Sticky Roadholders

Thanks for all your replies, which I've just checked. I took out the wheel and removed the mudguard and bridge first. This is what I've come up with:

Originally the fork stem was out of alignment with the top yoke so that the tubular part of the fork top nut was very hard to locate in the hole. After the yokes were straightened the nut fitted easily, as did the stanchions into the tapers.

The wheel spindle is free to slide through the left slider and the pinch bolt pinches. The spindle isn't bent, according to Barry's test.

Sighting across the forks suggests that end of the right leg is slightly forward in relation to the left leg. The wheel spindle jams as it enters the right slider, suggesting either a bent stanchion or yoke, right forwards or left backwards.

The right slider can be extended fully downwards until the bush on the stanchion contacts the bush in the slider. But it sticks when pushing upwards against the spring.

The left slider is quite free to push upwards against the spring but won't extend fully downwards, even by hammering. It jams solid.

After rebuilding the forks I noticed, as Howard mentions, that the left stanchion tended to stick in the bottom of the slider, but it could be freed with a good pull so I hoped it would free up in use.

When I first re-fitted the forks to the bike both sliders were fully extended but the left one projected downwards slightly more than the right one, This is something I've seen reported on a Commando, either here or on accessnorton, I can't remember which.

I've tried loosening everything off, including freeing the stanchions from the tapers in the top yoke, re-fitting the wheel (the spindle was impossible to get all the way through the right slider) and twisting the handlebars with the wheel gripped between my knees, but it makes no difference.

The bike came with a Norvil invoice for various engine parts, so the stanchions may have come from there, but I've no proof.

So it seems I have a problem with worn sliders, for one thing, and a misalignment caused by a bent yoke, probably. Or a stanchion, which is easy to check when I strip the forks, as seems will have to be done. The yokes were worked on by a well-regarded frame and wheel builder in West Yorkshire, so if they're still not straight I don't know where to go. Any suggestions within about 50 miles of Sheffield?

As for "careful machining of the sliders", would valve grinding paste be worth a try to start with, to fit the stanchion bushes to the sliders? Can't do any harm I suppose. I don't doubt Howard's knowledge, but I don't see why they would jam because of wear, I'd have thought they would be too loose if anything. I'm sure I'm about to be enlightened!

I wonder if my left slider distorted when the pinch bolt lug was re-welded?

Since my last reply I've looked at it again and discovered why the right leg extended so much further than the left: when I took the stanchion top nut off, the damper rod wasn't connected to it! Either a senior moment, or it unscrewed when I was loosening everything.

I also read Dan's mind before his reply arrived, and rotated the stanchion to a point where I imagined it looked a little better. I then tightened everything in the correct order, starting with the fork top nuts, not with the stem nut as I mistakenly did before, and the forks now move reasonably well. I haven't yet re-fitted the mudguard, but if I can do that leaving everything tightened up I hope it won't upset things.

I'm not convinced the handlebars are in alignment with the wheel, but at least now I can try riding it. There is some fore and aft play in the sliders so I'll see what the MOT tester has to say. I suspect re-boring them would be a good idea, if I can find someone to do it.

The brake stop was rocking in the groove in the slider when the brake was applied so I used my usual method of jamming in a spare feeler gauge of an appropriate thickness.

I had a first ride today. The forks appear to be working, wheels are in line, steers straight hands-off, goes round corners like a Featherbed should. The only thing is that the handlebars are turned a bit to the right when the wheel is straight ahead. Is this an MOT fail? I suppose it means a twisted yoke.

No, the bars themselves are straight. I loosened off the bottom yoke pinch bolts and the stem nut, clamped the front wheel and twisted the bars hard, and it seems to have done the trick. There's some play in the sliders but it passed the MOT today so it'll do for now.

Sorry this has been a bit of a non-issue in the end, but thanks for everybody's input.

Now onto the next problem...