VIRAGO BRAKES


HISTORY

Front Brakes

     In 1981 the Virago 750 and the 920 (chain drive) RH hit our shores. The 750's were fitted with a single disk and an unusual caliper set-up that used slanted brake pads. You have to see it to understand it. I've never found this set-up on any other bike but Yamaha may have used it on some other models of that era. The 920 came with dual disks. All disks were solid, and all calipers were single piston. These systems continued unchanged for the 750 through 1983, and for the 920 RH, RJ (chain drive) through 1982, when that model was dropped.

     In 1982 Yamaha shipped us the Virago 920 J which had shaft drive. It also had dual disks, and these were slotted. In 1983 the Virago 920 K model reverted to a single disk, which was also slotted, as I recall.

     In 1984, the major "cruiser" style change included dual disks for the 700 and 1000 models, and these were continued for all the later 750 and 1100 models as well. The disks started out solid, become slotted probably in the late 80's early 90's, and finally became drilled around 1996. All calipers were single piston, although I understand that dual piston calipers were fitted in England and elsewhere in later years.

Rear Brakes

     Rear brakes for all models started out, and have remained, simple drums brakes with a leading and following shoe setup

BRAKING QUALITY

     I would class Virago brakes as adequate for the style of riding practiced by most Virago owners. The designers were clearly not thinking about a bike that would be pulling down hard from 100mph on a repeated basis. The early single disks were just fair in my opinion. The dual disks were better. I'm not persuaded that the slotted and drilled disks provide much advantage over the earlier solid disks, although it can be argued that slots and holes do clean the pads better, are lighter (less unsprung weight), and have better heat dissipation properties. In my opinion, good brake pads will probably make more of a difference than slots or holes.

     The rear drums are powerful enough to lock the rear wheel, but will fade under hard, repeated braking.

     In summary all these bikes will stop, and the later models better than the earlier ones. .

BRAKE LINES

     On all Viragos, the rear drums are mechanically operated, so there are no brake lines. The front brakes are hydraulic, so we have master cylinders holding brake fluid, and hoses (lines) transferring pressure to the caliper pistons when the brake lever is pulled.

     In early 750's we had one long brake line. The stock line is a typical line made of rubber with a fiber reinforcement around the inner pipe ("bore") which carries the fluid. Even when new, these lines had a little "give" to them, so that the brake lever felt soft when it was pulled. This condition gets worse as the brake line ages. The solution is to replace it with a steel braided brake line, which pretty much eliminates any expansion, and gives a much firmer lever feel. The same problem occurs to a lesser extent with the dual disk models. Here we have one line going from the master cylinder to a "splitter" which has two lines running from it to the two calipers. So if we want to move to steel braided lines here, we are looking at three of them. See section on steel braided lines later in this article.

BRAKE FLUID (DOT=Department Of Transportation)

     DOT 3 brake fluid is specified by Yamaha for all Viragos, and DOT 4 can also be used. The chemistry (glycol based) is similar and these fluids can be mixed together. There is a brake fluid called DOT 5, but it is based on entirely different chemicals (silicon), and is seldom used in motorcycles. It does not mix with DOT 3 and 4, and once in your system, it is hard to completely clean out, so I wouldn't be tempted to use it in your Virago. For a good discussion of the different kinds of brake fluids, go to Google, search on "Dot 5 brake fluid" and read the article entitled "Tech Tip, Brake Fluid Debate". For our purposes, we'll confine our discussion to DOT 3 and 4 brakes fluids.

     What's the difference? The main issue is resistance to heat. Under heavy braking the calipers can heat up to the point where the brake fluid can boil, causing vapor lock (bubbles) and fading problems. As a practical matter this is much more of a concern with racing bikes. But in general, the higher the boiling point, the better the brake fluid.

     DOT 3 and 4 brake fluids are hydrophilic, that is, they have a strong affinity for water, and will absorb any that comes their way. (I've always heard that characteristic described as "hydroscopic", but unfortunately that word has never made in into the dictionary, best I can tell.) Anyway, whatever name you choose, this affinity for moisture in the air will, over time, cause water to sneak its way into your brake fluid. It gets there through slightly porous brake lines, joints in the lines, past the brake piston and master cylinder seals, and so on. It is estimated that the average braking system absorbs about 1% water per year. 3% is considered the maximum allowable.

     This has two consequences. First water will cause corrosion. Brake fluid contains corrosion inhibitors, but as they work they are used up, so if brake fluid is left in too long, corrosion will occur and sludge will form. The second consequence is that, since water boils at 212° F, the more water in the brake fluid, the lower the boiling point. Check out the following table. To pass DOT 3 and DOT 4 tests, brake fluids must meet the following specifications:

     Boiling Point Dry Boiling Point Wet (2.7% water)

     DOT 3     401° F     284° F
     DOT 4     446° F     311° F

     But note that for more money can now buy a better brake fluid (probably overkill for cruising type riding):

     Motul RBF 600     594° F     421° F (Racing Brake Fluid)

     All these brake fluids can be mixed. And all will trash paint in a hurry so don't spill any on your bike. Or if you do, clean it off immediately-and follow with some soap and water.

BRAKE PADS

     There are several attributes of brake pads worth mentioning. First and foremost, we'd like them to stop the bike quickly and safely. But we don't want them to grab too hard initially. And we don't want them fading under hard or repeated braking. We don't want the pads to wear too quickly, but we would like them a little softer than the rotor material, since a worn rotor is much more difficult and costly to replace than are brake pads.

     Pad materials were described in one article I read as follows:

     "Organic" The friction materials in these pads contain no metal content and are made of such compounds as Kevlar, ceramics, and other materials. (Typical "cruiser" pads)

     "Semi Metallic" Friction materials here have up to a 50% metal content. This metal is present as small particles and mixed with other friction materials, all of which are suspended in the resin base. My understanding is that metal is used because it has a higher coefficient of friction (grabs better) and dissipates heat better, transferring less to the caliper.

     "Sintered" The friction materials suspended in the base are more than 50% metal.

     I think I've got this more-or-less right, but a Google search will get you a lot of information here and you can dig deeper if you want to. Check out EBC, Galfer, and SBS.

     Generally, cruising style riding places moderate demands on brake pads as opposed to racing or aggressive sport riding. And typically organic brake pads are specified for cruisers, and fitted to new cruiser bikes (OEM) by manufacturers. These give adequate and controllable (not grabby) stopping power, and are easy on rotors. Heat dissipation is adequate, since the pads are not subjected to repeated or prolonged hard braking. Cruiser pads are designed to grip well when they are cold. Some racing pads are designed to grip at there best when hot, so "warming up your brake pads" can be an issue for racers. If you thrash your Virago like a sportbike, you might consider some metal content, at the expense of shortening rotor life somewhat. EBC, for one, offered sintered pads for Viragos as of a couple of years ago, and maybe still does.

     Brake pads usually have wear grooves in them which can be seen by removing an inspection plate fitted on most calipers. When the grooves are gone it is time to replace the pads.

     Pad suppliers are constantly experimenting and changing friction materials in response to the new rotor materials that are coming out.

     I can say with some assurance that most dealers sell their customers OEM pads from the bike manufacturer, with EBC as the next biggest seller. Ferodo maybe the choice of many serious sportbike riders, but they are harder to find and I doubt if many shops stock them.

BRAKE ROTORS

     Virago rotors are made of low-grade stainless steel. This is steel with nickel (and perhaps some other metals) added to inhibit rust. Any of you who have owned a bike with cast iron rotors will understand rust. At the slightest of damp conditions, a brown patina will start to develop on cast iron rotors. Rotor material keeps changing, and carbon fiber rotors are now offered for sport bikes.

     Virago rotors are "fixed" rotors. That is, they are bolted solidly to the front wheel. A very slight amount "runout", (side-to-side motion in the rotor as it spins, or "deflection" as Yamaha calls it) is permitted. But if the runout exceeds specs, then you may start to feel some vibration and throbbing in the brake lever when you brake, and you may get some intermittent rubbing when the brake is not being applied. Maximum runout is given in the service manual as .15 mm or .006 inch. If you exceed this, it is time to have the rotor straightened, or to replace it. Modern sport bike rotors are "floating" rotors, where runout can be handled better through the rotor's ability to move back and forth.

     Over time, rotors do wear, and once they get too thin, they should be replaced. The manual gives the standard rotor thickness 5 mm, and the minimum allowable rotor thickness as 4.5 mm. Rotors can sometimes get scored to the point that the owner may want to resurface them. Be careful that you find someone who really knows how to do this. The slightest difference in thickness will give you the same runout problem as warping, but such a rotor can't be straightened.

     Warping from heat is really not a common problem, so don't lose any sleep over it. Of the three types of rotors, one mechanic I know would say that slotted rotors are the most prone to it. I have no statistics or experience to back this up. As noted above a warped rotor can possibly be straightened, but a competent shop should be found which can evaluate the rotor to determine whether it can be safely straightened or not. The Frame Man in Sacramento, California is a shop in these parts that I trust.

     While you can debate whether drilled disks perform better than solid or slotted, they certainly do look cool. You should be able to find a shop nearby which will drill a pattern into your solid disks-but for a pretty good price. For those of you in the north country, you can find a drill pattern you like, transfer it onto your disks, get a cobalt drill of the right size, and while away those long winter evenings drilling your own disks. A drill press would be a must.

MAINTENANCE

     Change brake pads (wear indicators will tell you when)
     Change brake fluid every couple of years.

BLEEDING TIP

     When components (calipers) are removed for some reason, it maybe hard to start to feel a "lever" when bleeding. This is caused by air bubbles in the system that are not getting released through the bleeders in the calipers.. Try cracking the joint of the break line at the master cylinder-which is where the peccant bubbles typically hide.

DISASSEMBLING MASTER CYLINDERS AND CALIPERS

     For those of you who decide to disassemble your calipers for cleaning and perhaps new seals, you'll find that the pistons don't just drop out. They have to be pushed out. One way to attempt this is to pull the calipers off the rotors and push the pistons out with brake fluid by pumping the lever. Another way (and the one I use) is to remove the calipers completely and push the pistons out with air. But, either way you are faced with the problem of getting them out one at a time. To just apply fluid or air pressure will tend to move them both out at once, and they will meet in the middle and there you are. Two pistons part way out with no place to go. I use a C clamp and a piece of wood to hold one piston in place while I push the other piston all the way out. Then reposition the wood and C clamp over the open hole and us a piece of inner tube under the wood to provide a seal. Then the remaining piston can be pushed out. Note that the piston can pop out with some force using air. So you want to arrange things so it is not going to hit something hard that will damage it. Hitting wood is no problem.

SMALL HANDS

     Some folks with small hands have trouble reaching the brake and clutch levers. These levers can be modified by welding on a bit of metal to bring them closer. Just pull the lever in a little and you'll see where the build-up has to occur. The problem is that you lose "throw" and if the lever has a lot of play before it takes up, you may lose braking. However, with steel braided brake lines the play is usually small, so you should be able to do some modification here and still retain the full breaking leverage. However, such a modification is solely up to you so be careful to assure that it is going to work properly. The clutch lever is a different problem since the full throw maybe required to fully disengage the clutch.

REAR BRAKES

     As mentioned above, the stock rear brakes on all Viragos are good old fashioned drum brakes. They are operated mechanically and have an adjustment screw at the little arm on the drum. The only caution here is not to adjust them too tight. If too tight, they may not rub when cold, but on downhills, when you use them hard, they will heat up. They will expand, and can start to rub all the time, even when you are off the peddle. When this occurs the drums get really hot, and that heat is transferred into the hub of the wheel. One result is that the grease on your rear wheel splines can be boiled off, which in turn causes your splines to wear away-with expensive consequences.

Maintenance

     Maintenance of the rear brake is simple and includes changing out the shoes when they are worn out, and lightly lubing the cam (shaft and faces) now and then.

BRAKE LIGHTS

     Just check to see that your brake lights work when either the front or the rear brake is applied. And adjust if needed. I once had a friend who said, "I saw a bike with a really bright tail light, much brighter than mine. Can I get my tail light to be that bright?" "Of course", I reposted. "Just adjust your brake light to be on all the time. Then you too, can have a really bright taillight."

BRAKING TECHNIQUES

     This is a little beyond the scope of this article, but here are some basics. When you apply the brakes, the weight of your bike is thrown forward. This makes your front brake the major stopper of the two. It is generally taught that you should apply both brakes more or less together, with emphasis on the front brake. That's for on the road. If you find yourself on dirt, things reverse. In general, go slowly, and stay off the front brake, using the back brake only. This is because the front brake can lock, and (particularly when turning) cause the front wheel to "wash out" and the bike to go down.

STEEL BRAIDED BRAKE LINES

     You can buy these for Viragos from several different suppliers, or you can make your own. I personally use Goodridge components, and have always gotten good results. While not that hard, there are a few tricks to making them. In the interests of getting this article posted, I won't go into here. For anyone who has made it this far and would like to give building their own brake lines a shot, e-mail me and that will be my motivation to write out some instructions.