TR6 Hardtop Restoration (side project...)

[RichardB]

When I sent my Spitfire away for paint removal, I also included a steel hard top that we'd got for my Dad's TR6 many years ago. We hired a van to go up north to pick it up, and straight away realised it was going to need a bit more work than we'd expected. It then spent the best part of the next 10 years languishing in the garden shed, surprisingly not getting any worse which I suppose is a good advert for pop up plastic sheds.

Headlining off and bits all stored away ready for use another day.

The extent of the pitting and holes is really easy to see now, and it constitutes a good opportunity for me to practice fabrication and MIG/spot welding whilst I'm doing my own car. It only cost about £120 + the cost of a van hire many years ago, so if it all goes wrong it's no drama - but I think we will be able to make something out of it that matches the high standard of the signal red car it's going on.

I've started with an easy repair, making a patch for the rot under the window (pictured above). The rot you can see in the photo is just as bad in the area behind what's shown in the photo as well - effectively both sides of the box have rotted out.

This front side is just two folds, the upper is a bit more acute than 90 degrees.

To get the lower fold at the right distance away from the upper fold, I cheated a bit. I used the hard top itself as a buck, because the profile is just the same further up. Tapping carefully to fold the metal down, I planished the lip very lightly and roughly in place. This worked but left a large, soft radius in the fold that needed to be corrected.

Once corrected by clamping it over my welding table and planishing over the table lip, I offered it up to check. Very happy with this. It's a nice, crisp edge.

I was then able to scribe more accurately and cut out the very porous section of steel, with only a couple of weak spot welds to drill out.

Didn't have time to weld it up today, but I think it already looks better? I think I will get the sides welded in before removing the rot behind and under this section - that way I can preserve the shape of everything rather than cutting the lot out and finding that it's moved. Then once the parts near it are ready, paint behind it, fit the other parts and spot weld the seams together.

There's many more repairs needed, some with a bit of curve in them, some pin holes, some flat parts above the rear deck... lots of fun to be had. One good thing is that I'm getting faster already, I spent less than 2 hours in the garage today doing this and a good portion of that was chatting and drinking tea.

[Escadrille Ecosse]

On 2/5/2023 at 9:07 PM, RichardB said:

and a good portion of that was chatting and drinking tea.

An excellent way to spend some time in the garage...

Good job that though

[Nick Jones]

Ah rotty hard-tops…. Difficult to repair. Very complicated shapes.  I actually binned a Spitfire one - it was RUFF!

 

[RichardB]

Thanks and agree Nick. It's almost like they designed them to rot and get stuffed with filler. So many water traps and compound curves that are hard to patch with metal...

[RichardB]

Got the next patch welded in today, just a little bit more weld dressing to do. Very happy with it, I'm impressed at how neat a job you can get with a MIG welder, some metal things to bang against and a hammer.

Next up is this holed bit of mess on the other side. I've started by quickly cutting off the rubber seal channel, making a perhaps optimistic assumption that it will be really easy to fabricate a new one.

Making a card template....

Repair patch made, metal cut out and the patch offered up. I'm not going to weld this in just yet though, it needs a bit more finessing.

I also want to treat the inside of the box section whilst things are apart, and will probably make a patch for the rear deck above it first. You can just about see where the panel on the other side has folded up, it's a bit scruffy too so will need addressing.

[RichardB]

No photos today, other than trimming the patch I had a tidying up day. Discovered something really useful though.

I was in 2 minds as to whether to get a bigger compressor and use an air die grinder for dressing welds, as I'm getting fed up with grinding stones in the dremel. They do the job, but take a fairly long time and half the time break not long after using them. The conical ones lose their shape too quickly and then become useless at getting in corners.

Before splurging I thought I'd try out some miniature tungsten carbide burrs in the dremel, effectively the same things people use in die grinders, but smaller with a 1/8" shank. You can get a pack of 10 various shapes for about £8 on ebay. What a difference - they make lighter work of mig welds and cut through sheet steel like butter. The tiny shavings are annoying, but I managed to catch most of them with a magnet.

Much cheaper than a new compressor, which is also great as our 2.5HP/50L direct drive one gets in the way enough as it is.

 

Edited February 26, 2023 by RichardB

[JohnD]

Quote, "The tiny shavings are annoying"

Quite right, Richard!   I hope you've been wearing a respirator while using stones - carborundum is nasty inside the lungs.   No need for that with a burr, but do wear disposable gloves!  Those tiny needles of steel get into your skin and last until they rust away!   Even a thin rubber/vinyl glove will protect you.

John

[RichardB]

Agree John. My current mask of choice is the JSP Force 8, I like how I can swap between P3 and ABEK1P3 filters depending on whether I need to protect against dust or vapour. Today I used gauntlets, but I've also got some soft leather gloves that work quite well.

The thing that nags at the back of my mind is dust that hangs in the air from resto work. It will be there for hours after the grinding or sanding finishes, so it's tricky knowing how to keep the garage air clear.

If you open the garage ventilation is easier with a large fan, but then that's less pleasant for neighbours with the noise of the grinder or dremel. An alternative I think might be to just stay masked up all morning with the door shut, purge the air once finished for the day. Either that or get an overhead air filter, but those generally don't filter to HEPA standard and leave a lot of the finest dust in the air - which just happens to be the most dangerous for lungs.

Today's tidying effort was largely because I want to keep the floor as empty as possible, as an incentive to regularly wet vac all the dust that gathers on the floor.

Edited February 26, 2023 by RichardB

[Nick Jones]

Some nice tidy repairs happening there. Entirely possible with MIG.
 

Yep, carbide burrs are great, except for the barbed needles they produce as swarf. I’m not convinced nitrile gloves are fully effective so use dipped fabric ones and clean up often.

[JohnD]

You're quite right, Richard!  Once I was painting an entire body's underside ( bulk head and rear tub) with Hammerite (excellent protection!).    It was a filthy day, and I kept the doors closed.  My wife brought me a tea, and had to retreat from the fumes!  But I was - probably - high.

That night I suffered the worst headache I have ever had.  Head banging time!   And later I discovered that Hammerite contained Xylene as a solvent, toxic in concentration of ten part per million!  Goodness knows what I was breathing.

Since then, even the slightest exposure to Hammerite will bring on a similar headache!    Except I think it doesn't contain Xylene any more!

John

[Mark]

I generally use flap discs 40 , 80 grit on an angle grinder for grinding, smoothing out Mig welds. Zirconium Oxide seem to last longer. Less aggressive and quieter than a carborundum disc. Although some dust, no where near as much as grinding with carborundum. Flap discs are slightly less accurate so I go slow, checking as I go. Smoother finish than a grinding disc.

Edited February 27, 2023 by Mark

[Nick Jones]

When grinding back on thin panels my preferred method is to initially use a well-worn slitting disc on the weld bead only operating at close to 90deg to the weld. This isn’t how these discs are supposed to be used so subtlety is needed, but material removal is quite rapid even with light pressure.

Once the bead is pretty much flat, check for pinholes (there will be some unless you are a welding god!) repair those and reflatten as above. Check again…. And repeat as needed.

Finally a light run over with a 120 flap wheel.

 

[RedRooster]

More control if you use an air cut off tool. 

[Nick Jones]

5 hours ago, RedRooster said:

More control if you use an air cut off tool.

Indeed. But only you have one…..

[RichardB]

I like the zirconium flap disks, they seem faster and hold up better than sanding discs on a rubber backing pad. Then again the rubber pad backed discs seem more controllable as they just disintegrate rather than change shape when the edge wears.

I have one of those air cut off tools but sadly our 2.5HP compressor (8.7cfm) is too puny to keep up with it. One of the pros to getting a bigger compressor would be to using tools like that, but perhaps still not useful enough to warrant losing the space a larger compressor would require.

[Mark]

I have a SIP 3hp 100 ltr compressor, 14cfm 10 fad, biggest you can run off a domestic supply, think next step would be 3 phase. 

It still struggles to maintain enough air to run DA's, grinders, cut off tools etc. I like air tools because they are compact, but they use a lot of air and are noisy, especially with the tool and compressor running together. Ideal in a commercial set up with a huge compressor.

Found the electric angle grinder, and more recently, electric belt file, (really useful) does the job, at a DIY'er level

[RichardB]

Thanks Mark, that's really useful info and confirms what I was worried about. I'm reluctant to go down the rabbit hole of trying to get a bigger compressor just for a few air tools, and then find I've no room to get around the car to use them!

One day I probably will end up getting a larger belt drive compressor, but I'd rather hang on until I get a place with more space.

[Nick Jones]

9 hours ago, Mark said:

and more recently, electric belt file, (really useful) does the job

Yes! I have one of these. Not especially expensive and very effective. Finding belts that give a reasonable balance between cost and life is a little tricky.

Also have a Makita electric die grinder which is an absolute beast when fitted with a carbide burr, though the earlier comments about the swarf apply!

[RedRooster]

Doesn't everyone have 3phase 

[RedRooster]

Zirconium belts lasted the longest when I was doing the Beam. 

[Nick Jones]

No. £15k apparently. The electric pole is 20m from the garage….

[RedRooster]

17 minutes ago, Nick Jones said:

No. £15k apparently. The electric pole is 20m from the garage….

Cheaper to extend your garage 

[RichardB]

It has a while since I posted an update, but I have been making slow progress in that time. Cutting out metal and dressing welds in tight spaces just seems to take ages some times. However, I think my technique is improving and it vindicates my decision to use this hard top as an opportunity to improve my skills with welding and fabrication.

Since I last posted, the patch shown has been fettled and welded in, and I've just about finished what I think is worth doing on this complicated 3 piece repair section. I've also welded two new small patches to cover some holed metal below the rear window.

Here's what I've learnt in that time:

Welding

• Welder settings that I perfected on the bench... needed a lot of honing in later on. Metal can still look perfectly sound with no pitting, but be a bit thinner and blowing holes can come as a surprise. Of course the rule is to always weld to sound metal, but you can't always be 100% sure how thick it is. I think I've now found a good range of settings to tweak the power for when this happens.
• Conversely, I've found in some circumstances I need to up the power to get better penetration on the weld. The main thing is that 'bacon frying' sound is now consistent with my welds, whether it's a series of tack welds or a pulse weld.
• I think partially pressing the torch to get the gas on before the welding starts seems to help get a consistent weld when doing little tacks on thin metal.

Grinding

• Blue zirconium pads work a lot better in the rubber type dronco discs, than the more common burgundy type. They seem to work faster and cleaner.
• I still really like the carbide burrs for the dremel. Very noisy though, I think I'm going to try some ear defenders with a higher SNR level (number of decibels they reduce by). Clean up is relatively easy with a purpose made magnet swarf collector thingy.

Some photos of progress:

 

So that section is nearly done except the channel for the rubber seal. A couple of holes from blow-through on very thin metal, but I think given that the upper one is covered by headlining, it's fine just to leave it. I'll address the one underneath when doing the channel repair.

I'm not sure yet how I'm going to form the seal channel to repair that part. I could probably get away without anything there, but I think to do a good job it should have something. It would be easy to make a former if it was straight, I'm tempted to try make a straight one and see if I can shrink it in the base, and massage the folded over lips with a hammer. Either that or make a really short buck (like 1cm long) with a handle that I could walk through the channel whilst tapping the lips over?

It's a bit like one of these, but a more gradual curve shape:

https://www.moss-europe.co.uk/retainer-channel-outer-rh-713038.html?assoc=119311

but it isn't listed in any parts catalogues I have come across.

Today's work was repairing some holes under the rear window. Much, much easier to do as I had great access. I started by making some templates and patches, then cut out the rot.

Cleaned and painted inside the box section then held the patches in with a magnet to tack:

joining the dots...

These are much better welds than the ones I was doing before on the Spitfire's boot lid. The bead is smaller, but the penetration is wider and deeper.

The final result.

Very happy with these, the patches are flush with the rest of the panel. I think having a corner nearby helped to prevent distortion.

The next job to tackle is going to be a lot trickier:

There's some real rot in this window frame at the top.

Any advice on how to get the gentle arc of the window right when forming these? My thoughts so far are:

• Do it in stages, possibly 2 or 3 patches to avoid the arc becoming too wide and thus harder to shape accurately?
• The folded edges should be easy to form, just needs careful attention to the radius so they look appropriately sharp or soft.
• Spot weld the bottom lips as per factory assembly
• Cut out up to ~1cm above the uppermost inside bend is, so there's nice thick, clean metal to weld to.
• I don't have a shrinker/stretcher, so perhaps form a straight shape like the original one, then hammer shrink it?

There's not much to lose other than time, as like always, I'd want to be happy with the patch pieces before cutting metal out.

 

[JMH]

If you don't have a shrinker/stretcher and if you are not used to work with a hand-made-tool for this, I would go for small patches.

If you can get access from the backside, a small cobber strip will help you when welding :-)

[RichardB]

Cooking on gas now. Patches, welding and grinding is taking a lot less time, now that I'm happy with my workflow and have more practice.

Edited May 8, 2023 by RichardB
grammar