Tech Tuesday - Bleeding Hayes Prime Brakes
Why Bleed? Are your brakes feeling a little down on power? Lever throw a bit excessive? It could be time to give your brakes a bleed in order to breathe some life back into them. You may not even realize that they are down on power simply because the degradation happens so slowly over time, but spending twenty minutes on this task could be just what the doctor ordered. So, how does your supposedly sealed brake system become contaminated? It happens in a few ways, but a major factor is both air and moisture seeping past the seals over time. This is especially true of older braking systems who's seals have become more worn and brittle after years of use. DOT 4 fluid is hygroscopic, meaning that it absorbs water, lowering both the fluid's quality and its ability to deal with rising temperatures under extreme use. The result can manifest as power fade and lever pumping (the bite point moves out as the temperature in the brake system rises) during prolonged use. Contamination can also occur from the seals themselves as they break down slowly, releasing tiny pieces into the system that can gum up the brake's small bleed ports.
When To Bleed? How often should your brakes be bled? Once per year is a good rule of thumb if you ride on a regular basis, but those who spend multiple days per week at a bike park will likely have to do it more often. You'll know that you're behind schedule when you purge the system of the old fluid and discover that it is black and cloudy with gunk. Yes, a well bled brake should be able to go for quite awhile without requiring any attention, but thinking of your brakes as being maintenance free is a mistake.
Bleeding Hayes Prime Brakes
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When To Bleed? How often should your brakes be bled? Once per year is a good rule of thumb if you ride on a regular basis, but those who spend multiple days per week at a bike park will likely have to do it more often. You'll know that you're behind schedule when you purge the system of the old fluid and discover that it is black and cloudy with gunk. Yes, a well bled brake should be able to go for quite awhile without requiring any attention, but thinking of your brakes as being maintenance free is a mistake.
What's needed: • T10 torx driver • 2.5mm hex key • 4mm hex key • 5mm hex key • 8mm box end wrench • Hayes Pro bleed kit • DOT 4 brake fluid • Pad spacer • Clean rags • Isopropyl alcohol • Nitrile gloves | Some helpful pointers: • Watch the video below before starting and make an honest decision as to if this job is out of your league. Nervous? Don't have ALL of the tools required? You'll be much better off taking the bike down to your local shop and paying the professionals to do the job correctly. • As you should any time that you are dealing with brake fluid, place the pads and wheel/rotor in a safe place where they cannot be contaminated during the bleed. • Instead of using DOT 4 fluide from that old bottle of yours that you've had for a long time, spend a few bucks on a new, unopened bottle that hasn't had a chance to be contaminated or exposed to air for long. • When pushing the pistons back in with the box end wrench, be careful to not apply pressure to the edge of the piston - it can be chipped. A stiff plastic tire lever can also be used to limit the chance of causing damage. • Performing the bleed with the master cylinder in multiple positions offers the best chance of removing air from the system, but this can be hard to do with the brake still on the bike. To simplify the process, simply remove the lever/master cylinder assembly from the bike, but leave the caliper bolted in place, and have a friend hold it for you while you perform the bleed. • Spray the caliper down with isopropyl alcohol and give it a good cleaning before reinstalling the brake pads. |
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9dot 5) from the autopart store.
On the other hand...who gives a hoot about Hayes anyway ...