No matter how much power your engine makes, it will do you absolutely no good if the bike’s chassis is the limiting factor. Although most modern sportbikes have suspension that is far superior to the stock suspension shipped with bikes even just five years ago, it still tends to be primarily engineered for a sedate street pace with soft springs and incomprehensible valving choices by the OEMs. At a number of recent late-model press launches the factory technicians had set the rear rebound damping adjuster at full hard or one click off of full hard. You would think that at some point they would recognize that if they are shipping the bikes with a suggested setting of "full hard" they might want to rethink the valving selections they are making at the factory.

Until the factories decide to up the specification on the stock suspension, building a front-running Supersport-class racebike is going to mean hitting the checkbook for a few purchases. On the 600s built in this series of articles we re-valved and re-sprung the forks, replaced the rear shock outright, baselined the sag and damping in the garage and then tuned the front and rear ride height at the track. In the process we disassembled most of the chassis to grease and adjust all the major suspension bearings. The R and R of the suspension will be covered in this installment; the tuning of the components will be covered separately.

In the dark days of the early 1990s when we used square wooden wheels and friction damper suspension we did our own fork work. However, the modern cartridge forks (and especially the inverted forks) usually require special tools to disassemble without harming the workings of the damper and are generally a pain in the ass to work with and so for the last six years we have taken to contracting out our fork work.

There are a number of good shops in the country for fork work. Over the past 13 years we have used forks from Lindemann Engineering, Traxxion Dynamics and Thermosman Suspension. There are really three main factors we consider when we get ready to send out a set of forks. The first is reputation (i.e., did we like their work in the past, did others like their work in the past), the second is trackside support (i.e., will the guy who worked on the forks be at the track to help tune them, replace seals when they blow and perform other trackside support services) and the third is price. Although the professionals will be able to get your bike in the ball park, perhaps even to the 90 percent level, we usually end up making some adjustments to the fork specification ourselves—usually fork oil level but sometime springs and almost always the adjusters.

The forks on the Suzuki have some pretty good internals and a re-valve and re-spring will usually cost around $300-$400. The internals on the R6 are not as good and, since more pieces need to be replaced, they cost about $750 a set to be reworked.

We usually hang the bike from a garage rafter using a couple of soft ties and a come-along and remove the forks. Once off the bike the forks are pretty delicate pieces and should be packaged for shipping with a fair degree of paranoia before entrusting them to UPS.

While the forks are away for surgery you can tend to a few other items of business. The first is the suspension bearings. The Japanese might not have invented the concept of planned obsolescence but they have certainly done an admirable job of instituting it. One of the most visible manifestations of this is the fact that the motorcycles are shipped with only the most parsimonious allotment of grease in the steering head bearings. With the forks away and the chassis suspended by soft ties through the frame (not the top tree) it is a pretty simple matter to remove the trees and thoroughly grease the steering head bearings. We usually keep a tube of synthetic grease around for this purpose.

Apparently there is some sort of endemic shortage of grease on the Japanese assembly line. This is a classic example of what you can find on the steering head bearings of any brand new showroom model. You really shouldn’t be able to see that much shiny metal.

Much better. You can just barely see the dull glint of ball bearing straining to peek through a heavy veil of grease on the lower stem bearing, and the upper stem bearing in the foreground has a solid topcoat of grease and is about to receive the same treatment on the other side. Use generous amounts of grease and spread it thickly over and throughout the bearings, spinning the balls as best you can to ensure full grease coverage. It’s hard to use too much grease. You can always wipe off the excess once you have the front end assembled.

In the bad old days motorcycles came with loose-ball-bearing head bearings. These had the average life expectancy of a tsetse fly and the trick upgrade on your RD350 was replacing the ball bearings with tapered roller bearings. The tapered bearings had a much-improved life (probably because when they were installed the owner usually greased them at the same time) but had to be adjusted very carefully. Even slightly over-tightening a tapered-roller-bearing steering stem will cause the bike to wander drunkenly akin to a steering damper that is turned up too high. On streetbikes an indication of notched or overly tight steering bearings is the bumping of more car mirrors with your handlebars than you planned while lane splitting. In the mid-1990s the trend reversed and most bikes now come with ball bearings again, although the bearings are now captive. These suffer from the same durability issues of their ancestors (we have seen brand new bikes with corroded head bearings) and it is very important to grease the snot out of them. Another downside to the trend back to ball bearings is that in a pinch (say, North Carolina at 2:00 a.m. on a Sunday) you could pull the tapered roller bearing out of the steering head on your FZR400 and use it to replace the smoked wheel bearing on the van to get the rig 20 miles down the road to the next auto parts store with Sunday hours but you can’t do that with the ball bearing type.

After you’ve drowned your bearings in grease, it’s time to adjust them. With the top triple clamp off but the forks and front wheel installed, remove the lock washer and loosen the locknut. Tighten the adjuster nut (the one on the bottom) until you feel a slight bit of friction when turning the front end just off of center but the front end will still gently fall to one side, and them jam the locknut against the adjuster, holding the adjuster nut to make sure it doesn’t spin. We find the spanner wrench included in a stock BMW motorcycle toolkit to be especially handy for adjusting these nuts. When you have the proper feel, install the lock washer, the top triple clamp, and the steering stem washer, and then tighten the steering stem nut to spec. Then, check the feel again. If there is too much friction in the side-to-side movement or if you feel any notchiness, back everything off and try again. Typically the bearings will tighten dramatically when you torque the top nut.

If you asked a suspension tuner what the most commonly overlooked handling problems were he would probably say "tire pressure" closely followed by "loose head bearings." Since most racers use rear stands, the head bearings will rarely be checked for condition or adjustment. This is a big mistake. Head bearings usually corrode or notch with a groove right in the middle of steering travel, i.e. when the wheel is pointed straight. The swingarm pivot on some bikes has a large enough inner diameter to pass through a 5/8-inch rod that can be used as a support to pivot the front end up in the air for quick checks. We have a purpose-built stand for this, and Pit Bull may sell one. This stand also allows removal of the rear shock and wheel without garages and rafters nearby.

With the front end unweighted (i.e., the bike suspended from the frame or pivoted up around a swingarm stand) and the steering damper removed the steering should move freely side-to-side with absolutely no little faint notch in the middle. Any notchiness means it is time for new head bearings (and this time put some grease on them). There should also be absolutely no free play front-to-back on the forks when pulling and pushing them from the bottom of the fork legs. If there is any free play, the steering bearings need to be tightened. If you have to adjust them and you have clip-ons installed under the top triple clamp, remember to loosen the clip-ons before performing the adjustment. After tightening the bearings, feel for a notch again.

We had heard from several people about the frailty of the previous generation R6’s steering head, and how in a crash it was possible for the steering stop to hit the steering so hard as to knock a chunk off the frame, thereby destroying the frame. We heard of two ways to prevent this from happening: 1. affix wheel weights to the frame where the steering stops contact, forcing the wheel weights to absorb the force of impact, or 2. make relief cuts in the steering stops so they would shear off before the frame would break. There was no inexpensive way to determine if the new frames have the same weakness as the old frames so here we are with our hacksaw blade relieving the steering stops.

Without a steering damper on the bike we aim for a front end which will just fall to the side under its own weight with the fork tubes and front wheel installed and after the top nut has been torqued, but which has no free play front-to-back. Those top nuts seem to fall off a lot at the track so many people seem to have a problem with tightening them to spec. Tapered head bearings are much more sensitive to adjustment than the ball bearings, which is probably why ball bearings have come back into fashion. Overly tight head bearings make the bike wander at low speed and make it difficult to hold a line. Loose head bearings will allow the bike to wobble at speed and especially on deceleration, and generally have loose and imprecise steering.

While you are working around the triple clamps, drill and wire the mounting bolts for your steering damper. Many preventable crashes have been caused by one of the mounting bolts or nuts falling off of the steering damper which then, at best, no longer damps the steering, and, at worst, wedges the forks to one side or another. These bolts are subject to a lot of twisting motion from the damper working back-and-forth on them which is probably why they have a tendency to loosen more so than, say, a rearset bolt. These bolts are often supported on one side, in single shear, so it’s not a bad idea to replace them every now and again with a new one, from a reputable bolt manufacturer. Read Carroll Smith’s Nuts, Bolts and Fasteners and Plumbing Handbook (known affectionately to many as Screw to Win) for chilling tales of counterfeit bolts and bad design.

Once you are sure you have achieved steering head bearing adjustment nirvana, our recommended tightening sequence for the remainder of the front end is as follows:

Then, check your front-end alignment, which is usually best done by riding the bike and making sure that the triple clamps point in the direction the bike is going. If your alignment is off, loosen everything and tweak accordingly. If you continue to have trouble with the alignment, check to see if your axle spins smoothly and if you can slide the forks easily through the triple clamps. A sticky fork or binding axle is indicative of a bent axle and/or front end.

Make absolutely certain that all bolts (triple clamp, clip-ons, axles, etc.) are torqued when you finish messing around with the front end. Marks punched into the triple clamp can help with aligning clip-ons in a hurry after adjusting the front end.

Most factories are a bit better about greasing the rear suspension bearings than the steering head bearings but it is still worth the time and effort to remove the swingarm and suspension linkage from the frame and thoroughly grease all the bearings. These linkages have a very hard life and will tend to start showing free play pretty quickly, which leads to imprecise rear suspension action. With the bike hung from a chain and the rear wheel removed it is pretty easy to feel any free play in the shock linkage just by pulling up and down on the swingarm rails. Changing out all the bearings and sleeves is a real pain in the ass so it is much better to grease them thoroughly when new and try to eek all the life out of them that you can.

Where’s the grease? Here’s a practically naked rear suspension linkage dogbone. Children, cover your eyes.

There’s the grease. Remember, this is America, and more is better.

As a side note, if you are switching to 520 chain and sprockets and do not have the tools to install a rivet-type masterlink in your new 520 chain, take the chain to a dealership, get it cut to the proper length, have them install the masterlink, and then install the whole "endless" chain on your bike while you have the swingarm off. If you have a bike that has a braced swingarm (ala YZF-R6, GSX-R750) you will need to bring the swingarm with you to the dealership so they can thread the chain through it before installing the rivet.

Grease smeared all over everything is a good indication that you used enough grease. Here, part of the thoroughly greased suspension linkage is about to be united for the first time with an aftermarket shock. The red anodized piece on the shock under the knurled bit is the rebound damping adjuster.

After re-installing the swingarm and one or two of the bolts of the shock linkage we install our high-dollar race shock. We’ve used Fox and Penske and have heard good things about Ohlins. The question of which shock to use really comes down to the same criteria as the forks, namely trackside support and price. If your local suspension consultant is an expert with Fox shocks you are probably better off getting what he is familiar with than getting a different brand and trying to find a set-up on your own. At a minimum it prevents you from having the guy tell you "Those (insert the name of your shock) aren’t worth shit you need a (insert name of shock he sells)." We use Penske because that is what the suspension guys who attend WERA Nationals are regularly tuning. That said, our favorite shock of all time was a Fox that Keith Perry had set up for Josh Hayes a long time ago. At a minimum you will want a shock with adjustable ride height, compression damping, rebound and spring preload.

Whatever you decide to use, make sure you torque all the bolts to the specification in your shop manual and make sure you don’t let anyone interrupt you while you are performing this most delicate task. Also, we try to feed the bolts in from the side away from the exhaust pipe to allow us to remove the shock or change springs without having to disturb the exhaust. It is a very good idea to make sure that the shock reservoir has ample clearance to the rear wheel as we’ve seen this cause accidents when the rear wheel wedges on the reservoir. We’ve also seen the hose from the shock to the reservoir rub through on the rear tire of a bike (with ugly consequences). We typically use really thick and heavy-duty cable ties to secure the reservoir because they’re handy. If you decide to use hose clamps make sure that you only tighten the hose clamps on the ends of the reservoir to avoid distorting the reservoir and thus keeping the internal piston from moving freely.

Torque that linkage! If you always use a torque wrench to tighten all of your bolts you can avoid the twin evils of bolts that loosen while riding or break while tightening.

Of course, removing your suspension and putting it back on won’t make the bike much better so in a later chapter we will discuss what rake, trail, spring rates and damping mean.