Z900

Please login or register.

News: A big welcome to all new members !



Author [ES] [MY] [PL] [PT] [IT] [DE] [FR] [NL] [DK] [NO] [GR] [TR] Topic: Fully adjustable Wilbers shock.  (Read 1966 times)

0 Members and 1 Guest are viewing this topic.

Online JohnCW

  • Z900 Pro
  • ***
  • Posts: 245
  • Town / City: Sydney
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #30 on: July 19, 2019, 12:41:02 AM »
*Originally Posted by RobZ900 [+]
No worries, itís all useful information. Personally, Iíve never upgraded the suspension on any bike before, so Iíve got zero experience of it, so this is all a learning curve for me. I understand sag, static sag, and rebound and I know what compression is, but still figuring out low and high speed comp. Obviously low speed is for small bumps etc. and high speed is for things like pot holes when you hit them harder/faster, Iím just figuring out how to set them all. I know how to measure and set sag and fork rebound. As for rebound on the shock, it seems a bit harder to judge what should be about right. Then compression is a different animal all together. Seems to me that thereís no real science to it, rather setting a starting point and then adjusting to suit, all by feel, which would be a very personal thing.

All I know right now is that my suspension isnít up to the job for someone my size. At 6í 6Ē and 116 kgs/255lbs, I donít think Kawasaki had someone like me in mind when they fitted the suspension lol.

The methodology I use to set damping has progressed from originally a pretty much 'trial and error' method to one that sort of make technical sense (at least to me).  The problem with a triple clicker is which dial to adjust???? 

As rebound is the most important and also affects compression it needs to be set pretty close to correct first.  So what I do is initially back both low and high compression damping way out to largely eliminate them from the equation so as to focus on the most important rebound damping.

While the 'bounce test' may serve as a starting point for setting rebound, that about all its good for.   A slow rebound may initially feel good as it makes a bike feel really stable in a straight line, BUT that comes at the cost of being harder to turn.  It takes more muscle to push a bike into a corner when rebound is excessively slow.  Think of it as the suspension having 'arthritis' in the suspension, resisting the small movements that allow the bike to float into the corner.  What I'm looking for is the slowest rebound setting that doesn't affect cornering effort.  I'll increase or decrease rebound speed till I find that point.  If loosing it makes the bike turn easier, I'll keep coming out one click at a time till it doesn't make a difference.  That's my rebound setting.  That will generally be a quite quick rebound.

Next I take slow speed compression up till I get exactly the same result.  Excessive slow speed compression just like excessive rebound will make the bike feel real stable in a straight line, at the cost of turning effort for exactly the same reasons.   So I increase it one click at a time till I find that point where again greater effort is required to make the bike turn, then back it off one turn.  Slow speed damping basically set.

Then finally high speed damping.  On the road I reckon that's the easiest one.  Just increase/decrease to find the point that the 'bang' (technical term) when you hit a big square edged pothole is tolerable.   For the track this setting can be tightened up as there won't be those potholes.   

Record the above settings, and from there experimentation a bit if you want, you can always go back.  Just remember when counting clicks to always count 'zero' as the first click out from fully seated to return to your original setting.  If you count say 9 clicks in till fully seated, and then 9 clicks out using 1 as the first click out you will end up at a different setting (one less) to what you started.   Try it with pencil marks on a piece of paper to see why.

Online JohnCW

  • Z900 Pro
  • ***
  • Posts: 245
  • Town / City: Sydney
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #31 on: July 19, 2019, 01:56:30 AM »
No one should feel inadequate (can't think of a better word) struggling to understand how to set damping.  While there are literally thousands of articles written on the subject, I've never found one that was really helpful.

They'll spend 99% of the time explaining what each function does, and then virtually skip the very bit you really want to know, how to best adjust em.

The closest to helpful I've seen regarding setting rebound is with excessively slow rebound 'the bike will want to run wide in corners'.  In practice I've found that to be true, but it's much more than that.  Even to tip the bike into the corner takes more effort, running wide is just a part of this greater effort to turn.

The most common 'problem' I see in articles regarding excessive rebound is the suspension will 'pack' down.  Honestly if the rebound is so slow that the suspension packs down it became a real dog to turn well before it got that slow.

"Less is More" is one of the most helpful saying when setting damping.

Online JohnCW

  • Z900 Pro
  • ***
  • Posts: 245
  • Town / City: Sydney
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #32 on: July 21, 2019, 11:30:56 AM »
*Originally Posted by KellyL [+]
There's pretty bad small bump compliance, but acceptable high speed (square edge bumps etc). Harsh at low speed, but handling improves at higher speed. Promecha also modded the fork spring rate by slicing off some of the tighter coils (i.e. the 'softer' bit)

Just occurred to me.   What you written above may be your problem.  The very reason for running a dual rate front spring is a 'quick and dirty' way to give a plush ride over small road imperfections.  That's the very reason for the soft 'bit'.  If you slice off a chunk of this section, what's left of the soft section is probably fully compressed supporting just you and the bike.  So every bump in the road you are hitting is likely being taken on the heavy spring rate section.

I once asked Wilbers what the two spring rates were in their dual rate springs (commonly incorrectly marketed as progressive springs).  Now I can't remember the exact numbers but it was something like 0.70 Kg/mm and 1.20Kg/mm.   Probably typical of many manufacturers.  Stick a set of 1.20 Kg/mm linear springs in a 220ish Kg bike with a rider of normal weight, and it'll rattle the filling out of your teeth on less that billiard table smooth roads.

Offline KellyL

  • Z900 Member
  • **
  • Posts: 81
  • Bike: Z900, W800, RS250
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #33 on: July 21, 2019, 12:27:04 PM »
*Originally Posted by JohnCW [+]
Just occurred to me... So every bump in the road you are hitting is likely being taken on the heavy spring rate section.
Thanks. Yes the Ikon fork springs are dual rate, and the actual rates are nowhere to be found. I had considered your idea as a possible explanation a year ago, and tried running the bike with only 5mm installed preload (basically cut the spacer tube to nothing) so that the low rate bit was active. There was no additional plushness; all that happened was my sag went to 50% travel and the handling got quite twitchy.

I suspect the harsh low speed ride has something to do with the 20W oil and the emulator design. The little bumps are probably not generating enough force to move the thick oil through the bleed area around the shims, but big whacks will be enough to distort the shims and open up the orifice. So basically extreme digressive damping, AKA a blow off valve! If this hypothesis is correct then the solution would be what you suggested earlier, i.e. lower weight fork oil and shrinking the rebound bleed hole. Tossing the Ikons for some 0.9 linears would also simplify the problem solving.
« Last Edit: July 21, 2019, 12:33:15 PM by KellyL »

Online JohnCW

  • Z900 Pro
  • ***
  • Posts: 245
  • Town / City: Sydney
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #34 on: July 21, 2019, 11:00:10 PM »
*Originally Posted by KellyL [+]
tried running the bike with only 5mm installed preload (basically cut the spacer tube to nothing) so that the low rate bit was active. There was no additional plushness; all that happened was my sag went to 50% travel and the handling got quite twitchy.

I suspect the harsh low speed ride has something to do with the 20W oil and the emulator design.

Just be aware that contrary to popular internet belief, dual rate or even true progressive springs don't behave any different to linear springs when it comes to preload.  Changing preload won't alter the amount of soft section spring compressed (other than when the forks are fully extended).  No matter the amount of preload the soft section will compress down till the spring's upward force is equal to the weight it has to support, beings the fronts share of bike and rider weight.   As this weight doesn't change, the spring will always compress to the exact same final length, no matter the initial preload.  All that will be different is the ride height.

You're probably right on the heavy fork oil weight (to set rebound) and the emulator design.  That's the very reason I contact him once to try and understand.  There have been a number of products around over the years that claim they are simple drop in solutions.  No need to pull the forks apart and eliminate the damper rod's original compression damping holes, just run very light oil with no regard for its effect on rebound etc.  Total 'snake-oil' stuff.

Offline KellyL

  • Z900 Member
  • **
  • Posts: 81
  • Bike: Z900, W800, RS250
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #35 on: July 21, 2019, 11:50:00 PM »
*Originally Posted by JohnCW [+]
the spring will always compress to the exact same final length, no matter the initial preload.  All that will be different is the ride height.
A great explanation. I'm never too old to learn new things!

Offline RobZ900

  • Z900 God
  • *****
  • Topic Author (OP)
  • Posts: 1418
  • Bike: Z900
  • Town / City: Wiltshire
  • Country: gb
Re: Fully adjustable Wilbers shock.
« Reply #36 on: August 10, 2019, 10:10:35 PM »
Gone and done it. Pulled the trigger and ordered it in the nightline colour combo. Also added the height adjustment. As far as I can see, with the height adjuster added, this is on par with the Nitron R3 shock but for about £130 cheaper. Now just got a long 2 week wait til it arrives before figuring out how the bloody hell I'm going to support the bike while swapping out the shock. Also, I read that you should replace the mounting bolts/nuts every time the shock is removed. Anybody else heard about this?
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Offline KellyL

  • Z900 Member
  • **
  • Posts: 81
  • Bike: Z900, W800, RS250
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #37 on: August 10, 2019, 11:48:35 PM »
*Originally Posted by RobZ900 [+]
I read that you should replace the mounting bolts/nuts every time the shock is removed. Anybody else heard about this?


Offline RobZ900

  • Z900 God
  • *****
  • Topic Author (OP)
  • Posts: 1418
  • Bike: Z900
  • Town / City: Wiltshire
  • Country: gb
Re: Fully adjustable Wilbers shock.
« Reply #38 on: August 11, 2019, 12:31:48 AM »
Ah ok, so just the nuts then, donít need to worry about the bolts. Was thinking Iíd have to replace all the mounting hardware. I wonder why you have to replace the nuts but not the rest?
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Online JohnCW

  • Z900 Pro
  • ***
  • Posts: 245
  • Town / City: Sydney
  • Country: au
Re: Fully adjustable Wilbers shock.
« Reply #39 on: August 11, 2019, 04:47:23 AM »
*Originally Posted by RobZ900 [+]
Ah ok, so just the nuts then, donít need to worry about the bolts. Was thinking Iíd have to replace all the mounting hardware. I wonder why you have to replace the nuts but not the rest?

If the only reason for replacing the nuts is because they are self-locking, a quite acceptable option would be to stick a little 'blue' Locktite (243) on the threads and reuse the old nuts.  Don't use the 'red' stuff (263) as you may never get them undone again, well not easily.

You made the right decision getting the length adjustment option.  Might not want to use it at the moment but possibly in the future, and its not viable to retrofit later.