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Re: What to do with a worn Roadholder fork leg?

Submitted by hans_eberlein on Sun, 14/08/2016
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NOC Riders Section

Hi all,

By restoring my Model 18, 1947, I found a worn bronze bushed left hand fork leg, when I tried to replace the bushes bought by British Only Austria.

Fortunately, the ID of the bronze bush was a bit less then the standard, so, I made in my lathe a reamer that worked reasonably well.

Fitting the leg dry with the new bushings onto the stanchions, they slided with no play at the entirely length.

I attached a picture of the leg with the reamer, and, if of interest for anyone, I could add details and measures in more pictures.

Attachments roadholder-leg-reamer-jpg

Submitted by hans_eberlein on Sun, 14/08/2016

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Hi Dan,

No, the leg were bushed, and, as undersized, it allowed to be reamed to a standard stanchion bushes.

I think, if should the standard leg be worn, the reamer should be also suitable for this job, as reaming the minimum necessary, and make oversized top and bottom bushes, taking in mind that to find legs in good condition is not easy, and at least, expensive.

Submitted by hans_eberlein on Mon, 15/08/2016

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Dan,

I bought the Norton in this condition, so, no idea how it was bushed. The bush is a one piece and reaches the bottom of the leg.

I will try to upload a picture if not too heavy.

No, noy possible for the moment. A new lighter picture further.

Submitted by john_holmes on Mon, 15/08/2016

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So you have a leg with a liner installed, hopefully a std tube of some sort, will have to take some measurements and look online for tube with the correct OD. The fork lowers wear well but do end up worn mostly in the middle of the leg where the bottom bush spends most of its time. Wear is worst on the internally sprung legs as the springs rust inside the unsealed legs and also rub against the stanchions. The filings and rust mix with the oil to creating grinding paste.

Need to see your reamer as in your pic its hidden inside the leg, the ones I have with the correct diameter to ream a liner would not come out through the bottom hole. Is it an expanding reamer.

Submitted by peter_stowe on Mon, 15/08/2016

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I am interested in this thread as my long Roadholders sliders are worn from when the bike had a sidecar fitted.

The guy who used to make Lansdown dampers had a service where he would ream out the sliders, then resleeve them to standard. But unfortunay he has passed away, and I dont know of anybody else with this service.

I was going to contact Pete Lovell to ask if he could do it.

Unless anybody else has a recomendation?

Submitted by hans_eberlein on Mon, 15/08/2016

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Due to restriction of the picture sizes, I took another smaller ones. In the first picture, one can see the long bush -or liner- which was succesfully reamed with my home made reamer.

Also, the same reamer did the job of making flush the end of the bush with the recess of the leg, as the bush has had a protrusion of about 1/16", also seen at the first picture.

In the second picture, the cutting disc is at the outer side, acting as a flat reamer for the bush protrusion, while the inner disc -with the same stanchion bottom bush diameter, act as a guide.

To ream the bush, comes of course, the cutting disc first, having the small portion between the bottom surface and the cutter, the diameter of the bush before reamed, while the cutter protrudes to the second disc diameter.

Both the cutter disc and the guide disc are attached to a 1/2" steel rod that slides smoothly through the leg bottom hole. I used a 5/16"x26 TPI thread for the discs, secured by a nut, and used a chuck to handle the tool.

As the amount of reamed material was quite few, at the middle of the stroke remained unreamed spots, but small, which will not affect the sliding of the bushes.

If anyone want more details or pictures, please, don?t hesitate to ask me.

At least, I hope having been clear enough to understand the text.

Attachments img_4029-jpg

Submitted by hans_eberlein on Mon, 15/08/2016

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About the reamer: Both the reamer with a fixed diameter, and the reamer that expands by means of sliding cutters, are not suitable for this job, as they are "conical", instead of my reamer, which has a small "dead" area, between the bottom of the cutting disc and the cutter, less than the nut and tab washer distance.

Submitted by john_holmes on Mon, 15/08/2016

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I would call that a boring bar rather than a reamer, neat to use the bottom hole to guide the cutting end. Take it has 2 or more teeth/inserts so they also guide by using the depth of cut to balance the head. In a lathe coming in from the top you risk going off centre.

Submitted by hans_eberlein on Mon, 15/08/2016

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OK John. Thank you for the correction. Then, a boring bar.

Now, going further with the forks: Do you know if the bottom stanchion bush is pressed by the nut against the stanchion shoulder, or has it a small vertical play?

Submitted by john_holmes on Tue, 16/08/2016

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I don't have an older Norton, on the Commando the nut is replaced by a retaining circlip and the bush can rotate and has slight vertical movement. I have pondered on this point over the years and it may be a good way of reducing stiction as the stanchion has some speed before the bush starts to move. Downside is the bush can wear on the inside and you get more clearance in an already wide tolerance area compared to modern forks but its an issue that I have not seen come up and on the used forks I have dismantled the inside of the bush shows no sign of wear.

Submitted by hans_eberlein on Tue, 16/08/2016

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Thank you John. I agree with the explanation.

The set of bushes I bought from British Only Austria came with your mentioned circlips, not useful for me, but included worthy damper rod fibre washers, as well as fibre washers for the drain plugs. Also a paper washers.

 


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