SD restoration

[Oyster 49]

My first 2 refurbished tanks are now completed. I took the chance of trying out different paints to see how each compared. The screw tank was sprayed with satin Hammerite, whilst the bayonet tank was sprayed with gloss Halfords on brand. Both were then cutted back with T cut and sprayed with Halfords fuel resistant lacquer. Bayonet tank had decal applied screw tank did not.

Before application of the lacquer the Hammerite was very dull, to the point of nearly being rubbed down and repainted. However the lacquer turned both into an excellent finish. The Hammerite was very thin and prone to runs, the Halfords finish did not seem to be.

The lacquer has to be recoated within 15 minutes or so, and seems to be better applied fairly generously.

I think my preference of the 2 was for the Halfords paint, for ease of spraying and also easier to T cut back as it is a softer finish.

[Oyster 49]

Had a session on the driveshaft leg tonight. A rotary wire brush got the corrosion off to reveal a sound but pitted surface below, but with plenty of steel left to clean up. This is all good news, as I originally expected this leg to be scrap

No sign of any previous zinc coating, only the remains of chrome plating at the bottom of the leg.

Next job will be to try to dress out the worst of the pitting, before finding a decent plating works. There is a good one in Derby, but they are expensive.

Anybody know any good value plating shops? If so any previous experience as to cost?

[Double Dutch]

Hello Oyster,
I had my leg zinc plated together with some other parts, eg bolts, nuts and the tank straps.
It cost my 40 euros, I think chrome plating would cost you about 75 pound for the leg only.
The surface of your leg is badly pitted, if you let it plated it probanbly wouldn't fit anymore. ( to lose)
I spend more money than the whole motor will be worth.

[Charles uk]

The vast majority of SD's had zinc plated drive shaft tubes, the chrome examples could well have been later repairs to replace badly rusted zinc plated ones.

All the SD's I've seen & owned were not fitted with tank straps, but had Jubilee clips instead I would have thought tank straps were probably a later replacement/repair.

Oyster try dipping the "chrome" traces on your tube in a medium strong acid, zinc will fizz & nothing will happen with chrome.

[Oyster 49]

I had another good session with the emery disc earlier. Most of the pitting is now dressed out, but I was carefull not to remove any material around the lower end. So it is still a tight fit, even better after plating.

I was thinking about filling the deepest pitting with either braze or solder and dressing it back to shape. Has anybody tried this and had the resultant repair chromed? I could of course paint with a zinc finish which would be similar to the dull grey "dipped" finish. However I'm keeep to have it plated, my choice will be a satin chrome finish.

[Collector Inspector]

I rather like the look of the clips on this shape tank. I would imagine that they were painted Charles?

[OwdJockey]

hi oyster, I am surprised no-one has suggested the au natural look, i.e. keeping the steel shaft as it is and working on polishing up the surface. Below is a photo of my Silver Century shaft before clean-up and polishing. The end of the shaft was protected from the worst of the pitting by it's encasement within the upper gearbox housing.

I did consider chrome plating but baulked at the cost. I achieved similar results by polishing on the aluminium exhaust as well.

This driveshaft is not the finished article, requiring a quick final polish and then lacquer applied.

Silver Century Driveshaft - before clean-up & polishing


After clean-up & polishing

[Collector Inspector]

Yeh?

[Oyster 49]

How many hours to get your leg polished up to that finish?

All this does of course lead to the question wether to restore to original or close to, or to make it better with the benefit of modern techniques. Opinion seems to agree that original SD legs were zinc dipped or galvanised with a resultant matt grey finish, like galvanised roof sheets etc. It is also suggested that some legs were painted.

However it also seems to be true that most SD engines have legs in very poor condition due to rust and deep pitting, so the question opens up - "to try and replicate the original or not" Now I have a restorable leg, I must admit that chroming is looking attractive, but expensive! I will shop around and report back

[OwdJockey]

I can't remember exactly how many hours, but I would hazard a guess at less than 15hrs total.

The result will be good, but not pristine or concours standard.

My rebuild is aimed at a reasonable level of originality, but as I am not aiming at a concours standard I am not going to beat myself up over not making it 100% original.

However, doing these Century pieces did teach me a bit about metal polishing, something I have never done before.

[SAE140]

... most SD engines have legs in very poor condition due to rust and deep pitting, so the question opens up - "to try and replicate the original or not" Now I have a restorable leg, I must admit that chroming is looking attractive, but expensive! I will shop around and report back

I've just put a wire brush and sander over some flaking chrome plate on a drive tube, only to discover a thin layer of copper underneath ... Curious choice of metal - as copper will accelerate steel corrosion, once started.

For myself, I'm not bothered with looks (originality etc), as long as the engine is functioning as intended and reasonably tidy - but if I was into looks and faced with your dilemma, then I'd at least consider 'chrome-look' paint. I've never used it, or even seen it used - only heard of it third-hand - so can't comment on it's performance.
Being paint of course, it would cover any patches of JB Weld used to fill deep corrosion pits.

[Oyster 49]

Is copper used as a base coat for chrome plate, followed by nickel, then chrome? I think it is.

I had a couple of hours working on this leg this afternoon. All of the corrosion pitting is now dressed out, so the tube needs a final polish using a strip of emery paper to remove the dressing marks. I used an emery disc on the end of a drill, using a circular motion to avoid putting flat spots on the tube. I'm very pleased with the result

I suspect that the depth of the pitting was less than 10% of the parent material. Full marks to seagull for the quality and thickness of the steel! Considering I originally thought this leg was going to be like a teabag, I'm CHUFFED!

I might not be as happy when I get a price for rechroming 2 legs..

[SAE140]

Is copper used as a base coat for chrome plate, followed by nickel, then chrome? I think it is.

I don't want to sound too knowledgable about this, 'cause I'm not - but afaik, there are 2 types of chrome plating: the copper/ nickle/ chrome route is about plating for appearance - the chrome plate is itself very thin, and can be prone to flaking. The other method is direct-to-steel chroming which produces a much thicker coat and is used where long service with hardness is required - on bearing surfaces, hydraulic rams etc. Perhaps this second method would last longer on a leg ?

[woodbutchergraham]

Come on chaps it’s all gone quite on this post. Or are you all too busy polishing your parts?

[Oyster 49]

Hello Graham,

Sorry but I have been installing kitchen units and was away sailing at the weekend. Force 8 in the Thames Estuary all last weekend, with sunshine I have found the time to build a seagull rack in my garage, should hold 8 engines at least

Apart from the leg which needs a little bit more fettling, the SD is ready for rebuild. I've not managed to visit 2 chrome platers I've found locally yet, one in Nottingham and 2 in Derby. I need to price the job up.