How To Service The Front Brake Master Cylinder On Your 2009 – 2010 Honda CRF450R
The Tools You Will Need Are:
- 12mm Socket
- 10mm Socket
- 8mm Socket
- Screwdriver
- Small Pick
- Stiff Brush
- Long Nose Snap Ring Pliers → https://amzn.to/4h1uxc7
- Calipers → https://amzn.to/40Eye1z
- Foot-Pound Torque Wrench → https://amzn.to/3WonMsn
- Fine Grit Emery Paper
- Shop Towels
- Safety Glasses → https://bulltru.com
The Parts You Will Need Are:
- Front Master Cylinder Rebuild Kit → https://amzn.to/3EfVc6i
- DOT 4 Brake Fluid → https://amzn.to/3WucSkS
- Rubber Grease → https://amzn.to/4awR9Po
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! → https://amzn.to/4h4lDKq
- 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
- Loosen and remove the banjo bolt, and wrap the end in a shop towel.
- Loosen and remove the mounting bolts.
![Remove Banjo Bolt](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Remove-Banjo-Bolt.jpg)
![Remove The Front Master Cylinder Mounting Bolts](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Remove-Mounting-Bolts.jpg)
Front Master Cylinder Disassembly
- Completely disassemble the master cylinder.
- Be careful when removing the snap ring; the piston is under pressure and will jump out at you.
![Disassemble The Front Master Cylinder](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Disassemble-Master-Cylinder.jpg)
![Pull Piston](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Pull-Piston.jpg)
Clean And Inspect
Clean
- Wipe every part inside and out with fresh brake fluid and a shop towel.
- If you need to scrub anything, make sure you use a non-metallic brush.
Inspect
- Inspect every component for noticeable damage.
- If you find any rough spots, gently sand them down with fine-grit emery paper. To be safe, I always give the pivot bolt and the pushrod a once-over.
Measure
- Measure the cylinder bore’s inside diameter and the piston’s outside diameter.
- The cylinder bore should be no Greater than 11.05 mm, and the piston should be no LESS than 10.84 mm.
- If your cylinder bore and piston are out of spec, they must be replaced.
Related: How to bleed the brake system on your 09-10 CRF450r.
New Brake Parts
- Before assembly, take stock of your new parts.
- 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.
- Match the old parts with the new ones so you don’t accidentally throw away something you need.
- Soak your new piston cups in fresh brake fluid for 15 minutes before assembly.
Front Master Cylinder Assembly
- Start your assembly with the piston. Install the piston cups with the large side facing in.
- Take your time with the cups; if they are damaged during installation, your brakes will not work.
- Install the new piston spring.
- Coat the master cylinder bore with brake fluid and install the piston past the first cup.
- Install the piston in a twisting motion to avoid rolling the cups.
- Place the piston washer and spring clip on the piston.
- When installing the spring clip, ball up a piece of shop towel and place it in the pushrod. Then, using a screwdriver, push the piston down to make room for the snap-ring pliers.
- This is the hardest part of assembly because you almost need three hands, and too many things are in too small of a space.
- I find it easier to compress the spring clip before I push the piston down; that way, the spring clip stays level.
- But be patient, and you will get it.
- To ensure the clip is in the groove, rotate it with your pick. If it moves, it’s seated.
- Install the new boot on the pushrod. Pull the boot up, grease the pushrod, and then place the pushrod in the piston.
- Gently push the boot down into the bore.
- Align the knocker arm with the pushrod, install the brake lever spring, and then the pivot bolt.
- Carefully pull the boot up into the groove on the knocker arm.
- Install the diaphragm and reservoir cap.
![2009-2010 Honda CRF450r - Front Master Cylinder - Assemble Piston](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Assemble-Piston.jpg)
![Install Spring](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-Spring.jpg)
![Install Piston Into Bore](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-Piston-Into-Bore.jpg)
![Place Piston Washer And Spring Clip](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Place-Piston-Washer-And-Spring-Clip.jpg)
![Use Screwdriver To Press Piston Down](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Use-Screwdriver-To-Press-Piston-Down.jpg)
![Install Spring Clip](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-Spring-Clip.jpg)
![Rotate Clip](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Rotate-Clip.jpg)
![Grease The Front Master Cylinder Pushrod](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Grease-Pushrod.jpg)
![Install Pushrod](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-Piston.jpg)
![Install Lever](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-Lever.jpg)
![Pull Boot Onto Knocker Arm](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Pull-Boot-Onto-Knocker-Arm.jpg)
![Install Diaphragm And Reservoir Cap](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-Diaphragm-And-Reservoir-Cap.jpg)
Front Master Cylinder Installation
- 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](https://www.fixyourdirtbike.com/wp-content/uploads/2018/06/2009-2010-Honda-DRF450r-Front-Master-Cylinder-Install-And-Torque-Banjo-Bolt.jpg)
Torque Specifications
- Banjo Bolt – 25 ft-lbs
- Mounting Bolt – 7 ft-lbs
If you have any questions or comments, please leave them in the comments or on our Facebook page!
Keep Your ’09-’10 CRF450r Running Right!