Tuesday, 26 May 2020

Bonnet Repairs

I have had this bonnet since I won a bid on eBay back in March 2013. That's 7 years ago!! These are one of the areas that are prone to rusting out. Mine was no exception.



It still looks the same so no real deterioration over those 7 years. 



But what I really wanted to check was how bad was the metal behind these holes. 

Time to start drilling out some spot welds.



Which revealed unsurprisingly...yes more rust!



Now I could see behind here I notice that the this slam panel had a lot of rust that needed sorting, so there was no alternative but to remove it.



This was actually much easier than I first imagined. There are only eight spot welds on the outer skin and fourteen holding the slam panel in place and without the lip which needed replacing the panel just slid out.



I'm glad I took this out because it has given me the chance to be sure the rust will be gone for years to come. First job was to wire brush the surface rust off using the drill attachment. Amazing how it comes up really.


There is some pitting on the surface of the metal, but for the majority of the bonnet it is in good condition. Not bad for a £16 eBay win. Time to stabilise the the area with rust converter.


Looking better already!


So now for the slam panel. I have been reading a lot about rust removal via electrolysis and so set up my own experiment.


Items required:
1. plastic bucket - I'm using a 40 litre one, but for some parts you might want a bigger one.
2. car battery charger - I'm using a 2amp 12v
3. copper wire - stripped from main cable
4. Soda crystals - 1/4 of a 1 kg bag
5. 4 x steel plates
6. length of steel wire
7. length of wood
8. a rusty object

So hopefully the photo is clear enough to show the set up. Things to note are not to get the copper wire in the water. Use the steel wire to hold the metal in the water and wrapped around the length of wood and then connect the negative lead on the charger.

I have 4 metal plates to surround the rusty metal. Just improves the process.

Make sure the soda crystals are well mixed in. I put them into the bucket before filling with water.

Only things to really be careful of is the build up of hydrogen and oxygen, so needs to be in a ventilated room to avoid potential explosion and not to use this method on any steel that is normally under stress, like a suspension spring for example. Apparently there is a process called hydrogen embrittlement that can weaken tensile steel.

I left the panel in for only 4 hours and it came up really well after a small amount of wire brushing and washing in clean water. But due to the size of my bucket I could only get just under half of the panel in at a time. 


This gave me the chance to see the difference between this process and a wire brush.



I hope you can see from this photo that the pits that have been in the bucket (on the right) and subject to electrolysis are completely clean of rust, whereas the pits with the wire brush (on the left) still have a small amount of rust in the bottom of the pit. This is why rust converter is so useful as it stabilises the metal surface and prevents from further rusting. 

Time to paint the panel in rust converter and start replacing some of the metal.


Final clean up and coat of primer. Panel is now ready to go back in. I also made a new lower lip of the outer skin. 


Time to start welding up the holes on the nose of the bonnet. Finished off the preparation of the nose and slid the slam panel back into place. Went in perfectly.



Next up was to weld that in place and tidy the edges and align the new lip. 


All looking good so far.


and after some grinding and welding and grinding and welding and grinding and welding...


It will need a little bit of filler to make it perfect, but overall I'm really happy, especially as there is no rust behind that slam panel any more.

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