2009-2010 Honda CRF450R – Front Master Cylinder Service

How To Service The Front Brake Master Cylinder On Your 2009 – 2010 Honda CRF450R

2009 - 2010 Honda CRF450r - Front Master Cylinder Service FeaturedThe Tools You Will Need Are:

  • 12mm Socket
  • 10mm Socket
  • 8mm Socket
  • Screwdriver
  • Small Pick
  • Stiff Brush
  • Long Nose Snap Ring Pliers
  • Calipers
  • Torque Wrench
  • Fine Grit Emery Paper
  • Shop Towels

The Parts You Will Need Are:

  • Front Master Cylinder Rebuild Kit
  • Dot 4 Brake Fluid
  • Rubber Grease

This front master cylinder rebuild should cost around $25 and take approximately 30 minutes to complete.

Pre-Service Notes

  • I recommend opening the Service & Torque Specs in a new tab for easy reference.
  • If you need parts and tools, make sure to buy them here!
  • Pictures with captions are after the steps below.
  • Brake fluid will damage everything, so keep your shop towels ready!
  • If you need any help don’t hesitate to ask!

Front Master Cylinder Removal

  1. Loosen and remove the banjo bolt, and wrap the end in a shop towel.
  2. Loosen and remove the mounting bolts.
Remove Banjo Bolt
Loosen and remove the banjo bolt, and wrap the end in a shop towel.

Wrap Brake Line

Remove The Front Master Cylinder Mounting Bolts
Loosen and remove the mounting bolts.

Front Master Cylinder Disassembly

  1. Completely disassemble the master cylinder.
  2. Be careful when removing the snap ring; the piston is under pressure and will jump out at you.
Disassemble The Front Master Cylinder
Completely disassemble the master cylinder.
Pull Piston
Be careful when removing the snap ring; the piston is under pressure and will jump out at you.

Clean And Inspect

Clean

  1. Wipe every part inside and out with fresh brake fluid and a shop towel.
  2. If you need to scrub anything, make sure you use a nonmetallic brush.

2009-2010 Honda DRF450r - Front Master Cylinder - Clean

Inspect

  1. Inspect every component for noticeable damage.
  2. If you find any rough spots, gently sand it down with fine-grit emery paper. I always give the pivot bolt and the pushrod a once over to be safe.

2009-2010 Honda DRF450r - Front Master Cylinder - Inspect

Sand The Front Master Cylinder Pushrod

Measure

  1. Measure the inside diameter of the cylinder bore and the outside diameter of the piston.
  2. The cylinder bore should be no Greater than 11.05 mm, and the piston should be no LESS than 10.84 mm.
  3. If your cylinder bore and piston are out of spec, they need to be replaced.

Measure The Front Master Cylinder Piston

Measure The Front Master Cylinder Bore

Related: How to bleed the brake system on your 09-10 CRF450r.

New Brake Parts

  1. Before assembly, take stock of your new parts.
  2. I am installing an All Balls rebuild kit that includes a new piston spring, pushrod boot, piston cups, spring clip, piston washer, and banjo bolt seal washers.
  3. Make sure to match the old parts with the new ones, so you don’t accidentally throw away something you need.
  4. Soak your new piston cups in fresh brake fluid for 15 minutes before assembly.

New Parts

Soak New CupsFront Master Cylinder Assembly

  1. Start your assembly with the piston. Install the piston cups with the large side facing in.
  2. Take your time with the cups; if they are damaged during install, your brakes will not work.
  3. Install the new piston spring.
  4. Coat the master cylinder bore with brake fluid, and install the piston past the first cup.
  5. Install the piston in a twisting motion to avoid rolling the cups.
  6. Place the piston washer and spring clip on the piston.
  7. When installing the spring clip, ball up a piece of shop towel and place it in the pushrod, then push the piston down with a screwdriver to make room for the snap ring pliers.
  8. This is the hardest part of assembly because you almost need three hands, and too many things are in too small of a space.
  9. I find it easier to compress the spring clip before I push the piston down; that way the spring clip will stay level.
  10. But be patient, and you will get it.
  11. To make sure the clip is in the groove, use your pick to rotate it. If it moves, it’s seated.
  12. Install the new boot on the pushrod. Pull the boot up and grease the pushrod, then place the pushrod in the piston.
  13. Gently push the boot down into the bore.
  14. Align the knocker arm with the pushrod, and install the brake lever spring, followed by the pivot bolt.
  15. Carefully pull the boot up into the groove on the knocker arm.
  16. Install the diaphragm and reservoir cap.
2009-2010 Honda CRF450r - Front Master Cylinder - Assemble Piston
Start your assembly with the piston. Install the piston cups with the large side facing in.
Install Spring
Install the new piston spring.
Install Piston Into Bore
Coat the master cylinder bore with brake fluid, and install the piston past the first cup.
Place Piston Washer And Spring Clip
Place the piston washer and spring clip on the piston.
Use Screwdriver To Press Piston Down
When installing the spring clip, ball up a piece of shop towel and place it in the pushrod, then push the piston down with a screwdriver to make room for the snap ring pliers.
Install Spring Clip
I find it easier to compress the spring clip before I push the piston down; that way the spring clip will stay level.
Rotate Clip
To make sure the clip is in the groove, use your pick to rotate it. If it moves, it’s seated.
Grease The Front Master Cylinder Pushrod
Install the new boot on the pushrod. Pull the boot up and grease the pushrod, then place the pushrod in the piston.
Install Pushrod
Gently push the boot down into the bore.
Install Lever
Align the knocker arm with the pushrod, and install the brake lever spring, followed by the pivot bolt.
Pull Boot Onto Knocker Arm
Carefully pull the boot up into the groove on the knocker arm.
Install Diaphragm And Reservoir Cap
Install the diaphragm and reservoir cap.

Front Master Cylinder Installation

  1. Install the master cylinder mounting bolts hand right. Install the banjo bolt with the new seal washers, and make sure the shank rests on the tab.
Install And Torque The Front Master Cylinder Banjo Bolt
Install the master cylinder mounting bolts hand right. Install the banjo bolt with the new seal washers, and make sure the shank rests on the tab.

Torque Specifications

  1. Banjo Bolt – 25 ft-lbs
  2. Mounting Bolt – 7 ft-lbs

If you have any questions or anything to add, please leave them in the comments or on our FaceBook page!

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