Summary: the heart of your system
The 22SR EVO piston is a precision piece. Unlike appearances, it's not just a metal cylinder. It is machined with extremely low tolerances to allow the joints (cups) to slide without flee while generating a constant hydraulic pressure.
- Technical specifications
| Feature |
Specification |
| Mark |
Birelart (Freeline Original Parts) |
| Compatibility |
Birelart 22SR / 22SR EVO pump |
| Material |
High strength aluminum (hard anodizing treated) |
| Finishing |
Mirror (for reduced friction) |
| Use |
Competition (high performance braking) |
| Note |
Calibrated piece for 22SR tolerance |
- Mounting tuto: the rule of the "mirror" appearance
The mounting of a piston does not tolerate no surface error.
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Inspection before assembly: Look at the piston under a good light. It must be perfectly smooth. If you see circular scratches (related to impurities in joints) or oxidation sting, replace the. An absorbed piston "will eat" new joints in some braking.
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Lubrication: Never climb a dry piston. Dip it in DOT 4 or 5.1 clean brake fluid.
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Insertion into the body: Present the piston in the bore of the pump body. If he does not fit freely with a slight thumb, do not force. Check the alignment. If you force, you will hurt the lips of the new cups, and the pump will fire immediately.
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Race test: Once the piston is inserted, it must slide with a very low and uniform resistance. No "hard point" should be felt.
💡 Michel's trick
"I am often asked if we can polish a striped piston with very fine sandpaper. My Pro Council: Forget. These pistons are treated with hard anodizing or a specific surface coating. If you sand, you remove this protection, and the 'naked' metal to wear at a crazy speed against the cups in EPDM. The trick: If your piston has traces, is that your brake fluid was contaminated or your piston arrived at the end of life. In doubt, replace it. The cost of the piston is derisory compared to a track output due to braking that fades at the end of the race. "
❓ FAQ SEO (Frequently Asked Questions)
Q: Why my 22SR EVO piston seems different from my old model ?
A: Birelart has changed the 22SR range to the EVO model to improve braking progressivity. Internal geometry can be slightly different. Make sure you use the seal kit (cups) that specifically corresponds to the EVO reference.
Q: Can a seed piston be saved ?
A: If the seizure is due to dried dirt, a cleaning may suffice. If the seizure is due to an oxidation of aluminum (white / gray traces), the metal is corroded. The piston is to be replaced, and it is imperative to clean the bottom of the pump.
Q: Should we grease the piston with silicone grease ?
A: Only a specific grease for braking system (EPDM compatible) can be used. If you have a doubt, simply use clean brake fluid, it's the best lubricant and the safest.
✅ Ready for your maintenance ?
You have now inspected the central element of your pump. Finally: