The BSA A7-A10 Forum
Bikes, Pictures, Stories & more => Introductions, Stories, Meetings & Pictures => Topic started by: MattH on 03.04. 2021 15:14
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My first "real" bike was an oily, noisy gloriously worn out '54 A7 Shooting Star with a '53 650 T110 engine that I bought of a guy called Steve one evening at the Sussex Arms in Tunbridge Wells. I was ogling his perfect blue and white Starfire, which was for sale and when I said that price was too high for me he said he had an old TriBSA that I might find interesting that was much more affordable (£70 sticks in my memory...). The next day I rode to his mum's place and test rode the beast -- it was love at first kick. He delivered it to my house later and a handshake deal was agreed under which I would go to the Sussex Arms every Friday night and give him most of my weekly pay packet (I was a trainee panel beater and paint sprayer at the time). He loved this since I would usually arrive just as he ran out of money! :)
After enjoying the TriBSA as-is for the remainder of the summer, I wheeled it into the garage (thanks, Dad!) and stripped it to the frame for me to paint. Over the next few years it evolved into a lovely slightly grungy cafe racer. In 1978 it was stolen from the middle of Oxford never to be seen again.
So when I saw a rusty old A10 frame leaning against a shed in Nova Scotia last year, I knew it was time to have a TriBSA again. This is that journey, let's hope it's not too epic!
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Step 1: Gathering the Key Elements
Frame: included swing arm (seized of course), oil tank and left side toolbox (both dented)
Engine: Found an unfinished bobber online, which has a '69 T120R engine and '71 Triumph front end with conical TLS hub. The engine has belt drive and a cut-away primary chain case which looks kinda cool.
Tank: My first TriBSA and the round badge A10 tank (okay, it had a hairline crack at the front - I was a student!), so finding used one in great condition from Walridge gave me what I wanted. The tank is beautifully painted, but I prefer black and gold, so chances are I'll do a photo shoot for the red paint and then sand it off for repainting.
Photos show my original TriBSA and the key elements to create a new one!
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The first order of the day was to see if I could get the swing arm off without resorting to professional help. It was a long and hard battle as many of you will have also experienced but in the end I won:
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Enjoying this thread already. Keep it coming.
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With the frame in salvageable shape I had two concerns about getting it rolling: 1) would I be able to fit the Triumph front end attached to the A10 frame; and 2) would I be able to track down the critical bits needed for a rear wheel?
The solution to the first came from SRM Engineering in England: a drop-in bearing set that marries the 1971 Triumph forks to my 1960 frame.
Ebay provided the second in the form of a used but good shape full width cast iron hub from Texas. I'm expecting to get the aluminium brake plate and related parts from Australia.
So I optimistically think that I have a rolling chassis well under way!
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The thing that drew me to this forum was the 1954 frame drawing, so that is the next chapter in the story. Since custom engine plates are needed for the Triumph unit engine to attach to the A10 frame, I took a bunch of measurements so I could triangulate the positions of the each attachment point on the frame and engine. Those got dumped into Adobe Illustrator at full size and the resulting model is attached -- I used photos of the frame and engine as a guide. This let me print full size templates to cut prototype front plates out of 3/8" plywood (the real plates will be 3/8" Dural). The engine placement in the model turned out to be too high in the the real world, so you can see the revised placement of the engine bolt hole in the photo. You can also see how tight the frame brackets under the engine are to the engine mount, so I am considering cut them off and welding new ones on so the Triumph just drops into place (this was the 20/20 hindsight recommendation from another TriBSA build I read about, so there's a good chance...).
In other news I've placed my order for the rear brakes parts, which are coming from Mike's Classic Cycle Spares in Queensland, Australia.
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That last pic looks like a frame for holding a whiffing line (type of fishing line with weights along its length for trolling). And I note the quality of plywood is the same as we get here.
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Haha - yeah, the plywood is scruffy (and not cheap these days!), but the drill was sharp and the dowels fit snug, so I think it's on the right track.
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I very luckily found a guy on a Triumph board who had drawings for the plates I needed! Upon his recommendation I made some adjustments and then had the plates waterjet cut in 3/8" alloy.
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Photo 1: TriBSA engine plates installed to both check fit. If you look to the left of the silver lower mounting lug on the engine you can see the lower frame bracket has been removed to make way for a T120R-specific bracket. You can see there are two holes in the rear engine plate -- these need to have holes drilled into the swing arm mounting plates to complete the attachment. Also, on the same plate, big bolt (upper left)
Photo 2: I cut the two tabs for the new brackets from flat bar stock and can be seen here checking the fit. With all the new engine plates holding the engine in place the lower bracket tabs will be welded to the frame. NOTE: This is the adjustment that the guy I got the plate drawings said he wished he had done. His front engine plates extended down to a lower crankcase bolt -- I always wanted something to grab the lower lug on the T120R so I was glad his recommendation supported that decision. Doing this meant I could cut the extension from the front engine plates.
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Good thread Matt, -keep it coming.