TIPTOP BRAKE TIPS

[dirt dame 561]

Now that it is summer and too hot to ride as often and as many places as we like, it is a good time to do the servicing to your bike that it needs.

Today, I am going to talk about brake service. After all, they are about as important as anything else on your machine, and timely work can save you big headaches later.

As many of you may know, you should flush your hydralic brake systems at least once a year or sooner if the fluid gets contaminated. Most systems run on DOT4 brake fluid these days, and it should appear almost colorless or a very faint gold and completely clear through the sight glass on the master cylinder. If it becomes opaque, cloudy or dark, you should flush the system. A change of color or clarity is a signal that the fluid is contaminated and may not perform properly (as in overheating) Symtoms of brake problems are lever pressure losing feel as in a mushy feel when you apply pressure to the lever, or a hard feel with little corresponding pressure at the disc. You may experience a choppy or jerky feel at the lever also.

Contaminated or dirty fluid can eat away at the seals, o-rings and plungers in your brake system, making replacement of them neccessary, as well as oxidizing the metal parts of the system. All of this can reduce the efficiency of your braking system, little by little until when you need your brakes the most, you could experience complete failure. If you are just adding in fluid, make sure that your fluids you are mixing are compatible or else within just a couple of days you'll have pudding in your master cylinder. And don't mix DOT4 with DOT5. Don't use any DOT3 either. It will work okay for moderate braking, but will overheat and lose pressure under heavy loading.

Pads. Make sure your pads are in good shape. If they are old and thin, glazed or contaminated in anyway, they will have lost much of their stopping power. Don't buy a bargain brand, unless you know for sure that they will perform. I have had cheap pads start to break loose from their backing plates under heavy use after only a few hundred miles. The two most common types of material that pads are made from are carbon base or sintered metal. Carbon is good for dry riding, and I am told, takes heat well. They do not do so well in water and mud, as I have found out the hard way. Sintered metal is great in mud and water and is what alot of motorcycle manufacturers put on their machines stock. When you buy pads for your bike, you will notice that there are two little letters stamped on the back of the pads like EE or FG. These are temperature co-efficient ratings. The first letter is for cold operation, the second is for hot operation. The higher the letter, the better the operation at the specified temp. So a rating of EF would mean that the performance of the pad is okay at cold temperatures, but better at hot or high speed temperatures.

Lines are often overlooked, but have their problems too. Some of the rubber covered OEM brake lines distend a bit under breaking pressure, and with time will distend even more, taking away stopping power at the disc. After a few years of service, especially if you motorcycle has been out in the elements alot, you may wish to replace you hydralic lines. Most european bikes come with steel braided lines. These tend to distend less and give better feel and control at the lever, while increasing pressure at the disc. There are a few braided kits for Japanese bikes on the market, and performance shops out there that will build you custom braided lines for a reasonable price.

If you feel your lever or pedal pulsating under pressure, then you have a warped or bent disc. MC rotors are made for the most part of alloys that can't be turned on a lathe, or straightened in any way. They are pretty thin to begin with, so there isn't room for cutting them down, though I had one precision ground once, but didn't like the results. This means a bent or worn disc needs replacement.

If you wish to do your own work, remember that motocycle brake systems are not like those on cars. When you go to flush the system, you have to close the bleeder each time, before you let up on the lever pressure, then pull the lever till you fill resistance, then crack the bleeder again. Failure to do so, may cause you to suck air into your caliper and make purging more difficult.

Happy and safe braking to all adventure riders out there.

[Joliet 0]

"DD, quite the coincidence, I just came back from the store where I purchased a brake bleeder and a quart of dot 4. My front brake is overfilled and locked up on me the other day when I overheated it slightly doing some brake tests on the KTM. In my youth I don't ever remember touching the brakes on any of my bikes, they always seemed to stop O.K. I always seemed to wear out the rest of the bike or outgrow them before the brakes went. Thanks for the write-up. Ken

[dirt dame 561]

"DD, quite the coincidence, I just came back from the store where I purchased a brake bleeder and a quart of dot 4. My front brake is overfilled and locked up on me the other day when I overheated it slightly doing some brake tests on the KTM. In my youth I don't ever remember touching the brakes on any of my bikes, they always seemed to stop O.K. I always seemed to wear out the rest of the bike or outgrow them before the brakes went. Thanks for the write-up. Ken

Possibly, the person that you bought your KTM from had put fresh pads in without checking the fluid level.

Again, unlike car brakes (or at least the ones on my Ford and Jeep) the master cylinder on a motorcycle is sealed and not vented. It then has a little rubber bootie on top that creates the air space for it and that little rubber bootie is vented from the out or dry side. It creates the little pocket that can contract, if your fluid should expand slightly from overheating. If the bootie is compressed by fluid while cold, say from installing new thick pads, or being crumpled or compressed while reinstalling, then there is no more room for the bootie to compress when the system heats up and the brake fluid won't compress either, so pressure ends up...well, you know where. Then your brakes drag or lock. Then you might fall on your booty

[mrorange 0]

In the manual (Art. Nr. 3.210.50 04/2002) for my 2003 KTM EXC it states the front and rear brakes use DOT 5.1 brake fluid. The reservoir cap on the front brake master cylinder says to use DOT 4. I guess they are compatible with each other as far as seals and hoses are concerned. I think (disclaimer) that DOT 5.1 can handle higher heat.

The manual says:

BRAKE FLUID:

KTM fills the brake system with SHELL ADVANCE BRAKE DOT 5.1 brake fluid, one of the beat currently available. We recommend that you continue to use it. DOT 5.1 is based on glycol ether and of an amber color. If you do not have DOT 5.1 for refilling, you may use DOT 4 brake fluid. However, you should replace it as soon as possible with DOT 5.1.

Never use brake fluid DOT 5. The color of this silicon oil-based product is purple red. The gaskets and the brake hoses of KTM motorcycles are not designed for DOT 5 brake fluid.

Refilling the front brake fluid reservoir*

Loosen screws (2) and remove lid (3) and membrane (4).

Place hand brake cylinder in a horizontal position and fill the brake fluid

reservoir to 5 mm (0.2 in) below the rim with clean brake fluid DOT 5.1

(e.g. Shell Advance Brake DOT 5.1). Replace membrane and lid, tighten

screws. Rinse off spilled or overflowing brake fluid with water.

Warning

- Never use DOT 5 brake fluid! It is based on silicone oil and of a purple

color. Seals and brake hoses must be especially adapted to it.

Refilling the rear brake fluid reservoir

When the brake fluid level has dropped to the MIN mark, you need to refill

the brake fluid reservoir. For this purpose, it is recommended to remove

screw and to pull the brake fluid reservoir outwards. Unscrewing the cap (7)

and the rubber bellows (8). Add brake fluid DOT 5.1 (Shell Advance Brake DOT

5.1). until it reaches the MAX mark, then screw rubber bellows and cap back on. Rinse off spilled or overflowing brake fluid with water.

Warning

- Never use DOT 5 brake fluid! It is based on silicone oil and of a purple

color. Seals and brake hoses must be especially adapted to it.

I use a Motion Pro Hydraulic Brake Bleeder (Part No. 08-0143) when playing with the brakes. It is just a one way check valve with tubing but you can do the work by yourself. Some people use a large irrigation type syringe and force the brake fluid from the slave cylinder (bottom) up to the master cylinder (top). It is just sort of an easy way to remove the air bubbles but you have to be careful not to pump brake fluid all over your bike. It does all kinds of damage to painted surfaces and other materials.

I guess maybe KTM was getting a kick back from Shell that year?

Just remember to never put brake/hydraulic fluid in the Magura clutch master cylinder. Use only Mineral Oil or Magura Blood. I have never had to add or change the oil in my clutch but I did purchase a Magura Oil and Bleeder kit. It was like $10.00. On ktmtalk.com I recall (disclaimer) you can purchase mineral oil at any drug store.

[Joliet 0]

Just remember to never put brake/hydraulic fluid in the Magura clutch master cylinder. Use only Mineral Oil or Magura Blood. I have never had to add or change the oil in my clutch but I did purchase a Magura Oil and Bleeder kit. It was like $10.00. On ktmtalk.com I recall (disclaimer) you can purchase mineral oil at any drug store.

Thanks for the KTM info. I have heard that alot of people are using ATF in the hydraulic clutches. I havn't read enough about it to know if it makes a difference what ATF you use or not. Ken

[dirt dame 561]

Just remember to never put brake/hydraulic fluid in the Magura clutch master cylinder. Use only Mineral Oil or Magura Blood. I have never had to add or change the oil in my clutch but I did purchase a Magura Oil and Bleeder kit. It was like $10.00. On ktmtalk.com I recall (disclaimer) you can purchase mineral oil at any drug store.

Thanks for the KTM info. I have heard that alot of people are using ATF in the hydraulic clutches. I havn't read enough about it to know if it makes a difference what ATF you use or not. Ken

I bought a little teeny bottle of Magura Blood from NCY and it was 4 or 5 bucks. I wondered about ATF, as I used to use it in Bultaco primary cases and have used it very successfully in coventional forks, but decided not to experiment with my KTMs clutch. It is more difficult to bleed than brakes. I couldn't get pressure at the lever with the cover off, so I reinstalled it to bleed my clutch. That worked very well.

[mrorange 0]

Here's a scan of the instructions that are in my Magura clutch service kit.

The kit contains a large syringe, short length of tubing and two different diameter threaded barb fittings. I think the barb fittings are for applications that don’t have a bleeder valve such as a hydraulic clutch conversion kit for a Honda.

If you need large syringes with a taper tip you can purchase them at Marshall’s Industrial Hardware, 8423 Production Ave, San Diego, CA 92121. Not cheap.

McMaster-Carr (www.mcmaster.com) has almost everything in the world of hardware. Not cheap but great service.

I have read that you can purchase them from veterinarians also.

I have never (disclaimer) serviced or bled my clutch but this is what I remember when checking out the information on www.ktmtalk.com and the instructions in the kit.

I always enjoy reading instructions from people who have never actually done the job before but here goes:

Attach the tubing to the syringe barrel tip and fill syringe by drawing the fluid into the syringe through the tubing. Purge all the bubbles out of the tubing.

Remove the cover and diaphragm on the master cylinder.

Attach the tubing to the bleeder valve on the slave cylinder.

Open the bleeder valve and push fluid slowly through the system until the bubbles stop appearing in the open master cylinder.

Close the bleeder valve.

Check fluid level in master cylinder and install diaphragm and cover.

Check that the clutch system has pressure (no air in the system).

HYMEC_Bleeding_and_filling_for_all_models.pdf