Routine servicing of the swingarm and linkage bearings, as well as the pivots at each end of the rear shock(s) on a modern, or vintage style dirt bike is something that is supposed to be considered routine dirt bike maintenance, but It's pretty well known that servicing swingarm and linkage bearings, as well as service of the shock absorber(s) / damper(s) pivots is something that is commonly put off until "next time" on a lot of dirt bikes, so this article is written for those with vintage style bikes or modern weaponry, (linkless bikes included) to get their rear suspension dialed and any slop gone.
It's really no secret that servicing / lubricating the rear suspension of a dirt bike on a regular basis can provide a smoother ride, and a better handling or more predictable motorcycle the next time you're railing berms and charging into some of the deepest, gnarliest braking bumps at a motocross track, as well as a freshly serviced rear suspension providing a better ride next time you head out in the woods for a Trail Ride, GNCC Race, Hare Scramble or Enduro, as well as "going off" on the ramps.
If you have a bike without linkage, just skip over the info about linkage throughout the article and you'll find the rest is applicable.
If you recently bought a used dirt bike, it's probably safe to assume that the swingarm and linkage bearings and / or shock absorber(s) / damper(s) pivots all need servicing.
We cover this below but don't be surprised if you see parts falling out in a pile of red dust upon disassembly...
In addition to the above mentioned signs of the swingarm and linkage bearings needing service, and / or shock pivots being in need of service, Another good indicator is while the dirt bike is on a stand, with the rear wheel off the ground, there should be NO movement (slop) up and down, nor from side to side.
A simple and effective way to check for wear within the rear suspension is with the motorcycle on a stand and the rear wheel hanging. Grab the rear wheel or swingarm by hand and lift upward slightly, as well as pushing and pulling from side to side.
Note: When lifting on the swingarm, you are only wanting to lift with enough pressure to feel for any slop in any bearings, and not lift the swingarm in a way that the shock begins to compress, or the entire motorcycle comes up off the stand.
If there is enough wear that it's noticeable while doing this, the swingarm and linkage bearings and / or shock pivots are definitely in need of service and should likely be replaced as well, since cleaning and lubricating alone will not take this slop out, and pretty much everything you need to know is detailed below.
Before you get too far ahead of yourself, it's also a good idea to get a factory service manual specific to the motorcycle you're working on, as you'll be needing
this during reassembly for torque specs, and setting bearing depths, as
well as other info throughout your days of working on the dirt bike.
Using improper tools here WILL result in damaged threads at a minimum, and likely a "Mushroomed" shaft which will require grinding and additional work to get it to pass through the collars / races.
If there is any "beating"
required, make sure to use some good, quality penetrating oil,
A Brass
Punch and a brass hammer to help move the bolt / pivot shaft through the
swingarm and linkage bearings races / collars or shock absorber(s) /
damper(s) just don't keep beating the shaft / bolt through the
swingarm and linkage bearings in one direction only. You'll need to
"work" the shaft / bolt back and forth from both directions, gradually
working it loose and out.
If you get the idea to fire up the torch and heat things, that may not be such a good idea. When working on the rear suspension / swingarm and linkage bearings, as well as the rear shock absorber / damper (which is gas charged), if the pivots are seized and not moving, heat is not going to help much, as the heat often cannot be directed where it needs to be, which is directly at the inner collar / race that the pivot bolt passes through and is seized to. Bottom line is applying heat to the swingarm or linkage is not going to do much good.
On the linkage or shock(s)... When you're cleaning the linkage bearings or shock bearings, be sure to pay close attention so you don't lose any of the needles that make up these bearings, as there are a lot of them and they will all come out during cleaning.
For those only needing specific parts, there are separately packaged Swingarm Bearing Kits, linkage bearing kits
which come complete with bearings, collars, races and seals to facilitate a full overhaul of the linkage,
leaving you only needing a Shock Bearing Kit
, some good,
high quality, high performance grease, rags, cleaners and time to do this right.
Note: Shock absorber bearing / pivot kits frequently come with a top spherical, or needle bearing, as well as a bearing or bushing that goes into the part that the shock absorber bottom mount attaches to. This is generally the swingarm on linkless setups, or the rocker on linkage style setups.
Additionally, If things have been going smoothly with disassembly, and even if you were not aware of any slop in the rear suspension, but after cleaning the parts and inspecting them, if you notice any "Blueing", "Pitting", "Notching", "Grooving", Corrosion or other noticeable wear of the needle bearings, collars, bushings or any of the other parts that make up the rear suspension's pivoting, as well as if you notice any missing needles from a bearing during reassembly, it is highly recommended that you replace these parts while you have it all apart, this way you will be able to obtain the best performance from your rear suspension and have a sweet handling ride.
If everything looks good after cleaning,
and only
needs a fresh coating of grease,
Here's a Quick link to Lubricating the Rear
Suspension
First grab the new parts (bearings) and apply a light coating of an "Anti-Seize" compound to the outer shell / race of the bearings where they will be in contact with the swingarm, linkage or shock absorber(s) / damper(s) and then throw 'em in the freezer for a few hours (overnight is better), then we'll continue.
If you don't have any "Anti-Seize", you'll be needing it in future uses as well, so now is a good time to get some and it is available at most auto parts stores, but be sure to get the anti-seize in a jar with an applicator brush.
Removal of either swingarm and linkage bearings or shock absorber / damper pivots needs to be done by steady pressing action. If you don't have access to a press, all is not lost as this can be done with a vise and sockets, (although a press is the preferred method).
Below, you'll find instructions for using a vise and sockets to remove and install the swingarm and linkage bearings, as this is what most people have access to, although before continuing, it is recommended that you have "Soft Jaw Inserts" in the vise, so as to not damage expensive suspension pieces with the jaws of a vise, which are commonly sharp and of a very hard material that easily damages aluminum or other suspension pieces and tools.
If you need soft jaw inserts for your vise in a hurry, and don't want to, or have time to wait for magnetic inserts to show up in the mail, nor can you find any locally, you can head down to the hardware store and pick up a length of 1" aluminum angle material and cut 2 pieces the width of your vise jaws which you'll find will work very effectively.
Once you've cleaned the part to where details are visible, removed any retaining clips, and examined the parts for any shoulders that the bearing(s) may be butted against, it's a good idea to make a note of the depth of each bearing in it's bore so you know how deep to install the new bearing(s).
It's important to clean all the parts which may be reused and thoroughly inspect the bores, looking carefully for any nicks, gouges, burs or raised areas in the aluminum, steel or unobtainium that may have been caused during removal of the old bearing(s). During your inspection, you'll likely find that using your finger to feel for any irregularities is the best way to ensure a smooth bore for the bearing to be reinstalled to.
If there is any damage / irregularities noticed in the bores where the bearings are going to be installed, it's important to address this before re-installation of a new bearing, and this can be done best by using a light grit sandpaper held on your finger, but when removing any burs or the like, it's important to use care so as to not remove any more material than is necessary to restore a smooth bore, then go over the bore once again with scotch-brite to achieve a nice smooth hole for the bearing to fit into.
Considering
that there is little to no grease installed from the manufacturer in
replacement swingarm and linkage bearings, as well as shock absorber /
damper pivot bearings (whether OEM or Aftermarket) you will need to
apply a good, high quality, high performance grease such as Bel-Ray's Waterproof Grease to the bearings before reassembly of the pivot collars and seals, or
assembly of assembled components to the motorcycle, all of which is
discussed below.
If you're working with new, freshly installed bearings...
If you just finished installing new bearings with the steps detailed
above, before you begin installing the collars and seals and
reassembling everything, it is highly recommended that you slather some
good, high quality, high performance grease such as Bel-Ray's Waterproof Grease into the bearings before assembly, then assemble everything,
torquing all bolts to the manufacturers recommendations as can be found
in a factory service manual
specific to the motorcycle you are working on.
For those who are working with preexisting bearings...
If you're only in this for some routine preventative maintenance and
you are working with bearings that have just been cleaned, and are in
good shape, you likely have a pile of needles laid out on a clean rag and
are ready to get this whole mess put back together.
With everything clean and either inspected or replaced, go ahead and apply a layer of grease to the bearings in the swingarm as these are generally caged bearings and all the needles remain intact during cleaning (or should anyways). Once these bearings have been greased, the remainder of the swingarm pieces such as thrust washers and thrust bearings, as well as the inner collars and outer seals can be reinstalled to the swingarm as illustrated in a factory service manual specific to the motorcycle being serviced.
After reassembling all the pieces to the swingarm pivot, you'll need to reinstall the loose
needles back into their respective bearing's outer races. Reinstalling the needle bearings is best
done by applying a thick coating of grease to the inner circumference of
each outer bearing race, then reinstall the individual needles to each
race, being certain there are no gaps remaining between needles before
installing any collars through the middle, finishing this by
reinstalling any seals or outer collars while being certain to pay attention to the direction of any collars or
seals and reassembling the shock
linkage, then reinstall the assembled linkage to the swingarm and lastly installing this assembly to the
motorcycle and install the rear
shock absorber(s) / damper(s) to the motorcycle, torquing everything per
the manufacturers recommendations as can be found in a factory service manual specific to the motorcycle you
are working on, then completing the job by reassembling any other parts that were removed.