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Audi S4 Clutch Master Cylinders

Audi S4 Clutch master cylinders

Starting at $38.95, AutoBuffy stocks 11 clutch master cylinders from LuK, Valeo, and Sachs to fit the Audi S4. The clutch master cylinder converts pedal pressure into hydraulic force that disengages the clutch. When it fails, the clutch loses the pressure needed to shift gears, leaving you unable to drive safely.

Signs your Audi S4 needs a new clutch master cylinder

  • Clutch pedal sinks slowly to the floor and stays there under normal foot pressure
  • Pedal feels spongy, soft, or has inconsistent resistance compared to normal
  • Difficulty engaging or fully disengaging gears, especially first and reverse
  • Visible brake fluid leak or wet spot on the firewall near the master cylinder body
  • Clutch fluid reservoir level drops repeatedly with no obvious external leak elsewhere
  • Clutch engages only at the very top of pedal travel instead of mid-stroke as usual

Which clutch master cylinder should you buy for your Audi S4?

The main decision is between an OE-equivalent remanufactured unit, a new aftermarket cylinder, or a direct OEM replacement. Fit, bore diameter, and reservoir configuration must match the Audi S4 exactly — a mismatched bore size changes pedal feel and hydraulic pressure. Consider whether your slave cylinder should be replaced at the same time, since both share fluid and wear together.

New Aftermarket
Best for
Budget-conscious daily drivers who want a fresh unit
What you get
Brand-new internals and seals, no core charge, full hydraulic integrity from day one
Remanufactured (Reman)
Best for
Cost savings with OE-spec performance
What you get
Rebuilt OE housing with new seals and bore honing, often includes a core charge refund
OEM / Dealer-Spec
Best for
Owners wanting exact factory fit and finish
What you get
Precise bore, port, and reservoir match to Audi S4 factory specs, longest expected service life
Master + Slave Cylinder Kit
Best for
High-mileage vehicles or first-time clutch hydraulic failure
What you get
Both hydraulic components replaced together, eliminating the most common source of comeback failures

Clutch master cylinders brands we stock for your Audi S4

LuK
4 options · from $138.95
Valeo
3 options · from $156.95
Sachs
2 options · from $105.95
SKP
1 option · from $38.95
Beck/Arnley
1 option · from $208.95

Replacing the clutch master cylinder on a Audi S4

Moderate⏱ 1–2 hoursCombination wrench set (metric and standard)Flare-nut or line wrench for the hydraulic fittingNeedle-nose pliers (for clevis pin and snap ring)Catch pan and turkey baster or fluid syringeVacuum or pressure bleeder kit

The clutch master cylinder mounts on the firewall inside the engine bay and connects to the clutch pedal via a clevis pin and to the hydraulic line via a threaded fitting. After draining the old fluid, disconnecting the line, and unbolting the cylinder, installation is the reverse of removal with careful attention to clevis pin alignment and fitting torque. The system must be bled of all air before test-driving the Audi S4.

Frequently asked questions

How much does it cost to replace clutch master cylinders on a Audi S4?
The part alone starts at $38.95 on AutoBuffy. Total replacement cost depends on whether you DIY or use a shop. Professional labor typically adds one to two hours of shop time. Replacing the slave cylinder at the same visit is often recommended and can reduce overall labor cost compared to two separate jobs.
Can I drive my Audi S4 with a failing clutch master cylinder?
No — not safely or for long. A failing clutch master cylinder can cause sudden, complete loss of clutch engagement while driving. You may be unable to shift out of gear or come to a controlled stop in traffic. Drive only to a repair location if the pedal still has some resistance, then park the vehicle.
How long does a clutch master cylinder last on a Audi S4?
Most clutch master cylinders last somewhere between 80,000 and 150,000 miles, though driving style, fluid condition, and climate all affect lifespan. Neglecting clutch fluid changes allows moisture absorption that corrodes internal seals and accelerates failure. Inspect the unit any time you notice changes in clutch pedal feel or fluid level.
Should I replace the clutch slave cylinder at the same time on my Audi S4?
Yes, in most cases. The master and slave cylinders share fluid, age together, and require similar labor to access. If one has failed due to seal wear or internal corrosion, the other is likely near the end of its service life too. Replacing both at once saves labor costs and prevents a second hydraulic failure shortly after.
Do I need to bleed the clutch after replacing the master cylinder on my Audi S4?
Yes, bleeding is required. Replacing the clutch master cylinder introduces air into the hydraulic line, which must be purged before the clutch will operate correctly. Bleeding can be done with a hand vacuum pump, a pressure bleeder, or the traditional two-person pedal method. Use the fluid type specified for the Audi S4.
What type of fluid does the clutch master cylinder on a Audi S4 use?
Most clutch master cylinders share a reservoir with the brake system and use DOT 3 or DOT 4 brake fluid, but some manufacturers specify a different fluid entirely. Always confirm the correct specification in your Audi S4 owner's manual or on the reservoir cap before adding fluid. Mixing fluid types can damage seals and cause hydraulic failure.

Shop clutch master cylinders by year for the Audi S4

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