Layshaft bush in kickstart

I've been looking at this very thing on my MKIIA Commando today, the internal diameter of my new bush is smaller than that of the one in the kickstart shaft, and the new one fits the layshaft more sweetly, so the old one's coming out. Sorry Robert, that doesn't answer your question, but I'm watching with interest. Is the fit within the shaft so tight that the bush will be compressed that much?

When you get an answer, I'll also be interested to know how you planned to get the old one out â I've cut mine internally and taken a cold chisel to it, as I've seen recommended, but it doesn't want to budge! C'est la vie ...

Oh for such a pal! Although I mustn't grumble, I do have some great guys locally to help with my Triumph car, when they have the time! Fingers crossed that your bush does what you want.

On closer inspection, I think maybe I just haven't cut fully through the bush yet â either I need stronger glasses, or something stronger in my glass. Or a friend with a laparoscope. If I get the job done, tomorrow now at the earliest, I'll let you know what occurred. Cheers.

Hi Colin,

I found the Mick Hemmings of both engine strip & rebuild and gearbox DVDâs invaluable. Mick advised no heat to be used on the kick-start / lay shaft bush assembly but to tap with an appropriate size, sorry canât remember what I used now but as long as the tap core diameter stays in the bush so to speak that will do. Then grip the tap firmly in a suitable engineering vice and give the lay shaft / kick start assây a few sharp blows with a copper faced mallet and out she cones. To replace the bush use the lay shaft as a âdollyâ but you do need a press. If you are a singles man Mike Pembertonâs DVD is also a must have!

All available from the NOC store and well worth the dosh!

Good luck!

Regards from South Australia, Steve .

The layshaft support bush in the end of the kick start is reasonably thick and I wouldn't expect it to compress on fitting. Robert, I think Colin has cut down the side of the bush with a hacksaw blade and some suitable holding device (a rag) the kickstart shaft is reasonably hard so with care your hacksaw blade will do little damage and once you get close to through, the bush will give up without a further fight. Win

David Evans, you've assessed my method and available equipment pretty accurately â only for a rag, substitute a Black & Decker Workmate. An engineering vice, let alone a press, would be the stuff of dreams. I'm still sawing, but more tentatively since my chemistry set magnet is now picking up a small proportion of steel swarf.

Robert I don't mean to hijack this thread, as I say if I get the job done I'll let you know how I got on. For now, and FWIW, I make the internal diameter of the new bush to be in the region of .693", if that sounds about right. I think the old one's much too bashed about now to get a reading from. I know, I should've written this all down, but I'm not an engineer...!

Steve in Australia, thanks for the tip about the videos, I have them on VHS! If I get nowhere soon I'll try re-connecting my old VHS player, if it still works...!

You can fit a needle roller if you can get the layshaft ground down to suit. The OD of the needle roller is the correct size for the kickstart shaft bush housing.

Previously steve_adkins wrote:

Hi Colin,

I found the Mick Hemmings of both engine strip & rebuild and gearbox DVDâs invaluable. Mick advised no heat to be used on the kick-start / lay shaft bush assembly but to tap with an appropriate size, sorry canât remember what I used now but as long as the tap core diameter stays in the bush so to speak that will do. Then grip the tap firmly in a suitable engineering vice and give the lay shaft / kick start assây a few sharp blows with a copper faced mallet and out she cones. To replace the bush use the lay shaft as a âdollyâ but you do need a press. If you are a singles man Mike Pembertonâs DVD is also a must have!

All available from the NOC store and well worth the dosh!

Good luck!

Regards from South Australia, Steve .

I had the same problem trying to remove a camshaft bush from a blind hole, before using a coarse tap, I made a tool as per the attached rough drawing. The copper pipe was epoxied into the bush and then jacked out with the nut. I used a little heat from a hot air gun to warm the area around the bush and it came out without a hitch, also the bush was not damaged as a little more heat was enough to release the epoxy.

The bush had to be cleaned with spirits or thinners and the copper pipe was roughed with emery. The next step would have been to roughen the bush if it slipped.

http://www.nortonownersclub.org/noc-chat/technical3-light-twins-forum/337809532/877499312/navigator-camshaft-bush-tool-png

Regards

Andrew

Thanks Robert! And Andrew, I wouldn't have thought of your method. And ... Finally! After about 24 hours' work (including sleeps, fag breaks etc.), the old bush has surrendered. See the pic, if only to check out my working conditions â better than nothing! And note the longitudinal score inside the shaft, the product of my hacksaw. I don't suppose it matters, but it does mean I cut too far. Thing is, that bush wasn't falling apart for anyone, it took a lot of bashing even at that point to conquer it. With that in mind, and short of being able to climb inside the shaft to have a look, I ended up over-cutting.

I've just put the new bush in the freezer, I'll put the shaft in the oven when I've decided what to have for lunch.

D'you know, I wanted to continue studying metalwork at school, but they wouldn't let me because I was too good at languages ... Point being, if I were an engineer I'd be able to read my vernier gauge properly! Robert, I gave an internal diameter of .693" for my new, uninserted bush: I'm pretty sure I read that wrong, and it should've been .688". I've now inserted the bush, I started it with a G-cramp and got it home (I think!) with a socket and club hammer. The internal diameter now reads .686". Supposing I've got that right! I've added a pic of the reading on the gauge from the inserted bush, in case anyone wants to correct me!

Previously robert_tuck wrote:

Its not easy to get an accurate reading in a small dia bush, but a couple of thou squash would help ,seems like you got that. More importantly did you get a better fit to the shaft?.I think the grey sludge in my cover comes from gears rubbing in places they have not been before.A needle roller conversion would reduce the friction and probably the kickstart movement too.

Yes, it does look like I got a couple of thou squash â the fit is better Robert, there's less slop, but still some. At this point, though, whatever anyone says the layshaft looks fine to me and I'm not buying a new one! I hope that's been of some help to you!

I've been looking at this very thing on my MKIIA Commando today, the internal diameter of my new bush is smaller than that of the one in the kickstart shaft, and the new one fits the layshaft more sweetly, so the old one's coming out. Sorry Robert, that doesn't answer your question, but I'm watching with interest. Is the fit within the shaft so tight that the bush will be compressed that much?

When you get an answer, I'll also be interested to know how you planned to get the old one out â I've cut mine internally and taken a cold chisel to it, as I've seen recommended, but it doesn't want to budge! C'est la vie ...

Thanks, actually I did try putting it in the oven while failing to get it out any other way, and that didn't work either. Just so you know.