It's now time to address the chain case and all things contained within. Having already polished the inner chain case, I offered it onto the crank case, with a new gasket and plenty of blue sealant and tightened the two internal fixing bolts, which are drilled to accept a locking wire that passes between them. The two original bolts went in OK but as I tightened the second one, it snapped! leaving the thread in the crank case. OMG! I removed the other bolt and the inner chain case again and to my horror there was no thread sticking proud of the crank case to get hold of. How to remove it? I took a long thin screwdriver and poked it through the other fixing hole to see if it was a blind hole or if it went right through into the crankcase. It went right through!. That was more bad news as it meant that, if I drilled out the broken thread, the metal swarfe could drop inside the crank case and require a full engine strip again.
I decided to measure the one remaining good bolt and work out how much thread was left inside my crank case. I then put a collar on a small drill to prevent the drill going right through the broken bolt thread, allowing me to drill a blind hole in the stud. I centre punched the middle of the broken stud and drilled, very, very carefully. There was always the chance that if the drill bit into the broken stud stuck, it could screw it straight through the crank case and deposit it inside the engine, but fortunately the broken stud was well stuck. Once the hole was done I then took a small "easy-out" (which is like a left hand thread tap) and screwed it into the hole. As it bit, to my relief, the broken stud unscrewed out of the crank case in one piece. Brilliant!!.
I was then considering re-assembly when I was going through my draws containing parts I had removed from the bike, when I came across a large round flat plate. It was obvious that this plate was the same shape as the inner chain case where it fits to the crank case. Obviously a spacer. It turns out that in order to line up the inner chain case with the frame where it fixed at the back of the bike, BSA introduced a spacer to space the inner chain case off the crank case and this was it. So I now needed to order two new fixing bolts and two new gaskets, one to fit each side of the spacer. Once they arrived the inner chain case and spacer could be mounted in place and the two new bolts tightened and secured with the locking wire. Also the adjustable plate that fits behind the clutch was fitted with new bolts and the felt seal to prevent oil leaking out of the chain case onto the gearbox. The securing bolts for this plate could not be tightened as the plate moves with the gearbox to adjust the primary chain tension, once the chain is fitted.
Time to fit the clutch and cush-drive. The outer clutch bell fits with 20 loose roller bearings which are held in place by the inner clutch bell (or basket). Having fitted the centre washer locking plate and nut, I was disturbed to notice that the only thing holding the clutch together was the thin tab washer. This did not seem right, so I sent photos to Lightning Spares and they confirmed that the washer under the nut was the wrong one and that a much larger and thicker washer was needed to hold the inner bell onto the splined shaft in the centre. I also sent pictures of the clutch plates and was advised to change all of the friction plates as these were soaked in oil. I had assumed that the clutch ran in oil, like my Lambretta, but was was informed that the small amount of oil in the chain case only sits in the bottom to lubricate the primary chain and that the clutch runs dry.
So on with the new clutch plates, and after making a screwdriver with a slot in it (for adjusting the clutch spring tension), the outer pressure plate with it's four springs and adjusters, the clutch is now in place. The cush drive was fitted and the two sprockets aligned and the nice new chain run around the two sprockets. The cush drive was fitted with a new special SRM hexagon nut/plate and torqued to the correct setting and the gearbox could now be adjusted to tension the primary chain to the correct half inch play tension. Then the adjustable splash plate behind the clutch could be tightened in its final position. Now just a case a fitting the outer chain case cover and job done! Excellent.
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 07.12.12 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
I decided to measure the one remaining good bolt and work out how much thread was left inside my crank case. I then put a collar on a small drill to prevent the drill going right through the broken bolt thread, allowing me to drill a blind hole in the stud. I centre punched the middle of the broken stud and drilled, very, very carefully. There was always the chance that if the drill bit into the broken stud stuck, it could screw it straight through the crank case and deposit it inside the engine, but fortunately the broken stud was well stuck. Once the hole was done I then took a small "easy-out" (which is like a left hand thread tap) and screwed it into the hole. As it bit, to my relief, the broken stud unscrewed out of the crank case in one piece. Brilliant!!.
I was then considering re-assembly when I was going through my draws containing parts I had removed from the bike, when I came across a large round flat plate. It was obvious that this plate was the same shape as the inner chain case where it fits to the crank case. Obviously a spacer. It turns out that in order to line up the inner chain case with the frame where it fixed at the back of the bike, BSA introduced a spacer to space the inner chain case off the crank case and this was it. So I now needed to order two new fixing bolts and two new gaskets, one to fit each side of the spacer. Once they arrived the inner chain case and spacer could be mounted in place and the two new bolts tightened and secured with the locking wire. Also the adjustable plate that fits behind the clutch was fitted with new bolts and the felt seal to prevent oil leaking out of the chain case onto the gearbox. The securing bolts for this plate could not be tightened as the plate moves with the gearbox to adjust the primary chain tension, once the chain is fitted.
Time to fit the clutch and cush-drive. The outer clutch bell fits with 20 loose roller bearings which are held in place by the inner clutch bell (or basket). Having fitted the centre washer locking plate and nut, I was disturbed to notice that the only thing holding the clutch together was the thin tab washer. This did not seem right, so I sent photos to Lightning Spares and they confirmed that the washer under the nut was the wrong one and that a much larger and thicker washer was needed to hold the inner bell onto the splined shaft in the centre. I also sent pictures of the clutch plates and was advised to change all of the friction plates as these were soaked in oil. I had assumed that the clutch ran in oil, like my Lambretta, but was was informed that the small amount of oil in the chain case only sits in the bottom to lubricate the primary chain and that the clutch runs dry.
So on with the new clutch plates, and after making a screwdriver with a slot in it (for adjusting the clutch spring tension), the outer pressure plate with it's four springs and adjusters, the clutch is now in place. The cush drive was fitted and the two sprockets aligned and the nice new chain run around the two sprockets. The cush drive was fitted with a new special SRM hexagon nut/plate and torqued to the correct setting and the gearbox could now be adjusted to tension the primary chain to the correct half inch play tension. Then the adjustable splash plate behind the clutch could be tightened in its final position. Now just a case a fitting the outer chain case cover and job done! Excellent.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 07.12.12 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
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