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BSA Unit Singles - Top Fork Yoke Differences ? #759330 12/14/18 9:58 pm
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Jon W. Whitley Online Content OP
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Can anybody tell me what the difference is for the top yoke/triple tree for 1966-1967 part number 40-5114 is as opposed to the 1968-1970 top 97-2525 top triple tree/yoke ? In pictures they look identical from the top but definitely differ from the bottom view.

TIA


[Linked Image]

[Linked Image]


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project

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Re: BSA Unit Singles - Top Fork Yoke Differences ? [Re: Jon W. Whitley] #759347 12/15/18 12:31 am
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VicCyclone Offline
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Measure them between the stanchion centres. I think that you will find that the earlier ones are narrower. They used the 7" front brake whereas the later yokes were used with the 8" brake which is wider.


VicCyclone

1965 A50 Cyclone Clubman
1966 Victor GP
1967 Victor Special
1968 Victor Special
1968 A65L

2009 HD FXDC
Re: BSA Unit Singles - Top Fork Yoke Differences ? [Re: Jon W. Whitley] #759383 12/15/18 9:37 am
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kommando Online Content
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The wider ones were also used with the 7" TLS, maybe for commonality with the VS or maybe because the brakeplate needed it, not measured to see which.

Re: BSA Unit Singles - Top Fork Yoke Differences ? [Re: Jon W. Whitley] #759404 12/15/18 3:49 pm
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Gordon Gray Offline
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Originally Posted by Jon W. Whitley
Can anybody tell me what the difference is for the top yoke/triple tree for 1966-1967 part number 40-5114 is as opposed to the 1968-1970 top 97-2525 top triple tree/yoke ? In pictures they look identical from the top but definitely differ from the bottom view.

TIA


[Linked Image]

[Linked Image]



Jon, I should know better but I saw this yesterday and since nobody else is going to say it..........you wrote <.......snip......."they look identical from the top"....snip....>

UH........no they don't. The later ones are sometimes referred to as "sunken". Look at where the lower triple's stem passes through the upper. With the later models that area is sunken which makes it easy to ID the late from the early. There's also a simple way to tell which lower goes with which upper......but I'll let somebody else tell you that one.

AND.....the fellows are correct the later triples are the "wide" ones.

Proud to be one of the BSA unit single guys.........Gordon in NC

Last edited by Gordon Gray; 12/15/18 3:52 pm.
Re: BSA Unit Singles - Top Fork Yoke Differences ? [Re: Gordon Gray] #759432 12/16/18 1:03 am
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Jon W. Whitley Online Content OP
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Originally Posted by Gordon Gray

UH........no they don't. The later ones are sometimes referred to as "sunken". Look at where the lower triple's stem passes through the upper. With the later models that area is sunken which makes it easy to ID the late from the early. There's also a simple way to tell which lower goes with which upper......but I'll let somebody else tell you that one.



Hi Gordon,

Thanks for pointing that out. In my defense, I must have seen one marked as a 40-5114 with the recess but was actually a 97-2525 in Google images. However, looking at the picture I posted, it is immediately evident, so thanks again ! It looks like I have choices. I may just go with the later triples and run a 7" TLS wheel, since I have a few.




Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project

Re: BSA Unit Singles - Top Fork Yoke Differences ? [Re: Jon W. Whitley] #759434 12/16/18 2:11 am
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Gordon Gray Offline
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Jon, IMO (which doesn't mean much) you're making the right choice for the brake......that 7" TLS is a nice set up. Heck, just when a fellow thinks he has some of this stuff figured out....ya find something else out. It almost seems like the more I learn about these things the more I realize I really don't know much at all. I'm in the process of setting up an 8" TLS for my unit single sidecar rig. 1968 B44SS wheel with an 8" TLS brake off one of the twins of the era. All I had to do was swap out the axle and it was a straight fit.

Edit: I forgot to mention that on my front brake upgrade I swapped the stock 1967 B44R front forks ( Narrow, QD) out for the later "Wide Yoke" version (1969 B44SS)

Take care my friend......and have the BEST HOLIDAYS ever.........Gordon in NC

Last edited by Gordon Gray; 12/16/18 12:20 pm.

Moderated by  Allan Gill, Jon W. Whitley 

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