1972 commando rebuild

L.A.B.

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

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?

 

BERT

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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?

Yes, the part numbers should be visible in the enclosed pics. I didn't notice anything wonky disassembling the forks with alignment, but then I wasn't particularly looking for anything. And yes the rivets are definitely Al pop rivets, not the hammer type. Supposedly the frame was powder coated so maybe they just replaced them with these. Is there some type of modification guys do to utilize mix -matched the yolks or is it a no- no? Ugh.
 

L.A.B.

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

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


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

The upper yoke could be 'ANG'.
 

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




The upper yoke could be 'ANG'.
Sorry, forgot to attach pics!
 

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L.A.B.

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BERT

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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!

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.
20210225_151442.jpg
 

L.A.B.

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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.

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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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.
 

L.A.B.

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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, fitted to the same stem.
003.jpg
 
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BERT

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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.
Hmmm. Much to rack the brain about. Thanks for your time and insight today,it must be evening where you are, and I will see if I can figure out what is going on and what I need to do. You have been a great help . Cheers,Dave.
 

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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.
003.jpg
This lower yoke offset measures 67.5mm or so.
20210225_162122.jpg
 

BERT

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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.
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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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.

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" )
 

L.A.B.

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

Yes, they're not the easiest of things to measure accurately.
The ANG and 750 yokes fitted to the same stem does show the difference.
Same the other side:
004.jpg


Edit: Dimensions given by dynodave in a previous thread:
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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BERT

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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" )
Yes for sure. It's a tedious job, and by the time one is finished, with so many figure 8's and dreams about lap dancing, the length of the spindle could easily be forgotten.
 
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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.
You can buy parts for them.

 

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I think that's what the bottom photo is...
Take a pic with them stacked up, with the steering head tube holes aligned, so we can see the stanchion holes?
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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BERT

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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.
It goes together nicely. The yokes don't look modified in any way, I am thinking it was a serious mistake made and the best thing for me to do is to put the correct yoke on it and not to bother trying to figure out something that isn't right. The 850 offset difference between top and bottom is 0.165" over 8.5". Proportionally it would about 0.020" over the thickness of the bottom yoke. That is hard to see and tightening them up on the stanchions could lead to something serious. It is a mystery why the why the mismatched parts were engraved "266" but I hope there are not 265 more of these.
 
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