Fork Hyper Extension

I assume the " bleed" holes are the ones drilled in the stanchions? If so forget about them with Lansdowne units,they dont do a DARN thing.

dennisbleed gb said:

L.A.B. said:

dennisgb said:

Read this...it's long, but it tells the story

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As Lansdowne dampers are fitted, it won't be the right story.

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I think, although I might be wrong, that the uncovering of the oil bleed hole still can happen with the Landsdowne dampers installed.

Maybe John will see this and chime in.

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Tried 20W fork oil?

The first step is to set sag even on a relic when it becomes an option.
Sag, unladen and loaded is dictated by the spring, the spring options for the Commando seem very limited which is why that was asked.
New hard parts and fancy damper kits are of little use if old springs are retained (if that is the case) , back to basics, start at the first step and that is set up.

Never seen a hydraulic lock , when the manx racers return to the pits the forks are still compliant , if this "locking" was possible won't all forks become air locked.? surly Not!

hobot said:

I missed fogged over the Lansdowne kit part and don't mean to confuse or distract but would like to know how much fill Lansdowne take before air pocket spring pumps down to nothing to hydro lock.

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john robert bould said:

I assume the " bleed" holes are the ones drilled in the stanchions? If so forget about them with Lansdowne units,they dont do a DARN thing.

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Yes I was referring to the holes in the stanchions. I have your kit in my forks...but I didn't realize that those holes don't make any difference with the Landsdowne dampers. It's confusing because I bought the JS Turkite Busings and they come with plugs for the holes so you can move them. My mistake.

Ok, no normal level filled forks should ever hydro lock but they all can if over filled, though - some can't really be over filled d/t a sealed air pocket spring but others like factory Roadholders can be filled enough the air pocket spring space works a treat, till pumped out to become a stiff legged broncho. The volume displaced by various internals would influence the amounts some. If air could be trapped it would help last instant of bottoming control and tend to suck back some the velocity/force of full extension travel and be adjustable to boot.

Some restless-bore owners still pester me on DIY forking. Current hot to trot is Ed The Tomato Man Ostack with early CNW 850. He put a leg in a tallish fluid container to feel the action vs distance pumping up/dn to change hole size and locations till sweeter. I was too poor and reasonable price effective kit not available, especially for raw off road. I'd just by gosh/golly quesimated this on Peel and luckedTF out if worked out for me. Of course I admit I may not be good enough to appreciate better fork action like proven Lansdownes so itchy to find out and fascinated by all the factors perfecting progress. Keeping mostly outer Roadholders is a big feature to me to confuse the moderns no end.

Steve , I have fitted a pressure gauge to the forks and pumped up a few LBS , but the pressure leaks away vaa the top nut, total agree with you if the forks where 3/4 filled but that would be a bit silly putting approx 500ml in them ?

hobot said:

Of course I admit I may not be good enough to appreciate better fork action like proven Lansdownes so itchy to find out and fascinated by all the factors perfecting progress. Keeping mostly outer Roadholders is a big feature to me to confuse the moderns no end.

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You should just do it. You have half a mil in Peel already what's another 400 bucks?

John does a nice job on them and the top nuts look cool too

Till mine locked after 1/4 m I had no idea that Roadholders were not air tight at top as no fluid ever leaked there. Will have to fill a barrel and see where they leak air. The thing about better handling to me is the temptation to really test in public. Each improvement just means that much faster when next mood swing hits. Mechanical based forks are pretty much topped out in development from Roadholders to MotoGP so off on another path myself.

So far I hear options could be
1- Play with the settings on the Landowne, and see if I can give up some performance as a compromise for less or no hyper extension.
2- Change Oil viscosity making it thicker from the current 10Wt oil
3- Increase Oil Level

Other suggestions, not necessarily related to the hyper extension but good solid suspension set up, and a potential contributor to matter at hand, is proper measurement and set up of static and rider sag control to the springs in the Road Holder forks. This is typically done by adding washers under the top nut inside the fork OR cutting the spring, etc

Cheers.

SvenSven said:

So far I hear options could be
1- Play with the settings on the Landowne, and see if I can give up some performance as a compromise for less or no hyper extension.
2- Change Oil viscosity making it thicker from the current 10Wt oil
3- Increase Oil Level

Other suggestions, not necessarily related to the hyper extension but good solid suspension set up, and a potential contributor to matter at hand, is proper measurement and set up of static and rider sag control to the springs in the Road Holder forks. This is typically done by adding washers under the top nut inside the fork OR cutting the spring, etc

Cheers.

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Or new Progressive springs.

So.. the source of all of this was a broken snap clip ring at bottom of the stanchion fork tube. This allowed the lower (silver) bushing to slide off. It just sat there at the bottom of the slider minimizing travel, banging on things etc etc. yuk yuk yuk. Oh well.

Having reported this failure to some "elders" I was given the following apt title: "The most stupid Norton owner mechanic". Such is life!

As I was rebuilding I looked )Carefully) at all internals. Things were surprisingly in good shape including the fork slider tube. So, I carefully rebuilt the fork with a new clip and new oil seal and placed the bushings and all in place. I tested things and nothing was too loose or wobbly. Upon installation, on the bike the bottoming out etc were gone in static testing. I filled both sides with 150cc of clean honda red 15W oil (up from recommended 10W). Next I took her out for a few short slow rides ... it was clear things are MUCH better. N more hyper-extension. Duuh.

Back to square 1... which is ok.

A quick reminder. I'm around 180lbs and 5'11". My regular bikes are all track orientated almost pure race bikes including 2015 BMW s1000rr Premium (HP4), 1995 Aprilia RS-250 (2 smoke), etc. These have all had suspension modifications and are truly stellar systems. Clearly from a different eon and I'm very happy with them.

Bottom line, I'm used to and like my performance bikes and all that. With this in mind, I still find the Norton front continues to bounce around a tad too much, on both 10W and 15W on max Rebound setting. Maybe I'm expecting too much from a 40 year old bike even with Landsdownes. Similarly, I find the new adjustable Hagon's 2810 shocks on the rear ar on max rebound setting and still a tad bouncy. They sort of hinted at that when I bought them. I was to cheap to order the American Works Performance shocks that I know work!

Next and final option in current game is using 20W oil.. that might be too much.. but I'll report back.
I'll also try to ride another rebuild Norton with just progressive springs and different oils. Being the dumbest Norton owner, I can now comfortably do asinine things and tell all. It liberating really.

-->FJ

Make sure you are comparing apples to apples. Check out the viscosities not the claimed weight rating.

http://mahonkin.com/~milktree/motorcycles/fork-oil.html

Thanks to responses from several of you including viscosities etc. Short answer; the oils being used were checked and seem not to be the issue.

However,..... given my bike has very much of a caferace profile including a Corbin seat that pushes one backwards during riding, and super low jotta/condor type clip-ons; seems it may be partially due to a rearward weight transfer issue. Specifically, I'm sitting way back, this moves more weight on rear shock and my front end gets light. Now speed things up and go over bumps! So, it is possible a lot of my ongoing "bouncy front end issues" are more about poor weight distribution and not so much about fork rebound. I've started to test the theory by moving my weight up front and going fast as I could over moderate slightly irregular and bump roads. Indeed things were better.

Wonder why no one has started this topic..... Cafe Racers due to rear wards weight transfer of rider MUST whole chapters of suspension issues.. and solutions I hope!

More to follow... if u care of course...

-->FJ

So, The plot thickens, my mate as this notion that sat right back makes him look cool ,like the sixties racers , Infact he as the seat stuffed at the front so this forces him back . Not only does he look a right Knob,but last season whilst leaning into a bend the front end slid from under him. He reputed my remark he had transfered all the weight off the front end and lost grip.
Instead he went and bought semi race/track day rubber... :roll: I hope he knows these tires need to be hot ,other wise he will be kissing the tarmac again.

Not a Norton, but after spending a few quid on getting Ron at Maxton to do his thing on my Marzzochi/Koni's, the biggest improvement to the roadholding /handling was - at Ron's suggestion - dropping the stanchions through the yokes a couple of mm at a time. Sweet spot at around 15mm for me. (plus slightly longer spacer at the rear, increasing the effect).
The resulting forwards weight bias really plants the front tyre, much improved feel and confidence. Not fallen off since!

I realise its not so easy on Roadholders with the tapered top, but maybe there are ways round it.
Maybe some one has already tried it?

nickguzzi said:

..............I realise its not so easy on Roadholders with the tapered top, but maybe there are ways round it........Maybe some one has already tried it?

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Check the nycnorton website for their triple clamps.

Yes, many bikes with the geometry and weight distribution typical of the '60s and '70s handle better when the rider's weight is forward. When the pace picks up, I move up, almost on top of the gas tank. That increases wind resistance but it plants the front end. So . . . yes, with roadrace tank/seat combos, many roadracers of that era to get both less wind and to get front end bite, used shorter forks, or lowered the triple tree clamps relative to the forks, or, jacked up the rear with longer shocks - all to steepen the fork angle and reduce trail.

Geometry has evolved. As power levels went up, wheels/tires had to get wider, wide tires need quicker steering, rake got steeper, trail shorter, engine weight had to be moved forward, swing arms got longer/frames got shorter.

British twins generally have the luxury of a stable "Rock of Gibraltar" front end. They get that with rearward weight bias and a front end with slow stable geometry; they get away with it because of their modest power levels.

When the Big Three, in the '80s pushed power into triple digits, the rear tire couldn't handle both rear weight bias and more power, traction duties had to be shifted forward, that meant wider rear tires and fronts too; that greater tire width demanded steeper head angles and less trail.