Gents, Gentiles and Ge… Ok Ladies. In the strung out commissioning of my vehicle you tend to expect things to be the way they are without really appreciating that they shouldn’t be like that. And that sometimes takes a long time to dawn on you. My front fork stem goes through the frame tube and has bearings top and bottom and that big round knurled thread can be liberally twatted with a big hammer to tighten it up and then knocked back a quarter turn as my dad said to give it a bit of play. The number of balls fitted in the cups without spaces and I am sure I checked the ball size too. You would.
Anyway, when my front “brake” is operated the whole forks flop about backwards and forwards because the play in the bearings and cups is too big. It’s dangerous. Roger supplied me with a new threaded collar which took up a bit more play and the bike originally came with a Weldonia fork brace which I then fitted. It is smart and appears to do a great job of holding the front end together and gives me confidence at least. But it still flops about and it shouldn’t. Or do they a little bit?
So when I get back home I will strip the front end down and look for something amiss. I would not have looked for something amiss in the first place as it did all seem very conventional, but it could be that one of the bearing cups in the frame is not in the right place, twisted etc.
Has anyone experienced this before please? Compressor works lovely now so will be back at backfiring / spitting my way round Cheshire again.
Who knows what went before.? Whilst the balls might sit snuggly in the cups the cup register diameters may have been changed so check that the cups locate and hold position. It is quite common in engineering to have pairs of cups etc with different diameters on the pairs as the cups stay fixed in one part but free to rotate in the other. It follows therefore that a previous owner may have altered diameters to suit standard thrust races and away from what should be there. Some sizes are not now readily available and cheaper substitutes are looked for. I am a Scott novice but have been selling and modifying bearings for a few decades.
A quarter of a turn sounds rather a lot Will, I tighten the head race so that the forks turn from lock to lock without binding and hopefully with no play at all, usually there is a little. The forks do flex if your front brake works well but only a little. If your races and bearings are correct the forks should be stable. If it won’t tighten nicely maybe a cup isn’t square.
Just as an extra. When the balls are fitted ( presumably the correct size) there should be about one ball space left otherwise they ride up. It is not difficult to pick the wrong size ball if too small they will not hold position. Some metric balls are smaller than the imperial look alike!
Thanks Gents. I gather from the replies that there is no mysterious and usually encountered gremlim I should be looking out for then.
The next thing then is to check what I have against what I should have. Since I am not running out of thread on the spindle it must be the fitment of the ball in the cups. The steering turns without being notchy at all so I will have a look at the balls themselves. I know the bike was stripped completely before I had it and I would say that the cups would be a less likely /easy thing to renew than the balls during any renovation.
You can see a lot of ball when the arrangement is supposedly tight, to the point where I suspect that they might fall out. OK thanks for the feedback. the picture is becoming clearer.