12. BSA A10 Blood Sweat & Gears

Time to strip the gearbox and see what secrets lie inside. Having removed the gearbox earlier, it has laid untouched since the original bike strip back in February. Now is the time to do an inspection.

I drained the oil and to my relief there was no metal particles in it and so the strip began. Removing the outer cover revealed the kick-start mechanism and the clutch actuating lever mechanism. Apart from the clutch lever itself, which needed cleaning and chroming, the rest of the clutch mechanism seemed in fairly good condition. Unfortunately, I couldn't say the same for the kick-start parts.

Both the quadrant kick-start gear and the ratchet gear that it mates with were both in pretty poor condition. I decided that, as this would hopefully be the only time I would strip the gearbox, to do it properly.

I got in touch with lightning spares and ordered a new quadrant and ratchet gear along with a new return spring, adjustment plunger housing and nut, side plate, bearings, oil seals and all gaskets.

I then set about polishing the outer cover and inner cover, with the hope that I could polish the main gearbox housing without having to remove all the inner gears.
Once the parts arrived, my idea was to rebuild the outer casing with the new parts, assemble the gearbox and then polish the whole thing. As usual this turned out to be impossible and so the next stage was a complete strip with all gears and gear-selector parts out on the bench.

But first I had to remove the main final drive sprocket. To do this you need a special spanner as the nut holding it on is round with just two side notches in it. I could not find a tool that fitted or find one for sale on the Internet. Having secured the sprocket in a vice by rapping the old chain around it and then clamping the chain in the vice, I tried knocking it around with a hammer and drift. No luck!. So I set about making a suitable spanner out of an old 27mm open-end spanner that I already had. Lots of sawing, filing and grinding later, the spanner fit and with a couple of sharpe knocks on the end with a lump hammer, the spanner did its job and the nut came loose.

More gearbox tales on the next blog

I would love to read your comments on this blog. If you would like to make some please click "Subscribe to: Post Comments (Atom)" at the bottom of this page. If you would like to be automatically informed when a new episode is posted then please tick the "Join this site" box at the bottom of the page. Thanks for reading. Kevin

 Copyright K. Hopcroft  30.09.12 All rights reserved
 You can contact me on: hopcroftscoot@gmail.com

My Other Blogs:

1961 Ariel Arrow Super Sport Motorcycle :
http://60sclassicmotorbikes.blogspot.co.uk/2014/01/1961-aerial-golden-arrow-restoration.html

Miniature Land Rover Defender:
http://miniaturelandrover.blogspot.co.uk/2016/02/1-miniature-land-rover-defender-idea.html?view=timeslide

1971 VW Karman Ghia Convertible Car:
http://karmannghiarestoration.blogspot.co.uk/2017/03/1-karmann-ghia-retoration-project.html

Motorcycle Trailers / Caravans:
http://motorcycletrailersandcaravans.blogspot.co.uk/2018/01/1-motorcycle-trailers-problem.html

11. BSA A10 Unbreak My Head!!

More on the continuing saga of the creation of a BSA Rocket Gold Star Replica. I should mention that we are getting very close to the present day and the current point of progress with this project. With the engine fixed in the frame and the cylinder head in place, it's time to fit the rockers and cover.

As with other points in this rebuild it's time to make more mistakes. It's at times like this that I am aware of my lack of specific BSA A10 knowledge. Looking at the cylinder head, it looked as though of the four fixed studs in the rocker box, the two rear ones should be longer as I would never get nuts on them as they would be hidden inside the fins of the head. So I put longer stainless steel studs in the back two rocker box fixings. Wrong! If you do this, you can't get the rocker box on at all as it hits the frame before the studs go into the head. Still on the wrong track, I decided to remove the two long studs, drop them in the holes in the fins, fix the rocker box and then feed the remaining long studs back up into the rocker box from underneath. The box went on, using the correct BSA tool (comb) which holds the push rods in the correct position.

Here's the next big mistake. As I didn't have the head-steady bracket yet, I decided to bolt the rocker box down and then remove the four long bolts, that pass through the rocker box into the head, again once I had the bracket. Wrong, wrong, wrong!!!. These long bolts are exactly the right length and, if the head-steady bracket is not in place, then the bolts bottom in the threaded holes in the aluminium cylinder head and when you tighten them you crack your cylinder head. What is worse, you cannot see the damage until you take the rocker box off again.

Whilst going through the original nuts and bolts off the cylinder head, I discovered two special nuts with deep collars, still on two short rocker box studs. All was revealed. All four rocker box studs should be the same length and these two special nuts fit up into the fins at the back of the head to reach the short studs. Unaware of the damage awaiting discovery, I decided to remove the rocker box again and fit the correct studs. O.M.G. With the rocker box removed the damage was immediately apparent . Two of the rocker box threaded bushes in the head were broken away from the head. I can only describe the feeling as how a football fanatic would feel having followed his favourite team to the cup final and then seeing them lose. Total devastation.

I removed the head and inspected the damage. Fortunately no cracks had gone through to the combustion chamber or the inlet or exhaust ports. I took the head to a friend who is a wizard with a welding plant. After long discussions he rigged up a pipe to feed gas between the fins of the head while he welded the head with an extended mig (or is it tig?) welding rod. It took him a whole morning but in the end it was welded, but not very pretty. Several hours of my time followed as I reworked the head with a Dremel until the welds blended into the head and virtually disappeared.

All that was left was to bolt the head back on again, with another new head gasket and refit the rocker box, with spacers on the long bolts, to stop them bottoming again. I should say that even with the right comb tool, fitting the push rods into the rockers is not easy and takes considerable time and patience. But it is all back together, bolted down and when I turned over the engine, the rockers opened and closed the valves beautifully.


I would love to read your comments on this blog. If you would like to make some please click "Subscribe to: Post Comments (Atom)" at the bottom of this page. If you would like to be automatically informed when a new episode is posted then please tick the "Join this site" box at the bottom of the page. Thanks for reading. Kevin

Copyright K. Hopcroft  08.09.12 All rights reserved
 You can contact me on: hopcroftscoot@gmail.com

My Other Blogs:

1961 Ariel Arrow Super Sport Motorcycle :
http://60sclassicmotorbikes.blogspot.co.uk/2014/01/1961-aerial-golden-arrow-restoration.html

Miniature Land Rover Defender:
http://miniaturelandrover.blogspot.co.uk/2016/02/1-miniature-land-rover-defender-idea.html?view=timeslide

1971 VW Karman Ghia Convertible Car:
http://karmannghiarestoration.blogspot.co.uk/2017/03/1-karmann-ghia-retoration-project.html

Motorcycle Trailers / Caravans:
http://motorcycletrailersandcaravans.blogspot.co.uk/2018/01/1-motorcycle-trailers-problem.html