Husaberg Motorcycle Rear Suspension

This information is generally accepted for all Husaberg motorcycles. And make sure you check out the dedicated Husaberg Suspension and Handling forum.

Rear Shock Absorber Service Manuals

Rear Suspension Charts

Rear Suspension

About the Rear Shock

It’s very difficult to meddle with the rear shock bar the clickers, spring and preload. The shock needs re-gassing after any work and unlike Japanese units, they have to be done with a special tool so unless you want to go to a bladder, the shock needs charging by a WP Suspension specialist. The bladder is considered of equal performance by many to a re-nitrogen-charged standard unit. Fitting a shrader valve could possibly lead to the chain ripping it out of the reservoir body on G-outs unless it’s VERY short!

The code is written on the Spring around it’s middle. The 250mm long springs are easy to swap in and out but the 265’s are very awkward and need compressing just to uncouple the end cup.

Lightly tighten the preload ring as it can squeeze an internal piston creating wear. Tighten the pinch screw with it facing you so that an allen key can loosen it for making adjustments. It’s possible to measure the spring preload in the bike with a tape measure, just get the paddock stand under the belly and the rear wheel free of the ground. This is also the best way to adjust the preload; with the swingarm/wheel dangling off the back of the paddock stand, it should be easy to turn the spring with preload ring all by hand. Each turn of the ring is worth 2mm + – preload.

Setting Sag and Ride Height

2001 and 2002’s have a race sag of between 85-100mm and a sag of 30-35mm. The 2003’s+ need 90-105mm. Best place to measure is from the top of the spindle nut to the ‘V’ in between the ducktail and the number plate. Cut a little flat edge into the plastic to help accuracy. Have you checked BOTH Heim bearings, if worn, your figures are useless!

Where the rear axle is in the adjustment slot makes a difference to which spring rate is required. Example; your axle is at beginning of slot and you achieve static sag and rider sag with an 84-250 spring if now you had the axle at the end of adjustment slot you would need an 88-250 spring to achieve the same sag. It is the law of mechanical leverage as consequence of that your rebound has also changed. (Viking)

Shock Setup

Firstly, set the correct race sag and the clicks as per manual. Next, try the clicks in and out for fun-about 4 clicks per time will let you know.

Try different sag settings for better steering around slow obstacles. Around 90-95mm will give excellent turning response whilst the suspension may have been compromised (I.E it may now feel too stiff). If you have raised or lowered the rear you can go back to ‘as was’ and keep the change in pitch by raising or lowering the front forks through the triple clamps. So if you raised the rear initially and liked the steering, put it back to ‘as was’ and instead lower the front to set the bike at the same ‘pitch’ (raise forks through the clamps).

What Does It Need?

Generally, if the bike sinks a long, long way at the rear it’s a soft spring. A straight rate can fall through it’s travel on all pre ’06s and feel similar to this. If the bike does a ‘whap, whap, whap’ at the rear as the bike sinks and rises under hard acceleration in a curve – it’s either of these.

If it gives a ‘whack’ and settles very quickly it may be too stiff. There are two types of compression damping: HSC is for big whallops/G-outs and to stop the bike sinking forever. Until the bike stops sinking you can’t really travel forward/open the throttle. This is a classic lack of HSCD. LSCD is for all the small stuff and a lack of it shows in the bike spending too much time with the wheel off the ground.

Rebound is the easiest to describe. This should be backed off and ‘added’, the worst of ‘too little’ is that you get catapulted up when climbing a hump at speed, and especially when sat down! Try to stand for these rare occasions and think of the rest of your ride.

What Can We Do to Them?

We’ve started with the obvious, the cheap and easy. Set your sags, adjust your clickers. If the sag numbers don’t add up and you don’t have the spring recommended here, maybe that should be next?

If changing the spring you may wish to consider which type of spring to fit. One that gets harder as it compresses or one that remains the same throughout? It’s explained below.

Shim stacks are always worth uprating to the very latest spec and indeed after paying ‘too much money’ for my shock to be tweaked, all I got was the latest production shim stack… a lesson learned.

All pre 2006’s will benefit from a new needle – especially if riding with a straight rate as it helps stop the shock washing through the travel.

Well, you’ve got to be keen!!! but there are those that put two primary pistons in instead of a primary and secondary, also, latest tests show a new piston matching a new needle from RT.

Steve McFarland (2005FC550) has done a great deal of trial and error on his bike to achieve improvements. Amongst his changes are to put a shorter 2006+ ‘bumper stop’. This improved medium bumps as the bumper stop had been coming into effect too soon. Steve has also fitted the larger diameter reservoir with it’s greater capacity. Again an improvement was noted. The reservoir was twisted using offset/eccentric washers for the top Heim joint so that the chain would miss the reservoir.

Terry Hay, the Australian suspension tuner likes to fit a 3mm spacer in the shock which keeps the rear end 10mm lower but allows the suspension to work quicker over shorter travel. Again Steve has done this and liked the results.

Shim Stack Information

Steve supplied us with these shim stacks to ponder!

Bladder vs Remote Reservoir?

Tests and graphs carefully done, show the two to be virtually identical. Also those that have tried them back-to-back haven’t noticed a difference. Essentially the bladder will fit inside the reservoir and removes the need to recharge the shock. Perfect for those prepared to do their own testing.

For more details check out the article Bladder Verses Piston Arguments in PDS Shock Absorbers. Another unique problem for Husaberg motorcycles is that our reservoirs sit over the run of the chain. To use a bladder would put the valve right over the middle of the run of the chain with the consequent damage that may cause on a ‘G-out’….

Fitting a Schrader Valve

These are the same valves we see when we pump up our car tires. If these are used, the run of the chain may break the valve out of the body on a ‘G-out’ but one suggestion (as yet untried i believe) is that the schrader valve be put in on the edge of the reservoir cap. The run of the chain is a clear 1″ away. However if you fit a schrader valve you need to know that when you put 175psi in that it stays in!

This tool does it by unscrewing after the nitrogen is in - to stay!
This tool does it by unscrewing after the nitrogen is in – to stay!

Staying with the OEM Screw

Check out this rear shock rebuild thread. The recess in the top of the reservoir is slightly tapered which keeps an ‘O’ ring squeezed ‘in’ helping to keep a good seal.

WP Suspension cap for recharging. Note the T-bar on top for getting to the Allen screw and the ripples in the shock.
WP Suspension cap for recharging. Note the T-bar on top for getting to the Allen screw and the ripples in the shock.
The pin through goes across a ripple in the reservoir.
The pin through goes across a ripple in the reservoir.
This is a really cool tool from Australia! You can see the large wheel for screwing down the allen screw and the schrader valve for charging it on the side.
This is a really cool tool from Australia! You can see the large wheel for screwing down the allen screw and the schrader valve for charging it on the side.
Based on the idea from Australia, I had a pair of half clamps made.
Based on the idea from Australia, I had a pair of half clamps made.
Clamped up!
Clamped up!
Note the two screw holes in the top plain.
Note the two screw holes in the top plain.
Screw holes in the face, an allen screw 'ready' in the hole and a schrader valve off to the side
Screw holes in the face, an allen screw ‘ready’ in the hole and a schrader valve off to the side.
The 'O' ring on the edge can clearly be seen. The brass center moves back.
The ‘O’ ring on the edge can clearly be seen. The brass center moves back.
Not aesthetically pleasing, but does the job!
Not aesthetically pleasing, but does the job!
The T-bar on top pushes down and screws flat into the top of the reservoir.
The T-bar on top pushes down and screws flat into the top of the reservoir.

Polish the Inside of the Reservoir

Steve McFarland (2005FC550) felt the difference when he did this to his bike!

KTM and Husaberg – Shock Angle

Unlike the forks, the angles of the respective rear shocks are different. The KTM shock is layed forwards while the Husaberg motorcycles are upright. This forward angle means that initial small bumps on the KTM are harder to control but later in the stroke they’re better than the Husaberg. The opposite is true for the Husaberg. Word has it that in general, we got the better deal!

Rear Shock Bleeding

The oil contains minute air bubbles that must be purged. There are several ways to do this. There is naturally which allows air to find it’s way to the compression screw exit. There is vacuum which actually creates a suction trying to draw the oil out using air. This actually makes the minute air bubbles larger and they head for the exit even quicker! Finally there is force which drives oil through the shock – oil that is clear of any air.

Here are some photos of the various tools used to bleed air from the oil. There are three ways of removing air from the oil. Firstly, you can agitate and decant the shock in order to dislodge the bubbles and Terry Hay says that this is good enough if done well, secondly, you can create a vacuum that sucks on the oil and makes the air bubbles larger(around 10″hg). The other way is to create a vacuum pump that works at. This way they rise and leave and the job is done quicker. Thirdly, you can drive oil through using the HSCD bleed hole as the exit and this will then have to be carefully fitted afterwards.

Keep feeding down and in, just agitate for good results!
Keep feeding down and in,
just agitate for good results! (Khan Cross)
Shock set fair to be agitated at the shaft to help air and oil swap
Shock set fair to be agitated at the shaft to help air and oil swap (Khan Cross)
Stick this bleed bottle in the screw hole near the comp clicker and agitate. Excellent results apparently!
Stick this bleed bottle in the screw hole near the comp clicker and agitate. Excellent results apparently! (Husky510)
Bleedpump. The chamber is for creating a vacuum NOT for pressure.
Bleedpump. The chamber is for creating a vacuum NOT for pressure. (Drehwurm)
The pipe on the right, er, well it er! Look take it from me. It works!
The pipe on the right, er, well it er! Look take it from me. It works! (Drehwurm)
All parts available in kit form!
All parts available in kit form!
Huge cap and pressure gauge.
Huge cap and pressure gauge.
The two-way valve can be seen.
The two-way valve can be seen.
Note green vacuum pump behind and shock held in the extended position
Note green vacuum pump behind and shock held in the extended position (Folie)

Rear Shock Recharge

Yes you can. There are several lads that have made a simple unit to do this. A gas canister including pressure gauge, a 90 degree on/off tap, a pressure gauge for what’s in the unit and then the difficult bit – the ‘lip’ that sits on the shock body.

Bleedpump equipment
Bleedpump equipment
Bleedpump fitting
Bleedpump fitting

KTM Shocks – Brief and Vague!

About the reservoirs:

  • Early styles prior to 2002 is small diameter long length, 2003/2004 are large diameter longer length, and 2005 and later are large diameter shorter length.
  • 2002 and earlier have no negative springs, 2003/2004 have negative springs, 2005 and after have no negative springs.
  • 1998 series uses a long needle, 1999 through 2002 use a very short needle (bottoming control), 2003 is slightly longer, with each later year longer still, but no where near the 1998 version.
  • Early dampers, 2001 and prior have a weak clevis and also have seen the upper ends of the body fail. On a KTM, the 2003/2004 compression adjuster and body in that area is sometimes worn through from the riders boot causing a leak. 2005 and later have the reservoir indexed slightly differently to prevent this.
  • As for internals, there are several key points; 2005 and later shafts and needles must be used in sets, late style needle with late style shaft, etc. 2002 through 2004 style will work together (and possibly as early as 1999).
  • Early style dampers prior to 2003 used the same piston for each position, however they were changed in 2000(?). The 2003/2004 series uses different, but similar pistons for #1 and #2, and the 2005 and later use completely different pistons for #1 and #2.
  • Why do tuners recommend a piston swap? Mainly for the 2005 and later style damper. Use the aftermarket piston in #1 position and move the OEM #1 into #2. The alternative is to run a 2004 and prior #2 which is the same as the #1 and #2 from 2000(?) through 2002 (PMK).
2005 FC550, KTM PDS rear shock
2005 FC550, KTM PDS rear shock

Factory Rear Shock

Factory Husaberg Rear Shock Factory Husaberg Rear Shock Factory Husaberg Rear Shock

Needles

The needle is there to block the movement of fluid and the design is such that it fills the hole more and more the deeper into the stroke you go. OEM needles from ’06+ have been designed for the straight rate spring and heavily dampen the end of the stroke. One of our members had trouble with a Race-Tech version, however others have been OK and Terry Hay has managed to get a material change for the RT team.

Progressive (Dual Rate) or Straight Rate?

Husaberg Rear Spring

This is the dilemma! The jury is out on this one, and if you follow the detective story you’ll see that there are two outcomes we can pursue here. First of all, until 2006, the shock damping was set for a progressive but didn’t stop ‘blowing through’ on big bumps despite the spring getting ‘stronger’ at the end of the stroke. Now though the rear damping is set for a straight rate and is very heavily damped at the end of the stroke. The straight rate spring on pre 2006 bikes is nice on the small and medium bumps but alas blows through on bigger stuff. A progressive spring can seem hard on medium bumps as the secondary ‘weight’ stops the shock earlier in the stroke than is desired. This problem is known to the top tuners and the ideal answer is for the progressive part of the spring to be delayed in an ideal world.

The straight rate spring is best with the correct needle and shim stack fitted to stop this ‘blowing through’ (so that’s 2006 and onwards) whilst the progressive spring is a good stand alone item. Fitting a progressive spring to the latest straight rate needle and it’s stronger end of stroke damping could be good especially for the heavier rider because there are two things stopping the shock blowing through, and you could then back the valving and the preload off to soften for light bumps. Unfortunately, WP Suspension stops at a 8.5/11.1 which is light and other manufacturers of ‘progressives’ are sought such as Factory Connections; 9.0/11.5.

PDS Spring Codes

To understand the codes on a PDS spring: “76/90 250” means that the spring has a 7.6 start and 9.0 finishing weight. Rate 1 @ 20mm of deflection. Rate 2 @ 100mm deflection. That’s why it’s called a progressive spring. 250 means 250mm free length.

PDS0-250 6.5 – 8.3
PDS1-250 7 – 9
PDS2-250 7.5 – 9.7
PDS3-250 8 – 10.3
PDS4-250 8.5 – 11 This is for riders weighing around 190 lbs.
PDS5-265 6.6 – 8.6
PDS6-265 7.15 – 9.05
PDS7-265 7.6 – 9.5
PDS8-265 8.1 – 9.95 This is for riders weighing around 180 lbs.

There are now several aftermarket springs available for the bigger rider. Factory Connection does a 9.0 -11.0 and John F3 (220 lbs.) loves it. Word has it that the Race Tech spring comes on too hard too soon…

The above recommendations are from riders who have adjusted the damping to suit the spring.

However, expert rider Moto520 did some extensive testing on many, many springs and says, “the 260mm length spring had a better transition point from super plushness to firming up from midway on down. In other words a more gradual increase. The shorter springs had a spiky reading and got stiff sooner”. Further, he mentions how the 250’s bow out at the sides and this can be inflamed by the spring not being flush across the ends but instead bowed, bent or rippled.

Straight Rate Codes

Said to have better mid suspension properties than the PDS, but it does fall through on big jumps. The WP Suspension springs generally move up in 0.2 increments. So an 8.0kg is followed by an 8.2kg etc, all the way to 9.0kg which is the largest WP Suspension does. However K-Tech in the United Kingdom claim to have springs manufactured by the same company and go all the way to 10.0kg in 0.50kg increments. Funny how it’s not in 0.2’s given they’re the same factory?

Figures for rider naked! (approximate):

9.2 9.4 9.6 9.8 10.0 10.2 10.4 10.6 10.8
180 lbs. 195 lbs. 210 lbs. 220 lbs. 230 lbs. 240 lbs. 255 lbs. 270 lbs. 285 lbs.

Lower Heim Bearing

Needs to be stripped and greased mid season or expensive to replace. Tighten the preload collar to the recommended setting or it will wear out the piston inside (squeezed body). The upper Heim needs greasing once per season. The upper Heim will go eventually, even though they see less muck.

Swingarm Slack

Play in the needle rollers and pin. Here try industrial hardened steel rod. Found .4mm more pin diameter and still fitted. Later models improved with far wider oil seals on the needle rollers to keep the water out. I found that oiling instead of greasing the needle rollers vastly improved service life. Read this discussion thread on Husaberg pivot pin slack handling problems.

Handy Tools

Rebound Adjuster Screwdriver (Viking)
Rebound Adjuster Screwdriver (Viking)