Norton Roadholder modifications (2009)

For an expert opinion I'd search on Peter Crespin as he has discussed his modifications quite recently.
I used the RGM kit based upon Crespin's work and it improves compression bump stop with the 1/4" holes drilled as per the Matchless Teledraulic fork design, i.e. above the taper. The fork still tops out despite the sleeves fitted below the upp bush and preload of the springs so I just get on with it. I'd imagine the smaller hole will make the fork quite stiff and you could emulate that with 30wt fork oil. I found it too stiff and went back to 20 wt and 5-10 ml more than the manual recommends.

There are several ways to improve the forks with damper modifications or kits. I've tried and compared different techniques and tested them. Here is what I found:

"Leak proof" seals increase stiction. A simple slider test before installing the fender, springs or axles makes this obvious.

To avoid top out you need to either use longer top bushings or add the aluminum sleeves (fixed in place at the top). And you must also plug the two 1/8" holes near the bottom of the steel fork legs or it can still top out as mentioned in the post above.

Increasing the spring length or installing stronger springs that push the aluminum sliders out further is a bad idea because it reduces the the overlap distance between the bushings. The distance between the bushings is already too short simply because the sliders are too short. The short distance increases stiction, stress and wear. Increasing the distance by extending the length of the slider with a fitting that screws onto the top of the slider and relocates the upper bushings gives a dramatic improvement but it requires machining and I only know of two people who have done it.

You can install expensive dampers or you can make modifications to improve the existing dampers and get satisfactory results either way. To see the modifications go to:

https://jsmotorsport.com/js-motorsport-technicalmore-norton-fork-upgrades/

The important thing is to have adequate rebound dampening and you can test this by simply pumping the forks as hard as you can with the ft brake on and observe how quickly the forks rebound. The stock rebound dampening is a bit wimpy unless you have new parts and use at least 20 wt oil. Its also nice to have a little compression dampening and the stock setup does not provide any. For compression dampening you need the aftermarket damper units or make the modifications shown below with only one 1/16" hole at the bottom of the stock damper.

Thanks, but now I am back where I started.

'HoveToo' advocating the Crespin modification & 'jseng' advocating the JS Motorsport modification...

Hi , I want to lower the Commando fork height to fit on a seeley , I know I could buy the NYC yokes , but I am cheap , so the way is to fit Atlas short roadholder stanchions and damper tube , is Norbsa providing his kit for short roadholder ? John Robert Bould was making his kit for them ,but Madass don't do it , what's your thought ..............?

marinatlas said:

Hi , I want to lower the Commando fork height to fit on a seeley , I know I could buy the NYC yokes , but I am cheap , so the way is to fit Atlas short roadholder stanchions and damper tube , is Norbsa providing his kit for short roadholder ? John Robert Bould was making his kit for them ,but Madass don't do it , what's your thought ..............?

Click to expand...

Take a look at RGM site they seem to have all you would need.

Regards

Esme