What size are the nuts on the gr86 header?
Short answer: The GR86 header uses M8 hex nuts to secure the exhaust manifold flange, paired with M8 bolts (typically M8 x 1.25) on the FA24 engine.
Context: Hardware can vary by model year and by whether you’re looking at the header-to-head flange or other mounting points like a heat shield. Always check the official service manual or parts diagrams for your specific GR86. This article provides general guidance and steps to verify the correct size for your vehicle.
Understanding GR86 header hardware
In practice, the most common configuration on 2022–present GR86 models is eight fastening points around the exhaust manifold flange, typically using eight M8 bolts with corresponding M8 nuts. Some variations or aftermarket headers may use different hardware, so confirm for your exact VIN.
- Exhaust manifold bolts to the cylinder head: typically eight bolts, size M8 x 1.25
- Exhaust manifold nuts: standard M8 hex nuts (across flats ~13 mm)
- Studs as an alternative: some configurations use studs and nuts instead of direct bolts
- Heat shield fasteners: various sizes, often smaller, commonly M6 or M5 depending on year
Common header hardware you may encounter:
Concluding: Always verify with the factory diagrams for your exact model year to ensure you have the correct size, length, and thread pitch. Using the wrong hardware can affect seal and torque integrity.
How to verify the nut size on your GR86
Follow these steps to confirm the actual nut size on your vehicle:
- Pull up the GR86 service manual or official Parts Catalog for your year and VIN to locate the header flange hardware.
- Measure the nut across its flats with a caliper or use a hardware gauge to determine the size and thread pitch (likely M8 x 1.25 or M10 x 1.25).
- When in doubt, bring a removed nut to a parts store or contact a Toyota/Subaru dealer parts desk to match the exact size and grade.
Concluding: Once you have the correct nuts, torque and re-tighten to the service manual specification to maintain a proper seal and prevent leaks.
Summary
The nuts used on the GR86 header are generally M8 hex nuts for the exhaust manifold flange on the FA24 engine, with eight bolts securing the flange. Because hardware can vary by year, model, and aftermarket parts, always verify with the official service manual or parts diagrams for your exact vehicle. This article provides a framework to identify and confirm the correct size before any replacement or installation.
