A7 rigid

[prewarbsa]

G'Day folks, just a thought: has anyone ever consider putting a pre-unit A10 motor into a A7 tele-rigid frame? Cheers, Matt

[Brian]

BSA did, they made rigid A10's. I saw one for sale [basket case] here in AUS last year. It was missing a lot of parts so I didnt buy it but it didnt sell so if it turns up at the same swap this year maybe.

[fido]

The A10 rigid frame was the bolt together type though so you could get the same result by bolting on the rigid back end to an existing plunger A10. The early A7 like my 1948 bike had a one piece frame which I don't think was ever fitted with a 650 engine. Also Brian, the engine was semi-unit construction. I'm not sure if there would be room for the swinging arm engine and pivoting gearbox. By the way, welcome to the forum, prewarbsa. 

[prewarbsa]

Thanks folks, and thank you for the welcome, Fido. I was under the impression that the A7 motor was semi-unit construction as well: am I heading down the wrong path here?

[fido]

You could certainly fit a plunger A10  engine in the early A7 rigid frame but there may not be room for the swinging arm version as you need space for the gearbox to move. It is a bit confusing using the term "pre-unit" in the case of BSAs as they started with a bolt on gearbox with primary chain tensioner; changed to a pivoting gearbox, which was moved to tension the primary chain; then introduced the unit construction A50 & A65 range.

[Brian]

Obviously some confusion here as to which engine Matt is refering to. If you mean the plunger [bolt on gearbox] type then as I said BSA have beaten you to it. If you mean the s/arm type then you would be looking at a lot of work. Just having a quick look at my plunger A10 I doubt there would be enough room to get the engine and gearbox in the frame. Even if you did manage to squeeze it in building a set of primary covers would be a huge task. Next question is why? Maybe you have a rigid frame and a s/arm type motor lying around but I would sell the motor and buy a plunger type, save a lot of work. Anyway good luck with whatever you decide.  Brian.

[prewarbsa]

Ahh, maybe I should have explained a bit better. What I have is a '47 frame...and that's it. What you've told me is I should look for a plunger A10 motor, which is the exact answer I was looking for. Thanks so much for all your help, and I guess you can expect to see me a fair bit in here!!

[fido]

Obviously some confusion here as to which engine Matt is refering to. If you mean the plunger [bolt on gearbox] type then as I said BSA have beaten you to it.   Brian.

Are you saying that they did make a 650 with the one piece rigid frame then? 

[Brian]

Hi Fido, no, not in the early one piece frame. As far as I can find out they made rigid A10's from 50' to 53'. I think the first A10's were actually released late in 49' but for export only. I have also come across some references to girder fork A10's but never been able to find out if they did make any. I am not sure how the frame nos' on the rigid ones were stamped. All the dating info shows the plungers with a "S'' in the no. eg. ZA7S 0000 and the rigid ones without the S. However the rigid frame one I came across at a swap had the frame no ZA7R 7782 which would make it a 51' model. Without access to factory records its hard to work out some of this stuff. Going back to Matt's query, he has a early one piece frame and wanted to know if he could put a A10 motor in it and I think he could put a plunger type in but would need to sit the engine in the frame to be sure. It would be a lot of work and cost to find all the parts required, I've built bikes from parts and it is a lot cheaper to buy a complete bike.       Brian.

[fido]

I would agree with you on the relative costs and it would be better to get a complete plunger A10 for restoration / basket case as a donor bike. Most of the cycle parts are either the same or would fit the early frame. My own A7 is listed in the V5 as a 1947 but I've always assumed it is really a 1948 as it has the conventional centre stand and does not have the speedo etc mounted in the tank. Mine is frame No. YA7 2201, engine No. YA7 2148.

[prewarbsa]

Yes, I'd figured it would be easier to get a plunger as a donor bike. I was under the impression that many of the cycle parts were the same, so you have confirmed that for me. I'm not at all sure how many rigid A7's were exported to Australia, (hence the questions about inter-change of parts) but in my humble opinion it is an extremely pretty motorcycle, and beautifully proportioned. I think it certainly deserves to go back on the road in one form or another!