Brodie's Bastard BSA

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So I found them rattlin' bits in the gearbox.

Looks like I am up for a new sliding gear and a new batch gear. At least that is what they are called on all the part sites.

The lack of any oil or grease in the gearbox also has me concerned. I know it has not been taken apart in the past 30 years and it was a PITA to pull apart, infact the input shaft nut is still stuck on.
 
Guess I've been lucky with old gearboxes...so may of the ones I have rebuilt have looked absolutely horrid on the outside, but more often than not, they were usually in pretty decent shape internally. Anyhow, stick with it...you will have a fully functional gearbox before you know it!
 
Yep. Just bought a replacement sliding gear. Not easy to find. Looks like it is from a twin.

The new gearboxes have a 18/21 sliding gear where as this has a 21/25
 
So from what I can find this gearbox is a road race ratio box and parts are hard to come by. I have found a new sliding gear but am having a hard time finding a 30 tooth main lay shaft gear which also serves as the kick gear. The teeth look like they have been broken off for some time and I believe it to be the reason this box was set aside for so long.

Going to a swap meet next month and will see if I can find a gear for it there. If not I may have to get a new one made up.
 
If you get very stuck on sourcing parts PM me, lots of old gits here in the UK with stuff squirrelled away in their sheds.
 
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Magdyno arrived today. Cost me a bloody fortune but it works very well, everything is there and it even has a few stainless parts added on. Very clean as well, looks as if it just had a rebuild inside.
 
Looks like you have a good set there...whatever it cost, it was probably worth it. A decent magdyno will make the difference between a bike that starts first kick and one that you have to kick until you have a stroke to get it running. :)
 
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Forgot to post this one up.

Looks like the pushrod angle might be off a bit. Shouldn't be to much of a problem though.
 
I had a thought when I was looking at the head and base gasket sitting on top of the M20 cylinder.
Why do I need to cut that up? I need a box for the pushrod adjustment but why do I need that one? Won't it be much easier to just have flanges made up to match both bolt styles of the bases and then just get the spacing right between them for the stroke and weld a section of pipe with cooling fins and a tappet box between them.

Looks like I will be heading down to my local machine shop some time soon.
 
Brodie said:
I had a thought when I was looking at the head and base gasket sitting on top of the M20 cylinder.
Why do I need to cut that up? I need a box for the pushrod adjustment but why do I need that one? Won't it be much easier to just have flanges made up to match both bolt styles of the bases and then just get the spacing right between them for the stroke and weld a section of pipe with cooling fins and a tappet box between them.

Looks like I will be heading down to my local machine shop some time soon.

Ats what I was thinking you were planning, why not use some cast finned tube and adjustable rods.

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Hmm, interesting option. I was going to try and avoid cast since it is a pain to weld on. I was tossing up between alloy or steel. Might even be able to do it in stainless if the boys at work will help me out.
 
Brodie said:
Hmm, interesting option. I was going to try and avoid cast since it is a pain to weld on. I was tossing up between alloy or steel. Might even be able to do it in stainless if the boys at work will help me out.

"Cast" can be easy to weld "cast iron" is full of crap so it's tough, you can weld cast aluminum and cast steel much easier.

I built up this float post yesterday, looks like crap because it's so small and it kept falling through just as the metal flowed out. took a few shots but it worked fine.

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Oh and those fins are fusion welded to mild steel tube. The tube will be easy to weld with heliarc, mig or stick
 
Thanks Tune, looks like this will be the way to go then. Do you have a link for the mild steel stuff?

Ohh and that float post would have been a pain to weld because of the size. Nice work mate.
 
This the site from the image, likely someone closer to you or a supplier close.

http://www.ekstromsvarme.se/finnedtubes.html
 
Cheers mate, thought you might have had a supplier. Had a look at a few other sites like that.

So now I just new to get the cylinder flanges made. It is all coming together now.

Hmm I wonder if there is an old pasteurizer laying around work somewhere...
 
Brodie said:
So from what I can find this gearbox is a road race ratio box and parts are hard to come by. I have found a new sliding gear but am having a hard time finding a 30 tooth main lay shaft gear which also serves as the kick gear. The teeth look like they have been broken off for some time and I believe it to be the reason this box was set aside for so long.

Going to a swap meet next month and will see if I can find a gear for it there. If not I may have to get a new one made up.
Teeth can be welded up with stellite and ground to shape, then again its a cost issue, diminishing returns and whatnot
 
I hope Swan doesn't mind me borrowing an image of his beautiful Gold Star to use as a base for a "Inspirational" example of what the finished motor should look like.
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So by the look of that the motor won't look to out of place.
 
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