Restoring an  S7-deluxe - A case study in restoration - page 1.
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In March 2017,  I asked a car forum I subscribe to whether they would be interested in my sharing with them the restoration of my post war Sunbeam S7-deluxe.  My thoughts were to write these notes here, so as to share the experience I'd gained over the years both as a practical Design Engineer and as an ex-professional Sunbeam Restorer / mechanic with Sunbeam owners, but for reasons of motivation I choose to write it where I might get feedback (no-one writes to me here :cry: ) .  

The response was, and has since remained, favourable to enthusiastic ..and so I can now transfer that topic to here (..only slightly edited for succinctness).

NB.  you can find & read the full topic on a great website called 'Autoshite'.
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Posted -
21st March 2017 - 2:28pm :

Question :  Is the restoration of a post-war Sunbeam motorcycle of interest here., or should I leave it with the specific marque motorcycle club ? 

Sunbeam s7d - Pudge (c) Sunbeam R&amp;R

^ This particular bike is a 1953 S7-deluxe, which I started restoring a few years ago but never got around to getting done.  She does have an interesting history and was semi-customised, but I'm putting her back to almost standard specification (without ape hangers), and I have had its unusual 'monochromatic' silver livery repainted.

 I've already done quite a lot, but the engine rebuild needs to be completed and then 'a little' reassembling of other parts...

Sunbeam S7-d restoration - in progress
NB.. I'm working on this now because my tennis-elbow has been giving me jip, so I need to do light work for a while.  But, as and when I'm able, I'll need to get on with other projects - so this one still isn't likely to pull together quickly.. :roll:

Although bought it reasonably cheaply five years ago, the prices of old/classic bikes have subsequently gone stupid.  I'm also 'restoring'  it., so it's not exactly Autoshite territory any more. interesting ? :  Yeah  :)   or   Not 4 'ere mate  :evil:   (like or not ? )


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Comments received included :

" Absolutely - you will find we are a very broad church here.  It might even motivate me to fix the PC50

" More please.

" YES!
" WAIT, you're restoring one of these?  Oh, you mean the Sunbeam S7 motorbike. Carry on.

" More to the point, give a reason why folk WOULDN'T be interested. Get sharing!

" I always thought they came in black or green.  I knew someone who had one with side car chassis on. he had a flat board where the sidecar went and carried model steam engines on it which he used to make in his cellar. The proper model trains they use to take children for rides on. Said they were an engineering masterpiece. Sunbeams and his models. He also had me looking for the chain for a while.

" I missed out of one of these about twenty years ago. I rang up the second the paper arrived but was beaten to it by someone who had just rang up before me. A few weeks later I saw it up the street from me, only about two hundred yards away and got to know the new owner quite well. If the damn paper boy had gone the other way round it would have been mine.

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Posted - 21st March 2017 - 7:08pm :

Wow  great response.. 11 yeses out of 99 views in just four hours.  ..guess I'd better extract my digitum then.. :shock: and show you what's happening.. 

The bikes were incredibly unpopular for so many years (until very recently), so I'm always glad to hear anecdotes ..however far back they go back.. whether good,  bad.  or just amusing. :lol:

Thanks to you all ..I really appreciate the motivation :-D

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One reply was ..

Is this an S7 ?




I went to this as a cut out / non start job one chilly Sunday morning. The battery was showing about 2v and it wouldn't produce a decent spark when it was kicked over so the resourceful owner had got his wife to drop over a spare 6v battery to him but that was also dead flat. We briefly thought about trying to bump start it but looking at the tiny drive shaft going to the back wheel and the possibility of damaging something that idea soon got parked up. 

I needed to get some charge into the Sunbeams 6 volt battery but my van is strictly 12v but as we now had two batteries to play with i was able to wire them in series,sit them on the vans side step and give them both 15 mins of jump lead action without fear of damage.  This worked on the bikes original battery (the other battery was goosed) and gave us enough charge to easily restart the bike and the little ammeter was showing a couple of amps charge when the engine was revved but sod all with the lights on.

The chap said he thought the short,leisurely ride out from his nearby home wasn't long enough to put back in to the battery more charge than the lights were taking out.  

He also told me the story that after the war BSA / Sunbeam acquired the plans of a BMW R75 and the bike was loosely based on the German machine. 

It was a lovely bike though,quirky and scruffy / original.

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To which I replied :

/\   Yes., it's a Sunbeam S8,  nicely adorned with both period and contemporary accessories. (NB. pin stripes were not a post-war thing with Sunbeams, these appear to have been home applied).  'Sportingly' weighing in 25lb lighter than the S7., the S8 had a very similar frame (seat mounts only differ), but then used BSA A7 front forks and skinny chromed wheel rims. These in turn led to the exhaust silencer being changed to an upswept one ..rather nicely defined in cast aluminium.  And of course it's mudguards were very much slimmer, allowing luggage bags to sit tighter. 

The only other differences were the type of saddle and front brakes. The engine with in-series flywheel, clutch, & gearbox, then shaft drive to the rear wheel worm drive (differential) - were the same for either bike. As was the rear plunger-suspension and all electrics.  Below.,  is my own S8 from July '53.  I bought her in 2012 and was used for my commute to work (because she's so easy in town traffic). She is still my 'daily' ride.  Likewise 'a lovely bike though, quirky and scruffy'. :mrgreen:


The eagle eyed Shiter will spot ; 'Pudge'  the s7-d  (feature of this thread's restoration) and 'Nudge' the above S8 are sister bikes (clue in their registrations) with just five and a half weeks difference in age.

I ought to declare that aside from a lifetime of affection for these bikes.., for 18 months I restored these bikes professionally.  :rolleyes:   I'd been made redundant and so to pay the rent - turned a hobby into a business.  As a motorcyclist and as a Design Engineer ( the Sunbeam - from the West Midlands) - I was intrigued by the Beam's quirky/advanced features (in context of the immediate post-war era) and that led me to look deeper.  I had my own website, which I've kept going for those wanting to know more about the bikes.  If you suffer insomnia or are otherwise bored silly at work then < start here >. -_-

 "after the war BSA / Sunbeam acquired the plans of a BMW R75 and the bike was loosely based on the German machine an oft' repeated story.  No offense to your source - but from research and my own career experience - I dismiss it as being rooted in the blabbering of yet another wordsmith who can't be arsed to research or to actually think any deeper than the sweaty fluff in his own belly button.  On the (above linked) website you'll see an alternative to that version of history.   :ph34r: 

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(c) Hallets of Canterbury(c) Hallets

Sunbeam s7 with sidecar feature in Hallets of Canterbury front window c. 1951/52.   It's not where my bike came from but still a tasty aperitif.. :-D

 Ok., here we go.

 A little background about 'Pudge' ..this particular S7-d...  

 The Sunbeam S7 was the flagship model of not only Sunbeam Motor Cycles but the whole of the BSA Motorcycle group (who had bought Sunbeam in 1943).   And although this bike left the factory in the standard light-green colour - it was completely stripped down and professionally painted monochromatic Silver (earliest form of metallic paint) very early in it's life.  Records no longer exist as to exactly when she was painted but we may reasonable speculate..  

NXN 530 was originally registered in London on Thursday 4th June 1953  ..the first working day after Her Majesty the Queen's Coronation (2nd June).  NB. Wednesday was a public holiday ...time to get over the hangover from Tuesday's celebrations.!

So, picture in your mind's eye if you will ; London in a buzz of excited anticipation not felt since V.E.-Day  ..of horse-drawn Royal carriage parades, flags flying high across every street and square. And in the summer sunshine.. the Coronation of Princess Elizabeth.   Just streets away, there on the High Street, in the broad expanse of a glitzy whitewashed Art Deco motorcycle showroom, centre-piece under tungsten spot lamps on raised plinth  is a brand new highly-polished metallic-silver Sunbeam S7-deluxe  amidst red, white & blue buntings.!  Strategically placed all around would be gleaming  BSA.,  Ariel,  and Villier  classics in their standard red, white and blue livery.

 ..even today that would look spectacular, but in context of post war austerity.. such a front window display would have had a mega WOW factor.!  :-D  :-D  :-D 

 p.s. some of you may remember Triumph Bonneville's Silver Jubilee edition.?

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A comment :

Sorry to put a dampener on your glorious picture - but it pissed it down on Coronation Day and the maximum temp was 12 deg C.

As for the Sunbeam - carry on with the news. These particular Sunbeams along with Aerial Square Fours were rare flashes of originality amongst the monotonous parade of parallel twins and singles churned out by the British factories.

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To which I replied :

Are you the sort to piss on my parade ?  :lol:

However, you're almost right was cool, not least because of the brisk north-easterly blowing (Tropical Storm Alice ?)  ..there was just 1.5mm of rain recorded in London ..but also 2.2 hours of Sunshine  8)                                                < met office > :P

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where I'm at now ?

..well the bike is an ongoing project.  It was bought as a runner (just) but had been neglected, and then was  unused & forgotten in the back of a Bristol garage for several years.  Being a 60 year old bike,  run on a very tight budget by a young lad (a junior chef) who didn't even have a motorcycle license - I knew from the outset that the mechanicals would need to be stripped to be checked and to replace perished oil seals and home-bodged gaskets, to replace the cam-chain, and to clean out the oil-ways of sludge.

And aside from the mechanicals ; I've completely stripped the tinware to be repainted ..ostensibly because the rear mudguard was dented and otherwise in a poor state.  Even 'silver' gaffer tape didn't hide the fact that the hole surrounds for mudguard bracket and (removed) pillion seat were dented, rust frayed, and otherwise scabby & cracked.  Without a pillion seat (as I wanted this bike) the top curve of the rear mudguard is a real in-your-face feature of the bike's cool style. And being aged monochromatic paint, I couldn't simply hammer out, weld repair and neatly paint over it. 

I then tripped arse-over-tit down the slippery slope.. 

Reasoning that it would have looked odd if the rear mudguard was beautifully repainted - but petrol tank, headlamp shell, and front mudguard were left sun crazed, faded, and just a little scabby (..truly a fine Autoshite patina which I wanted to keep and use as was)....  

And so the 'get it on the road and enjoy as is'  became.. 'yet another time consuming & expensive,  yet unfinished project'. :blink2: 

The headlamp (electrics) and fork shrouds were stripped down too. And then, on this particular bike many 'bits' had been chrome plated. The side boxes under the seat contain electrics on one side and the battery on the other. The battery had clearly leaked at some time, and so the boxes were removed to be re-chromed. Having discovered the bike's early and then a later celebrity history - the 1970's Easy Rider style ape-hanger handlebars were not the style I wanted.  I chose to restore the bike to not as original (mist green ..same as every other) but as it was when used as a prop by Mike Prior - London photographer. 8)

^ American Rock - The Nelson Brothers (son of Ricky Nelson) photographed on this bike by Mike Prior, when they were on tour in London.  The bike also featured on the book cover of a 'Bit more Fry & Laurie'  and then also co-starred with Robbie Coltrane,  David Hasselhoft,  and Martin 'Youth' Gover (who subsequently bought and frequently used the bike around London). I found a set of original bars, which also needed re-chroming.. And so it went on ..and on.  And then those infamous words came to the forefront  "While you are at it / have gone this far " .. I decided that I might as well repaint the frame properly, and that meant every bracket, the centre & side stands,  and foot pegs, engine mounts, rear suspension, brake linkages.., et all.  :o  

Beware all ye who follow this road..!

The alloy rimmed wheels now on the bike are not as it was back then, but I like them - so will keep 'em.  The paintwork & chrome I had professionally redone.  And I had the frame blasted back to bare metal (more on these things anon). 

So I now have a pile of a thousand (expensive) bits rather than a quirky and great fun motorcycle. :help:


The tale continues..  A few years ago I'd been made redundant and started a Sunbeam m/c restoration business. It was successful enough - that even after just 18 months, when I declared that I was going to retire early by dropping out of society to live on my old boat, a chap (from the owners club and based down near Guildford) wanting to buy it..  In exchange for a very modest sum, he had a list of my suppliers & parts lists,  adopted my business template,  and copied what he wanted off my website set him up.  With a little telephone help & technical advice ..and my passing on a few customers - his business got off the ground immediately.  He's now doing very nicely for himself and appeared grateful for what I'd done for him (over & above the agreement). 

So last October,  seeing as I had one or two other projects on the go (one of which was abroad) and recognising that this pile of bits was not happening - I asked him (said purveyor of the business) "what it would cost to rebuild my engine and gearbox ?"  I explained that the engine gearbox was running/engaging fine, but needed cleaning inside & out,  checking,  plus any repairs & wear,  seals,  etc.  It was for the Coronation bike so had to look good, but as the intended future mileage of this bike wasn't going to be very much - tightly blueprinted engineering wasn't necessary.  We discussed a price for labour, and also that my timescale was 6+ months (ie., it was to be a fill-in job).

All very amicable, I dropped the motor assembly down to him, along with two spare cylinder heads (to choose & use the best)  plus new gaskets,  seals,  and other parts - should they be needed.  Off I head to Slovenia for a month - to try and get ahead with another project.   Upon my return I checked what's been done with my engine/gearbox ..not really expecting much to have happened, but found the bill already closing on three times the amount discussed ...with the engine is still in bits.!  :signs053:

I call him up immediately to halt any further work and arrange to collect as is. Nothing had been put in writing - as I thought we were friends (who I'd gone out of my way to help).  I paid the bill but cordial conversation was notable in its absence.  Inside., from top of my head to the pit of my stomach shouted oh mighty darn !  it's happened to me again..  I must be the dumbest chap in Sunbeamland.. ever ! (NB. obtuse language has been moderated for sake of the genteel)

I got back and put the engine under a bench ..not wanting to even think about it.  I just needed to pick myself up, grasp my bruised bollocks, re-evaluate my crumbling financial position,  and try to move on with said other project as best I could.  And that's where we are now.

Perhaps it also helps explain why your supporting me through this website forum is bit of a lifeline.  

Thank you guys (..& any ladies) B)

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So.,   I've now pulled this bike out ..and will do bits as and when I can between aches and other pending projects, the garden becoming overgrown, and bills pecking away at my very finite resources. 

For those not familiar with restoration work, the first and often crucially important task is to thoroughly clean and inspect what condition the bits are in  ..even where you cannot see..


^  The inside of the crankshaft is drilled lengthways (7/8" bore)  as an oil way to the big ends. When the crank spins it exerts centrifugal force on the oil within. As a result the heavier dirt particles (in oil suspension) are thrown to the outside of the plenum and stick to it (it is designed as a centrifugal filter - but with high mileages and infrequent oil changes it can become almost completely clogged).   One can check the internal state without removing the end core plug, which in turn necessitates pulling the caged front main bearing off (which tends to destroy it). It's done by feeling the inside wall with stiff u-bent wire. If clean (like this was) you can even hear the metallic sound when tapping. But if it's clogged then the sound is dull and scraping will pull out some of the softer-packed sludge.

The crank pins look to have been reground to +0.025" and the shells are like new - so are good to go. The main bearings are likewise fine, albeit with very minor wear - they are well within tolerance. 

In the past I rebuilt my S8's engine ..and blue printed every bearing and the pistons to tightest minimum tolerances. Subsequently it was an absolute bitch to get started ( brakes were on inside the engine !).   It's fine now but, despite utmost care, she seized half a dozen times while running in. Seems like everything being to a tight tolerance doesn't suit these old engines, so I'll not make that mistake on this motor. 

Personally I like to thoroughly clean everything oily, greasy and dirty, externally - before stripping it down.  It's very much easier to work with clean parts, hands and tools. And sockets/spanners fit better if things like the sump nuts are not encased in crud.  Apparently said professional doesn't work in the same way.  They've got to be cleaned at sometime, so yesterday I systematically removed parcels of still filthy fastenings and cleaned them.  



^   I don't want surface rust nor aged staining and dirt inside the engine,  so the crankshaft and other ferrous internal engine parts have been thoroughly wire brushed. 

The geared oil pump, built into the timing gear backplate (mid-rhs of photo) had a little too much end float for my liking and so I dismantled that and skimmed (on emery cloth) a couple of thou off its closing face.

Special fastenings (mainly Whitworth thread on this bike)  like the cylinder-head nuts are surprising expensive to replace and so I also redressed their spanner flats. They weren't in bad condition just minor spanner burrs.  However, the oil filter /sump baffle plate (lhs of photos) had been home-modified ..and that included drilled holes / countersunk bolts through the bottom of the oil sump,  so I'm replacing those. 


^ The cam-chain tensioner had been chewed up and seen better days and although still serviceable after being redressed - I'll also replace that with a better one I have.

One of the things about thoroughly cleaning and closely inspecting parts early-on in the task is that you can see what needs replacing, or professionally welded/repaired in advance.  Then you have time to order / get it done.. before being needed in final assembly. :unsure: 

An example of this.  In a packet of fastenings I found a coil of aluminium.  It was two or three winds of stripped thread from where a gearbox mounting stud had been over tightened.  Fitting a thread insert is a task which (imo) ought to be done before the cases were blast cleaned - to avoid the risk of scratching the cases when working on them (as has happened on this one) ! 

Disappointing and a waste of time, effort and money,  is to finish cleaning something before the work of rectification is done...


^ what does this show me.. Firstly are the dents to the gasket face, these can be seen when the cover is on and do nothing at all to help seal the cover.  Like every other defect or damage - It ought to have been redressed before blast cleaning.

Then, the tappet adjustment nuts are a different size ?  And.,   I happen to know these engines well enough, but just looking at the exploded diagram in the workshop manual tells anyone - there are washers fitted here where there were none. One washer I see is the wrong size, and the flats of the nuts haven't been redressed to remove their wrong-spanner-size rounding-off / burrs. 

And aside from it all being stained (..which means inspection for hairline cracks is impossible) - I noted this.. 


^   should either  lump of steel break away.. then really I prefer them not to be inside my professionally rebuilt engine.! NB. the shiny washer you see (left) isn't meant to be there.! ..more on that little issue later.

.. And here (below) is another unpleasant (albeit cosmetic) detail . . . 


^ this is the other side of the cylinder head to that previously shown.  Aside from the dents visible in the top gasket face is the broken fin, and the fin above that is hammered bent,  is cracked & with scars.  

He had cut away other broken cooling fins (from under the inlet manifold) and then paid (my money) to have weld-repair yet another broken off corner..  So why didn't he just use one of the others I'd supplied (choice of two other cyl. heads without damaged fins).?

This cylinder head had been stripped out, checked and blasted clean, and then reassembled - Is it ready to go ? 

No.,  sorry not nearly good enough. !

Every stud had been removed from this engine, but for those in the picture above ..imo for no good reason.  To remove the studs, and then have the case blast cleaned means that all the dusty, gritty, shite goes into those drilled & tapped holes.  Then it's a very time consuming job to clean them out.  Blast cleaning of cast aluminium is a relatively gentle process.  I doesn't touch the toughened steel of studs or their threads.. it just cleans them.

Incidentally the engine's crankcase and cylinder head were blast cleaned ..but not the sump pan, the rocker cover, nor the gearbox and bell-housing. With their texture being different, those bits no longer visually match each other !

I could go on and on,  but I suspect you the reader have had enough by now ..and there are just so many such faults to document.

Bottom line being that is - What has been done.. needs to come apart again, and I have a lot of rework to do.  That of course includes more cleaning, measuring, welding, and re-blast cleaning ..before I can even start to put this engine together.

Never-the less she'll be a fantastic bike when done, and following the advice of RayMK  of this parish - I'm trying to win over to the mindset  "..hope that you will fall in love with the car (and equally this motorcycle)  and keep it.  Sod the bank manager

Bfg :-D

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Welcome support from another member :

All too familiar overtones to me in your tale, BFG.   Suspect that deep down you realised you were going to be doing all this yourself at some point!    The rocky path back to the road is never easy, is it?    I have always liked these 'Beams but realise that they are not for everybody and that probably includes me.   How they never picked any of the Harley aura up is quite amazing (and probably  certainly for the best) as is the fact that they have so far escaped being copy-catted.     

Carry on with the cathartic therapy of documenting the rebuild, stories like this are never easy to tell, live or read but only add to the mystique of a machine.

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