LAKO Performance Group is more than willing to consult
with our customers and get to a custom setup that is perfect for a particular
machine, its special use and its rider. If you are not a current customer -
have warranty or setup questions about your shocks - please contact the manufacturer. If there is any issue
or question with any shock or fork we modified, built, revalved or rebuilt, contact us. Now on to the good stuff!
When I speak of the "art of communication" I am referring to the racer or rider talking to us about what the sled is doing. The layman would say, "Every time I hit a bump, It throws me right off the seat". The racer might say, "It has too much bump dampening" or, "It has too much initial spring" or, "It has too much spring rate" or, "There is not enough rebound dampening" or, "too much rebound, the skid frame is packing up and ran out of travel" or, "The shock faded - it's all spring now". Even though all of the racers examples would cause what the layman described, they are all very different issues that require radically different approaches to correct. Changes made to the shock's spring or valving for the wrong reasons would be bad for your joints and your wallet.
Shock valving changes: LAKO can make major strides in the right direction just based on what we know about your particular machine and your personal stats (weight, riding style, etc.) however, to setup a set of shocks and springs, you have to know what you like and dislike about the behavior of your machine. Understand that your weight and riding style have a lot to do with the way the machine handles. Being honest about your riding style (don't say aggressive, when your cruising 95% of the time) is a big factor in satisfaction. Certain sleds (chassis designs) have their own strong points and issues. Understanding that the amount of complexity and setup options on some of today's skid frames is literally way beyond any other suspension system being used on the planet is important. Ask yourself if you have tried the manufactures recommendations for setup completely - then move forward from there.
Ski and track changes - we'll hit on this again - but for now, keep this in mind: When going straight at a relatively constant pace - attacking moguls that have even or irregular spacing - pretty much takes the track and ski design out of the picture. Your shocks, springs and riding ergonomics are 95% of the equation. When accelerating, braking or turning, the chassis setup, ski and track design come into the picture in a very big way. An overly aggressive track might turn quite well on a sno-cross track that has 5 inches of beaten-up granular snow and ice crystals, but put that same sled on hard-pack groomed trails and that same track will make the sled go wherever it's pointed if it has traction. You can compensate by using aggressive skis and increasing ski pressure, but at the high cost of rider fatigue. So if you wonder why we ask what Track/studs and Skis/carbides are on your setup before revalving or setup, it helps us make the proper changes with more working information.
Making valving changes will require a scientific approach to figuring out what the machine is doing. You have to really think and commit to paper what the suspension is doing and on what kind terrain and speed. Now, pay close attention: If the shocks and suspension components are not in perfect working order during testing and evaluation, valving and/or spring changes to compensate could be a waste of time and money. Many LAKO customers are well trained. They get a new sled, take it out for testing and good shakedown run - or a trip through many sorts of terrain and conditions - then drop off the sled or shocks with a detailed account of what they experienced and what they would like to see changed.
Never alter shock gas pressure to change a setup. Too high a pressure for the design will cause seal issues as well as a possibility for catastrophic failure. Too low a pressure and shock fade comes into play quicker as well as contaminant ingestion.
Get a good understanding of all those adjustments. For you guys that have adjustable coupling in the rear skid, its the best way to radically change the personality of the sled. Your sleds manual should have clear information on what each adjustment does and why. Again, the shocks and pivots must be in perfect condition to gain true knowledge of what is going on.
Remember that your track and stud choice along with your ski and carbide choice must be balanced. A lot can be done to compensate for these variables, but its always better to start with something in the ball park. If you like running a lot of studs near the outside edge of the track, don't be surprised that the sled understeers more and more when the snow is hard. This can also happen in loose churned-up snow when running a deep and/or aggressive tracks with less than aggressive ski profiles - regardless of carbide or studs!
|The FAQ list|
My friend and I have the same sled, but his is always faster and handles different - what gives?
Although chassis manufacturing has become much better, it is not up to race prepared standards. I want to stress that OEMs have become much better at chassis quality and repeatability in recent years. That being said, put two exact sleds on a surface plate (pick any one of the four manufacturers), and start measuring points along the tunnel and bulkhead, skid frame mounting locations, shock mounts, drive axle, jack shaft, etc. It will become painfully clear that every sled is unique. Couple this with all the variables introduced with the shocks and springs thrown in the picture; Gas pressure levels, shim pack errors, gas mixed in with the oil, spring rate differences, etc. The list gets pretty long. Imagine if the drive wheels on your driveshaft were just a quarter of and inch off of skid frame centerline - or if the skid frame was not dead perpendicular to the drive system. The parasitic losses from friction alone would eat up quite a few horses right there.
Pro race teams spend hundreds of hours getting all these variables out of the picture so they have a repeatable baseline to start from every time. If you were to have the chassis blueprinted to true spec, plan on spending north of a thousand dollars at bare minimum. We've seen as much as a 15 horsepower increase to the track in a blueprinted chassis and driveline. That's like adding 25-30 hp to the engine at the crank!
My buddy has the same sled, studs and carbides , why does he seem to turn better?
Does they have the same stud pattern? Do you have more studs on the outside section of the track ? The more studs you have in the outside area of the track, the more the sled is going to want to go straight. Spring selection and preload settings - are they the same? Skid frame coupling adjustments - are they the same?
How much do you weigh compared to you friend? Heavier riders have a harder time with "understeer" (skis turned but sled wants to go straight) than their lighter counterparts. A 220# rider would put more down force on the track and less on the skis than a 170# rider. This is why heavy engine sleds seem to turn better with heavy riders compared to the light engine sleds. The big engines put more weight bias on the skis.
What is your riding position in comparison? Riders that crowd the tank while diving into a corner will turn faster. Again, more weight is shifted to the skis and removed from the track. Many riders use the "outside foot push" to get the sled to stick the corner. For example, while coming into a left turn, slide your weight to the inside (seems normal right?) of the sled and at the same time put most of your weight on your right foot as far forward as ergonomics allow. This will move more weight to the outside ski and make it bite harder.
Try reducing the spring preload on the center shock (avoid using the front limiter strap unless you know what you're doing and know the consequences). This will put more weight on the rear of the track and on the skis making the turning more aggressive. Compensate ride height by turning up preload on the rear and ski springs. Most savvy aggressive trail riders have put in a higher rate center spring in the minimum preload setting to keep ski pressure and also resist bottoming. That center shock's rebound circuits had better be changed for that new higher spring energy as well.
One area where the manufactures are lacking focus, is in the linkage of the center shock (or should I say "complete lack of"). A rising rate geometry design is begged for here. Yes, given the space, weight and cost considerations of the front skid frame, I understand the reluctance (we're working on our own at the time of this writing). A fully coupled suspension would have less of an issue with this since the coupled design "borrows" rate from the rear shock and springs - but sacrifices terrain following and traction in all but the smoothest conditions.
How long do rebuilds last before I notice issues?
If you notice an issue, you have already passed the rebuild point. Shock rebuild intervals are not mileage dependent. I have seen shocks trashed in 500 miles in one weekend and others 2 years old with 3000 miles that really could have gone a bit longer. Why?
Shock design: I'm not going to pick on any brands here, but some use better components, seal systems and fluids than others. Data on how good or bad they were 10 years ago is worthless today. So don't go by past experience. Anodized aluminum bodies cause less main piston seal wear and contamination than steel bodied shocks. Hard anodized bodies (internal and external surfaces) are by far the best.
Manufacturers design: If your sled brand of choice has shock mounting components that puts the shock into any load other than straight down the shaft, the shock will see bending loads as well. This in turn causes premature wear on the seals, bearing cap and main piston seals. It also speeds up water ingestion. Check your sled; if you only mounted one end of the shock and tightened it, the shock should move on the bushing axis with ease. Now check the other end as well. Bushing condition and design are one of the keys to suspension performance and longevity.
Water ingestion: You may ask, "What? how can water get into a 200 or 300 psi shock?" Easy. When a shock goes into compression, there is a pressure drop on the back side of the main piston (that's the shaft side!) and a pressure increase toward the internal floating piston on the other side. The harder the hit - or compression speed - the greater the "Vacuum" felt on the shaft side. Yes, it will actually go into a true vacuum state relative to surrounding air pressure. If the seals can't scrape off all bits of water and frost, they get sucked right in and start the dirty work of contaminating the shock internals.
Very cold weather (below 0°f): Yes, again it's water and air ingestion, but now it's accelerated by very cold temps. Ice crystals get harder and stick better to shafts the colder it is. Shocks get quite warm when ridden hard, but If the shock shaft temp doesn't stay above freezing so the seal is only dealing with water, the ingestion issue gets worse. The more hydrophobic the shock shaft surface is, the better. BTW, frost on a shock shaft is abrasive to seals. So it stands to reason that seals can only deal with this condition for a relatively short period. The Fox Zero Pro ice scraping seal design was the first I saw that really helped this issue.
Gas leakage: This is a big one. lose that pressure and things get bad quickly. Shock fade/oil foaming, water ingestion, drop in spring rate, etc. I have yet to see two exact OEM shocks lose pressure in exactly the same way and amount. This is why we go beyond normal seals and procedures at LAKO. We know how important it is to hang onto every last molecule of nitrogen pressure, so on the Pro-Synthetic rebuilds, we go above and beyond factory rebuilds to virtually double gas retention times using our proprietary processes and sealing techniques.
Riding style: Last but not least - all other things being equal - the harder you ride, the sooner the rebuild interval should be. Unless you had us do a LAKO Pro-Synthetic rebuild, you should have them done every year or 2000 miles, whichever comes first. The Pro-Synthetic rebuild can double that rebuild life.
I'm going to race and the sled is new. Should I be concerned about the shocks?
In a word, yes. Serious racers can't afford the off-chance the shocks are right from the factory. Have them gone through before the first ride or race. We have never seen pro racers use factory delivered valving in their shocks - ever. Amateurs getting their feet wet will learn pretty quickly in a couple of races what a good setup really means. We have a vast database of setup history for Polaris, Arctic Cat and Ski-Doo snowmobiles. We can get you real close to a great race setup the first time.
We only do Pro-Synthetic shock builds for racers (see pricing page). All synthetic fluids used at LAKO are the best available. These ultra pure synthetics resist fade up to three times as long as the petro/synthetic blends (which are much better than the stock oils) and will at least double the rebuild interval for racing sleds. The difference for trail riders is in ride quality. Our pure ester based synthetics will act softer when cold and firmer when hot as compared to OEM race fluids. We go an extra step with the Pro-Synthetic builds as well; virtually all oxygen is removed in a special chamber and the fluid is stored in a Nitrogen/Argon environment. This treatment insures that no moisture or reactive gases are present inside the completed shock.
What should I do after the weekend ride?
Get any salt and dirt off the machine. Careful not to power wash into the skid frame bearings. Grease the sled. Spray the exposed shock shafts with a good silicone spray when not in use. This will help remove moisture, keep corrosion at bay and de-gum the seal edges. Spray down the ungreased pivot bushings with a good lubricant as well.
What should I do when installing the shocks?
If you have typical steel spacers within polyurethane bushings, make sure they are clean and well greased. Grease is not needed if you are using aftermarket stainless steel sleeves (no stock sled uses SS sleeves). By removing the steel sleeve and prying the polyurethane bushing out, you can fill the internal gap with grease and re-install the steel sleeve. Place in a vise to squeeze the bushings back together. This forces the grease into all cavities. Do this every 2500 miles. Some sleds with inner and outer steel-on-steel oil-lite bushings (held in the shock eye by a poly bushing or hard rubber) need not do this. For this type of setup, a light oil sprayed on the bushings is fine, but not mandatory. This so-called steel-on-steel pivot uses water as the primary lubricant/coolant
Before tightening the mounting fasteners, load the shocks in the direction of force encountered during compression. This will make sure any play in the mountings is taken up in the direction they will end up in anyway. All shock mounts must be tight. The steel inner sleeve must never rotate or shift positions in the chassis. The bushing must rotate with minimal friction. If it binds, the shock will encounter bending loads along with the normal compression loads. These bending loads will cause premature wear to many components within the shock, including the top bearing, shaft, seals and main piston control ring, consequently costing much more to rebuild. Don't blame the shock for poor geometry, binding bushings or lack of maintenance.
Sometimes, the cost of all the parts damaged from this can cost in excess of a new unit.
Is there a way to check the condition of my shocks?
Beyond looking at them for any shaft pits or other damage, there is very little you can garner with them on the sled. One thing that says it is past rebuild time is the gushing sound of air in the fluid section of the shock. If you push down on the suspension and then lift up, if you hear a change in sound at the top of the shock travel, you can bet you have air in the fluid section - and if air travelled in via the common route of the shaft seal, you can bet water came in too.
For a quick gas pressure check without invading the shock (shock removed from sled), remove the spring and check how much force it takes to move the shaft. A Fox, ACT, RydeFX, etc. with a 1.45" inside body diameter, standard 1/2" shaft and 200 psi of nitrogen should require a little more than 43 lbs. of force to move the shaft in from the fully extended position. If you're down to 100 psi (read not good) the force would also be cut in half (20+ pounds). This force will increase as you drive the shaft further into the shock because the shaft displaces fluid - which moves the floating piston further down - compresses the gas and consequently increases that pressure which makes it harder to compress the shock. The lower the gas pressure, the quicker the fluid will foam and cause shock fade.
Consistency of the factory units (valving, gas pressure, floating piston positions) are better than years past, but are still very suspect. Have the shocks rebuilt before 500 miles if at all possible. Subsequent rebuilds last longer if done properly.
OK, I need them redone and may want valving changes - now what?
Want to know the difference in rebuilds? Go to the "What is special about the LAKO Pro-Synthetic rebuild" page.
Go to the Snowmobile shock services and pricing page for info on how to get your shocks to us, pay for the servicing and any options you may want.
You can email us at firstname.lastname@example.org with specific questions.
The cost along with the time required in running high pressure gas shocks might seem a little excessive to riders that remember when they never even looked at their old, standard air-hydraulic shocks. If you can deal with sled that fades its shocks after 30 seconds of hard bump riding (or never ride hard), then you may want trade in the sled for a model that suits your style better (or change the shocks). Beyond their ability to resist fade, rebuildable high pressure gas shocks gives one the ability to modify the dampening characteristics infinitely. This ability to custom tailor your sled to your specifications alone is worth the cost admission.
The LAKO Performance Group hopes these tips will help you in having a more enjoyable riding season. Happiness is a sled that goes where you point it, when you point it.