1969 A65 Front Fork Lengths.

[Wilf2019]

Hi all,

Is it normal for the front fork bottom tubes to be different lengths? When fitting the front wheel it was not sitting central within the forks, and cocked over top to bottom.

Therefore, I stripped both fork legs and noticed the bottoms are different lengths by about 3.5mm.

I followed the procedure in the manual when fitting the wheel, by tightening the brake side cap first and then pumped the forks prior to tightening the left hand side. The wheel was still not central, and caused the forks to bind up when both clamps were tightened.

Any advice on this would be greatly appreciated.

[Rupert]

Hi, fork bottoms/sliders of different lengths isn't normal for any bsa as far as I'm aware. You have the triumph type forks which bsa fitted for 1969/70. Have a look on the flat surface of the sliders next to the end of the spindle, is there a dot like a centre punch mark on either of the sliders?
Rupert.

[Wilf2019]

Hi Rupert,

Yes there is a centre dot mark on each fork bottom and each end cap. I believe these should both line up?
I have read a few post where people have experienced this. But have seen no real conclusion of what to do for the wheel alignment / tipping over.
Do you have any idea?

Wilf.

[DAVE BRADY]

Hi Wilf,

Just some random thoughts.  Were these on the bike and working OK?  Are they brand new and where were they made?
Are the mudguard bracket lugs in the same position on each slider?
This is a bit of a poser but I wonder if BSA made these in pairs or singly on separate lines and matched up later - have you got a rogue pair?
We know some strange things happened in the factory.

Dave.

[Bess]

Hi,
    Some A65 forks sliders were manufactured with the wheel shaft 1° off the horizontal to improve steering. This will give the anomalously you are experiencing.

Worth a read:
https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=1817.msg9885#msg9885

Best wishes...

[DAVE BRADY]

Another thought. Would the 1deg. angle for the spindle necessitate the sliders being different lengths? 

Dave.

[Wilf2019]

Thank you all for the replies.
These are the forks that came on the bike. But I bought it as a restoration project. The bike was complete and running, but the forks were seized up with no oil. So they could well be the original forks.
I have fitted new stantions, bushes and seals etc.

I have already read the post that Bess has shared. But it doesn't really come to any conclusion as it appears the OP fitted new / different sliders. But I am experiencing exactly the same.

It seems to be a common issue. I have even read of people machining the fork bottoms to correct the length difference. But not sure that this is necessary or if the current length difference is as was originally designed?

[Bess]

Hi,
     These images show the sliders with the 1° angle and effect on the the fork lengths. The s/s attached states the type you have.

Best wishes...

[DAVE BRADY]

The difference in the ends is quite large considering that only a 1deg angle was to achieved.  Was this angle from left to right or vice versa?  Where about on the mud guard brackets are the 'A' stamped?

Dave.

[Bess]

Hi Dave,
             The angle rose towards the brake. I don't know where the A is stamped I have never seen this type.

I believe later, when they were fitted as standard, they had counter bores as an indication of the offset and the end cap sizes changed heights, these had to be fitted onto the correct slider. I have seen this type and the counter bores are adjacent to the wheel spindle hole.

Best wishes...

[DAVE BRADY]

Thanks Bess,

I suppose the next and probably rhetorical question is what was the problem with the handling and how did this slight angle improve handling and it implies that there was a defect somewhere else and this was a rather crude way to rectify it.  I do not think that sidecar set up had any thing to do with it.

Dave.

[Wilf2019]

Bess, the pictures you show is what I have. So this must be correct. I don't understand how it would be possible for the wheel to sit vertical between the fork legs?

However, I have just rebuilt the forks again and refitted the wheel. Firstly I refitted the wheel without the brake plate to ensure the anti rotation lug was not fouling and the wheel still leans over by approximately 5mm measured at the top of the rim.

Could anyone advise if this is normal?

[LightningAndStarfire]

Thanks Bess,

I suppose the next and probably rhetorical question is what was the problem with the handling and how did this slight angle improve handling and it implies that there was a defect somewhere else and this was a rather crude way to rectify it.  I do not think that sidecar set up had any thing to do with it.

Dave.

The only thing I can think of is the bike's center of gravity, if offset from centerline

[DAVE BRADY]

Hi Wilf,

I would say that this is definitely not normal.  I believe that the mudguard brackets have to fit in this gap as well so something is amiss.  Why would the slider need to be that much longer to counter a 1deg angle across the width of the wheel spindle clamps?
If the centre of gravity needed this at the front then surely the back would need the same?

Dave.

[JulianS]

I would check 2 things;

First the rim offset - factory figure, in manual, from edge of brake drum to centre of rim is 1 11/64 inch.

Second- what does it look like with the bike off stand and load on the wheels?