Welding rear car arches

[rustyoldford]

Good evening and hello, Ive been lurking around this site checking out all the tips which are tip top to be fair
I am doing a bit of resto work on my cosworth 2.9 v6 powered sierra estate which i have fitted recently and I'm changing the rear arches.I am going to lap weld the top part of the arch and butt weld all the other areas where dirt can get too,the reason behind not butt welding the top panel is that that area is inside the car so it is not exposed, Is this acceptable ? or would it be a lot easier it butt weld the lot ?

 

[zardoz]

Nice motor. I dont see why lap welding wont be acceptable for arches.

Can you get some pics of the weld area ?

 

[normspanners]

Yep put the new arch under the original cut metal , but if you can get an edge joggler you could shape the new panels edge so that it doesnt distort to badly when welding .

 

[Spot the welders dog]

would it be a lot easier it butt weld the lot ?

Not the easiest way - no, and alot will depend of your level of skill.
Bear in mind that the replacement arch will almost certainly be an oversized panel designed to fit over the existing bodywork, hence it would not be a direct 'drop into place' without a bit of a fettle.
Like zardoz, I would have no qualms doing a lap joint in that area.
Acceptable by whom-ever is of no consequence: It's your car and you decide what is acceptable.

 

[Lawnmowerboy]

If it's lap jointed it also gives a bit of leeway for a skim of filler without grinding as much away.

 

[pedrobedro]

I've always put them on the outside because it's easier and my theory is if there is any damp on the inside it will run over the joint instead of into it. Grind and fill and they are not seen anyway so it's your secret, just be sure to take all the bad metal out.

 

[rustyoldford]

The arch has been badly repaired in the past and just filled !!



Boy it is time consuming defiantly need some new tools like clamps and seriously need a good vice to fabricate small pieces.
The 0.8 car panels are quite hard to weld but with a little fiddling with the controls i have set it onto a good consistent setting. Im using a snap on 160 welder with plain co2 as my pub sorts me out with the stuff for free only paid £80 as spares or repair put a new reel of wire on it and it works very well.

Thought i would do a couple of small bits before i did the arches just incase i messed up





Ive folded the steel plate around and welded underside which worked well


Just need more practice now before i do the arches as i know the welds aren't perfect but they have good penetration but a little higher than i wanted to a little more work grinding back

 

[SiPMerlin150]

Just go easy with how much heat you put into those thin panels as they WILL warp all to easily...very noticeable on the finished result when the paint is polished up with a mirror shine..... I know that! from my mistake Spread the tack welds out in random places to keep it all cool. I like old ford and shall enjoy further updates on this project. I have an old fiesta that could do with new rear arches!

 

[zardoz]

Just take your time. Even cut out trial template pieces in cardboard first if you cant offer up the metal and get a good idea of its final posistion. Then fashion from the template. Then get stich welding to keep from warpage.

As you say here is where a good vice is needed. (My own big vice weighs 5 stone! )

 

[Coo]

I find it easier welding square patches.

Looking good though

 

[Metalsculptor]

If you are using that extension to power your welder, be careful it doesn't get too hot. I did that once and the extension cable caught fire.
Unwinding it when welding can be a good idea - I just need to remember that myself.

 

[rustyoldford]

If you are using that extension to power your welder, be careful it doesn't get too hot. I did that once and the extension cable caught fire.
Unwinding it when welding can be a good idea - I just need to remember that myself.

Why ? its only a 400amp hobart and its been working fine,
Just messing lol I've put a 4mm armoured cable in from my house a few months back with a garage consumer unit.The lead is just for my angle grinder
Think square plates is the way forward for patches but the bits that I'm experimenting on are behind the bumper so as long as there is no rust it does not matter so much on an a1 finish. Ive used quite a high ish power setting with about 15% wire speed and seems to work well for tacking as it puts a good bit of heat to get good fusion when doing this type of stop start welding but you do have to leave the bead just go off red before i lay the next weld down.

 

[pedrobedro]

If you cut square plates round off the corners and they don't burn off as quick leaving you a hole to fill.

 

[rustyoldford]

Been getting involved with these arches not too much rust there and I've got to say it went quite well but filler still has to be used but only a light fill it seems











Just got the other side to do now i have enjoyed doing it but with a full time job and not loads of time to spare it was a little rushed

 

[Coo]

Looks good !

 

[Metalsculptor]

Yep, very nice.
Well shaped around the door section.
How many hours d'you reckon'?

 

[rustyoldford]

Yep, very nice.
Well shaped around the door section.
How many hours d'you reckon'?

About 5 hours to grind all the rot out and fettle the arch and weld in and about 2 hours to grind to what you see but still got to do the other arch and the inner arches too as I've got heaps of room to do it with the wheel off. its labour intensive but it keeps another old ford from the scrap man and its giving me the welding training as i go too

 

[Jim Davey]

I know you mentioned in another thread that you bought the welder with a suspected fault. I'd be tempted to give it the once over, diodes, contactor, voltage switch and welding circuit, (torch, earth and clamp lead) as the welds look a little piled up with low pen and excessive spatter. This could be just settings, but will become more evident if you try to weld something thicker, have a go on some 3-4mm and see how it goes. You might just find the set has an issue after all and didn't realise as you can still get decent pen on thin sections.

 

[rustyoldford]

I know you mentioned in another thread that you bought the welder with a suspected fault. I'd be tempted to give it the once over, diodes, contactor, voltage switch and welding circuit, (torch, earth and clamp lead) as the welds look a little piled up with low pen and excessive spatter. This could be just settings, but will become more evident if you try to weld something thicker, have a go on some 3-4mm and see how it goes. You might just find the set has an issue after all and didn't realise as you can still get decent pen on thin sections.

Yeah the first photos it was splattering and piling up it was down to the old welding wire in the machine i swapped it for a new 15kg 0.8 wire and its much much better now with very little splatter.Also I'm welding on setting 2 out of 6 and welding 3mm thick pipe i get real good penetration and a nice flat shiny weld when switched up to 5-6 with a 20% wire feed.
Ive also striped the transformer, rectifier and metered the transformer output voltages that are spot on with the manufactures spec all diodes are a ok.

 

[plum loco]

That's not a bad job at all,I am doing an old ford van that needs arches and lots of patch repairs.It's great to DIY it yourself,theres just not enought hours in a day.Can't wait to get up in the morning,i love welding and spraying.