Author Topic: Inside gearbox  (Read 690 times)

Offline paintingsteve123

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Inside gearbox
« on: 11.04. 2024 18:41 »
Hi all,
I took all the internals out of my 1951 a10 goldflash gearbox
I found these 4 shims on top of the cam plate  I can't find any info on whether they should be there or not, they are pretty managled so would assume something else must be worn.
They look like crank shims and are very thin.
Any info would be grateful.
61 A10

Offline KiwiGF

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Re: Inside gearbox
« Reply #1 on: 11.04. 2024 23:46 »
Hi all,
I took all the internals out of my 1951 a10 goldflash gearbox
I found these 4 shims on top of the cam plate  I can't find any info on whether they should be there or not, they are pretty managled so would assume something else must be worn.
They look like crank shims and are very thin.
Any info would be grateful.

Who knows what was in the PO’s mind when he added the shims, but a thin shim (in my opinion) should not be in that sort of location, a hardened washer maybe.

I reckon you rebuild the box as standard, and try to see if the cam plate position could be improved, if so then the easiest option is a washer. Building up the case with weld and machining it would be expensive and tricky. Maybe there would be an advantage in “sticking” the washer to the case  *dunno*
New Zealand

1956 A10 Golden Flash  (1st finished project)
1949 B31 rigid “400cc”  (2nd finished project)
1968 B44 Victor Special (3rd finished project)
2001 GL1800 Goldwing, well, the wife likes it
2009 KTM 990 Adventure, cos it’s 100% nuts

Offline Swarfcut

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Re: Inside gearbox
« Reply #2 on: 12.04. 2024 09:57 »
 Not a standard part methinks. Basic camplate design is the same on all boxes, so this applies to the later S/A box as well.

   The face of the camplate should not press heavily onto the selector forks when the selector rod and inner cover are in place. Conversely if the camplate can move towards the inner face of the case, the depth of engagement for the pegs in the camplate tracks is less, so you need a happy medium. Enough freedom to rotate, close but not binding, but not too loose to be sloppy. Standard build with new parts all was fine, no adjustment needed or provision for. Looks like a P.O. mod of some sort. I have had the odd camplate that was too thick (factory second?) that caused a problem, solved by a bit of detective work. viz....

   The down changes in the box are assisted by the plunger and spring, too tight between forks and camplate and you can change up OK, but it won't change down, binding too much for the plunger to nudge the cam.

 With this particular gearbox, look for wear to the camplate, gearbox casing and a bent selector rod.

 As a hint, fit the grubscrew last, to avoid breaking a chunk off the casing when you accidently smack the end of the seleector shaft when fitting the inner cover. Selector mechanism will work without the gears for testing purposes. Early version of the plunger box uses flat clockspring on the kicker, no grease nipple on clutch arm. It may also not have a sprocket oilseal. Good news is that later sprockets and oilseal are a straight swap as a pair.

 Swarfy.

Offline paintingsteve123

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Re: Inside gearbox
« Reply #3 on: 12.04. 2024 13:26 »
Thank-you guys
61 A10

Offline limeyrob

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Re: Inside gearbox
« Reply #4 on: 14.04. 2024 09:21 »
I wonder if the PO was thinking that the selectors pins were not far enough engaged and wanted to push the plate onto the pins more?  Not a good idea so as other's have said, junk the shims.  If the selector plate tracks look OK and the pins look OK it should be good to go, if not consider replacing them.
From bitter experience when I've found equally illogical PO "repairs" there's always been one or two more horrors so check everything really carefully, assume nothing!
Slough 59 GF/SR

Offline Swarfcut

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Re: Inside gearbox
« Reply #5 on: 14.04. 2024 09:52 »
 I'd add a couple of thoughts to Rob's warning. There are two profiles to the kickstart teeth. Early type have flat tops, later type has pointed teeth. All types interchange, BUT!!! you need the matching profile on the small kickstart ratchet pinion, otherwise the mechanism will jam.

 This distinction is not made clear with aftermarket or used parts, so folks need to be aware when checking an unknown P.O.'s mis guided efforts that the wrong bits have been fitted. Quadrant type is easy to spot, pinion less so, especially when worn and abused.

 Lots on the Forum about other gearbox pitfalls, plenty there to help. Hardened Layshaft thrust washer goes under the big first gear cog, but ensure the inner chamfered edge faces towards the clutch, in order to clear the fine radius on the layshaft where the shaft diameter changes.

 Swarfy

 PS. Richard Clamp in Atherstone, near Tamworth, Staffs is a guru for boxes and bits. Find him in the suppliers section of the Forum.

Online Craigy

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Re: Inside gearbox
« Reply #6 on: 04.05. 2024 15:46 »
Sorry my last post was on the wrong thread 😞
52 GF, 59 GF