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Lansdowne dampers not damping...

Discussion in 'Norton Commando Motorcycles (Classic)' started by Fast Eddie, Jul 8, 2018.

  1. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I seem to have lost most / all rebound damping in my forks (fitted with original Lansdowne dampers).

    I haven’t had a look-see yet, is there anything in particular I should look for? Anyone else had this? It’s a few years since I fitted them and I can’t remember ANYTHING about how they work or go together !
     
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  2. kommando

    kommando

    Joined:
    May 7, 2005
    Low oil would be first item to look at.
     
  3. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    From what I understand one leg does compression one does rebound!

    Checking oils can't be a bad idea, but unless you have seen a leak or puddle!

    .....maybe you have had the damper rod on the rebound leg undo itself?


    Or someone has adjusted it for you!
     
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  4. Craig

    Craig VIP MEMBER

    Joined:
    Dec 20, 2005
    Think I got my set from JRB back in ‘13 .... was happy with them , then this year not long ago on this forum I saw thread on settings , well once I dialed in the recommended settings , I am really pleased with them ! .... I would turn everything down to zero and then dial in suggested setting if no change .... go back to zero and pump the fork half dozen times or so , (you may have lost your prime) then dial in settings and try again .... worth a try maybe .....
    Craig
     
  5. Onder

    Onder

    Joined:
    May 11, 2010
    I have a set of original John dampers. Took them out last spring and stripped and inspected. The only thing I had trouble with that was
    obvious was that the little tiny springs in the caps were binding up. Removed a tiny amount off the outer diameter of the springs to
    make them free in the recess. The problem of binding and inability to move the little allens seems to be at least eased.
    The other problem was clunking or topping out. Today it seems to have gone away after increasing the rebound and the compression
    settings. Perhaps a red herring.
    Sometimes they work fine and sometimes not so. This may just be how I see things not how they actually are.
    And just to add, I have a set in my Trident which seem to work better. I said seem.....
    Thank you for letting me muddy the water!
     
  6. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Well, I failed to catch all of the oil to measure it (doh!) but my guess would be that quantity wasn’t the issue.

    But... the oil had the consistency of water. Maybe it’s lost it’s consitency ?

    I’ll try new oil before delving too much further into the forks.

    Symptom was quite a violent front wheel bounce around Gerard’s at Mallory (very long and fast right hander).

    I’ll be checking the front wheel hasn’t gone out of balance.

    But when I checked the feel of the forks by compressing them when stationary, there seemed to be almost no rebound damping at all.

    So, new oil and wheel balance check will be the next steps.
     
  7. Onder

    Onder

    Joined:
    May 11, 2010
    May I add that I had run what was purported to be 5 weight. Now Im running 10w I think it castrol fork oil. Suspect that since the carts are
    adjustable it may matter. Also you are, to use a technical term, "hauling ass" and the physics involved is pretty serious. On the road you might
    not notice a lot of this. Finally, Im probably about half your mass so again maybe you might be better off with 15W oil or higher. John suggested
    10W to start.
    ....and I must say may he RIP, not having him to do fork stuff is quite a loss.
     
  8. daveh

    daveh

    Joined:
    Jan 22, 2008
    Right now, these little islands are basking in a heat wave and the fork oil might be too thin. My Lansdowne dampers were quite temperature sensitive. I took mine apart once to have a look see. They are very simple. Have a look inside. If you can't find anything amiss, I suggest you try 10W in the rebound leg and report back.

    Dave
     
  9. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    So, I drained the forks and refilled with new 15 weight race spec oil, which hopefully means it’ll maintain its viscosity better.

    Previously I had used 10 weight, but it came out a dark grey 0 weight !

    I took the tops off for a look-see, and all seemed in order.

    Bounce testing them whilst stationary seemed to confirm a nicely damped feel had returned.

    The wheel was a tiny bit out of balance, not by enough to be the cause of the issue, but I corrected it anyway.

    I also found that the tyre had been gently, but persistently rubbing away at the inside of my cNw mudguard (I’m running a 100/90/19 Universal roadrider in the front). There’s not enough meat in the bracket to slot the mounting holes enough, so I think a new mudguard is on the cards. Hopefully a carbon Molnar one will fit and I can save a bit of unsprung weight too!
     
  10. daveh

    daveh

    Joined:
    Jan 22, 2008
    My mistake, I didn't read your post where you mentioned you were using 10 wt. Encouraging you have damping now!
     
  11. Onder

    Onder

    Joined:
    May 11, 2010
    As an immigrant, I have to laugh at the heat wave routine. This is SOP summertime in most of the states only it is HOTTER!
    But after such a nasty winter bikers are surely smiling as we ride in what appears to be northern Italy!
    And to keep on topic, has anyone used multi vis motor oil in the forks? Perhaps better to stay in-grade?
    Checked this morning and it is indeed Castrol synthetic 10w fork oil in the Norton right now.
     
  12. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Yes, I know folk who put multi grade engine oil in their Roadholders and swore by it.

    But I don’t know if anyone has used it with Lansdowne internals...?
     
  13. ntst8

    ntst8 VIP MEMBER

    Joined:
    Feb 14, 2004
    Wandering off topic but the cNw front guard seems to fit, and to my eye look, best with a 90/90 tyre.
     
  14. 850commando

    850commando

    Joined:
    Nov 1, 2014
    carbon molnar fender/mud guard from whom do you get it?
     
  15. CanukNortonNut

    CanukNortonNut

    Joined:
    Aug 8, 2005
    My correspondence with John
    (RIP), as follows:
    14. Fill with 150 ml of S.A.E 10 grade fork fluid in each leg.
    15. Fit the alloy needle top nuts to the damper rods and screw home into
    the stanchion. Ensure the stamped ‘R’ is fitted to the right leg and the
    stamped ‘C’ to the left leg.
    16. Reassemble all parts as per normal Norton practice. Check all
    fastenings are secure.
    17. Now Prime the Damper Cartridge. On both alloy top nuts turn the screw
    in the center of the fork top nut inwards (clockwise) until they stop. DO
    NOT USE EXCESSIVE FORCE. Now turn the screw out (anti
    clockwise) three full turns. Do this on both legs. At this setting no
    compression or rebound damping will be felt. Now sitting on the bike
    ‘pump’ the forks up and down 6 or 7 times. This has now primed the
    Damper cartridges.
    18. We now need to set the Dampers for initial riding. Turn the adjustment
    screw a quarter of a turn a time. Screw in the rebound side ‘R’ until the
    forks begin to respond with a smooth rebound resistance, and then
    adjust the compression side ‘C’ until the forks extend smoothly.
    REMEMBER only small adjustments are required to produce a big
    difference.
    19. Final adjustment is via road test. REMEMBER only small adjustments
    are required to produce a big difference. As a guide the range is
    normally between ½ - 2 turns out from full in. Actual settings are very
    much dependent on rider weight, riding style and use. Avoid too much
    compression adjustment as this can cause small road bumps to ‘Jolt’
    the front end. Better to start with lighter settings and gradually increase
    the resistance. A few hours riding and experimenting will produce a
    smooth, compliant feel and a better response to hard braking.
    20. Once you have set your dampers for example single road riding you
    can easily set them to be just as compliant when riding with a pillion or
    track setting. Remember once you have a setting for a style you can
    quickly return to that set up by adjusting the screw to that previous
    setting.
    21. We recommend that you change your fork oil every 12 months.
    Version 10 12 01
    as per his instructions.
    Cheers,
    Thomas
     
  16. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    First of all, you should be changing your fork oil annually. Secondly, I run 10 weight with no problems, even though I am a fat bastard in the classic sense. They take a lot of setting up, but in the end it is worth it. Beautiful fork action. Thirdly, having gone through the maddening exercise of finding a front guard to accommodate a 100/90 tyre, I find the proddy racer front guard to be an excellent period fitting. Matt even states somewhere that his front guard is not suitable for 100/90 front tyres. I think they are a Hardly Dangerous Sportster item. Bro.
     
  17. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
  18. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    The wheel and tyre spin beautifully when on the centre stand. Rubbing can only be due to tyre growth at speed I suspect. Lesson learnt: allow more space for tyre growth!

    I don’t know why the fork oil lost viscosity, I do confess I did not change it annually, but my mileage is pathetically low, so this really shouldn’t be a reason. Fork oil is one of those things I don’t tend to put much thought into, I tend to buy whatever is on the shelf when I need it. Perhaps I used cheapo no brand stuff that just wasn’t very good? Second lesson learnt: use good brand fork oil and keep a note of what, and when, its used!

    On the bright side, the rubbing must have been causing quite some drag. So sorting this out should yield a small performance boost...

    And the carbon mudguard will reduce unsprung weight too...

    So at least I’ve kept to my personal philosophy of always putting it back together (slightly) better than it was before!
     
    Last edited: Jul 10, 2018
  19. robs ss

    robs ss VIP MEMBER

    Joined:
    Aug 16, 2016
    Thanks Thomas - good to have.
    Thanks for sharing.
    Cheers
    Rob
     
  20. Onder

    Onder

    Joined:
    May 11, 2010
    This has already been mentioned on the list but changing the fork oil is very important when you have the spring inside v. outside.
    Even with low annual mileage you can get water along with metallic sediment build up. At least with Commando forks you can change out
    the bushes but despite the bother removing and completely cleaning the sliders is a good idea.
     
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