1972 commando rebuild

BERT said:

The yoke difference was well explained, I understand the difference. Thanks for that.

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L.A.B. said:

Are there no other markings on the underside of either yoke except for ANG on the lower and "266"?
The certification plate on the headstock has been removed at some point as it is not fixed with the normal hammer-drive 'rivets' (link. below) but what appears to be oversized pop rivets?

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BERT said:

Yes, the part numbers should be visible in the enclosed pics

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BERT said:

I didn't notice anything wonky disassembling the forks with alignment, but then I wasn't particularly looking for anything.

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L.A.B. said:

I don't see any pics? (note they are the casting numbers, not the actual 'part' numbers).




The upper yoke could be 'ANG'.

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L.A.B. said:

NM 061917 is the 750 yoke.
ANG 064083 is the '73-'74 850 lower yoke part 06.4078.

https://andover-norton.co.uk/en/shop-details/16241/lower-yoke-850-ang-type

Theoretically, if the stanchions are fitted through the lower ANG yoke then they shouldn't line up with the upper yoke tapers at least not without the aid of a large hammer!

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BERT said:

Golly, I'm stumped. When I removed the stanchions, A rap on the top nut with a soft hammer did it and they slid easily, per shop manual procedure. Nothing seemed askew. Now I am wondering if some individual did some custom work ( we call it farmer's fix it) to make things work. "266" hand engraving may mean something. Ugh.

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L.A.B. said:

I think the (lower yoke?) must have been tweaked to align to fork stanchions as the 750 yoke offsets are both approximately 65mm.

The ANG yokes are approx. 72mm upper and 69mm 64mm lower plus the stanchions do not pass through the ANG lower yoke parallel to the frame.

(Dimensions supplied by 'debbie in another 'yoke' discussion).

My concern would be the effect the resulting shorter 65mm upper and longer 69mm lower offset fork angle would have on handling.

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L.A.B. said:

Correction.
I've checked a couple of ANG lower yokes and the ones I have are approximately 63-64mm offset, not 69mm as I said in my previous post (now corrected) so the lower yoke is closer to the '750' offset but still angles the stanchion towards the 72mm offset of the upper yoke.

Edit: Difference in offset between the ANG lower yoke (on the top) and '750', directly underneath.

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Time Warp said:

The spindle for the floating gears is all but size for size to the dimension between the bronze end plate and driven spindle end body so that needs to be checked if the body dimension is reduced (lapped)

It would not take much to have the ends not seating on the main body faces if that spindle was not sized also.

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BERT said:

Thanks. Indeed, I lapped to shorten it to match the pump body subtract a half a thousand. Too bad replacement parts aren't available to rebuild these,eh? At least to my knowledge. They are built good and tough and are worthy of component replacement.

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BERT said:

This lower yoke offset measures 67.5mm or so.View attachment 22011

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dynodave said:

1. series 1 commando rolling chassis (68-69-70) used 27 deg (as I said in post #3) 2-1/4" offsert same as featherbed/all late slimline but all UN threads on commando triple trees

2. series 2A commando/ 71,72,73 750 rolling chassis still 27 degree but increased new fork offset and style top2.777" bottom 2.783"

3. series 2B commando / 850 rolling chassis NOW 28 degree and 850/ANG top 2.851" bottom 2.689"

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Time Warp said:

I wonder how many pump bodies have been lapped with no regard to the spindle length, it was a surprise when I measured the spindle (as a routine) and found it 0.06 mm longer. ( + 0.002" )

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BERT said:

This lower yoke offset measures 67.5mm or so.View attachment 22011

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gortnipper said:

Take a pic with them stacked up, with the steering head tube holes aligned, so we can see the stanchion holes?

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BERT said:

Thanks. Indeed, I lapped to shorten it to match the pump body subtract a half a thousand. Too bad replacement parts aren't available to rebuild these,eh? At least to my knowledge. They are built good and tough and are worthy of component replacement.

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grandpaul said:

I think that's what the bottom photo is...

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gortnipper said:

Take a pic with them stacked up, with the steering head tube holes aligned, so we can see the stanchion holes?

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BERT said:

Here they are stacked up, I think this is what you meant gortnipper. Looking at dynodaves offset dimensions, the 750 top and 850 bottom are very close . Therefore I'm thinking(?) the stanchions would be close to parallel with the frame head in this situation, like the stock 750 setup. In the 850 stock setup, the 850 bottom would be machined on on angle to line up with the 850 top since they have different offsets, I would think. I am going to reassemble and see if I missed any misalignment or binding with the bottom yoke when I took it apart, and check the fit of the stanchions in the lower yoke. It may tell me if something has been "customized", intentionally or not. Thanks for thoughts and ideas so far guys.

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