Author Topic: A65 front axle  (Read 468 times)

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Milemuncher

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Re: A65 front axle
« Reply #15 on: 17 May, 2022, 20:04:03 »
Julian, if that is the 1968 fork, you have the 1969 brake plate with the cable down the forks

Milemuncher

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Re: A65 front axle
« Reply #16 on: 17 May, 2022, 20:44:01 »
Guys, if the forks are slightly twisted in the yokes, would that increase or decrease the gap between the forks at the bottom, or would this stay the same?

JulianS

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Re: A65 front axle
« Reply #17 on: 17 May, 2022, 21:19:59 »
Yes that is correct, 1968 damper rod forks with 1969/70 brake, fitted to my A10.

Milemuncher

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Re: A65 front axle
« Reply #18 on: 17 May, 2022, 21:47:02 »
Thanks Julian, so I can rule out the 1968 forks.

Milemuncher

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Re: A65 front axle
« Reply #19 on: 17 May, 2022, 22:03:05 »
Spaceman, I have attempted to measure the offset, but the welds at the bottom of the forks are a pain and the fork bottom protrudes inwards slightly. Ill have another go in daylight

spaceman

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Re: A65 front axle
« Reply #20 on: 18 May, 2022, 06:09:11 »
It looks as though the only possibilities to explain why your clamp bolt separation is ~6" rather than the 'normal' 6.25" is if the fork separation is less than 6.75" or the bolts are more than 1/4" from the fork centrelines.

If you measure your fork separation to be 6.75" then this would imply you clamp bolts are 3/8" off centre rather than the 'normal' 1/4". This would then seem to imply the sliders are not standard.

If, on the other hand, your fork separation turns out to be 6.5" then that would seem to imply they are either twisted in the yokes or the yokes are non standard.

Bess

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Re: A65 front axle
« Reply #21 on: 18 May, 2022, 11:53:17 »
Hi,
    I have put together some forks with the different sliders, images might help:

Unfortunately there are 4 different spindles listed for the full hub so without knowing the history of yours I guess it is a bit of trial and error. The spindles I have I don't know the part numbers. I am happy to post my selection for you to try and you can return them when you've finished.

Best wishes...

Milemuncher

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Re: A65 front axle
« Reply #22 on: 18 May, 2022, 21:14:15 »
I’ve managed to grab the assistance of one of my daughters this evening so I’ve offered up the wheel to the forks and taken some pics using the 42-5824 spindle.

I’ve fitted the right hand side perfectly (brake plate), and the left hand side illustrates the difference in groove spacing. As far as I can tell, the forks are not twisted in the yokes and they are the correct 6 3/4” apart.
« Last Edit: 18 May, 2022, 21:23:04 by Milemuncher »

spaceman

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Re: A65 front axle
« Reply #23 on: 19 May, 2022, 06:16:47 »
If the fork spacing is standard BSA 6 3/4" then the problem is that your fork sliders are non standard and the clamp bolt offsets are 3/8" rather than the standard 1/4".

In terms of a possible background to this problem: When the Triumph TLS hub was introduced in 1968, because it was designed for the standard Triumph 6 1/2" fork spacing, BSA had to modify their fork slider end caps to allow them to fit the hub and axle. This mod was done just for 1968 as Triumph then changed their fork separation to match that of BSA so the subsequent TLS hubs fitted both standard arrangements.

It's possible the bike in question has the modified 1968 fork sliders but, as far as I can see, the mod made might have actually reduced the clamp bolt offsets rather than increasing them - both the BSA and Triumph TLS hub axles from 1968 seem to have a clamp bolt separation greater than 6.25" and so would not fit the bike in question.

So the solution to this particular problem would seem to be to either fit standard BSA fork sliders or to machine the current axle to fit or to source an axle of the correct dimensions. Bess looks as though he might have an axle that fits but it is not clear to me what this came off?


JulianS

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Re: A65 front axle
« Reply #24 on: 19 May, 2022, 10:32:40 »
This may help;

I have compared the clamp bolt off set between the 1968 and the 1962-65 forks, both are the same.

The 1968 bottom clamps are wider than the 1962-65 type making the outside length between clamps 7 7/8 inches.

The inside measurement between the clamps is 5 inches.

The clamp bolt centre to clamp bolt centre measures 6 1/8 inches.

Measurements from 1968 fork with A10 yokes.

The spindle should not stick out past the end of the clamp as in your last photo.

Your forks look like those originally fitted to 1958/59 A7 A10 B31 and B33 plus the Spitfire scramblers up to 1962.

The other visiual difference between 1962/65 and 1968 forks is the socket cap screw which passes through the base of the fork bottom to fix the damper tube.

I suspect your yokes may not be 6 3/4 between centres - could you post a photo of them?

Milemuncher

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Re: A65 front axle
« Reply #25 on: 19 May, 2022, 18:31:22 »
Thanks all for your posts  :)

Julian - My forks do not have the socket cap screws in the bottom of the forks, so we can now completely rule out the 1968 forks. I’ll see if I can get a clear photo of the fork spacing near the yokes, but when measured (twice now) they’re 6 3/4”. The A7/A10 forks look to have different mudguard fixings from what I have seen on Draganfly (likely generic pics though).

Bess - thanks for your pics. It would be helpful if it was known which bikes your spindles were off as a couple of them are likely to fit. I’m no closer to identifying what I have though.

Spaceman - very likely my solution is to turn a new groove on the new spindle. It doesn’t sound like I’m going to have much luck in identifying which forks I have.

Anyone know a machinist in Brighton?



« Last Edit: 19 May, 2022, 18:33:30 by Milemuncher »

spaceman

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Re: A65 front axle
« Reply #26 on: 19 May, 2022, 18:52:52 »
Machining the axle would seem to be the simplest solution. Since this is only needed to provide clearance for the two clamp bolts, you could probably just file the two flats needed either side of the axle - just need to make them the same depth as the existing groove. It won't really matter if the axle sticks out 1/4" on the LHS?
« Last Edit: 19 May, 2022, 18:55:10 by spaceman »

JulianS

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Re: A65 front axle
« Reply #27 on: 19 May, 2022, 19:28:16 »
These are 1958/59 A10 forks.

Milemuncher

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Re: A65 front axle
« Reply #28 on: 19 May, 2022, 21:40:12 »
Julian, they certainly look the most like my forks so far and they have both front and rear mudguard stay mounts on the bottom clamps.

Id recently looked at A10 fork parts, but they also appear to have the same 42-5824 spindle for the later models?

Ive re-measured the forks using metric (easier for me) half way down the fork bottoms:
Distance from outside fork edge to outside fork edge = 215mm (8.46)
Fork diameter = 40mm (1.57)
Therefore, fork centre to fork centre 215 - 40 = 175mm (6.88) which is <3mm over 6 3/4 which we could allow for my eyesight.


spaceman

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Re: A65 front axle
« Reply #29 on: 20 May, 2022, 09:29:01 »
Unless they are non BSA or Triumph yokes, I think the only two possibilities are fork separations of 6 3/4" or 6 1/2" with these looking to be standard BSA. I measured my fork separations just by measuring from the outside of one fork leg to the inside of the other. Just done this for my A10 and A65 and got 6 3/4" as expected (within a few mm measurement error)!