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Start ShoppingCometic C9179F1 AFM Primary Housing Gasket for Harley-Davidson Big Twin/Twin Cam Engines
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Description
Ensure optimal engine performance with Cometic's premium AFM primary housing gasket, engineered for Harley-Davidson Big Twin and Twin Cam engines. This durable solution provides reliable sealing while offering reusability when properly maintained.
Key Features
- AFM Aluminum Foam Material: Combines strength and flexibility for long-lasting sealing performance
- Reusable Design: Can be reused in good condition installs (always inspect before reusing)
- Engineered Fitment: Precision-machined for Harley-Davidson Big Twin/Twin Cam primary cover applications
Why Choose This Product
Cometic's C9179F1 gasket delivers exceptional durability and leak prevention for high-performance engines. The AFM material resists compression set and maintains sealing integrity under extreme temperatures. Ideal for riders seeking reliable engine sealing without compromising performance. Perfect for both original equipment installations and engine rebuilds.
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Ensure optimal engine performance with Cometic's premium AFM primary housing gasket, engineered for Harley-Davidson Big Twin and Twin Cam engines. This durable solution provides reliable sealing while offering reusability when properly maintained.
Key Features
- AFM Aluminum Foam Material: Combines strength and flexibility for long-lasting sealing performance
- Reusable Design: Can be reused in good condition installs (always inspect before reusing)
- Engineered Fitment: Precision-machined for Harley-Davidson Big Twin/Twin Cam primary cover applications
Why Choose This Product
Cometic's C9179F1 gasket delivers exceptional durability and leak prevention for high-performance engines. The AFM material resists compression set and maintains sealing integrity under extreme temperatures. Ideal for riders seeking reliable engine sealing without compromising performance. Perfect for both original equipment installations and engine rebuilds.| SKU | GMCA5699FA |
|---|---|
| MPN | C9179F1 |
| Brand | Cometic |
| Category | Gaskets/Seals |
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Frequently Asked Questions
Cometic primary gaskets are generally designed to seal dry on clean, flat surfaces. Most installers do not use additional RTV or sealant except at specific corners or case joints if the Harley‑Davidson service manual calls for it. Always follow your service manual and avoid heavy sealant use, which can squeeze out and contaminate the primary.
Cometic AFM‑style gaskets are marketed as capable of multiple assemblies if not damaged and if sealing surfaces remain good. In practice, many shops treat primary gaskets as a one‑time‑use part for maximum reliability. If the gasket shows crush marks, tears, or deformation, replace it rather than re‑use.
No. Primary cover gaskets are engine‑family and model‑specific. The C9179F1 is for certain Evo Big Twin and Twin Cam primary housings only. You must verify by part number and fitment chart from Cometic or your distributor using your exact year, model, and sub‑model before ordering.
For a standard primary cover gasket replacement you typically remove the primary cover only, not the clutch basket or compensator. However, you must drain the primary fluid, remove the derby cover, and then the primary cover fasteners. Refer to the Harley‑Davidson service manual for your model for the exact steps.
If the leak is from the primary cover gasket area and the mating surfaces are flat and undamaged, replacing the old gasket with a quality Cometic gasket often resolves the leak. If the cover is warped, fasteners are stripped, or seals (such as the mainshaft or shifter shaft seal) are leaking, those issues must also be addressed.
Installation Guide
Difficulty
Medium
Est. Time
1 hr 0 min
Tools Required
- Service manual for your specific Harley-Davidson model
- Allen/hex keys or Torx bits for primary cover screws (varies by model)
- Socket set and ratchet
- Torque wrench (inch‑pound and/or foot‑pound depending on model)
- Drain pan (for primary fluid)
- Plastic scraper or gasket scraper (non‑marring)
- Brake cleaner or suitable solvent for cleaning gasket surfaces
- Shop rags
Pro Tips
- Photograph the primary cover and fastener positions before removal so different‑length screws go back in the correct holes.
- Clean both mating surfaces completely and dry them before fitting the new Cometic gasket; avoid abrasive discs that can damage aluminum.
- Lightly snug all primary cover bolts in a criss‑cross pattern, then torque in stages to the factory spec from the service manual.
- Inspect the primary cover for warpage using a straightedge if you are chasing repeat leaks.
- Refill the primary with fresh fluid to the exact quantity and level specified by Harley‑Davidson for your model and year, then recheck for leaks after the first ride.
Common Mistakes to Avoid
- Not fully draining the primary fluid before removing the cover
- Prying between aluminum surfaces and damaging the primary cover or case
- Leaving old gasket material or sealant on the mating surfaces
- Misaligning the gasket during reassembly and pinching or tearing it
- Over‑torquing or unevenly torquing primary cover screws, causing warping or leaks
- Re‑using damaged or heavily compressed gaskets
Comparison vs Stock/OEM
Designed as a high‑quality aftermarket replacement for Harley‑Davidson OEM primary cover gaskets, using Cometic’s performance gasket technology.
Improvements
- Higher‑quality gasket materials aimed at better long‑term sealing compared to some paper/cellulose OEM gaskets.
- Better resistance to compression set, heat, and oil exposure common in Harley primary drives.
- Often used and trusted in performance and racing applications where repeated disassembly occurs.
Considerations
- Fitment must be verified by part number, as Harley updated primary covers over the years.
- Reusability depends heavily on installation quality and condition after removal; many technicians still prefer replacing gaskets each time the primary is opened.
Durability & Warranty
Expected Lifespan
Typically matches or exceeds OEM primary gasket life when installed on clean, flat surfaces and torqued correctly; often replaced only when the primary is opened again or if a leak develops.
Warranty
Standard Cometic limited manufacturer warranty against defects in materials and workmanship (details vary by distributor; check with seller).
Maintenance
Inspect primary area periodically for oil weeping or leaks; check primary fastener torque per the Harley‑Davidson service schedule. Replace gasket whenever the primary cover is removed for service if there is any sign of damage or compression set.
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