Front suspension
From Owner's Document
All items are generally accepted for all Husaberg models.
Also check out Handling and Suspension on UHE.
Fork Manuals
- WP 4357 MX Multi Adjuster 2000 Front Fork Manual for 2000 and later
Your 43mm right way ups!
- WP Extreme Fork Manual
More right way ups!
- WP MXMA Fork Owner's Manual
Todays upside downers!
Forks
Please read the parts manual for updates, read the fork manuals for how best to tackle the job. The owners manual tells you how to set the sag. All the information, unless stated is for Enduro, Green laning, Trail riding. A big thank you goes out to the lads at K-talk who gave their time, info and photos freely. Supertrunk did a great job of his photos i think you'll agree! (they are the clear ones!)
Front suspension chart of why!
Check out the Front suspension setup guide.
This chart is good for all models: Spring Advise List.
The air gap (marked as 110) is definately wrong!
Here is a spring rate calculator if you have no idea of the 'weight' of them.
Ride height
Read the manual for this but the following notes are pertinent:
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Sag for pre '02s is 85-100mm as per the manual. The Sag for bikes post '02 is stated as around 90-105mm.
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Forks - why not mix an old and new spring to see if it isn't a better combo? Label them clearly though! so a .44 and a .46 = a .45 - it's simple!
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Instead of getting yer togs on for the ride height check, chuck an old MX tyre over your shoulder 'Pancho Villa' style.
Balance
One thing the manual doesn't tell you is the term 'balance'. This subject should only apply to those that aren't the perfect weight for Mr Husaberg! Imagine two machines: a chopper and a speedway bike, it's hard to imagine bikes with two more different head (or fork) angles. The speedway bike is ALWAYS unstable, the chopper - unflappable! Most machines live close to this flappable point (ask a Katoom rider that one!) and so at any time the front dips, the steering head steepens, and the steering becomes unstable. Typical plces are: under braking, down a hill, over heavy chop. But if you feel the bike doesn't turn well - then it could be you have a 'kicked-out' front end.
The best way to tell what you prefer is to do either of the following: lift or lower the forks in the clamps OR change the front or rear preload. Changing the preload IS changing the suspension but try and think of the steering and handling first?
Husabergs are essentially so stable that 99% of testing can be done to steepen the front end up for quicker low speed handling.
The clickers!
As you're aware, the top adjuster is for rebound and the bottom one (under the leg) is for compression. Essentially, when the oil moves through the shimstacks it is also moving through a bleed hole. This is duplicitious behaviour! So you are in charge of how big that 'bleed-off' is. When adjusting the clickers, remember that it's a guide to how the shimstacks are. So if we go to extremes with the clickers, a change in the shimstack is called for. When all is finally 'right' we should be working in the middle area of the 30 clicks. Around 10 to 18 clicks would be right.
We ALWAYS measure the clicks by screwing the adjusters right in to a stop and then counting them off as we 'unscrew' the adjuster out. If you can imagine a hole being gradually uncovered, you'll appreciate that at the beginning we're revealing very little of the hole and therefore, as a rule, the first 8 and last 8 clicks do very little to change things. The calamity is going past 6 or 8 clicks from the 'norm' and NOT the fact that we carry on for another 8!
Terminology
Before working on the internals of your forks you need to understand what's happening in there. Try gleaning information from old UHE and K-talk threads and get the jargon right. Only KTM and Husaberg use White Power so here is some help:
KTMtalk.com suspension
UHE suspension
A run through your forks
Here are a few photos to help guide you through the fork leg:
You have two sets of shim stacks. The first set are screwed in the bottom of the fork leg and are static, this is the 'base valve'. The other set sit on the cartridge rod which is connected to the fork cap. That means that although they don't move, the lower fork leg does so it still effectively moves in and out the fork cartridge. The photo and the diagrams in cutaway below show the compression 'stack', also known as your base valve (BV).
Find it above in the fourth photo at the bottom of the fork leg.
Below are three diagrams of the 'midvalve' also known as the 'check-plate', they sit on the 'rebound tap'.
You get a very good idea of what is meant by 'the float' from these.
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| This exploded view shows the BV: tap and shims set out in order with the nut on the top right (then note the tiny float spring) then the first shim which is actually a thick metal washer called the 'check plate', then a piston, then many large 24mm shims before (in the lower row) the shims then get smaller, finishing with the dark and small 9mm@.3 thick shim. The piston cross section looks like a neuclear logo and can be best seen two photos down. |
Elsewhere, the long cartridge rod has two 'stacks' on the end of it each side of a piston in the middle, the shims you can flick on the top side are part of the check plate/check valve/mid-valve (CV/MV). It has many names and we'll explain them as we go!
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| By exploding the left photo you can just see some 'shiny' shims above the port hole of the piston. These are forced back by the oil as it rushes through from right to left as you view it. The distance the shims move here is called 'the float'. They stop moving when they hit the rim on the large nut. The small drill hole is your rebound bleed, you control this from the top of the fork leg. Below the piston, towards the nut on the right, is the rebound shim stack (unseen here). |
There's a 22mm (later became 34mm on later forks) spring on the cartridge rod known as the 'top out spring' (a photo above shows an enormous 75mm Terry Hay T-O spring) for when you are in mid-air and the forks want to fall apart! They cushion the bang!
When hitting a bump, the cartridge rod assembly goes down into the oil. The fork oil is either forced down through the BV or up through the 'check-plate/MV' but it goes through the check-plate three times as quickly. When the forks rebound the CP lets the oil back down through, then through the piston and then past the rebound stack.
Because the MV/CP moves three times the oil that the BV does, recently, the CP has found favour as another form of compression stack thus the change in term from 'check plate' to 'mid valve'. Check plate really means a solid item that simply floats to allow oil through without bowing over when hit really hard! Setting the MV as well as the BV is harder because that makes two sets of valving you're working on when setting the compression. A typical check plate will have 4 x 24mm shims and no flex whilst a MV will have a pyramid from 24 down to 10mm.
The rebound stack has 4 triangular shims called 'delta shims' on it next to the piston then the rest of the shims and the nut. Both the BV and MV/rebound shim stacks sit on posts known as 'taps'.
The fork spring surrounds a black plastic unit called the 'spring guide' that keeps the spring central. The guide dives into a 36mm deep cup called the 'bottoming cone' that helps resist bottoming as the guide blocks some oil/air off and creates a small compressed bubble.
We call the inner/chrome leg-the 'lower leg' and the bit we clamp in the triple clamps is the 'upper leg'.
Here are all the strange shim names
There is a really narrow but fat shim that's fitted at the bottom (say 9.5mm x .3 thick) called the 'clamping' shim. This shim is normally near a 10/11mm but if it's near a 14mm the name for it is now a 'pivot shim'. If a small thin shim then a large shim are near a piston: it's 'transition' or 'crossover' shim. If say a 14 divides two 24s it is a 'splitting' shim. If a thick (often 18@.25mm) shim is next to the nut it's a 'stopper' (as in 'stop' the others bending too far!). Shims are normally stacked like a pyramid, however, they can have a 'splitter' to aid flex in the larger shims and allowing them to bow and flex. It appears that flex is good but alas too much and the shims crack. However, the mid valve shim is unique from the others in that the shims sit on a shoulder and can literally 'float' 1-2mm AND then ('03+ :read just below) bend backwards on the tap centre's shoulder! These shim stacks therefore need supporting carefully by using 4+ shims or stepping them.
Updated Forks
The '03 model got the big axle pin-that's visible-but it also got new rebound and compression taps, also both sets of needles for these (that's 4 parts. Listed in the parts book). However, the only truly significant change was the rebound tap (which holds the MV shims, then the piston and finally the rebound shims and nut) which had the shoulder around the top machined away so that the MV shims can now bend and 'arch their backs'. The photo of the later '03+ tap on the right (below), shows the shoulder of the tap just above the line of the hexagonal nut, on the pre '03 the hexagonal nut had a rim all the way around that was level with the shoulder in the middle. A shim therefore just floated but never bowed as it had support on the inside and outside shoulder. ZP3's super modified tap is on the left which we discuss later.
'02 and '05-'06 have 2 fork bushes whilst the '03-'04 have 3 bushes. '02,'03,'04, have same upper fork tube but '05-'06 have a different taper on upper fork tube for more even flex under load but I have a hard time feeling the smoother action. '02,'03 have the same rigid mid valve while the '04-'06 have a flexible mid valve. '02-'03 have a softer mid valve float spring '04-'05 have a stiffer spring. "I like a softer spring, which is gentle over loose rocks. There have been different mid valve gaps-don't remember what year-but 1.5mm is what you want. The '06 bottom valve stack may not work on an '02 fork since the '06 has different mid valve"(Viking). The conflicting view is that the float gap should be .9 - 1.1mm if using less shims in the stack. Each year the internal shim stacks are updated by Husaberg so you could play 'dead safe' and ask for the latest OEM stack to try.
Carrying out suspension work
It is best to start by changing the oil and measuring it's level. Try the preload and maybe spring changes are next. Next would be to simply service the forks using the manual. Whilst the forks are down everything should be measured and checked to gain understanding and data. You may now reflect upon ride height, oil level, spring strength, riding area and skill before making your first charge into the forks to make changes.
What to look for when servicing
The plastic spacers pictured behind the leg (below) are the paking/preload spacers.
- Clean under the dust caps and regrease or even oil soak some sponge.
- Watch that the steel washers under the seals are flat. If not, flatten or renew and be careful next time you pull apart the forks! (Viking).
- Look for chips in the chrome leg or bubbles. Use a sharpening stone to flatten. Clean out, a blob of paint and then later, scrape gently with a safety razor blade.
- Check the bushes, they look worn quickly but aren't. The narrower bush takes more stick than the broad one.
- When removing the shims make a note of how they came off, lay them in order, write it down.
- Forget how they go back together? -then pull the other leg apart as well and copy immediately!
- The bushes and the piston rings may contain allos chips, use scotchbrite and jizer to remove.
- Put MV shims on a vernier and check for hollowing. If you use them again, turn them around.
- Check condition of shims looking for bending and cracking. If you know they haven't been serviced for a year you should consider all new shims but especially those in the MV.
- Only tighten the tap nuts to the correct torque and thread lock any nuts.
Tools required
Aluminium jaw plates for the vice or thick box cardboard will do. Loctite and a de-gunk bath are good. Then make a squeezy bottle with a tube on it for measuring the oil level. You can chop an old fork seal up, sit it over the new one and hammer it to get the new seals in.
Servicing notes
- It's a good tip to lightly undo the fork cap and the compression stack (under the legs) whilst in the bike with the wheel in etc. Also if struggling to tighten right up. Re-fit to machine and then compress front end (get a mate to help lean on the front or use your bike straps) to tighten.
- When replacing the fork cap turn the rebound CCW all the way. Otherwise as the cap screws on it can unwind completely the rebound spring/ball mechanism. When tight on the cartridge rod and everything then put together, turn the rebound CW to the bottom. Now turn out the appropriate amount of clicks.
- Don't panic that the BV unit can't be tightened in the leg: screw in as much as possible, pull the cartridge rod over to one side and continue to tighten. If this fails, re-fit forks to bike, fit everything else and drop onto the wheels. Now compress the forks and tighten. By the way you should only pinch up the right fork leg to the spindle AFTER you have pushed the forks down a few times. Better still, prise open the right leg clamp and then when forks are compressed-tighten.
- Check that the rebound rod (small alloy tube sticking slightly out of the top of the cartridge rod) can be pressed down flush using your thumb before fitting the fork cap. The middle picture below is wrong, the right: is correct because although not flush, the rod is on the needle and will press flush.
Air in forks
Bleed the Phillips screws immediately after a ride. Raise the bike and wheel clear of ground first. The air in the forks has a cushioning effect so do this after your ride!
Fork Oil
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Oil height
Forks do have a progressive rate of resistance, it's called 'air!'. The further we compress the forks, the more the air squeezes up and resists. We set the amount of fork oil to allow the forks to use maximum travel and no more because too little oil not only allows the fork to bottom easily but also may not cover the upper piston at times. Too much oil 'locks' the fork early in it's travel.
To 'set the air gap' you need to remove the fork cap and then the spring. Place the fork in a vice and allow the cartridge rod and outter leg to drop down until the dust cap rests on the axle casting. Using a syringe with a piece of pipe (or see the squeezy bottle photo!) connected of some 250mm size or so: place a long rod along it's side to keep it straight and zip-tie the two together.
With a clothes peg, measure along from the 'mouth' of the pipe the decided measurement you are aiming for: say 120mm and place the clothes peg here. Drop the pipe into the side of the cartridge rod. If it binds - pull the cartridge rod gently to the side and allow the pipe to fall and the clothes peg to rest on the outer leg (the outer WILL be the higher). Now pull the syringe. If you get bubbles, start again with a drop more oil and then 'suck'. You should re-measure the peg to pipe end distance and if satisfied you have now set the 'oil level' or the 'air gap' as it's called!
Problem solving
If you lose the clickers in the rebound it means that you have over turned the rebound adjuster clockwise whilst off the cartridge rod. Look inside the cap, the black pin is protruding, so turn the black pin back out-CCW. Re-screw the unit on top of the cartridge rod and NOW screw the rebound back down to a stop. It may be necessary to pop the black adjuster knob off. Do this inside a transparant bag as the two ball bearings are just 2mm in size!
The correct order of rebuild is: have the rebound screwed CCW completely, then fit the cap onto the cartridge rod and screw up the guide nut to the cap and tighten. Now adjust the rebound down (can use a philips screwdriver) until it's locked and then come back the correct amount of clicks. Re-fit the plastic adjustment cap.
Checking Preload
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| To do this you should build the rod, spring, spring cap and cartridge on the bench with no packing. Now measure the gap twixt spring and the underside of the cap. The ideal spring isn't slack but has between zero and 6mm preload. The left photo shows a 9mm gap between the end of the spring and the underside of the cap. So 10mm of packing will net just 1mm of preload. Remember, there's a difference between preload and packing! |
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Details to remember
- Always try to get full travel from the forks-to check, simply put a zip tie around the lower leg and check where it is after a good ride! Husabergs NEVER use the last 5mm due to the dimensions of the chrome tubes.
- The steering head angle was steepened by 1.5 degrees in 2003 however, weighing has confirmed that the balance is similar at 49% front and 51% back (51.8% to 48.2% for the old model).
- Remember that if you go to heavier springs as a rule: the compression will need softening slightly if at all whilst the rebound will need stiffening.
- The top out springs are tapered and must only fit the cartridge rod one-way.
- The clickers should end up as per the book if you're in the ball park. Use them as your 'Northern Star'.
- Bikes can sink and not rise quickly enough before hitting another bump. If they don't rebound quickly enough and get lower and lower it's called 'packing' or 'packing down'.
- Bikes can also change their attitude (pitch) due to the valving changes.
Basic set up
We can set the following right before we modify our forks: Fork oil weight-stick to SAE 5 and especially when testing as this is part of your baseline and will be destroyed by a late change to 2.5W for instance. Check your weight against the chart for the correct spring rate. Remember that we want little (around 6mm is considered the sweet spot) preload if we can help it and that packing and preload are two different things! If a new pair of heavier fork springs feel 'hard', then swop one new for one old and code them etc. Set the sag correctly. Next use your oil height in the fork to adjust the slow down of the fork at the end of it's travel both ways. We should very occasionally 'bottom out' that's all! The pre '02s are fitted with the softer MV 'float spring'. It's just a baby spring but it helps stop the suspension spiking on fast bumps.
Preload
This is the plastic spacer we put on top of a spring. There is a natural gap between the spring and the underside of the cap so you can rebuild a cartridge rod, spring and cap without the preload spacers to work out the gap. On my forks it's 9mm so i always write "15/6" meaning 15mm packing but 6mm preload. No preload up to about 6mm is the choice of champions.
In direct testing we have to look for two things: ride height and performance. If running no preload a front end may droop and so on hitting bumps riding downhill or under braking the front will weave. If we have too much preload the ride is harsh without even being hard, you'll just get battered and at corners the front won't 'dip' so that the bike is difficult to turn.
Spring Rate
This is really hard to help you with, it depends on your weight, speed and ability, terrain, riding style. However, on a series of bumps soft springs will ride in the bumps whilst a harder spring will 'flit' over the top. As nowadays more people are aware of what's needed, you may want to borrow some springs to test.
Back to Front
A good test of the balance of your machine is to take off from a flat jump and see how both ends 'pancake'. They should sink and rise together. This is another good indicator as to whether you're getting it right!
Simple things you can do for better performance
Some ideas that should always work:
1. Polish up the cartridge rod, springs and the inside of the cartridge.
2. Machine polish the lower leg for better finish-careful!
3. Purchase Race-Tech Gold Valves or similar (see below left). The 'Nost SS' basevalve (see below right) is like a re-valve with just the turn of a screwdriver. There is a bottom valve that you adjust 4-ways externally high speed, mid speed, low speed and supplenes (Viking).
4. Update internals (see above) especially machining the rebound taps.
5. Terry Hay's top out springs said to help the racer (70mm long).
6. Drill a 2 x 5mm holes (direction: across the bike) 18cm up the inner leg to halt air bilging.
7. Drill 2 x 2mm holes in the bottoming cones. One down 20mm the other down 40mm and around 180d apart.
8. Try fitting some oilly sponge under the dust seals.
9. Get the suspension right and THEN fit 'sub tanks'.
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| Enzo's subtanks | Valve on fork caps | Enzo's Caps |
Above are three photos. Left, are the Subtanks with plumbing to the top of the forks. Note the bleed off underneath, in truth though they are totally unnecassary as the oil doesn't follow the air out. Middle, are the small valves that release and re-introduce the air to the fork. They swivel and even have an air valve on them to regress progress of air, right, are the caps with small recesses machined to allow air to get past the packing/spacers.
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Base valve check plate nuts drilled to help the weak conical spring shut the check valve faster. And to open full wide faster by reducing oil cushioning in nut head. Drilled Ø2.5 mm. (Smorgasbord) |
More advanced suspension tuning
This can be all things to all men, however, here are some of the areas that help you to understand what you're doing if you decide to tamper with your own machine. Firstly the above "simple things ..." need more detailing so do a search on UHE/K-talk suspension sections. Remember that these are free mods in that they may reduce friction, add variability or react faster and are thus all gain and no loss but you may need a 'knock-on' adjustment however.
Ideas gleaned about shim stack changes
The BV (compression) (see below left) can lose two 24mm shims and a 22mm for sure. Next, a splitter can be put between the five 24s so: 24, 24, 14, 24, 24. This will mostly help low speed/small. The smaller shims are for HS damping (16 to 10) and you're softening the high speed/big bumps.
The MV (compression) (see below middle) starts with 5 x 24s and two should be your minimum. Less than this though and one would break perhaps. So a tapered stack is tried here: 4 x 24 becomes maybe 2 x 24, 22, 20, 18, 16, 14. The mid stack is said to aid the medium bumps (thus: mid!) whilst the BV does all. Playing with both at once though is said to be a skill! Some keep the thickset original CP set-up and only play with the BV initially so as to feel what it's all doing!
Standard float gap is 1.4mm (.056") so fine spacers need to be made if adjusting. The KTMs are running 0.8-1.1mm float gaps. To do this you need to machine down the 8mm step so as to make the float to small, then with special 6mm ID/8mm OD washers you can push the gap back out.
The rebound stack (see above second right) is kept essentially how it is. But again playing with removing from the large or small end will affect which part of the return stroke you want.
The general rule with the compression stacks is that shims get removed and at best a crossover is added, the rebound comes through pretty much as is. Sometimes the damping is s-o-o-o-o soft that it can feel hard. However this isn't normally a complaint with WP equiped bikes!
Remember that the rebound stack is working in duplicity with the rebound needle and rod. This is what you adjust at the top of the fork leg (cutaway diagram at top of page).
Some stacks to try
This can only ever be a guide. Unfortunately UHE doesn't have a big reputation for suspension 'geeks' so we are searching in the dark here. Many of these settings come from K-talkers and may have had other modifications prior to shim stack changes that we don't know of. Also check out:
So here goes:
Base Valve
- 24, 16, 24, 24, 22, 20, 18, 15, 13, 11, 9@.3
or you can try
- 24, 24, 16, 24, 19, 17, 15, 14, 13, 12, 11, 9@.3
Mid Valve
- 24, 24, 21, 20, 18, 16, 14, 9@.3, 18@.25
or you can try
- 24, 24, 18, 14, 11, 22@.25 with only 1.0mm float gap.
Rebound Valve
- 24d, 24d, 24d, 16, 24d, 22, 20, 18, 17, 14, 12, 10@.2 (x2)
or you can try
- 24d, 24d, 24d, 14, 22, 20, 17, 14, 12, 10@.2 (x2)
(the 24s are delta shims)
Record the Information
Taff's set up as of April 30th 2006: Hard ground, soft in woods, bike gripped well and handled very well. Cornering and 'dip' are now excellent.
FE400e (without electric start etc) weighs 246 pounds dry. Rider weighs 205 pounds plus gear. Forks .46 springs, 5W oil, 140mm air gap, 15/6 packing, Sag figures are: 33mm and 65mm. Comp out 15, rebound out 12, unused from the weekend = 33mm (5mm is unusable so it's actually 28mm unused), float =1.5mm. BV: 24, 18, 24, 24, 24, 22, 19, 15, 13, 11, 9@.3 MV: 23, 23, 13, 20, 15, 10mm ZP3-type tap post (see photo above) soft springs Rebound: 24d, 24d, 24d, 24d, 15, 20, 18, 16, 14, 12, 11, 10@.2, 10@.2, 16@.25
Set up on 1st August '06: Since the above more testing has been carried out. Fitted .48s which many deem too heavy but with a softer valving set-up they have been great! 2mm preload and an air gap of 120mm for full fork travel but no bottoming. The float has been reduced from 1.5mm to 1.1mm. Base valving is changed in under 30 minutes and stands at: 24, 16, 24, 22, 20, 18, 15, 11, 9@.3 whilst the MV is now a radical 23, 22, 20, 18, 16, 14 and all sits on a 10mm post around the tap as per ZP3's tap in the above photo. Rebound has now been beefed up with 24d x 4, 15, 20, 19, 18, 16, 14, 12, 11, 10@.2, 10@.2, 16@.25.
Handy tools
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| Keep your shims in one of these photo bags |
Rebound Adjuster Screwdriver (Viking) |
Supermoto spring preload
Spanner found the springs on his FS650 were already under 30mm of preload
