GM caliper bolts do not have a universal size; the correct bolt size depends on the specific vehicle model and year. In practice, you’ll commonly encounter 7/16-20 UNC bolts on older GM calipers and metric M12x1.5 bolts on many newer GM designs, but you should verify for your exact vehicle.
What determines the bolt size
The size is chosen to match the caliper design and the brake system architecture for a given model year. As GM transitioned from imperial to metric standards across different generations, the bolt options diversified. Always confirm with the vehicle’s service manual or a GM parts diagram for your exact year and trim.
Below are the sizes you’re most likely to encounter, depending on the model year and brake setup. Use this as a guide, not a guarantee.
- 7/16-20 UNC mounting bolts: commonly seen on older GM front calipers and some configurations across various generations.
- M12x1.5 (metric) bolts: frequently used on many newer GM calipers, especially in mid-2000s through 2020s models.
Note that the exact length, head type, and whether a bolt is imperial or metric can vary by model, so always verify with the factory documentation or a parts diagram. If you’re replacing hardware, use GM-approved bolts and follow the specified torque values for your vehicle.
How to identify the correct bolt size for your GM vehicle
Use these steps to confirm you’re using the right bolts for your caliper setup.
- Check the vehicle’s service manual or a GM parts catalog for your exact model/year to locate the caliper mounting bolts’ spec.
- Compare the bolt’s diameter and thread pitch with known standards (7/16-20 UNC or M12x1.5, etc.).
- Inspect the head style and length to ensure compatibility with your caliper and bracket.
- When replacing, install new bolts of the correct size and torque them to the manufacturer’s specification for your vehicle.
Confirming the correct bolt size before reassembly helps prevent caliper misalignment or brake system issues. If you’re unsure, consult a mechanic or reference the official GM parts diagrams for your exact car.
Summary
GM caliper bolts vary by model and year, with 7/16-20 UNC and M12x1.5 being the most commonly encountered sizes across different generations. Always verify the precise specification for your vehicle using the factory service manual or GM parts diagrams, and replace hardware with the correct bolts and torque settings to ensure safe, reliable braking performance.