Brake System Rebuild 2 - Disk Rotors and Brake Lines
IIn part one we rebuild the brake calipers on the 1990 Yamaha XTZ750. The front brake calipers were totally seized and I could barely push the bike around the garage. This is a common problem with neglected '90 model Super Teneres.
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After the caliper rebuild the brakes were still spongy and the disk rotors were severely worn and we still had the original brake pads on the bike. It was obvious that a complete refit was necessary including new disk rotors, brake pads and braided brake lines that hopefully fix the spongy feel at the lever.
A tell tale pool of brake fluid on the floor of the ORE Garage under the handlebars turned up just before our rebuild. By the time work was ready to get underway we were armed with a Yamaha front brake master cylinder rebuild kit, brake calliper seal kits (we still had to rebuild the rear caliper), Hel Performance Brakeline Kit and Metal Gear brakepads and disk brake rotors.
This job itself shouldn’t take more than a couple of hours but as we found the bikes maintenance and repair history can turn up some unexpected obstacles but the end result gave us the brake feel of a brand new bike and the power to efficiently pull up all 195kgs of the Super Tenere.
1. Dismantling the brakes is a messy job. Place a tray under the area you’re working to catch all the brake fluid otherwise there’ll be a stain on the floor to remind you of the day you rebuilt your brakes.
2. Since we had to fit a new the master cylinder seal kit we repainted the master cylinder with quality satin black engine paint. Before fitting the new seals make sure that all sealing surfaces are free of dirt and debris. Finish the job by using a brake cleaning spray.
3. To get the old disk brake pads you may need to use a brake piston spreader or big flat screwdriver to move the pistons outwards sufficiently to make enough space to get the old pads out.
4. When fitting the Metal Gear Sintered Pads make sure that you clean the brake pad locating pins and remove any corrosion, ridges or burs.
After fitting the new pads the next step is to fit the new Hel Performance brakelines. The spongy feel of the standard brakes are due to the expansion under pressure of the old brake lines. The Hel Performance brakelines are quality stainless steel and is used by professional race teams around the world. The kits are made to each bikes specifications and supplied with everything you need. Make sure that you use all of the copper washers supplied on both sides of the banjo bolt connections.
The old disk rotors were badly worn with ridges that would make short work of the new Metal Gear Sintered Brake Pads.
Fitting the disk rotors is relatively easy and quality aftermarket disk rotors like the Metal Gear disk rotors will line up perfectly. Make sure you clean the disks with brake cleaning fluid and apply medium strength Loctite 248 to the threads of the rotor bolts to stop the bolts vibrating loose.
Cross tighten the bolts as you would a car wheel to make sure the sits true to the hub. The disks need to be seated correctly against the hub otherwise over time the disk will wear unevenly causing vibration and premature wear to the pads.
With the newly rebuilt calipers push the pads apart in preparation to fit the front wheel.
Once the brake system is completely reassembled and the front wheel fitted it’s time to bleed the brakes. If the brake system has twin disks, bleed one side at a time. If you have rebuilt the calipers you would know by now if the mild steel bleed nipple is seized from corrosion. If it has seized replace it with a quality stainless steel nipple. Connect a clear tube to the bleed nipple and it run into a bottle to collect the excess oil. Do not shake the brake fluid bottle as it will only create bubbles in the fluid. Open the bleed nipple about half a turn and pour new brake fluid into the master cylinder reservoir and start pumping the brake lever. Watch for brake fluid coming out of the tube until there is no longer any air bubbles appearing in the tube. During this process make sure that there is plenty of oil in the master cylinder. If the level gets too low it will simply pump air into the line and you’ll have to repeat the process all over again.
Once all the air is out of the line tighten the bleed nipple and repeat the process on the other side.
Mission accomplished. Two new disk brake rotors, brake pads and brakelines. The difference it makes from the old system is phenomenal. Gone is the spongy brake feel and less pressure is needed to pull the old girl up. Next step will be to replace the old bolts with new items from a Bolt Kit from Pro Accessories
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Metal Gear
Bernie Dumke, CEO of Metal Gear in Queensland, has been engineering and manufacturing in Australia since 2002 and is now exporting to the world. Their product lines include Brake Pads and Disk Rotors for just about any bike. Simply go to their web site www.metalgear.com.au and enter your bike make and model and chances are they’ll have the brake parts you need in stock. We visited their warehouse and it’s pretty impressive. Some of their clients include one of Australias off-road enduro racing teams. Phone (07) 3881 0809 or email sales@metalgear.com.au
HelPerformance
Brake Lines
Dean is the Hel Performance manufacturer and supplier in Australia. Hel Performance supply quality stainless steel fittings swaged directly onto a hard drawn tensile stainless steel braided Teflon hose. The Stainless Steel Brake Line Kit includes stainless steel braided brake hose (10 colours), stainless steel fittings, stainless steel banjo bolts and copper washers and the kit comes with a lifetime warranty. The each kit is manufactured for your exact make, model and year. www.helperformance.com.au or phone 07 3869 3016 |