair panel, and i need to make some patches to repair the box section at the bottom of the rear arch.

i think the rot started here, when this panel fell apart, water and mud got thrown into the sill box section :(

i had to laugh when i saw the photo's i posted. obviously I knew what they were but they could be anywhere. :laugh:

here are some better ones of the rear sill.

http://i153.photobucket.com/albums/s229/sawdustcaeser/sill2.jpg

http://i153.photobucket.com/albums/s229/sawdustcaeser/sill1.jpg

http://i153.photobucket.com/albums/s229/sawdustcaeser/innersill.jpg

as you can see, the inner sill has a small pinhole i need to attend to.
 
Good luck with the restoration, I am embarking on one at the moment too - wish mine looked as solid as yours! lol
Will be interested to see the patching you perform
 
Sawdust...

Yeah - I reckon there'll be quite a few of us envious of how solid your car looks!

Good luck!

Phil.
 
That doesn't look too bad, certainly not worth complete replacement sills, just make up some repair sections.

Good luck

Its about time I did some more welding, need to spin the convertible round and get stuck into the other side. Seem to have been filling and sanding these doors/wings for ages....
 
lesson number one, dont think you can get away with anything ???

http://i153.photobucket.com/albums....ear.jpg

see this pinhole here? well i was going to be naughty and leave it painted over with POR15. But then i decided to be a hero and cut the rot out properly and weld a patch over it.

unfortunatley the bright steel i cleaned it back to must be about as thick as a coke tin because its blowing big holes in it.

minimum power, maximum gas (sureshield) big hole.

i've kind of rerpaired it by keeping the mig on the patch to build up as weld pool then trying to drag it over the hole, lanishing it back then repeating the process.

SOOOOOOOOOOO......... should i continue or chop the bugger out and accept that the inner sill is not as good as it looks.
 
i think i've worked out what the problem with the welding is. The patch repair is good solid metal that really needs the power setting 1max or 2 min. The sill that was pin holed and then cleaned with a grinder is now only slightly thicker than tin foil :( and so there is no penetration in the patch, and holes blown in the sill.

the crux of the matter is.... if i effect this patch to the inner sill, and then repair the centre sill and the box sections in the wheel arch, will the strength of the car be compromised.

or am i just trying not to accept that i need to get the grinder into the inner sill as well. it seems rusty but rigid. but disolves to pin holes when cleaned with a grinder.

hmmmmmm
 
Unfortunately you have to cut out the corroded metal until you get to a sound bit. Welding a patch to a piece which is paper thin will not restore strength
 
I had a problem trying to weld my p6 which was probably worse than yours. I had bought a good mig but never got any lessons or previous experience welding.

I found that when your trying to weld and end up BLOWING. the best thing to do was let the torch find the good metal by welding the area until it doesn't BLOW. (hope that makes sense).

You will eventually get knack of it. I would some times just take the torch to the areas I was going to weld to get an idea of how well it would handle the mig welding on to it. when you know how the weldeable area looks you can trim off the duff old metal and make up patches the right shape and size.


Colin
 
well, i'm going to get the old grinder out next week and chop a bit more out! unfortunately i've now also got to fit a helicoil in my lambretta. :( classic vehicles are ace. :D
 
For welding good metal onto rusty stuff. first of all you need to get rid of the rust surface. If its that bad then DON'T use a grinder, use a flap disc, which is much gentler to thin metal. Or at most use a wire wheel. Then when setting up your MIG don't forget to use 0.6mm wire, thats where many go wrong by just using the 0.8mm wire that they got with the welder. The thinner wire is better for thin metal as it goes at lower settings without burning through. Then when you are ready to go, After tacking it in place, carry on that way, just literally do a spot at a time, as if you were just tacking it all around. Do a spot then leave a few inches and go to the next place where the metal is a bit cooler. If you need to you can go over it again. This is called the stitch technique. This web site here is a good friendly place to ask questions http://www.mig-welding.co.uk/thin-metal.htm

Well thats of course unless you have a posh expensive AC/DC TIG machine, in which case ignore everything i've just said about welding thin metal. With a good TIG, even an amateur can be taught to weld a coke can within a few hours, if they have had experience on Oxy acetylene :D :wink:
 
Dont even consider welding to thin metal!! :shock:
Cut it back to good strong original steel,as if you donr the strength will have gone! Also cutting back should eliminate the threat of surface rust that is jusy wirebrushed off starting up again with vengance!!
Sadly too many people just tack or stich a cover plate,"even using old coke cans and biscuit tins" over a rusty hole just to make it look good!!
Thats why when we restore cars we find layers of rusty plates built up over the years! They are condensation traps and dont last long!! if its an area behind the sill,the MOT man cant see it,so many just botch it! Eventually the overall strength of the car will be comprimised and extreemly dangerous.
It is an art to learn how to weld thin,and probably rusty metal,but it is an art not worth bothering with!!
And any weld repair these days has to be done using a continuous weld,that should be done by using the stich method,but eventually joining up the stiches once an area has cooled down to stop warping!
 
pilkie said:
Dont even consider welding to thin metal!! :shock:
Click to expand...

Well i do agree to a point. however sometimes it simply cant be helped. Also it really depends on what ones definition of "thin metal" is. I would call anything less than 18 gauge or 1.2mm, 'thin'. The novice is better off buying or fabbing a new panel. It is easier if you are trained to gas weld, indeed in my humble opinion it is easier to gas weld thin metal than with a MIG. But then i had years of coaxing rusty wrecks through MOT's and all i had was oxy-ace and apprenticed to a mechanic who could weld thin air together, but had no patience to teach me. In those days a MIG was too expensive for all but the best body-shops and certainly no corner mechanic had one. However for a trained welder it can be done, albeit with patience. the aforementioned stitch method is the way to do it.
 
Hi I'm just new on here but was reading this string with interest as I am currently replacing the inner sills on my '67 2000 which had aluminium screwed over the bottom hiding all the nasty corrosion :shock: . I am going down the route of repairing the inner inners but replacing the full outer inners as they are rotten right up past the jacking tubes :roll: , I'm also replacing the D-posts & bottoms of the B/C pillars. I have found the panels from JRW to be a very good fit (with the exception of the base to floor panel) & excellent quality steel which welds really nicely. I will try & post some photos when I can
Regards Colin
 
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