Cavity Protection

Now that the underside of the chassis is fully painted with satin black chassis paint I wanted to add further protection to the cavities that lurk within the MG Midgets monocoque chassis. For this job I turned to Bilt Hamber's Dynax S50 (Other cavity protection waxes are available) because it also comes with a very useful lance that evenly sprays the wax all around the cavity walls.

The main areas requiring treatment include the whole rear bulk head that is very easy to access with the chassis on its side. MG very kindly left these holes behind to make this job so easy! 😉 I also applied a coat up inside the spring hanger area.

Other areas that need a coating include the cross member, between the inner and outer sills, front chassis legs, behind the foot plate, insides of the triangular supports, inside the a and b posts, inside the doors, under the front lip of the bonnet. or wherever the car is likely to rust, so basically everywhere! However don't spray this until you have painted that section as the paint will not stick to the wax and you'll have to thoroughly degrease everything!

I watched a couple of YouTube videos on how to do this to make sure I didn't waste too much of the product. 

The idea is to insert the lance right to the back of the cavity, start to release the wax and then fairly quickly pull the lance out of the cavity. The Dynax S50 is quite runny initially to allow it to settle into all the cracks and joints. I choose to apply two coats as I can still remember how badly rusted this whole area was.

Once dried the wax does have a tacky feel to it. So hopefully with the new metal, primer, chassis paint, seam sealer and now cavity protection this will last for a good few years.

Once I have completely finished the car I will probably apply underbody protection.

Painting Chassis Underside

Having completed the seam sealing on the underside of the chassis it was time to apply some paint. I wanted to use black chassis paint with a satin finish. 

Before spraying on the paint you need to remove any dust, grease and dirt. There didn't seem much to clean as the primer looked so fresh, but the blasting did leave the surface covered in very fine dust which needs to be brushed off first. I then rubbed it down with surface preparation cleaner which helps to remove any left over contaminates which might affect the paint from taking to the primer.

I have applied two coats to make sure the metal is as protected as it can be.

I am really pleased with how it turned out. You can hardly see the seam sealer, but I know it is there underneath doing its job.

I'm going to be getting some cavity spray to add a final protection to the cross member and the rear bulk head which always seems to get hit by rust. Hopefully not anymore!

Seam Sealer

Having had the chassis blasted and primed it wanted to finish the underside of the MG Midget in preparation for fitting the suspension. 

There are only two jobs really that need to be completed and first up was seam sealing all the joints on the underside of the chassis. 

The seam sealer is a thick glue like paste that seals the joints between two metal panels. It can also be used on welds that have some pin holes left behind. Once applied it drys hard and can be painted over.

I wanted to make sure that every seam and joint was carefully covered whilst not spoiling the freshly blasted metal, which looked so nice and clean with its coat of primer, but it is so important to stop any moisture from entering the gaps as I don't want to be doing any more welding for a good many years to come.

I soon realised there are quite a lot of joints on a monocoque chassis! Here are some photo's of the work, although it isn't that easy to see the seam sealing as it is also grey like the primer.

Now that has all been completed on the underside it is time to prepare for painting the underside with black chassis paint which will protect it from moisture, stone chips and general usage better than standard paint. 

Blasting Chassis

After just over seven and a half years the time has come to send the MG Midget off to the blasters. It has been one of the most exciting points that I have been looking forward to during this restoration. The chance to see the chassis all finished and in one colour. 

The reason for blasting now and not at the start is because once blasted the car is primed with epoxy paint to protect it, but this is only for a short while depending on the weather conditions. So while I was working on the rusty parts, the good metal was protected under the old paint. It is though now time to remove everything back to bare metal and start the process of preparing the chassis for a new coat of old English white paint.

First off a big thanks to James Shopland of The Shopland Collection who helped me with transportation.

A second thank you goes out to Joe Williamson and his Dad at Avon Blast Cleaning who did a fantastic job on the chassis as the photo's will show.

 

 

 

 

 

 

Back home, safe and sound. I mean that because there really are hardly any holes to weld up. Just a handful of pin holes which I am over the moon about.

Next job on the list is to start seem sealing all the panel joins to protect from rust and then I'll be painting the underside with chassis paint.

Bits and Bobs

Having now completed all of the main chassis components (can't believe I am typing this!!) I wanted to make sure that I had all the miscellaneous parts that I wanted to send to the blasters along with the chassis. 

This includes all the hinges from the doors, boot and bonnet. The bumper mounts and supporting brackets and splash guard brackets.

Most of these are rusty but thankfully require no welding. I did feel though that there were a few parts that I could get into my rust removal electrolysis experiment.

Here's an example of just how well it works.

Looking very rusty and ready for a dip.

All wired up

After 12 hours in the tub

And after a good go with the rotary wire brush, starting to get the shine back.

And finally primed ready for another 55 years!

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.