GT6 Update

You know, I haven't posted on the GT6 for simply ages now, so I thought I'd provide an update. I know you're dying to know how it's getting on - so a long read.

Most of my time has been spent researching suppliers for parts I need and pricing them in Excel. Excluding painting and engine refurb, I reckon I'm looking at roughly £2k in panels and bits (chrome, etc.). Engine and spraying will be another £3k, roughly - maybe a tad more.

I've been practicing butt welding. Butt welding with a gasless MiG welder is the most difficult, but there are some areas of the GT6 where there's just no other option. The secret, according to several YouTube videos I watched, is not to use a gasless MiG in the first place, as you simply can't avoid spatter marring your work. Use gas shielding.

One of my neighbours, who rebuilt a TR6 a couple of decades ago (it only comes out once or twice a year), said he has an Argon/CO2 gas cylinder at his dad's and has let me borrow it. The problem now is that I haven't a clue as to the size of the gas inlet on the MiG. It's Chinese, portraying itself as German, so presumably made for the European market. One thing I know is that it isn't 3/8ths BSP. Got myself a thread gauge for both Imperial and Metric, so this shouldn't be a problem any longer.

Strange how the most of the Imperial system existed well before the Empire. The foot, inch, yard, fathom, furlong and mile have bugger all to do with the Empire.

If you perversely insist on using gasless (like me), then the advice for thin sheet metal is to turn up the amperage and tack very, very quickly at large intervals, air cooling each tack as you go along, and then following up by gradually filling in the spaces with tacks alternately between the initial tacks. 

The short burst (1/4 second, or less) prevents burnthrough; the air cooling and spreading of the tacks prevent overheating and warping. Unfortunately, you can't avoid having to grind the result back if you want a flush finish, as you can't do a continuous, full bead without burning through.

Above is my first butt weld after grind-back (click to enlarge). It's solid and the black bits are just burned low spots, not holes. No blow-through, although there was plenty of warping due to it being a small test-piece and my haste to complete it. I'm grinding with a normal, rotary grinder, whereas I should be using Roloc pads on a die grinder, which isn't as aggressive and more controlled.

Here's my 2nd attempt, ground with a Roloc disk. No warping, as I took my time; however, I also used the copper block backing to disperse the heat. 

I now have enough confidence in my MiG welding ability now to perform butt welds on areas that will be visible, rather than hidden areas where aesthetics aren't an issue. I can also now fill small holes with the same technique. Last week I repaired a small section around the lip of the rear hatch surround using the technique - it had been bugging me for a while. It's a pity I don't take any photos of the before and after; however, I did have a go at filling some of the rust holes in the old tailgate that I was going to sell.

A decent enough attempt - it's now all solid metal. A bit more of a grind and a skim of filler to even it out, resulting in a perfect surface. 

However, I'm going to be using the other tailgate that has no rust. That said, if I can fill all the holes and prime it, I could sell it for a decent profit - perhaps £80 - certainly more than as a basket case tailgate that no-one wants.

Oh, and in respect of the rear valance, a fibreglass section where the dimple is cannot be considered as a solution (Richard - you are correct); however, I have enough of the valance remaining to make a complete carbon fibre replacement. Given my expertise with epoxy, creating a carbon fibre full valance impression would be a cinch, and it's stronger, pound-for-pound, than steel, as well as being lighter. Certainly not original, but an improvement that won't be obvious to the naked eye, given it's position. Fixing it in place? 1/8th inch diameter pop rivets will be more than enough - it's not structural. There again, a complete panel in mild steel is only £197.

Talking of lightness, there are several non-structural panels that would have been better made of aluminium to lighten the car, despite its tendency to bend a bit. Certainly the transmission tunnel, which is actually made of some form of compressed cardboard, believe it or not (not that this would make that particular panel lighter - replacements are made of plastic).

I had another go at the front of the roof, where the rear valance of a Mini was stitched on. This was done by the previous owner as the roof repair panels are no longer available, but it left a couple of pinch points due to the profile not being an exact match for the lip strip.

I could have left it, but it would have been a glaring flaw when painted in metallic, so I decided to adjust the profile with a skim of bodyfiller to harmonise the roofline with the metal lip.

Using a contour duplicator, I made a perspex former based on the profile at the pinch points and scraped it over a layer of bodyfiller, thus harmonising the curve along the front of the roof line.

The lower two photos show where I've brought the roofline closer to the lip, to match the pinch points of the Mini valance, which butt right up to the lip. A vast improvement.

I also had another go at making a repair panel - not exactly a large item, being the bonnet closing slide for the nearside, but nevertheless a relatively complex shape, the curve of which needs to be precise.

Below is the nearside one I copied. It guides the bonnet down over the bulkhead to locate the seating cones in the right position.

It should be welded at the top and bottom of the left-hand lip (in the above photo of the nearside) and fixed with a few tack welds at the bottom, although I think I'll fibreglass around the front lip (or just use resin) due to the bulkhead metal being a bit uneven and the fact it's not possible to get to the back of it to clean up the metal after welding. I don't want to lock in the potential for rust.

Here it is welded in place. Better than the original.

There are stainless steel sliders on the market, but that's just bling - and they have to be pop riveted on.

Shhh, don't tell Hay, but the air fryer is very handy for drying small, primed panels quickly....

Wonder if I can get a bigger one for larger panels....

Found a major issue with the replacement, front section for the chassis - whoever refurbished it didn't pay attention to measurements.

The chassis rails on the refurb unit are half a centimetre out at the front and almost a centimetre at the back, resulting in a mismatch with the original chassis rails. This means that, rather than replacing the entire front section, I'll have to hack off the outriggers and the bumper fixture boxes from the replacement and weld them on the old front end.

I have doubts I'll be using the Mk2 chassis I bought - while it's nicely galvanised, it does look a bit battered and thin in places and I'm convinced my original chassis is in much better condition; however, I won't be able to confirm this until I get the tub off it.

Next was tackling what I thought was a small repair on the rain channel on one of the windscreen pillars.

The channel is an L shaped piece of steel that's spot welded to the underside of the pillar, with the bottom of the L forming a narrow rain channel. 

I had a number of options.

1. Repair the section with a small plate.
2. Replace the entire channel - repair panels are only £8.50, or I could easily make a couple myself for both sides (the other side likely had rust under it too).
3. Completely remove the channels on both sides, as they're renowned as rust traps anyway.

In the instance of repairing or replacing, providing there was sound metal underneath, I decided I wouldn't weld either the repair section or the replacement into position, as that's just storing up a rust problem for the future - I'd pop rivet them with a thick layer of goo between the sections and the pillar to prevent water ingress. That would aid removal at any time in the future to see whether any rust had formed. 

I screwed up my courage last weekend and removed the entire channel from top to bottom by drilling the spot welds and using an air chisel to cut through. It revealed a latticework of rust and I'm glad I didn't just do a bodge repair.

The strength of the windscreen pillar is compromised - not dramatically, but enough to require a panel to be stitched in to add some integrity. On the basis of this I ordered a couple of replacement gutter panels but, on 2nd thoughts, I should just have made a couple without the drip channel, as that forces water between the pillar and drip channel, causing the rust in the first place.

On the basis of the O/S, I also removed the N/S drip channel. Luckily it wasn't anywhere near as bad, but bad enough. There are 2 large, circular holes in the pillar inside the car, which I used to spray generous quantities of Jenolite rust converter inside the pillar, halting the rust in its tracks.

I'll wait till the drip channel panels arrive and then decide what to do - whether to simply put a non-flanged piece of steel over the top (as in the photo below), or use the ordered panels and retain the drip channel. I can't do both, as the result would be too thick for the door gaps.

I thought I'd try to fit the new rear wing, but the outer mudguard that the previous owner had tacked on was far too low and also needed shifting slightly forward. I drilled the welds of the inner wing and air chiselled the outer mudguard off. Then I offered the wing with the mudguard attached up for positioning and scribed around where the mudguard should be. I then used a couple of pop rivets to hold the mudguard in position while I checked the wing for fit again, which was perfect. The mudguard was then plug welded into position before I offered up the wing for spot welding.

Above - the outer mudguard in the wrong position.

Above, correct position, held on with a couple of pop rivets.

Above, outer mudguard welded into the correct position.

Above, wing lines up perfectly with rear end.

Above, rear wing ready for welding into position.

I could only use the spot welder at the back half of the seam. The area forwards from the halfway point had to be plug welded and ground back, as the spot welder is simply too large and unwieldy to get into the space available.

Primered.

The underside and wheel arches need to wait for the valance to be repaired and the forward end requires a door closing panel to be ordered. The wheel arch welds would be best done on a rotisserie for ease of access with the spot welder. At least it looks almost complete. 

The bonnet can be tackled next, as it requires all the paint coming off before I order some repair panels.

Also paid attention to several small details. For example, there's a grotty section of roof gutter on the N/S, which I blobbed with weld (using a copper backing plate), ground back and painted in primer. The photo before is as it was.

Bloody difficult with a gasless MiG, but I managed it well enough. Pretty inconsequential in the overall scheme of things, but important for aesthetics.

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I wanted to tack the driver cross member to the new floor pan, but thought I couldn't do that till I had the bolts that attach it, as they go in diagonally, through the floor pan and into the chassis, not vertically, and I wanted to locate the bolts into position through the captive nuts before fixing it in place, just in case I misaligned it - and guess what? Yes, the original bolts are somewhere in a box among the many boxes of bits. However, duh, it suddenly dawned on me that I could use the bolts from the N/S cross member, which were still in situ.

I duly removed said bolts and tried to seat them on the other side, but to no avail. No matter what I did, one bolt refused to seat, despite me widening the hole through the floorpan with a burr drill bit. There was no option but to slice into the guide channel that the bolt ran through in the crossmember.

The photo below shows the guide.

The photo below shows the slide I made into it so as to provide more wiggle room.

It then fitted perfectly and I tack welded it into position.

I learned a neat trick of my own, more by logic than anything else. I had already welded the crossmember into place and sprayed it with weld-through primer, but wished to make a couple more tacks. Rather than scratching off the various layers of paint, I surmised that the weld-through primer, having lots of zinc in it, would be touching the bare welds I'd already done and so, wherever there was weld-through primer, I would be able to strike an arc without having to scratch through to bare metal - the zinc primer would compete the circuit long enough to burn through the paint to metal. The same as regards the earth clamp - the area would be earthed if I merely attached the earth clamp to something painted with the weld-through primer. It worked a treat. I intend to back-fill the spaces between welds at a later time.

Stop Press: just realised the complete, rear valance is £123 from an alternative supplier, not £197, so I think I'll go for it - I can save a few bob by making some other repair sections panels that don't require an English Wheel. In any case, looking at the existing valance in the light, you can see it sinks on the right, so there's no option but to remove it completely to do a proper job.

Lack of funds though unexpectedly having to bail out No.2 Son at university has caused a temporary halt to proceeding further with panel purchases this month. I could do with getting the Mercedes 500 SL back from the garage in Frampton Cotterell, where it has been languishing for almost a year while being fixed (the biodegradable loom issue), and selling it, thus releasing ample funds.

I did, however, get a load of air tools for £25 on Facebook Market. A long, flatbed sander (perfect for levelling body filler skims on flat panels), a couple of drills, a couple of die grinders and an air chisel All seen better days, but still serviceable. 

Deep joy! This is what retirement was designed for. Not a lot has been done in terms of what's obvious, but I have been doing a lot of minor stuff that's nevertheless important in the overall scheme of things, such as filling in small dents and re-working some decidedly iffy welding. All that's holding me back from getting the tub off and on a rotisserie are the rear valance, a door closing panel and the 5 remaining bolts holding the tub on the chassis (the others are already off). Oh, and space.

If the tub comes off to go on a rotisserie, the chassis is going to have to reside next to the tub, but I have so much crap lining the garage that it will be very tight and I'll be tripping over everything. I can't leave it cluttering the drive, as I share it with Hay's dad's car and he needs to be able to get it into and out of his garage. Perhaps I need a spares shed - or commandeer Hay's dad's garage. Now there's an idea!

Bodywork is my forte, engines less so (especially gearboxes) and electrics not at all, especially when I don't know the car that well and never took it apart in the first place. I'm a dab hand at spraying, but only in flat colour cellulose and primer, not water-based metallic. That said, when my mate does the spraying, I dare say he'll let me have a go.

Out of curiosity I looked up the MGB roadster I rebuilt some 40 years ago on the MoT database and it's still on the road - or was in 2019, when it last had an MoT (it doesn't actually need one). Granted it might have had another rebuild since I performed mine.