Hi to all again,
As anyone who has seen my previous posts, I've been having a lot of trouble with gear selection.
In an effort to see if the gearbox was the issue, I removed the inner gearbox cover to give access to the cam plate.
Moving the back wheel, it's possible to select all the gears with the occasional false neutral between second and third.
I fitted the gear selector quadrant in the hole and operated it with the gear change lever and the plungers would work ok.
To do a dry run I re-fitted the gearbox cover and fitted the return spring mechanism and gear change lever, but it's back to missing gears and it feels like the plungers sometimes go more than one gear.
Anyway on taking the gear cover back off, the idler timing gear came off with it and in a moment of stupidity I tuned the engine over with it off to align the timing mark with that on the crankshaft gear and as a result the timing marks on the idler and camshaft no longer line up.
Can anyone advise on the best way to re-align the marks on all three. Can i for example leave the idler off and rotate the crank and camshaft gears separately to the correct positions and re-fit the idler? or is there a better way?
Any help gratefully received.
It's getting to the stage that I'll be happy if I can get the engine boxed up and running and leave the gear change issue to someone better qualified than me to sort it out.
Regards
Clarke
Hi Clarke,
Have you got a workshop manual? In mine on page B29 there is an illustration of the timing marks and it shows that to be correctly set the marks do not line up exactly. So with the idler out start with the position of the crank and then turn the cam to as close as you can get it by eye. Offer up the the idler gear. The line facing the dot on the crank will pretty much line up exactly but the mark on the cam gear will look like it is a tooth out. If necessary turn the cam to get it in a better position. Put the idler in fully and turn the engine slowly forward to check that the marks for cam line up. When they do, do not be put off by the crank mark now looking a bit out.
With your gear selector problem, have you tried without the spring fitted? Do the gears select properly? If so then the spring is most likely the problem. With the spring removed check to see how the selector relates to the pin that the spring sits against. I have found that the selector will sit a neutral position and the part that pushes against the spring should line up with the pin. If there is a non-alignment there will be uneven pressure from the spring.
The pin may have a flat side so turn the pin so that it is lining up with the selector arm. Turn the pin to get the best alignment. Refit the spring and make sure that the selector it tight on the shaft as any play will reduce the amount of movement internally affecting the gear selection.
Dave.
Hi,
I do not have a complete early type gear change but I have a stop plate 68-3083 and few springs. With the spring fitted on the stop plate I noticed that the prongs that sit either side are not parallel. So if one is bent in a bit more against the anchor peg than the other, there will potentially be uneven pressure on the stop plate thus restricting full movement in one direction. This could cause the plungers to not quite engage with the slots in the cam plate affecting gear selection.
Dave.
Thanks Dave.
I'll give this a go.
Clarke
The attached diagram shows the alignment of the valve timing marks. As Dave said, the pairs of marks do not line up at the same time and you have to wiggle the engine back and firth to check the alignment of each pair separately.
In terms of the gear change problem, I seem to remember you had an earlier A65 which relies on the stop pins to limit gear change lever travel but you had a later stop plate meaning this didn't work. Have you now got an earlier stop plate fitted?
In terms of the actual problem, is the cam plate indexing correctly with the usual clunk but the gears are not being selected properly or is the cam plate simply not indexing or does the gear change not move beyond 2nd gear for example?
Hi Spaceman,
I still have the older 2 pin plate. The flats Dave mentioned are still on the wrong sides ie not the landing side of the return spring mechanism, but they're in pretty tight and I don't want to risk breaking the aluminium. Could apply a bit of heat or file new flats.
Dave did give me a new stop and spring which I tried. The original gear lever/quadrant had pretty badly chewed splines so I did manage to get a replacement one from eBay which came with a totally knackered inner gearbox cover.
When the inner cover and the gear lever are fitted along with the stop and spring (over the bottom pin) and I move the back wheel, it feels as though the plungers don't engage properly or return to the mid point after a change.
I've tried putting the quadrant in various gears before refitting the inner gearbox cover, 1st or 4th to match the diagrams in the manual as there doesn't seem to be any way that I can get the plungers to sit in the neutral position as shown when re-fitting the cover as the quadrant always slips down into what is shown as 1st (although the rear wheel is free to turn as if in neutral). The quadrant has axial play ie it is able to be pulled through a bit (5mm or so) when the cover is re-fitted. If I push it back through when fitting the stop and spring, the stop can foul on the casing. There is a mark on the case from the key from some time ago which must have caused the gear change to jam at some point.
I had thought about putting a washer or spacer on the gear shaft before it comes through the case to stop this movement as I thought that the plungers may be right at the ends of the slots in the cam and maybe coming out when changing gear.
Once I've got the timing gears sorted I'll give it another go but it would be frustrating to get everything boxed up and the bike running only to be back at square one.
Thanks for all the help and suggestions, I'll let you know how I get on.
Regards
Clarke
Not sure if this photo might also help to show the fact that the marks do not all line up at the same time. (or it might just show how out of whack my timing actually is...... Kidding, the engine runs beautifully- thanks to the good folk here...)
Good luck, you'll get on top of it no doubt.
Dave
Clarke.
The way the gearbox works is that for each gear, one or both plungers come to rest in a camplate cut-out hole. For 2nd and 3rd gear, both plungers come to rest in a cut-out hole while, for 1st and 4th gear, one of the plungers ends up in a hole. However, for neutral, the plungers end up resting on ribs between the holes and so it doesn't take much for them to fall into a hole and pull the gear box out of neutral. I think this is what you found?
I suspect the free play on the gear change quadrant isn't the cause of your problems but 5 mm of axial free play does seem a bit excessive. I'd have to look a bit closer into the design but I assume you can take out this free play when you do up the grub screw in the stop plate. However, I think you are saying that if you do this, the stop plate fouls the inner timing cover? Out of interest, what fouls on the stop plate - I assume it is not the stop arm but the spring tab? Assuming it causes no other problems, I would put a shim under the stop plate so that you can take out most of the axial free play while allowing the stop plate to rotate freely.
In terms of the fundamental problem with the gearbox, I'm not sure I fully understand what is happening especially with reference to the plungers. If you start in 1st gear then pulling up the gear lever (perhaps while turning the back wheel) should move the outside end of the camplate up a cut-out hole with the plungers ending up in holes #1 and #3 counting from the bottom. If you then change up to 3rd gear, the end of the camplate should move up another hole as will the plungers. What I'm not sure of is whether this is happening or whether the camplate movement is being hindered by the gear cluster movements meaning the box isn't indexing properly? Is it possible to elaborate?
Hi
I had exactly the same problem, I realised the return spring wasn't returning the gear pawl back to were it should be so it didn't engage the camp late. The main problem was someone had fitted a 1970 timing case to a 1967 crankcase, in the bsa manual it does say that they are not interchangeable and will cause bad gear selection, I got away with it because I had a offset return spring cup and I just turned it around until I got the gears to work, bloody frustrating
The problem is that the inner timing cover for a 1970 model has the gear change quadrant 'stops' cast into the inner side of the cover, whereas, the earlier gear change used the stop pins on the outer side and a stop plate for this purpose. The later cover could well cause movement problems for an earlier quadrant.