Front Jacking Point Replacement (Part 2) - Refitting

I finally found some time to finish replacing the right hand jacking point.

The jacking point had come off the car reluctantly and in several pieces.

VICTORY! But at a price.....

My efforts to remove the rusty one had left the underlying super-structure looking a little battle-scarred….The flanges were twisted and had some holes from drilling.

Collateral damage

In some cases the spot removal drill had done what I expected: top layers of spot-welded steel were cut-through, to leave a 'button' of weld on the bottom panel.

'Button' of weld left on the bottom layer

In other cases there was no 'button' - meaning the panels had separated. meaning the initial weld must have been weak.

No 'button'.....

In many cases the new repair panel would needed to be welded at the same points as it’s predecessor, so I felt it was important to make sure the flanges were in as good a shape as possible. It was comforting to know that even the Citroen factory repair manual acknowledges that there is an element of "making good" before the panel is replaced. Or as they call it, "planishing, grinding or welding".

Instructions for repair

All three would be needed! I temporarily wrapped the internal pipework in some heatproof plumbers matting to protect it from grinding and welding sparks. I put some weld over the holes, carefully ground them back (I didn’t want to take any more metal off the flanges) and flattened them out to make good/ better contact with the replacement jacking point piece. I reasoned that "less was more" here and didn't want to melt or grind away what precious flange was left.

Cleaning up the damage

One part needed a little more attention. The top edge of the jacking panel is sandwiched in place over the flange of the sill and behind the edge of the footwell wall. I had to cut open the wall to get access to the weld points.

I had to cut and fold the wall to get access to the spots on the flange

By the time I'd removed the old jacking point, I could see outside the car from the footwell!

The view of the garage floor. From the footwell......

A small length of the flange on the sill was also lost in the battle and need to be replaced to give me an edge to weld my new panel to.

I had to patch one of the flanges

I fashioned up a teeny, tiny repair piece and welded it in to the flange. With that done, I gave the flanges a protective coat of weld-through primer. 

Repaired flanges

The flanges still looked a little rough but better than they had been. I made a trial fit of my replacement jacking point panel. The replacement piece needed a bit or encouragement with several pairs of mole grips to take the necessary shape of the chassis.

It would be possible to spot weld the new piece around it’s outer edges and limit plug-welding to little more than the diagonal line that matched the internal spar. However I didn’t have access to a spot welder so the whole lot was going to need plug welding. That would man drilling holes in the replacement piece.

First of many test fits

I used an abrasive pad wheel to remove the paint from the new panel. With the piece now fitting quite snuggly, I began marking up the weld points with a Sharpie. Where there was scope to do so, I moved these marked points so as to avoid any areas of pox-marked or repaired flange underneath. To be honest, there wasn’t much scope for that anyway. The hardest part was working out where the weld points needed to be to align to the diagonal spar behind.

With my weld points marked. I needed to drill plug-welding holes through my lovely new part. I have a Tama joggler tool that includes a hole punch for plug-welding purpose. The holes it makes are 5mm diameter. That being so, I centre-punched my intended welding points and went at my part with a 5mm drill.

Holes drilled for plug welding. Note the diagonal line of holes

The very top edge of the replacement part is sandwiched between two other layers where it meets the footwell, so in some places did not need holes drilling through it - as it formed the base panel for plug welding. Glad I remembered that one!

All the holes aligned to flange with the exception of one of my holes on the crease of the diagonal flange. I drilled out the remaining holes - together with those on the small square closing panel behind the jacking panel……..

With the holes drilled, I sprayed up the panel with some weld-through primer to protect and went for another trial fit.

Checking the weld hole alignment

Not bad at all. In some places on the new panel I had had to drill through the jacking reinforcement plate as well as the plate behind. That meant I would be plug-welding three layers back together. I was a little nervous about whether I was capable of producing a strong weld. I needed to pre-check my welder settings anyway (wire size, feed speed and current setting), so I set up some triple-layer test pieces and got to it. If I’m honest, the results were mixed. After each experiment I clamped the pieces in a vice and then tried to split the welded layers.The first couple were encouraging – with the metal sandwich bending but holding. Then I had two ‘fails’ where the layers pulled apart very easily indeed. That shocked me.  I put it down to a failure to adequately prepare the surfaces in my haste. 

Test results: good welds and failed welds

Based on the results of my trial welds, I used an abrasive pad on a grinder to clean up and de-rust the chassis flange weld points and did the same to both sides of the new panels, and then gave everything a quick squirt of weld-through primer.

Rather than plug weld sequentially around the perimeter of the replacement panel, I did the odd weld in different places to tack the panel on, then gradually filled in the gaps. This meant I could be sure that the panel remained lined-up and fitted, and it also meant that I reduced the risk of any panel warping from excessive heat in any one area.

Main welding on front panel underway.....

Weld is harder than the base steel it is put on and it took forever to grind the buggers down. It was also very fiddly getting an angle grinder onto some of the welds without risking grind the edge of an adjacent panel - and this was quite an open and accessible area. It was particularly hard to get to the welds in/ under the top folded panel edge. I needed to remove this before I could fold the panel back down and finish spot welding it.

With the necessary spot welds ground back, I was able to fold the panel back down and shut daylight off from the footwell. Folding it down showed the two rows of holes left by the spot weld drill. If the 5mm holes I drilled in the new panel looked too small for plug welding, those 10mm holes looked too big! I guess that, in the majority of situations, the aim is to drill those big 10mm holes in the rusty panel you intend to discard and replace. I didn't have that luxury in this instance.

Big 10mm battle scars

To get a good weld, it's important that the two layers to be joined are held in contact with one another. Around the edges of the panel I'd used welding clamps and mole grips. That wasn't going to be possible in this area. With my 'peeled' panel now folded back, I drilled a few small holes along the weld line and used 'Cleco' fasteners to pull the layers together.

'Cleco' fastener and applicator tool

As well as finishing the top edge, I welded in place the square closing panel behind the main jacking point. Again, I used 'Cleco' fasteners to pull the layers together.

Rear closing panel in place

As I feared, I found plug welding through those large 10mm holes along the top edge quite tricky......To prevent burn through, I resorted to stitching around the edges of the holes to make the hole smaller, then filling in. This seemed to be at odd with my fears about only capping plug welds - leaving them weak - but in this case there was already an underlying of row plug welds. I reasoned that this second row played less of a structural role and that my repair was more cosmetic. Though the end result wasn't that pretty!

Nearly there

Again, more grinding of welds and the job was all but done.....at this stage I've just left everything coated in a layer of primer. I've got more painting to do so will spray the jacking point black at that time. There are also a couple of small gaps between the panels that need plugging with some kind of mastic. That's not my poor work - the panels on the other side have mastic plugging gaps in the same places. The will also get a coat of 'schutz' after painting and I will apply fresh Waxoyl or similar to the inside of the box sections.

Coated with primer. Waiting

In hindsight I’m a little concerned about the size of the plug-welding holes. 5mm looks awfully small. A good plug weld will be fairly quick, fill the plug hole from the centre out and leave little more than a slight dome on the top surface.

As I'm an inexperienced welder - and only once I'd started to the job - I began to wonder whether my welds were simply filling the 5mm hole in the top layer without fully penetrating through to the bottom layer. To get rid of these nagging doubts I spent longer on each weld and poured more heat in - my idea being to increase the likelihood that the molten metal pool included the bottom panel. The downside of this is that each of my welds had more added metal and tended to have a very definite domed crown to them. Making an effective weld was a key learning point and one I will remember based on the amount of time I then had to spend grinding those weld heads off! I think for the other jacking point (yes - I've got to do it all over again) I will maybe drill 7mm holes.

The other key learning point was not to go too deep with the spot weld cutter. I don't think pre-drilling a hole to guide the cutter (a 'tip' from a Youtube video) was such a good idea as I lost a sense of how deep I was cutting and damaged underlying flanges. instead I think I will drill no more than a guide 'dimple' to steady the cutter and rely on the spring loaded tip to help me keep more of a sense of how hard/ deep I am drilling. And if I could find a spot weld drill of less than 10mm, I would give that a go.