If you are reasonable competent with your welding and take your time it should be fine, just don't set fire to the place.
thanks @Twink80 - I think I’m going to first clean more and cut out some segments to see if I can create some easy shapes. I have cardboard for making templates - and yes I think I’ll have to get creative about the trans support member bolt locations - maybe even get new metal in and then reestablish those points with new bolts…
(laughing) not the first nor last time I’ll be all-capsed, I am sure. Challenge is the stuff that was applied to the metal - I think it’s old seam sealer of some sort - a thick layer that is a bear to remove just to see if the metal is good. Yuck! I’ve got a grinder and pads that I’m putting to the test…Yeah, cleaning more sounds like a good idea, this way you'll be able to SEE WHAT YOU'RE DEALING WITH..
Sorry, I think my finger accidentally hit the CapsLock key...
(or maybe not, there's a giveaway clue in what is written, try it and see...)
I have found the twisted wire/wire brush on angle grinder works fairly well. The trick is not to get the sealant too hot as it sticks even worse then.
Thanks @bugsymike - I have a hefty one of those twisted wire wheels - will take your advice on protections!I have found the twisted wire/wire brush on angle grinder works fairly well. The trick is not to get the sealant too hot as it sticks even worse then.
The other benefit is it only removes the rust plus sealant and not the remains of the metal, but leaves shiney metal to weld too.
Goggles are advisable as the wire strands can break off and penetrate the body etc. I often found strands stuck in quite thick overalls.
) and tend to tackle one relatively small area at a time. Remember that and depressions/hollows pressed into the floor pan are there for a reason e.g. to allow big feet to operate the pedals (Jaguar made this mistake on the early, so-called 'flat-floor' XKE types and had to incorporate a step down for this reason - strange that collectors will pay a lot more for these very early cars, I hope they've got smalll feet). Also, if you omit these depressions, the original carpet may not fit so well.
Thank you, @124BC1 - I’ll try some approaches to getting the coating off and report back with photos. And I’ll be noting the factory bends and recreating them when needed. You are correct about the cross member from tunnel to rocker panels: those seem good on both sides at the moment, however the seat rails that are integrated across the crossmembers are not in great shape (esp on driver side).To remove the original (factory) bitumen coating on the floor panels inside the car, I used an old wood chisel and mallet (I was hardly going to use a new chisel, was I? and note I did use a mallet, not a hammer - I'm not a heathen!), this took a long time but was controllable and I didn't sustain any injuries.
Some people recommend using a hot-air gun to soften the coating and then remove as much as possible using a decorator's scraper. Some say that using 'dry ice' will make the coating brittle allowing it to be shattered by a hammer blow. Others might recommend using an air chisel or maybe an air-operated needle de-scaler but these will likely punch holes in any weakened metal, plus you may injure yourself... Experts will say sand or soda blasting is the only way but I realise you're working at home (strange that these experts are the one's offering this service for a fee....).
I'm always in favour of minimal cutting out when repairing rust damage (have gotten myself into mucho trouble by cutting out large chunks
If you do however decide to buy and fit replacement floor pans, check if they are high enough at the sides to attach to sound metal - the rust often extends above any original perimeter turn-up/attachment, so you might have to make up repair sections to install at the sides before fitting the new floor pans.
Afaik, floor pans are usually installed from above - under the floor pans are various pressed steel strengthening members which will need to be retained or remade if they don't come with the new floor pans, plus consideration has to be given to the seat rail mountings etc.
Before cutting away any metal, it's a good idea to support the sill/rocker-panel ? to prevent any sag being introduced as you cut away metal. The sills/rocker panels are critical on a Spider and need to be in very sound condition (afaik, there is a centre diaphragm? panel inside between the inner and outer rocker panels, these can rust away unseen). Some people temporarily weld a support bar across the door opening to maintain correct alignment but I prefer a support under the sill/rocker + careful measurements of the door opening having been taken before any cutting and double-checked again before any welding is carried out.
Excellent - thanks again for your advice! I do have a couple of welders magnets but need to do some practicing before I go much further…
The small angle grinder with twisted wire, wire brush attachment would bring the metal back to shiny steel , which if MIG welding, is what you need to get a good weld, then once you have metal cut to shape , tack it into place where you want it and then just move along to different areas to join the "tacks" together without too much heat distortion which can happen if you try to do one long smooth weld.
Thanks @bugsymike - I was wondering about that a bit… I will clean the edges to make sure it’s bare metal. Would you advise cleaning upper and lower surfaces?The small angle grinder with twisted wire, wire brush attachment would bring the metal back to shiny steel , which if MIG welding, is what you need to get a good weld, then once you have metal cut to shape , tack it into place where you want it and then just move along to different areas to join the "tacks" together without too much heat distortion which can happen if you try to do one long smooth weld.
It also gives you time to check underneath to make sure nothing has caught fire.
A reasonably powerful Mig welder even on a low setting will do a better job than a cheap one on a higher setting and a bit of practice on some similar thickness steel will help get the welder settings right before you start the serious stuff.
A good "reactor" type welding mask and of course welding gloves and other protection will be important too.
Migs like shiny metal, I have actually had the mig wire bounce the torch off the work when poor electrical connection when using .8 mig wire, .6 usually bends the wire or can cause the wire to "birdsnest" in the welder, so clean metal is important, also put welder earthing clamp on shiny metal as near as possible to the weld area.
Thank you - I’ll check the bottle, I think it is a Co2 / argon mix. I’ll do my best to clean the edges of the cutouts - working underneath is not a lot of joyMigs like shiny metal, I have actually had the mig wire bounce the torch off the work when poor electrical connection when using .8 mig wire, .6 usually bends the wire or can cause the wire to "birdsnest" in the welder, so clean metal is important, also put welder earthing clamp on shiny metal as near as possible to the weld area.
So shiny metal and a bit of practice on spare steel to find best settings that suit you, also some users prefer different gases. I am assuming you are not using a "gasless" mig with cored wire, something I have had nothing to do with.
Many on mild steel over here use Cougar which is Argon/Co2 mix with success, personally when first started MIG welding I used Co2 (plain carbon dioxide) as I was never professionally taught welding and found the Argon mix to hot and was easy to blow holes in thin metal.
However do what you are happiest using that suits you.
One of my customers used to teach welding to a very high standard for piplines etc. His comments on car / Mot welding was he called it "sh*t welding, which to a degree I understand, but did point out that rather than in a warm College with brand new equipment and shiny metals, we have to often weld outside with the shielding gas blowing away on 20 year old thin rusty metal covered in underseal.
. And yep - I’m working outside but fortunately under a shed roof and the weather is cooperating….
