Dirt bike swingarm maintenance

1 Some owner's manuals suggest inspection and/or service of the linkage and swing arm bearings after every 7.5 hours of riding. This time frame may or may not be realistic, but you should definitely do it regularly. Your linkage and swing arm bearings take a pounding, so it is to your benefit to maintain them. In addition to the bearings, the chain sliders and chain adjusters should also be inspected and replaced if necessary. Note: Bearing replacement is not discussed here.

2 You don't always have to disconnect the brake line to remove the swingarm. Many configurations allow you to slide the caliper assembly off the swing arm with the hydraulic lines in place. You'll need to remove all of the hose anchors.

3 Tie the caliper out of the way as you see here. The location is not important so long as the caliper and hose are out of the way. Be careful not to twist or kink the brake hose. Move the caliper in such a way as to follow the natural bend of the brake line as closely as possible.

4 On most bikes, you will have to dismount the rear brake lever from the frame to allow room for the swing arm pivot bolt to slide out. Now is a good time to clean in and around the pedal pivot area. You should clean, inspect and grease the pivot pin and pedal bore during assembly. It is usually much easier to remove and install the pedal spring when the pedal bolt is removed. Watch for the washer that sits behind the pedal mount, when you remove the bolt.

5 You can let the pedal hang on the master cylinder connection. If you can't get it out of the way, another option is to remove the master cylinder with it. The entire rear brake system can sometimes be removed intact as an assembly.

6 Not all linkages are the same, but they are all very similar, having only subtle design differences that are unique to a particular brand of bike. To get the swing arm out, the lower shock must be disconnected and the linkage to frame connection must be undone. Depending on the bike, you may have to disconnect the linkage from the frame first to allow access to the shock bolt.

7 Make sure you use properly fitting sockets and wrenches. DO NOT use adjustable wrenches on your bike! The linkage bolts will likely be very tight. You may need a pin punch to drive the bolts out once the nuts have been removed. The bolts should come out easily and you should tap on them gently so you do not damage the threaded ends. Be aware that the swing arm is going to drop down, so you should support it while removing the bolts. Also, if you can support the swing arm, the bolts will slide out much easier. If your linkage has been negelcted, however, these bolts could be difficult to remove. For stubborn bolts, spray them with WD-40 and wait for a few minutes.

8 The linkage to frame connection is disconnected here. Now, only the shock absorber is preventing the swing arm from falling down and there is easy access to the lower shock bolt.

9 With the lower shock bolt removed, there is no longer anything to hold the swing arm up. Support the swing arm and lower it carefully.

10 Now only the swing arm pivot bolt remains. Remove the nut and drive the bolt out using a long punch. Do not carelessly beat on this to get it out. Carelessness can result in the end of the bolt being mushroomed. Light but firm tapping should suffice. A long punch will catch the swingarm when the bolt is extracted. Use a punch that is smaller in diameter than the bolt.

11 Once you have the bolt out, the swing arm may still be tight in the frame. This depends on the fit, type of bike etc. If the swing arm doesn't drop out, gently pull it straight back while wiggling it sided to side. Optionally, you may be able to lever it out with a large flat blade between the frame and swingarm. When handling the removed swing arm, watch that the seal bushings and bearings do not fall out. You can use ties or wire to hold them if necessary.

12 Now that it is out, you can work on it more conveniently on a work bench. Take some time here and clean any spots that were otherwise inaccessible.

13 Before getting involved with the linkage bearings, I suggest addressing the adjusters, chain guide and chain slider first. Working on these first will help you achieve a cleaner swing arm prior to servicing the bearings. What you choose to do first is soley your discretion, but cleanliness is crucial when servicing bearings and pivot points. Here you can see the adjuster lock nuts need replaced.

14 A socket on an extension makes it very easy to remove the adjusters, especially if you can't turn them with your fingers. Even if the adjusters look good, removing them for cleaning and inspection is beneficial. With them removed, you should brush the threads clean so they thread in and out easily. You may need to use a tap to clean the threads in the swingarm, which should be done with great care. You can damage good thread material with careless use of a tap.

15 Everything on this swing arm was in excellent shape except for the lock nuts. At this point I have the lock nuts replaced with some nice flange nuts. I locked them in place because I had previously measured their position with the chain correctly adjusted.

16 This is what happens when you fail to check your chain guide. Fortunately, the damage to the aluminum housing was minimal and all I needed to do was some file work.

17 The chain guide is as important as anything else on the bike. Make sure nothing is broken, stripped, bent etc.

18 Repaired chain guide housing with new insert.

19 Clean the screw threads with a brush and apply blue loctite.

20 Install the chain guide assembly. Get all of the screws started by hand first, then finish tightening them.

21 This chain slider had some life left in it, but it was worn enough that I decided to replace it. The cost of a swingarm is not worth neglecting the chain slider.

22 Before putting the new chain slider in place, clean the swing arm surface and inspect the screws and screw holes, replacing/repairing as needed.

23 Put a drop of blue Loctite on each of the screw ends and install the new slider. Leave the screws loose until all of them have been started, which will make lining up the holes much easier.

24 Now it is time to tackle the linkage. Even though the linkage components will only fit properly one way, I suggest marking them as you see here. This will make reassembly both easier and faster.

25 Disassemble the linkages and lay the pieces in an orderly fashion.

26 Clean the linkage parts again while being careful not to allow any of the seal bushings to come out. At this point, you need to insure there is no dirt on or near the parts and work area.

Remove dirt that is packed in the groove of a seal using a very small flat screw driver or pick tool. When doing this, you must be extremely careful not to poke the seal lip. The seal groove is between the seal lip and the seal body. Wipe the dirt from the tool as you gently extract it from the seal grooves.

27 Linkage systems use needle bearings. Hollow bearing shafts are used that ride directly on the needles. The ends of the shafts are capped with seal bushings to keep the elements out and the grease in. All of these components should come apart easily under normal conditions.

To remove a bearing shaft, first remove a seal bushing from one side. You may be able to do this by anchoring your finger in the hole of the bushing and pulling outward. If that does not work, you can use a small, thin screw driver tip and carefully push it between the contact point of the shaft and bushing from inside the bolt tunnel. Work around the circumference evenly to pop the bushing out. When a bushing is out on one side, you can drive the other out by pushing on the open end of the exposed bearing shaft.

Generally, there are two styles of needle bearings: Caged and non-caged. If you have non-caged needle bearings, the needles are going to fall out. This is to be expected, especially if the grease is gone or broken down. Don't worry about it though, just make sure not to lose them and definitely keep them clean. Remember to keep everything organized so you know where everything goes. If you have caged bearings (as is the case here), the needles should stay put. This is not always a given though. The cages do not always hold very well, especially with old bearings.

28 If the seals are in good condition, I prefer to clean the bearing bores with the seals in place, unless I can wiggle them out with my fingers. Leaving them in makes cleaning a little bit more difficult, but it eliminates the risk of damaging good seals. If they will slide out using your fingers, take them out. A good seal has a lipped edge that tightly fits around the seal bushing. There should be no gaps, cuts or abrasions on the seal lip. The outside of the seal should fit tight in the linkage bore.

29 Use a parts cleaning solvent or degreaser (such as Power Purple or Gunk Purple Cleaner) to clean the parts. For small parts such as these, I like to use a plastic jar. I put the parts in the jar with the cleaner and swirl it to dissolve the grease. I then remove them, dry them with a shop rag, and use compressed air to complete the cleaning. A good rule to follow is to clean the least critical parts last. Cleanliness is of utmost importance when dealing with parts such as bearings, so these should be cleaned first, then placed in a location so they can not get contaminated (use baggies or clean containers). After cleaning, carefully inspect each of the bearings, shafts, bushings and seals. Bearing condition will be evident by the condition of the shaft surfaces. If there is pitting, flaking, rust, flat spots or grooving, replace the suspect bearings and shafts. Never use a new bearing on an old shaft or a new shaft on an old bearing. You can drag the tip of your finger nail across the shaft surface to feel for grooving.

Caution! If your bearings are caged, be very careful when blowing them out with compressed air. The force of the air can dislodge them from the bearing cage causing the rollers to fly out.

  • Caged bearings: Must be cleaned while mounted.
  • Bearings that are not caged: The needle rollers should be removed and cleaned in a container as mentioned above. The bearing races (cages) will have to be cleaned in place.

30 If all of the parts are clean, dry and in good condition, you are ready for grease. I recommend Silkolene PRO RG2. There are also excellent automotive and industrial greases. I have had excellent results using extreme pressure lithium based industrial/automotive grease such as those by Valvoline and Citgo.

If you removed the seals, put them back or replace them. Set a seal in its bore straight. Use a socket that is slightly smaller than the outside diameter of the seal and gently tap on it to drive it in. Not all linkages have counterbores inside for the seals, so you will have to watch how far you drive them in. If there are no counterbores, stop driving the seal when it is flush with the outside surface of the linkage. Seals must be mounted squarely.

  • Non caged bearings (all of the rollers fall out): It can seem frightening when rollers fall out, but this is normal for this type of bearing. Reinstalling the rollers is no big deal, but you must pay careful attention to what you are doing. It is critical that you install the correct number of rollers as well as put them back in the same cage they came from. To do this, place a thick coat of grease around the inside of the bearing races. One by one, place the rollers in each bearing race. Make certain you have the correct number of rollers! The grease will hold the rollers in place, just be careful not to knock them back out.
  • For caged bearings (the rollers do not fall out): Work a liberal amount of grease into the spaces between the rollers using your finger.

31 When you have one set done (for one shaft), coat the correct bearing shaft with a light film of grease and carefully push it straight into the bearings while rotating it slowly. If you have bearings that are not caged, watch closely that you do not dislodge one of the rollers. Even after successful shaft placement, check for the presence of stray rollers that may be hiding behind the seals.

32 In this image, you can see that I have all of the bearing shafts installed and ready for seal bushings, which is fine. I would suggest an alternative however, which is to do one full bearing set at a time. The reason is: The placement of seal bushings will prevent the bearing shafts from sliding out while you are working on the next set. This would be a good practice, especially if your bearings are not caged.

33 Install the seal bushings. Here you can damage the seal lips if you are not careful. When you install the bushings, do not try to push them straight in. Rather, approach the seal lip from the side, pushing outwardly against it. Work the bushing into the seal around the circumference in this manner to prevent damage to the lip. Having a pinched seal lip ruins the seal. The lip edge must ride uniformly around the outside diameter of the bushing.

34 A completed linkage. Clean away excess grease. However, leave grease present inside to pin bores. This helps prevent bolts from seizing and makes disassembly easier next time.

35 The swing arm pivot bearings are no different than the linkage bearings although there may be subtle differences. The difference here is the design of the bearing pin.

36 Clean, dry and grease the bearings and pins just as you would the linkage bearings.

37 Assemble the linkages to the swing arm and torque the bolts to the proper specification. Your owner's manual should provide the torque specs for the linkage bolts.

38 Before you begin installing the completed swing arm, have a good look at the underside of the frame where the linkage and swing arm attach. Clean all of these areas and inside of the bolt holes so there is no dirt. Also, thoroughly clean all of the remaining fasteners. Brush the bolt threads if necessary.

39 Coat your clean swing arm pivot bolt with a thin layer of grease and position it where you can reach it easily when you start to install the swing arm. Here I was able to lay the bolt across the brake pedal with the bolt end already at the bolt hole.

40 Slide the swing arm in to place. Once it is between the frame rails, you should be able to hold it with one hand. Align the swing arm to the frame bolt hole with one hand, and feed the bolt in with your other hand. If this task proves to be difficult, find a clean rod or long extension that is about half the diameter of the swing arm bolt. Align the swing arm to the frame as closely as you can and insert the rod into the swing arm through the frame. This will hold it in place making it easier for you to align the bolt holes without the worry of dropping the swing arm. As you insert the swing arm bolt, simply push the holding rod out with it.

41 Install the pivot bolt retaining nut and torque it to specification.

42 Aligning the shock absorber bolt holes requires moving the swing arm up. This can be tricky because you have to move the shock also, while trying to insert the bolt. To make it easier to align, you can use a jack stand or bottle jack to position the swing arm at the correct height so you do not have to hold it. For many bike models, it is actually easier to have the shock removed completely and mount the lower shock end first. Aligning the top mount is easier when the bottom is mounted.

43 Torque the shock retaining nut to the correct torque specification.

44 Aligning the linkage to the frame is no different than aligning the shock to the linkage. Move the swing arm up or down as necessary to align the connecting link to the frame mount.

45 Before inserting the mounting bolt, coat it with a thin coat of grease.

46 Torque the nut to spec. The swing arm is now complete and you can reassemble the rest of the bike.


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