Lightweight gearbox problem

[clanger9]

Play detected between the input and output shafts even with the sprocket retightened to it - does this indicate bearing replacement here
Steve S.

Yes, play between the input and output shafts means the bushes are worn. I don't think wear here is a terminal problem (mine is pretty bad and the gearbox works just fine), but it leak oil past the gap, which is annoying. Definitely worth replacing these bushes if you've got the 'box to bits...

[Steve S]

Just opened up the box which looks in very good condition apart from the sliding gear dogs which are rounded. Some very light lines between the indents on the selector plate but I cannot detect any wear, just a line so I am hoping this is OK. The spring plunger appears ok as are the selector forks.

The large roller bearing for the sleeve gear appears fine as is the shoulder on the sleeve gear. The bushes in the sleeve gear are worn. The 3rd gear appears unworn.

So I guess I need as a minimum a sliding gear and new bushes for it - is this correct?

Clanger9 - do you have a sliding and 3rd gear as you mentioned? I could email you photos directly of mine.

Steve S.

[clanger9]

Here are some photos of what I've got. The sleeve gear bearing race looks to be badly corroded, so I think it's scrap. The sliding gear looks to be in excellent condition, but I don't think the dogs are the later undercut type.

IMG_0624 (1).jpg

IMG_0625 (1).jpg

PM me if you want either part. Good look with the repairs!

[ajscomboman]

Top picture is the later undercut sleeve and 3rd gear, you're right the sleeve gear is buggered. The bottom picture is the earlier pegged 3rd gear and the sleeve gear has 3 corresponding locating holes, those are the gears that are prone to jumping out!

[ajscomboman]

Actually looking closer it appears that the top picture shows the 3rd gear the other way round giving the impression it's undercut. Any how that's how the later gears would be on both faces.

[Steve S]

Thank you both for the pictures and the quick replies.

If I could post my pictures (I cannot compress the files yet) they would show a good sleeve gear but with very badly worn and chipped undercut dogs.

Strangely my third gear is identical to Clanger9's and is in usable condition. However this one you say is the older non-undercut one which should mate with a sleeve gear with holes for the pegs.

I therefore appear to have a later sleeve gear but with the earlier third gear. If so, no wonder it has failed.

Thank you for your kind offer Clanger 9, it seems I need a later undamaged sleeve gear and a third gear to match. I have asked Stephen at AMC spares but he doubts he any.

The gearbox on eBay at present is ludicrously expensive so I guess I'll be waiting for something to turn up!

Steve S.

[clanger9]

I guess it would be possible to undercut the pegs on your (good) sliding gear with a grinding stone? Just a thought, after all "undercut" just means a bit of the peg root is machined away (I think...)

[Ozmadman]

Also make sure that the layshaft bush (to the right of the sleeve gear) shown in the picture is in good nick and not worn oval, sitting just proud and not spinning in the casing. If you need to replace it (041289) make sure it looks like the one on the right and not on the left in my other picture. The one on the left will sit below the level of the casing which will cause your top gear to rub the casing away, you have been warned.. Also, here is a link to where I describe how I assembled my boxes, a lot easier than how that article explains in my opinion. The description is about halfway down the first page of the thread

http://www.jampot.com/forum/viewtopic.p ... ft#p119304

[Steve S]

Thanks for the pictures Paul, they are coming in handy for understanding the gearbox prior to me reassembling mine.

I have sourced a new 044075 (last one) sleeve gear from Norvil and am anxiously waiting for it to arrive.

Discovered how to reduce the size of photos using Windows 10 and attach pictures.

I believe the 3rd sliding gear is the early peg version which should not have been matched with the later type sleeve gear that was used.

The sleeve gear has damaged dogs and I also noted that it has the 2 bushes at one end instead of at each end - this must be incorrect?


Steve S

[clanger9]

That's got to be wrong. The bushes should be at each end of the sleeve gear...