There isn’t a single universal size for Honda flywheel bolts—the size varies by engine and model.
In practice, you may encounter common metric thread sizes such as M8 x 1.25 or M10 x 1.5, with bolt lengths typically in the range of about 18 to 25 millimeters. However, exact specifications depend on the engine family and year, so always confirm with the service manual or OEM replacement parts for your specific Honda.
Common bolt sizes you might see on Honda flywheels
Before listing typical sizes, it’s important to note that bolt dimensions are engine-specific. The following sizes appear in service literature for various Honda engines, but your exact model may differ.
- M8 x 1.25 bolts (a frequent choice for many smaller Honda four-cylinder engines)
- M10 x 1.5 bolts (used on some larger or higher-torque applications within Honda’s lineup)
Using the correct OEM bolt size is essential for proper engagement and torque. When in doubt, rely on the official parts catalog for your model and year.
How to verify the correct bolt size for your vehicle
To identify and confirm the right bolt size for your Honda, follow these steps:
- Consult the vehicle’s service manual or the Honda factory service bulletin for exact bolt size, length, head type, and torque specifications.
- Look up the OEM flywheel bolt kit for your engine family and year; replacing with the exact factory bolts is the safest approach.
- If replacing or reusing bolts, inspect the crankshaft threads and measure bolt diameter and pitch with appropriate tools; replace any damaged hardware with new OEM bolts.
Verifying against official specifications reduces the risk of stripping threads or improper torque, which can compromise engine timing and starting reliability.
Additional considerations when replacing flywheel bolts
Beyond diameter and pitch, consider bolt grade, head type, and engagement length. Honda flywheel bolts are high-tensile metric fasteners designed to withstand engine vibration and torque loads, and the exact grade can vary by model. Always follow the manufacturer’s torque sequence and specifications for your engine to ensure safe operation.
Summary
In short, Honda flywheel bolts do not have a single universal size. Sizes vary by model and engine family. To obtain the correct bolts for your vehicle, check the official service manual or OEM bolt kit for your specific Honda model and year, and replace with new hardware when servicing the flywheel. When in doubt, rely on the OEM data and torque specifications to ensure proper fit and safe operation.