Restoring 330 Fuel Filler Flap

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Darren C
Posts: 123
Joined: Fri Sep 06, 2013 3:56 pm
Location: Chichester UK

Restoring 330 Fuel Filler Flap

Post by Darren C »

The last few weeks have been quite tough, my cheap ebay Volvo needed a new rear tyre for its MOT test (it was picked up last year as on the minimum tread limit so after another 12 months it was pretty bald) Unfortunately it cleared out my savings for the Aluminium sheet I need to make the grille with, so it’s going to take me another month to save for it.
In the meantime I decided to get on with some no cost work on the parts I’d already amassed.

I started this week on the fuel filler flap. I took this off a very rusty 330 shell that was beyond salvage that had been parted out a few months ago. There was no key so the only way I could get it off the shell was to drive out the hinge pin. (Top tip if you ever get a broken fuel key or lock)
Once the lid was off I could remove the bezel from what was left of the rusted out 330 shell.

All the parts were in very bad condition so I got them for a good price.

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First I removed the lock and once painted insert panel from the top of the flap. The flap itself is made of stainless steel, so after many, many hours of working from a smooth file up to 1200 grit wet and dry; I got all the scratches and dents out. The once painted lid which is mild steel had rusted beyond repair and the rust had eaten in places into the stainless flap, etching and staining it. Again after many more hours I managed to sand it all out and polish it all up under where the painted insert sits. You’ll never see this once its all back together, but I’ll know it’s as good if not better than new.

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The bezel that sits in the car was in a terrible state. It’s made of plated aluminium, with a stainless hinge riveted at the top with stainless rivets and a mild steel latch riveted at the bottom with copper rivets. This then sits in the steel body of the 330 held in place with 3 mild steel screws. A recipe for massive galvanic corrosion!
Suffice to say it was in poor shape. After a week of 3-4 hours every evening with files, wire brushes and wet & dry, I got it back from the dead. The hinge interestingly was made from stainless plate with a stainless tube brazed along the edge making up the hinge part. This still had glass hard braze flux on it so after a damn good clean and polish I can say it is better than it left the factory now.

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With the painted mild steel insert on the top of the flap too far rusted to save, the only option I had was to make a new one. Again the original design is poor when it comes to corrosion resistance. The painted disc sits on top of the stainless flap in a recess. I would think that every time it got wet, capillary attraction would hold water under the disc and rot it from the inside out.
To stop it rusting out ever again I chose to make it from stainless steel. After roughing out with a hacksaw and chain drilling the flat sided hole for the lock; I filed in into shape.

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The lock was the next big problem.
Having got the lock out by driving the hinge pin to free the flap, I could then unscrew the securing ring on the back to take out the lock assembly. The lock casing is chrome plate Mazak and was again starting to crumble with age. After a few hours fiddling with the lock, a key from my house window double glazing locks (closest key blank match I could find) a set of Swiss files and marking blue, I filed a match and got the lock working.
Now with a working lock & key I had to do something with the bezel that was falling apart with corrosion.

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Having took the lock apart it became obvious that the Mazak body of the lock that has the bezel cast into it was something that could not easily be remade. After searching over 2 years for 330 parts I’d not seen another for sale, so I came to the conclusion that all I could do was try and make a discreet repair. This again was problematic. The lock bezel is barely 1mm in diameter larger than the lock body. This 1mm is all that holds the lock into the flap (as the head of a bolt does, with the lock ring acting as the nut). This caused me more trouble as simply turning down to loose the damage so the bezel was perfectly round again would mean it was undersize and would fall through the flap. The only solution I could think off that would be pleasing to the eye (albeit TEMPORARY until I could find a good new lock) was to turn down a tiny counter –bored sleeve. Again this was fiddly as it would need to be a neat fit around the damage bezel but only 0.5mm in diameter larger over all in comparison to the bezel, with a hole in the centre that the lock fitted through, but with a 0.5mm step inside the counterbore. The base of the new sleeve would also need to be around 0.25mm to stop it holding the lock too high in the flap and not latching properly. After an hour or so grinding some tool steel to make a bore tool I turned down the sleeve from some spare stainless bar I have.

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After a very tricky and fiddly de burr just trying to hold the part the lock was then gently pressed into the new bezel sleeve.

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I just need to clean up dress in and polish the new sleeve and once the lock is fitted in the flap it will have a perfect circular bezel edge without chunks missing as before.

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As I said earlier, this will please the eye and only on close inspection will you see it has a 0.25mm band around its circumference, but again I have to make good what I have.

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Should a good lock turn up some time in the future, or someone have one spare (please pm me) I’ll swap it over.

But for now, after a week working on it, I have a presentable fuel flap ready for the grand assembly one day.
330GT 2+2 4HL 6727
Small things make perfection, but perfection is no small thing.
Darren C
Posts: 123
Joined: Fri Sep 06, 2013 3:56 pm
Location: Chichester UK

Re: Restoring 330 Fuel Filler Flap

Post by Darren C »

Today I finally finished making the Fuel filler flap inserts in Stainless Steel.

I had a wait to get hold of some 0.6mm stainless sheet to make the small tabs that bend over to hold the insert into the flap. After a search I got a sample off ebay. Since the tabs are only 25mm x 5mm I managed to make quite a few for trial welding from the smallest of sample sheet.

The original has the tab spot welded quite crudely and this distorts the top surface of the metal insert, meaning a lot of preparation and even filler is required on the originals to hide the spot weld crater before the insert gets painted body colour.

I didn’t want distortion in the top surface so after a little thought a layer of copper on the top surface acted as a sacrificial conductor for the jaws of the spot welder.
This allowed a neat twin spot weld to secure the tab to the disc.

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Once cleaned up with a bit of fine wet & dry the top plate I previously made had no distortion at all and with a careful measure it fitted perfectly.

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As I said in my previous post the item can now be painted body colour to match the car without any worry about future rusting out.

While I made my insert I also made a few spare inserts. These are on offer to trade with any fellow members restoring their cars in exchange for small parts that I am still missing for my car. Please pm me if you have anything you’d like to offer in exchange for one of the fuel flap inserts. They are fully hand finished and ready for paint

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330GT 2+2 4HL 6727
Small things make perfection, but perfection is no small thing.
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