C15 side cover fitting

[Barnsey]

Dear all,

  I am in the process of repairing the broken kick on my C15.  I am at the stage of refitting the inner side cover.
I thought I would trial fit the cover before fitting the gasket and sealant and I am glad that I did.
Is the a clever trick to get everything to line up properly?  I put the cover on and started tightening up the bolts but he cover wouldn't lay flat.

  It looks like the slide rod which the selectors slide on isn't popping neatly into its hole.  Is there a trick to doing this?

   Regards,

    Ian

[Barnsey]

OK.

I managed to get the side cover on after a couple of attempts.

I am feeling five gear positions.  I am guessing that neutral is at the bottom between 1st and second. That is what it feels like.  However the back wheel won't turn at this point.  I think I need to open it up again and take another look .  Any ideas much appreciated of course.

Also the clutch not operating but that is another story.

  Time for a break I think before I open it all  up again.

  Regards,

  Ian

[Spaceman]

If you are getting 5 gear positions, it would imply that the selector forks at least  must be moving correctly otherwise they would jam. Can you use the kickstarter shaft to see whether this rotates the gearbox to check the gear shafts didn't lock up when you tightened down the inner timing cover?

[Barnsey]

Yep.  I took the inner cover of the engine again this morning and as the cover started to work loose I could feel the gears start to turn, so it seems that the bush was pushing the gears tight together locking them. 

  I watched one of the very useful youtube videos to check that I had the bush the right way around with the head on the inside, and it is. To be honest you can't put the head on the outside because it would not be possible then the fit The   little internal clutch lever.

  Measuring very inaccurately with my vernier calipers the new bush sticks out by around 3.5mm vs 2mm on the old (and very worn) one.

   So it looks very much like I will be filing a mm off of the new bush.  Of course I will mask up the mating surfaces of the plate to prevent accidental gouge marks from the file. I expect I will be looking to do that next weekend, so plenty of time for helpful suggestions via this forum in the meantime.

  Interestingly there is a tiny steel pin inserted into the alluminium casting alongside the brass bush which appears to be there to lock the bush.  It didn't work on the old bush and acted like a lathe tool chamfering the edge off when the bush spun.

[Spaceman]

Normally, when you put a gearbox back together with new bearings, whether they be bushes or ball races, you have to accurately measure the free play on all the shafts and then shim where necessary to bring the free play into spec.

In this case, it is possible that the old bush is now quite worn and may have started life at 2.5 mm or even 3 mm. Without accurately measuring the current free play, it will be difficult to work out how much of the bush to remove. The aim should be to leave a free play of the order of 10 thou.

I would definitely not recommend taking a file to the bush but, if you can work out how much of the bush flange needs to machined off, I would be happy to do it for you on my lathe.

[Barnsey]

Very kind of you spaceman, thanks.
So, going by your message, are there shims which I can take out? Not something I have noticed.

Before machining the bush,I will need to remove it from the cover (how annoying! ) Luckily we have a machine shop at work. I will see if they can make me up a simple drifting tool. That would save the ring marks on the end of the bush which I got as a result of using a deep socket.  And then, of course, they can skim the end of the bush too, so, hopefully I won't need to take advantage of your kind offer.

  I am definitely putting a small lathe on my wish list. 

      Ian

[chaz]

my B40 cover was binding, only found on assembly, a thread on here somewhere.
I took the middle part off and put up on my small lathe bed, as it has the drill/mill head attachment, I managed to put a small 8 or 10mm end mill up and using the cross side in two directions, managed to skim 0.008 thou off without having to remove any shafts and gears. covered them with a polythene bag.

if you have access to a machine shop, it should be an easy job, I couldnt wait to take in to work but the Clarke lathe/mill managed fine.

[Stubaker58]

I've got a similar issue with a D7 Bantam engine. When I do the cases up tight the gears lock solid. There are two bushes for the layshaft, should I be looking to take a little off both of them or can it all come off one?
TIA

[Spaceman]

If you only replace one D7 bush then that would be the one to skim. If you replaced both, it would probably be safer to skim each bush equally although, in a 3-speed Bantam gearbox, I doubt if it would make much difference if you skimmed just one!

[Barnsey]

I watched Michael Waller's video on Youtube   ( https://www.youtube.com/watch?v=6pvxNlggxOk )

After wading through a lot of irrelevent stuff I watched him put the cover on and BINGO, he had exactly the same problem as me.  It turned out that the kickstart stub shaft was in slightly the wrong position.  With the shaft aligned as it would be in operation everything popped together neatly and the engine turned over fine.

  Thank you Michael!!

[Barnsey]

BTW another question.

   Not knowing any better, when I put in the new bush, I pushed in the bush on top of the steel retaining pin on the assumption that the sharp end would grip the bush. 
Now looking at the broken remains of the original, it looks like maybe the bush was drilled through and the pin inserted afterwards.  Is this a problem?  Should I drift out the bush and the pin and re-do? 

  Thanks,

     Ian

[Barnsey]

OK Looking closer it appears that the pin was inserted first before the bush, so that the end surface is just brass, to rub against the steel of the gear next to it, so I think what I have done is correct. Before I put it back together, I am assumng that the C15 is a wasted spark engine? i.e. It sparks at the start of both the power and exhaust strokes.  There are marks on both of the two timing gears to line up, but one gear is twice the size of the other.  I was worried that I might put the big gear in 180 degrees out leading to an issue.

[Spaceman]

BTW another question.

   Not knowing any better, when I put in the new bush, I pushed in the bush on top of the steel retaining pin on the assumption that the sharp end would grip the bush. 
Now looking at the broken remains of the original, it looks like maybe the bush was drilled through and the pin inserted afterwards.  Is this a problem?  Should I drift out the bush and the pin and re-do? 

  Thanks,

     Ian

Yes. I would drill a slightly oversized hole in the bush to give you a bit more tolerance when putting it all back together - the pin does not need to be a tight fit in the bush - it's there just to stop teh bush from rotating!

[Spaceman]

OK Looking closer it appears that the pin was inserted first before the bush, so that the end surface is just brass, to rub against the steel of the gear next to it, so I think what I have done is correct. Before I put it back together, I am assumng that the C15 is a wasted spark engine? i.e. It sparks at the start of both the power and exhaust strokes.  There are marks on both of the two timing gears to line up, but one gear is twice the size of the other.  I was worried that I might put the big gear in 180 degrees out leading to an issue.

The camshaft and contact breaker cam rotate at half the engine speed and therefore generate a spark only on the compression stroke. If you line up the timing marks, everything will be fine

[Barnsey]

Thank you for that Spaceman.

  I'm in the process of fitting the inner cover with just a bead of sealant, no paper gasket.  I will put that somewhere safe for another day.

Most of the bolts I am torquing to a modest 10 foot lbs as per the manual.  One or two I am stopping slightly short on where I don't feel confident.

  I am fed up over the bottom-most.  The bolt which was in there had been hack-sawed too short and was the completely the wrong thread leading to stripping. Unfortunately I didn't notice in time and I aggravated it. For the present I will cut a brand new bolt to the correct length, for maximum bite, and apply a bead of thread lock.    At some point tho' I may need to do a proper job and drill and tap it. 

As always any tips or advice fully appreciated.