YZ/WR DRAFT Shock rebuild

D R A F T - YZ and WR SHOCK REBUILD – 16mm and 18mm

NOTE: WE HIGHLY RECOMMEND THAT SAFETY GLASSES OR A SAFETY FACE SHIELD BE WORN AT ALL TIMES WHEN WORKING WITH A SHOCK.

PLEASE NOTE that if this is your first time rebuilding a shock, we recommend reading through these instructions before beginning as to better prepare and understand the complete process. Please contact us with any questions or suggestions. PHOTOs are coming soon!

1. Remove the shock from the bike.

A. Remove the seat and the right side plate.

B. Remove the muffler.

C. Remove the top sub frame bolt

D. Remove the left and right sub frame bolts.

E. Remove the top and bottom shock bolt nuts.

F. Keep the air box boot attached to the carb and tilt the sub frame to the left.

G. While lifting the swing arm, remove either the top or bottom shock bolt, followed by the other.

H. Lift out the shock.

I. It’s also a good idea to wire or zip tie the bottom bearing bushings.

2. Wipe down and clean the shock. Remove any excess dirt. Clean the threads above the spring lock collars. Apply a light lubricant, such as silicon spray or WD-40 to the shock body threads. This will help the pre-load rings to spin more freely.

3. Measure and note the length of the spring as pre-loaded on the shock.

4. Pry the rubber bottom bumper up and out of the bottom cup. Use a flat screw driver to leverage the bumper up. This is easy to do on the 16mm shocks, but requires a bit more work on the 18mm shocks. You may want to add some silicon spray or WD-40 around the base of the bumper before attempting this. The 18mm bumpers tend to stick.

5. Unlock (separate) the top pre-load lock ring with a flat or round punch or dull screw driver.

6. Turn both pre-load rings all the way to the top. Sometimes it’s easy to mount the bottom of the shock into a vice (use soft jaws or a large soft towel to protect the shock) while doing this. Note that sometimes it’s easier to rotate the body of the shock than it is to rotate the rings. Additionally, it’s a good idea to wear gloves to help protect the hands from the sharp edges and burrs of the rings.

7. With the pre-load rings turned all the way up to the top thread, remove the shock from the vice and lay it flat on a workbench or space. With the bump rubber slid up and out of the way, you can now remove the lower c-ring from the bottom, followed by the spring spacer and then the spring. You can remove or keep the spring pre-load rings on the shock body.

8. Wipe down the body of the shock and clean the threads of the shock body. At this stage, it’s also good to cycle the shock a few times by hand and test for resistance and the present of air within the fluid. This may lead to an early discovery of concerns that will need further analysis after the shock is disassembled, such as a worn piston band or seal head.

9. Remove the bottom out plate from the bottom of the shock body. This item is lightly pressed into the shock body and has two holes along the edge, 180 degrees apart. This can be done with a small dull punch or a flat screw driver. A dull or round punch is best since it will leave less of a mark. You will have to tap this plate out by going from one side to the next. It may take about 10 to 15 taps. When it is free from the shock body, slide it all the way to the bumper and tape or zip tie into place. You will now be able to see the seal head and the dust seal.

10. Remove the valve cap from the nitrogen valve and bleed out the nitrogen by lightly pressing on the Schrader valve stem. Make sure not to bend the stem. It is also a good idea to measure the existing nitrogen pressure as to note the amount of loss, which indicates oil lose and the potential of a worn seal and/or seal head. Existing nitrogen pressures, compared to the original charge is a good measure of required service intervals and potentially the condition of the shock. A charge less than 100PSI would clearly indicate a major malfunction somewhere in the shock. Removing the valve stem is an option but ideally the atmosphere within the bladder should remain as moisture free as possible. Consider this within your plans to replace and/or purge the bladder before the final charge.

11. At this stage you can then test for a smooth and air free action by cycling the shock shaft. Make a note of any sections (distances within the stroke) that feel sticky or gritty as this may indicate concerns within the shock body such as damage to the internal coating.

12. Remount the shock into a vice or holding device, clamping the shock body in a position so that the shock body is laying flat with the compression adjustor assembly facing upwards. If you have a standard vice, it is highly recommended that the shock body be wrapped with one or two small towels as to protect it from damage. Never clamp the threaded surface of the shock body and never over clamp (tighten) when putting the shock body into any vice.

13. With the shaft fully extended, remove the compression assembly cap from the shock body. Do this with a special compression assembly removal/install tool or use a large adjustable wrench (18mm shafts) or

Channel Locks (16mm shafts). Without the use of a tool that fits this cap, some damage (most likely just scratches) are likely to occur. Contact us if you would like to purchase a cap tool.

WARNING: There will often be a substantial burst of air and oil when the compression assembly cap is removed even when the shock has been fully bled of all its nitrogen. We highly recommend winding a small towel around the neck between the shock body and reservoir, then using a second towel to hold over or smother the assembly and your tool during the last stages of the cap removal. The amount of burst is usually an indication of the air that was trapped within the shock. This burst will be fairly minor (it’s not an explosion) but could be a bit messy, and once it occurs it will not happen a second time through the remainder of the breakdown.

14. With the cap lifted up, keep an eye out for the small thin shim like washer that sits between the top of the spring (now visible) and compression assembly cap. This usually remains with the cap as it’s held in place from the residual fluid.

15. With the cap removed, reach in with your fingers or using some needle tips pliers and remove the aluminum cylinder and the metal spring of the compression assembly. Note which end is which when removing the aluminum cylinder, as this is important during its reinstallation.

16. Using some small Channel Lock type pliers, or small conventional pliers, grab the tip of the valve assembly. Slowly and gently tip from side to side while lifting. This is held in place by an o-ring that seals the head of the piston unit into the shock body. Therefore the resistance you are feeling is simply the compression against the o-ring. This will need to slide or work up about 4mm before coming free. Take your time and be careful not to damage the o-ring. With this removed, inspect the o-ring around the edge of the piston. Check for tears and scars. If damaged in any way, contact us for a replacement. Do no attempt to use any other o-ring than the KYB OEM unit.

17. Remove the shock from the vice and pour the remaining fluid out of the compression assembly hole into a beaker or drip pan. It may help to pump the shaft a few times while doing so. Examine the fluid and note condition and quantity.

18. Press a clean lint free towel into the hole of the compression assembly then mount the shock into a holding device (vice) with the bottom of the shock facing upwards, (clamp the top bearing mount). The shock may shift from side to side unless the two top bearing bushings are removed. Again, soft clamps or a towel is recommend to avoid damage, but additional clamping force may be necessary, and is likely, but not harmful to the shock or bearing.

19. With the shaft fully extended and the cap and bumper help up in place with tape or a zip tie, use a small punch or thin long screw driver (or seal head tool if you have one) to tap the seal head down into the shock body, (towards the vice) exposing the black metal snap ring within the shock body. Tap the seal head down into the shock body so that the upper edge is about one inch or 20mm down from the ring.

20. Use a small thin flat screw driver to lift the edge of the ring at the ring end. While lifting, work the ring down (not up) and out of the grove towards the direction of the seal head. You may want to use a second screw driver or tool to do this. Do not attempt to lift the ring out or upwards. With the ring fully out of the grove, and down towards the top of the seal head, keep the open end of the ring down, and pry or lift the opposite side of the ring upward. Avoid contact with the shock body wall. This will rotate the ring within the shock body making it significantly easier to lift out and remove and from keeping the shock body from getting scratched and damaged. The ring will rotate about 45 degrees or more - then can be easily lifted out. Wipe the inside or blast clean with pressurized solvent to remove any dirt or grit trapped around the seal head seal and shock body. Applying some light lubricant (such as WD40) to the inside of the shock body and to the top outer edge of the seal head may ease the removal of the assembly.

21. Remove the shock shaft assembly by grabbing the end of the shaft with your hand (gloves or towel wrap recommended) and lifting upwards with a steady and consistent force. Some slight rocking or tilting may help. It may also be necessary to stand above the shock while doing this.

WARNING: When the seal head releases from the shock body, it may be sudden and without warning. Be prepared for this by keeping your stance steady and your face (and teeth) clear of the shaft end. There may also be a small release of fluid wear so keep a towel handing. Lastly, there may be a vapor (looks like steam) that releases from the shock body after the seal head is lifted out. Allow this to vent and keep your distance (your lungs) away until this clears.

22. With the shock shaft assembly removed and placed to the side, use a small sharp punch (such as a center punch) to create a dimple into the bottom edge of the reservoir. This will note the position of the Schrader valve as to make sure that it is properly installed back to the original position, during the rebuild, keeping it clear of the exhaust and frame.

23. If there is any dirt buildup between the bladder cap the shock body, flush with a solvent and/or compresses air. Applying a light lubricant to the rim of the bladder cap is also recommended.

24. Press the bladder cap in towards the shock body. It may also be necessary to rotate the cap allowing the lubricant to get around the rubber bladder, making the cap easier to remove. The rubber of the bladder tends to dry out and lock itself up against the shock body. When you break this lock, the cap will rotate and remove a lot easier. Use a rubber mallet and/or some Channel Locks to grip the flat surfaces of the cap. You may want to protect the jaws of the Channel Lock from scratching the surface of the cap.

25. Press the cap down so that the Schrader valve is just slightly above the edge of the shock body. This will expose the black (sometimes gold) metal snap ring. Use the same procedure to remove this metal ring as you used to remove the seal head ring or simple lift out, (this one is easier to do). Be careful not to damage the threads of the Schrader valve.

26. Twist the bladder cap while lifting upwards. This will slide out with the bladder attached. Inspect the bladder. Note that it’s best to keep the bladder on the cap to avoid any dirt or moisture from entering. If the nitrogen pressures in the shock were lower than normal before disassembly, it may be necessary to test the bladder with a slight charge and a dip into some water or a bath of oil. Bladders that are old or damaged should be replaced.

27. With the shock body now removed from the vice, fully clean the inside and outside of the shock body with a high VOC solvent (such as carb clean, brake clean or contact cleaner). Do not use low VOC or kerosene based solvents. Wipe the body down with a clean lint free towel. Make sure that any towels used as a final wipe on parts were never used to clean dirt or metal particles. Keep a fresh stack of perfectly cleaned towels for this purpose. Always use compressed air to blow off any remaining lint after wiping. Cover up the shock body after cleaning to avoid contamination. Lastly, use a good source of light to inspect the inside coating or surface area in which the piston slides on. Some residual build-up can be removed with a special tool, but scratches or damage into the coating require that the shock body be replaced. Note that this is also a good time to inspect and lube the upper bearing. The bearing should be clean and free of any damage, and should not have any noticeable slack. Contact us if a new bearing is required. This bearing should be lubed using waterproof grease. If the bearing requires replacing it will need to be pressed in and out. There is a small ring clip and insert within the shock body, so the bearing can only be removed and installed from one side.

28. To inspect or replace the seal head or bumper, or to reconfigure the current valve stack, the shaft nut above the piston has to be removed. To do this, the shaft peen (the smashing or mushrooming of the shaft end) just above the nut has to be ground off. Do not attempt to remove the nut without fully removing this peen. This peen can be filed or ground off using a variety of machines, (grinder, Dremel, belt sander…etc.). Be sure to protect and at least cover the rest of the assembly while doing so to prevent damage from tool slippage and from metal filings. Note that it is common to have to grind into the nut in order to fully remove all the distortion from the peen.

29. With the shaft evenly ground and the peen removed, place the lower lug of the shaft into a vice and remove the nut. If the nut does not remove freely, some additional grinding may be necessary.

30. Attempt to slide the shims and piston assembly off of the shaft. It may be necessary to lightly grind or file any edges that remain at the end of the shaft in order to remove the shims and piston.

Note: As you remove the washers, shim stacks and piston, take extreme caution in noting the position and layout of each of these parts and be aware that many shims can stick together and feel as one. If you don’t plan on breaking the stack down, protect their order by sliding the shims onto a rod or keeping them grouped with a zip tie. Also note the position of the piston as to which end is up. The shims on the top of the piston are the rebound stacks (these have the smaller face shims) and the shim stacks on the bottom of the piston are the compression shims, (these have larger face shims).

31. With the piston assembly removed, you can now slide the seal head off of the shaft. Inspect the bushing, the seals and the outer o-ring. Seals head should be replaced or fully serviced at least once a year even if the bike is not used very frequently. The seals or seal head should be replaced more often if the bike is used in racing or ridden frequently. It’s also best to replace the entire seal head than it is to rebuild the existing unit, (KYB only). There may also be a ring of dirt build-up at the top of the bushing. Wipe this clean if the seal head is being re-used.

32. At this stage, it’s best to clean up the threads of the shock shaft. Chasing the threads with a M12x1.5 die is highly recommended. It the existing nut is to be used, it should fully cleaned and tested on the shaft. A new nut may be required but is not necessary. It may also be necessary to slightly counter sink the hole in the shaft to clean up the edge left from the grinding. We also recommend that you do a solvent flush into the shaft hole to remove any debris. Keep the shaft end pointed down when doing so and always follow up a solvent flush with compressed air. Note: Using only compressed air, instead of a solvent flush, may force particles further in the shaft end.

33. You may also want to consider replacing the rubber bumper. The bumper should be soft from top to bottom with no scalding or flaking, and/or missing chucks. Replace if questionable.

34. With the shaft free of the piston, seal head and bumper (and bottom cup) fully inspect the surface of the rod. We also recommend that the shaft be tested for straightness with the use of a flat surface and feeler gauge or lathe and dial micrometer. The shaft can also be polished by spinning the shaft within a lathe or power drill, while working a 2500 grit cloth or paper onto the surface. We also recommend finishing with a 3M or equivalent crocus cloth. Always clean the surface of the shaft with a solvent after polishing until no more residual compound is found.

35. At this stage it’s also a good idea to inspect, clean and/or replace the lower bearing as this bearing is susceptible to water damage. To inspect and clean, remove the outer seals and inner bushing. The bushing should be free of corrosion and the surface should be smooth and untarnished. The needle rollers can be removed and cleaned, or simply lubed depending on current condition. Note that some early model shocks did not use a needle bearing. These can be upgraded. Contact us if a new bearing is required. Note that a new bearing will need to be pressed in and out but can be done using a collection of sockets and a vice or a bearing press. There are no clips or insets with the lower bearing. Always use waterproof grease when lubing this bearing.

36. With the shaft fully cleaned, install the rebuilt, cleaned or new seal head assembly onto the shaft. This should be done with a special tool that helps to prevent the seal edge from getting caught or torn from the sharp edge of the shaft. However, if done slowly and cautiously, the seal head can be rotated and pressed down at an angle, working the lip of the seal over the edge of the shaft. Some lubrication should also be used. NEVER use any plastic wrap around the shaft when installing the seal head.

37. Install the piston assembly with all the shims and washers in their original order. Keep in mind that the compression side of the piston faces the seal head. Also double check that the bump rubber, cup and bottom out plate has been installed.

38. With the threads and shaft nut fully cleaned, apply one to two drops of a chemical thread lock, (such as red Locktite). Torque the nut to 25 ft pounds (300 inch pounds). Allow the locking compound to dry.

At this stage, there are two options to reassemble the shock. The first option, the more traditional approach, involves filling the shock with fluid as you add the various assemblies back into the shock. The second option is to assemble the shock dry, bleeding the shock, then closing it up via the compression assembly cap as your final stage. Because of our confidence in this new process, this is the only process now listed within our procedures.

Note: Some of the following steps and/or procedures are patented and owned by SMART Performance Incorporated. These patents may extend to various tooling or products not presented in this procedure. We fully welcome and encourage the use of these procedures to all professionals and non-professional alike, but we ask that they not be republished without prior consent, and that any additional means used within this process by verified by SMART Performance before making pubic.

REBUILDING THE SHOCK –AN ALTERNATIVE PROCESS by SMART PERFORMANCE

1. Mount the top of shock body into a holding device or vice (the compression adjustor remains out) and install the bladder. Note that you may have to fill the bladder with a small amount of nitrogen to keep the bladder in a non-collapsed state. Install the metal ring and pull the bladder cap up into position and reposition the valve to the stamp marking made earlier.

2. At this stage, also double check that you have all of the hardware installed on the shaft beneath the seal head (bumper, cup, bottom out…etc.) and verify the correct installation of the piston.

Note: You may need to apply some tape or a zip tie between the seal head and bottom cap to keep these items out of the way while installing the rod and seal head into the shock body.

3. Apply a small film of suspension fluid into the shock body and the outer edge of the seal head. Then install the piston assembly and shock head into the shock body. The seal head will need to be pressed down into the shock body with either a special seal head installation tool or by using a punch or screwdriver and a light hammer or mallet. Alternate the position of the punch as the seal head o-ring works past the edge of the shock body and inner ring grove.

4. With the seal head down into the shock body far enough to fully expose the snap ring grove, install the snap ring by placing the ring at the outer edge of the shock body and sliding down. Try not to allow the ring or any tools to go beyond the ring grove as to prevent any damage to the shock body. Double check the ring is fully seated in its grove. The ring should snap into the grove and not want to move or rotate. If not, replace the snap ring. Inspect the installation of the ring closely before proceeding.

5. Lift the end of the shaft upwards, forcing the edge of the seal head to seat or meet up with the snap ring.

6. Remove the shock from the vice and remount so that the shock body is laying flat with the compression adjustor hole facing upwards.

7. At this stage you will add your fluid into the compression adjustor hole, but before proceeding, we recommend that your fluid be free of any air bubbles before filling up the shock. Note that any fluid transfers between containers and from container to shock be done so with slow and gradual movements. Never allow fluid to splash or pour into itself as this will create small bubbles.

Pour the fluid into the compression adjustor hole and continue to fill the shock until no more fluid can be added and there are no more bubbles (large or small) that continue to rise upwards. Don’t worry about getting all the air out at this stage – you only need to remove the majority of the air.

8. Next, take the cap assembly of the compression adjustor assembly, (remove the spring washer if it’s still stuck in the cap) and screw this onto the hole far enough so that cap’s o-ring sits down and into the shock body. At this stage, the piston, the barrel and the spring and washer remain on out of the shock. You don’t need to go any further than past the point that the o-ring disappears.

9. With the shock still in the clamp and in this position, charge the bladder with about 20PSI of nitrogen.

10. Then position yourself at the shaft end of the shock assembly. Then slowly work the shaft in and out of the shock, rotating the shaft about a ¼ turn for each cycle. Repeat this about 15 to 20 times. The pressure in the shock will keep the seal head in position and help to force the fluid to the other side of the piston. Rotating the shaft while cycling it will help to remove any trapped air bubbles within the piston. A light tap with a mallet may further assist to release any trapped bubbles.

11. With the shaft fully extended, release the pressure within the bladder.

12. Remove the compression assembly cap. All the shock to sit until all the small bubbles are clear.

13. Hold the outer edge of the compression assembly cap with an alternative vice clamp and turn in the high speed nut with a 17mm socket or wrench as far as possible, until the tool can no longer bite the edge of the adjustor nut.

14. Using a screwdriver, turn the low speed screw clockwise until it bottoms. Then continue to turn thereby turning the high speed nut out and away from the main cap. This will separate the blue adjustor assembly from the outer cap. Place these two items off to the side.

15. Now return to the shock and fill the shock with additional fluid, up to the brim of the adjustor assembly hole. When no more oil can be added, place the palm of your hand over the adjustor assembly hole while removing the shock body from the vice, (get a third hand or get creative). With your hand securely clamped over the hole, rotate the shock upwards. This will bring out any air that resides within the reservoir. Then bring the shock back to a flat position, add more fluid, then repeat. Continue to repeat this process until no more fluid can be added to the shock. If this stage is done correctly, any air trapped within the reservoir or shock body should rise up, and any oil within the reservoir and shock body should remain intact. Keep the rotations of the shock body either upright or flat as to keep any bubbles from entering back into the shock body. After few runs of this, you’ll know when there is no more air within the shock and that the shock is filled with maximum fluid.

16. With the shock back into vice, with the compression adjustor hole flat and level (perpendicular to the ground) and the fluid at the edge of the oil, you can now install the piston portion of the compression adjustor. To do this, grab the tip end of the piston rod and dip the piston into the fluid, entering the fluid at an angle while rotating the assembly. This entry method will help to remove any air bubbles that may stick to the surface of the piston. Allow the piston to settle down to the bottom, just at the top edge of where the piston o-ring presses into the shock body. Next, grab the tip of the rod with some standard pliers and while lightly pressing downward, slightly tilt the assembly from side to side. This will work the o-ring into place. Take your time doing this, working the o-ring into the hole as evenly as possible.

Note: As the o-ring and assembly snaps into the shock body, there may be a squirt of fluid that comes out of the adjustor bleed hole. Beware of this, and as always, good eye protection is wise.

17. Take a flashlight and inspect the installation of the o-ring, making sure that the o-ring has not slid or popped out from the piston during the previous step. If so, repeat this step. If you damage the o-ring, please contact us for a replacement. Because of the learning curve associated with this portion of the shock assembly, and the chance of the o-ring getting damaged and running you day. We include a free KYB OEM o-ring with our 215/VM2-K5 orders. Do not attempt to substitute this or any o-ring with a universal replacement.

18. Now you can install the aluminum compression adjustor assembly barrel. Make sure the edge with the step faces downward. Inspect with flashlight. Note that there is a thin washer that isolates the steel adjustor piston from the aluminum of the barrel. Some shifting and repositioning of the barrel may be required to get both items into their proper position.

19. Now install the spring. Note that alternate spring rates are available, mostly for off-road or woods applications. Contact us for details.

20. Take the blue high/low speed adjustor and turn the low-speed screw outwards (counter-clockwise) using a standard screwdriver. Now install the blue portion of the adjustor onto the stem of the piston assembly. There is also a washer that sits between this piece and the spring. Either put the washer on the spring first, or retain the washer onto the adjustor with some oil.

21. Place the aluminum cap of the adjustor assembly over the blue adjustor so that cap is floating just above the shock body hole and the inner adjustor nut. At this stage, don’t force the cap into place. Then pour a small amount of fluid down into the center of the cap between the cap and blue adjustor nut. You may have to slightly lift the cap to get the fluid to purge up and from out of the space between the o-ring and shock body. At this stage, it becomes obvious that there is no air anywhere within the shock body or adjustor assembly. Even with the cap loose, the fluid will not flow out, but keep an eye on the cap just in case.

22. Slowing add about 2 to 3 PSI of pressure to the nitrogen bladder. This will cause a small amount of fluid to purge up and out from around the cap. If there was any trapped air within the cap, this will get it. Additionally, this step helps to insure that the bladder is not in a collapsed state. Note that we recommend only using nitrogen with filling a bladder as to prevent the entry of moisture into the bladder. However, if you don’t have the means to control a slow low pressure movement at this stage of the build, then a device such as a small bike bump may be a wiser option. You’ll also get a feel for how much pressure the bladder requires to be fully extended. Some bladders, due to their use and improper installation, will tend to fold in on themselves thereby requiring a bit more pressure to bring them up. The point here is that you use this step of the process to fully extend the bladder in an installed state, while removing any residual bubbles trapped within the adjustor cap.

23. Next, turn the cap down into the shock body (clockwise) at the same time you are turning the blue adjustor nut outwards (counter-clockwise) and back into the cap. This may require a few practice sessions, but once you do it once or twice, it becomes very simple. When you have the o-ring of the cap seated just into the shock body (so that it won’t leak) fully turnout the blue adjustor nut starting with a screw driver, then concluding with the use of a 17mm tool, (this helps to preserve the low speed screw).

24. With the blue adjustor fully into the cap, tighten the cap into the shock body. Note the position of the two peen dimples created at the factory.

25. Using your nitrogen source, fill and empty the bladder about 5 to 10 times, (about 10 to 20PSI) then do a final fill using a zero-loss release chuck. Your nitrogen pressures will vary depending on your weight and needs. Do not assume a one charge fits all approach. A nitrogen charge can be used to fine tune the performance and characteristics of the bike, so if you have any questions involving this matter, please feel free to contact us or use the following table.

Nitrogen Pressure Recommendations

Light Rider – Light Application	130 to 135PSI
Light Rider – Heavy Application	135 to 140PSI
Medium Rider – Light Application	140 to 145PSI
Medium Rider – Heavy Application	140 to 145PSI
Heavy Rider - Light Application	145 to 150PSI
Heavy Rider – Heavy Application	150 to 165PSI

If excessive hard bottoming occurs at a suitable sag setting, add more nitrogen. If the shock feels too harsh or too stiff at the end of the stroke, or if the rebound rate at the end of the stroke is too rapid, then lower the nitrogen pressure.

IF YOU HAVE ANY QUESTIONS:

Please contact us at

SMART Performance Inc.

217 Lorain Place

Los Gatos, CA. 95032

408-406-2089

info@smartperformanceinc.com