Question for bodywork experts

[Gary Schulz]

I need to separate the triple spot welded flange that consists of the rear valence, boot floor and rear panel.

20210205_122526.jpg

Since I am planning to use a replacement rear panel (at the least the lower section of it) and a new rear valence, what is the best way to separate this sandwich? Do I need to drill out the spot welds on both the bottom and the top of the flange in an effort to keep the boot floor intact or can I just drill through all three layers? Seems like a nasty job to try to do a double-sided spot weld removal and it would seem pretty likely the center boot floor section will suffer in the process.

What have you guys done here?

[swindrum]

I'm not sure I've seen a case where the lower panel and the valence require replacing, and the boot floor remains rust free... They tend to rust from the inside. You may find you have carefully drilled from both sides only to discover you need to weld the boot floor too.

That said, I would drill from both sides

[jayare]

How are you intending to put it back together? If you are plug welding, you may as well drill right through and use the hole in the boot floor to plug weld either the rear panel or valence back on, then drill plug weld holes in the other panel. If you are spot welding then you would probably need to drill from above and below.

JR

[Gary Schulz]

In this case it doesn't have anything to do with rust. this car was used as a race car early in its life so has basically zero rust (only trivial surface rust here and there). The issue is dealing with accident damage as can be seen in the following two pictures showing the left rear.

Inside view showing boot floor rippled and pushed together near where the car swiped into something big and hard-

20210205_144831.jpg

Also the curved area from around the left rear tail light to the boot hinge area is pretty wavy.

20210205_145234.jpg

I was thinking it would be best to just replace the panels instead of endless panel beating and body filler but maybe that is unheard of on rust free cars? In any case the boot floor isn't rusty so is more easily straightened once I remove the lower valence and rear panel, at least that was my thought process. Does this make sense?

[Dearg1275]

To my mind, if you have good metal then keep it. From your last photo it seems you have equipment that can push stuff back to where it belongs. If you have a ripple or two in the boot floor, what matter? It’s an old car with history. Cast off your perfectionist anorak and live with an exceptionally original boot floor / rear end. Most would be envious to have such.

D

[Gary Schulz]

I would keep all of it but the car has lost the curve in the lower part of the rear body seam. It is hard to get things right when the whole corner has been pushed in this much and trying to push it straight with all the panels assembled is very tough. They don't want to pull back into shape readily so it requires a great deal of force for the porta-power and there isn't anything too stout for it to react against on the other end!

[Andrew1967]

Is it feasible to carefully remove the affected rear panel and the lower valance sections, pull/dress out the boot floor, then same with the removed sections and then weld them back in ??

[scott6058]

Slow and steady pull and little time and tap dolly would suffice it fine.
Easy and simple.

[iain1967s]

Maybe slit the boot floor so that it weakens the crushed structure, then you can push/pull the corner out more easily with the ram. After the corner is back in shape with a dolly etc. flatten the floor ripples and then weld the slit back up to the reformed corner, letting in new metal if required to bridge the gap.

[Gary Schulz]

I did begin to separate the three panels at least at this corner. I can see if it allows me enough room to flatten or somehow pull the floor back out. The metal is pretty distorted and stretched so not sure if my relative lack of skill will be able to get the compound curve back into that area around the left tail light.

I gather the technique is to have the dolly on the inside and gradually hammer the outside until smooth? Easier said than done!

[MiNiKiN]

Although the pictures don't really give a clear indication of the damage - I would try to pull on the triple-seam with a puller, whilst at the same time whacking the boot floor (I use a big flat plastic anti-bounce-back mallet and a flat piece of i-beam with radiused edges as a dolly).
Set the puller in various angles around the edge, whilst you keep flattening the floor. This way you might get it to return to its original shape.

I you want to replace the panels and keept the oot floor: cut of the panels right at the seam and grind down the top and lower layer of metal until only the boot floor stays. That is what I did at the roller welded sills. PITA

[Gary Schulz]

Although the pictures don't really give a clear indication of the damage - I would try to pull on the triple-seam with a puller, whilst at the same time whacking the boot floor (I use a big flat plastic anti-bounce-back mallet and a flat piece of i-beam with radiused edges as a dolly).
Set the puller in various angles around the edge, whilst you keep flattening the floor. This way you might get it to return to its original shape.

I you want to replace the panels and keept the oot floor: cut of the panels right at the seam and grind down the top and lower layer of metal until only the boot floor stays. That is what I did at the roller welded sills. PITA

Thanks for the good ideas. I would love to be able to pull on the bumper flange but that assumes I have a way to hold down the car and can pull against something. Need to think about how to do that. I have a flange clamp and a slide-hammer setup but it seems unlikely that will generate enough force to pull this area flat.

Speaking of roller welding, are the exterior body flanges welded in a more or less continuous weld? That is another thing I need to tackle on the back of this car and I am having a very hard time identifying actual spot weld locations on those vertical seams.

I am beginning to realize why good bodywork is so expensive! I spend 4 hours staring at this thing pondering about how to tackle the job for every 15 minutes of actual work!

[MiNiKiN]

Thanks for the good ideas. I would love to be able to pull on the bumper flange but that assumes I have a way to hold down the car and can pull against something. Need to think about how to do that. I have a flange clamp and a slide-hammer setup but it seems unlikely that will generate enough force to pull this area flat.

Speaking of roller welding, are the exterior body flanges welded in a more or less continuous weld? That is another thing I need to tackle on the back of this car and I am having a very hard time identifying actual spot weld locations on those vertical seams.

I am beginning to realize why good bodywork is so expensive! I spend 4 hours staring at this thing pondering about how to tackle the job for every 15 minutes of actual work!

No chance to pull that with a slide-hammer - that is what you need:



On my Innocenti the A-panel, the outer sill to door step and the roof are roller (i.e. continous) welded. The rear valance to boot floor was spot welded.

AND: I do so understand what you say about 4 hours saring for every task- same here - but believe me, the professionals don't do it like that, they JFDI.

[Gary Schulz]

So how do you separate the two pieces of sheetmetal that form the vertical seams if they are more or less continuously welded? A very sharp air chisel?

Sorry for all the dumb questions. Maybe there should be an independent board topic under the heading "bodywork for neophytes".

[MiNiKiN]

If you did that with a chisel you would bend the panel to be safed.
So what I did, and this is a very cumbersome job, I ground an entire layer of metal off.
Like in my case the sill: I cut the sill off right next to the seam, and then removed the ~1mm of welded layer from the door step and side panel with a flap wheel and grinding disc in an angle grinder.
BTW: There is no such thing as "dumb questions".

[Stopped-again]

Sorry for all the dumb questions. Maybe there should be an independent board topic under the heading "bodywork for neophytes

Maybe there should be a “thesaurus” for those of us with a limited vocabulary, “neophytes”???

[Andrew1967]

How Minikin describes the process is how I do it, especially where spot welds are no longer visible or roller welds are originally employed.

If you grind back enough of the remaining layer to be removed on spot welded seams, you can peel off the wafer thin metal and the welds will pop undone with some side cutters. Then just linish back the remaining bits of spot weld flush.

Roller welds normally mean careful linishing off of the complete layer to be removed.

I cant speak highly enough of this little angle grinder with a 1mm slitting disc for getting in awkward areas ...

https://www.ebay.co.uk/itm/Mini-Electri ... Sw8lpZEuGp

[nick@dunsdale]

You dont have drill out the spot welds there are other options
A popular method in the bodyshop business these days is to use a belt sander sand through the welds, easier to control and less chance of going through the lower sheet metal

You mentioned you had a pull clamp
You can attach your clamp to the flange then a chain to a metal beam if you have one in your garage, and just push the car forward the weight of the car will pull out damage.

Or attach a chain to gate post anything that is sturdy, we do this all the time to pull out minor damage.

The car doesnt have to be pushed very fast the weight of the vehicle will do the work

[Nick W]

Or attach a chain to gate post anything that is sturdy, we do this all the time to pull out minor damage.

I've used my landrover for years to do quick pulls...that's why I never sell it

[Gary Schulz]

I cant speak highly enough of this little angle grinder with a 1mm slitting disc for getting in awkward areas ...

https://www.ebay.co.uk/itm/Mini-Electri ... Sw8lpZEuGp

Looks like a very useful little grinder- somewhere between a Dremel and a normal full sized unit. Might need to find a US source for that tool.

Sounds like I will be busy with the angle grinder and flap disks then!