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Vincent Motorcycle Gunga Din scratch build


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Ever since I finished my last project, that 3D printed steam engine. I've been racking my brain trying to think of a model that appeals to me for another scratch build.  It has been my own unwritten rule that I only ever build cars/boats/steam engines that are important to me or played a part in my past.   I had the use of a Vincent Rapide back in 1955 here in Ontario Canada, when I was 17 and a family friend asked if I'd look after it for him for 2 months while he went back to Scotland ... does a bear sh*t in the woods??

 

At the time I had an AJS 600 twin and a Matchless scrambler but they quickly got pushed aside and I rode that Vincent everywhere.   Now, almost 70 years on, I feel ready to tackle a bike model ... a scratch built one at that .. and a Vincent.  The one I'm going to attempt is called Gunga Din and was the development machine used by the factory for many years and has, in modern times, been found, restored, tied for first place at Pebble Beach concours and now belongs to an important man in the motorcycle world here in Toronto Canada.   What I'd give for an hour with the bike and a camera but as it stands I'm going to have to build it all from photographs.   Those familiar with my models may know that I'm not a stickler for absolute precision and correctness so, as usual, I'll be taking liberties as and where I feel like it.   Scratch building for me is mostly about 'the process' and figuring out 'how am I going to make this part?'.

 

I've begun the project armed with only a 'pretty decent side view' of the bike which I've since converted to a line drawing and scaled it to my default size ... 9 inches (see above about liberties).

 

http://52187352043_ba00159247_b.jpg

 

I've got off to a good start and have selected a lot of the 'low hanging fruit' to fabricate.    As usual, my parts are made from my stash of scrap aluminum, steel and brass salvaged from old printers, cameras, computers etc.

 

Gas tank, seat, oil tank and shock absorbers under way.

 

http://52187362201_bc4b8e13b0_c.jpg

 

Half hour of filing and sanding ...

 

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Seat and Gas tank are shaped using Renshape which is a composite pattern making material.

 

Here the oil tank, seat and shock absorbers are test fitted.

 

http://52187369656_c2065ab704_b.jpg

 

For those unfamiliar with the Vincent bikes they have no traditional frame in which the engine is bolted.   Instead, a strong, steel box-like oil tank resides under the gas tank and the front and rear suspensions are bolted to that ... very much ahead of the times.

 

I'll be moving on to the rear suspension members next so I'll leave you here.

 

Back soon.

 

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14 hours ago, Mark_C said:

I thought I'd add a pic of said Gunga Din:

What a beauty!  I look forward to watching you create the model.

 

9 hours ago, Pete in Lincs said:

It's a lovely looking bike and sounds like an interesting challenge. Good luck!

Thanks guys and thanks for that picture .. though I already have it.

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Now that it is a real project. Looking forward to seeing this through. What scale are you planning for your build? 

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Lovely!

One of my father's cousins was killed racing a Vincent back in the 50's. My dad still remembers seeing him push start it up the road when he'd been visiting.

 

Ian

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On 7/2/2022 at 12:04 PM, Pouln said:

Now that it is a real project. Looking forward to seeing this through. What scale are you planning for your build? 

Let's just say it's about 1/8h scale.   

6 hours ago, Brandy said:

 

My dad still remembers seeing him push start it up the road when he'd been visiting.

And that comment brings back memories of me doing just the same thing when kick-starting wouldn't fire it.   There was me (130 pounds dripping wet) pushing it down a slight incline praying ... "please, please fire" as I jumped onto the seat and dropped the clutch.

 

OK, moving along at a snail's pace.   I've made both fenders by band-sawing 2 lengths of aluminum from the al. strap I bought.    I have a small pipe bender jig that worked fine to induce a curve into the strip.   Kept placing it onto my drawing to see how close the curvature was.

 

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Once I was happy with the curve I filed the edges to give it the shape needed 

 

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When I had the shape I wanted I couldn't resist giving it a rub down with wet sandpaper then a polish.

 

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I've made a couple of pieces that the fender can now be test fitted into

 

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To give a more precise shape to  the fenders I turned some scrap material to the diameter of the inside radius of the fender and hammered it over this "mold" to get the right shape.

 

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I'd been laying my parts on the scale drawing to check sizes and that worked to a certain extent

 

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 But I decided to make up an apparatus where I've glued the lower parts of the model to a block of Renshape then glued the scale "drawing" to some plywood and fastened it at the right height to let me assemble the parts and check alignment.

 

52194873835_00cc7e983d_c.jpg

 

It's a bit crude but doing the job.   

 

This is turning out to be a difficult project ... and that's saying something after building three Gresley steam engines!

 

Thanks to those who find this interesting.

 

Frank

 

 

 

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Might as well throw in a couple more pictures of various parts.

 

These are dampers of some kind that attach to the back of the seat.  

 

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Tiny little blighters but fun to make.

 

Here's the knurled wheel that is part of it ... bleeding fingers too!

 

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Turned an oil filler cap and cut a knurled edge into it too

 

52194402438_5104c3c987_z.jpg

 

Back later

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This is going to be very interesting! Great progress so far.

I tried to bump start my bike too when I'd rebuilt the carbs, but it was NOT easy with all that weight.

(I have a 1978 Ducati 900GTS)

 

Ian

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A bit more progress.   Next step was to fabricate the bracket that anchors the rear fender.   This is a one-piece metal rod that wraps around the fender and is anchored to the frame down at the hub.   It needs 2 tiny tabs through which I can insert bolts.   I tried soldering tiny tabs but this didn't work too well so I bent a piece of scrap steel to the shape of the rod and soldered it on ... not pretty.

 

http://52205480308_8bf4792c7a.jpg

 

Used a sanding/cutting disk on my Dremel (cheap copy) to hack away at it till I just had the tabs showing.

 

http://52205726724_fc0199cf72.jpg

 

This is much stronger as it has a thin strip of steel running under the rod and joining the tabs.  

 

Next I have to anchor the leading edge of the fender and decided to solder a tiny steel bracket to the frame and drill a hole through this and the fender.   Now I can fit a small nut and bolt and the fender is secured.

 

http://52205475161_589fd334db.jpg


To fasten the ends of the wrap-around bracket I needed to add a tab through which I can drill a hole and fasten it to the hub.    This is fiddly but I cut a slot in a piece of scrap (all of which comes from salvaged ink-jet printers) and fitted the rod into the slot.   

 

http://52205500193_e3445778b7.jpg

 

Apply solder (messy) then grind the mess down to a decent shape.

 

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Looks pretty good once it's cleaned up ... now repeat for the other side.

 

Once this has been fastened down with a nut and bolt I can drill holes in the fender to take bolts there.

 

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Next I dismantled the whole apparatus and cleaned up the scratches and polished the fender then re-assembled it.

 

52205938780_44d59ccc8b_o.jpg

 

I re-fabbed quite a few of the pieces and got rid of all the brass and replaced it with steel and now I can fit those "dampers" that attach to the back of the seat.    Lots of trimming of rod lengths and locating new holes but now the seat fits perfectly above the fender.   My shaped cutout under the seat is now too large and I have to address that but I think I'm about ready to move to the front suspension.

 

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Thanks for looking in.

 

Later

 

 

 

 

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21 hours ago, Brandy said:

Are those adjustable dampers for seat height? It certainly looks as though that's their function...

 

It could be that's what they were as there's a threaded rod inside that upright.    Why it would need to be damped puzzles me though.   A simple pivot point at the base of that rod would have sufficed so I think it has an additional effect (along with the shock absorber under the gas tank) in slowing the rise and fall of the rear suspension. 

 

6 hours ago, Major_Error said:

Lovely! Just lovely!

Thanks ME.

 

3 hours ago, Noel Smith said:

Lovely subject and a very interesting thread. Nice piece of model engineering.

How did this bike yet named 'Gunga Din'?  Was it a one off special?

Noel ... Gunga Din was indeed a one-off in that it was a bike reserved by the works for development.   There's a good Wiki article on it here so I won't repeat it.   In short though, it seems a magazine writer named it thus when he was loaned the bike for a weekend and found it too much of a machine for him ... a better bike/man than I am Gunga Din.    Fascinating that it languished unseen for years under a tarp in the old factory before someone saw it and knew what it was.

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1 hour ago, albergman said:

Why it would need to be damped puzzles me though.   A simple pivot point at the base of that rod would have sufficed so

I don't think it is damped. The gnurled knob is an adjuster for seat height, hence the threaded rod. I don't see anything suggesting damping, but then I don't have references either. The odd thing is that if it were for seat height then the rear of the seat would rise and fall with the rear swing arm as it's all sprung, hinged at the front, but that certainly looks to me to be the way it was.

 

Ian

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7 minutes ago, Brandy said:

I don't think it is damped. The gnurled knob is an adjuster for seat height, hence the threaded rod. I don't see anything suggesting damping, but then I don't have references either. The odd thing is that if it were for seat height then the rear of the seat would rise and fall with the rear swing arm as it's all sprung, hinged at the front, but that certainly looks to me to be the way it was.

 

Ian

I believe you are right Brandy.   I'd been ignoring that other pivot point in the adjuster.   That apparatus allows the rod/seat to rotate around that offset bolt.   Good spotting!  And I agree with you that the seat will indeed rise/fall with the suspension because it definitely all pivots around that forward point.

 

52209623725_abe41909e7_o.jpg

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On 7/11/2022 at 12:30 PM, Noel Smith said:

Thanks for coming back. I had a look at the Wickileak info.  Made an interesting read as Stevenage where the factory was is about  14 miles from where I live.

Nice to be close to a bit of history ... but hard not to be near it in England 😁

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OK, got some time today to proceed with the front suspension.   I've decided I'll have to simplify the real thing as there are so many pieces that are just too small to model but it will barely be noticeable.   Today's project is to make the lower U-shaped bracket that joins the steering post to the front forks ... this one.

 

52223365058_44114f3635_o.jpg

 

I'll be making it from a flat strap of aluminum.   As you can see above on the real bike there are actually 2 separate horizontal bars that join the vertical parts but I'm going to make it a one-piece which will be stronger and a bit easier to fabricate.

 

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I'll spare you all the steps to shape it but here's a mid-stage ... lots of hand-filing.    The main post is already inserted here at the right angle 

 

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Eventually I get it down to the final shape.   Holes drilled through both ends to accept a locating pin.

 

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Here it is finally attached to the front suspension bars and the dampers at the back.

 

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That was a full afternoon's effort to make that piece and get them all fitted together.   Now I have to do a similar approach for the upper U-bracket and tie it into the steering post.

 

Thanks for looking in.

 

Frank

 

 

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Just a brief update today.   Rough shaped the front fender and its wrap-around bracket.   The bracket is unusual for a Vincent because it's not of the usual black, tubular style but a flat polished strap instead.    I had to rummage through my steel scrap and found a sample from an old stereo receiver (remember them?) that just happened to have enough unbroken metal to give me the piece I needed.

 

52225530331_e0366f3c07_c.jpg

 

Got it drilled and mounted roughly to the forks and the fender.

 

Another part I made was the shock absorber that is mounted at the top of the forks.   This was a simple thing to make on my little lathe and got it in place too.   

 

That's about it.

 

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