Early Bronco Motor Mounts

Early Bronco Motor Mounts Guide | 1966-77 Ford Bronco

The 1966-77 Ford Bronco motor mounts play a critical role in keeping your engine secure while allowing just enough movement to absorb vibration. Without properly functioning Early Bronco engine mounts, the power produced by your 289, 302, 351W, or inline-6 wouldn’t transfer smoothly to the drivetrain. Instead, you’d feel excessive vibration, clunking, and unwanted engine movement.

From the factory, Early Bronco motor mounts consist of two metal plates bonded together with a rubber insulator sandwiched between them. This design anchors the engine to the frame while allowing slight flex to isolate vibration. It’s a simple system — but an essential one.

Why Early Bronco Motor Mounts Fail

Like any rubber component on a classic vehicle, motor mounts wear out over time. Heat cycles, engine torque, and decades of use take their toll on the rubber isolator.

Common causes of Early Bronco motor mount failure include:

• Age and dry rot

• Oil, power steering fluid, or transmission fluid contamination

• Repeated hard acceleration and braking

• Off-road use and drivetrain shock loads

• Increased horsepower from engine upgrades

As the rubber deteriorates, it can crack, soften, separate, or completely fail. Once the bond between the metal plates breaks down, engine movement increases dramatically — especially under throttle or when shifting between drive and reverse. We’ve even seen Early Bronco motor mounts so worn out that when the driver dropped the Bronco into reverse, the engine torqued enough to send the fan straight into the radiator. That’s the kind of failure that turns a simple mount replacement into a much bigger repair.

Signs Your 1966-77 Ford Bronco Motor Mounts Are Worn

Failing motor mounts often show clear warning signs:

• Excessive engine movement when revving

• Thunking or clunking sounds under acceleration

• Noticeable vibration inside the cab

• Engine lifting or twisting under throttle

• Visible separation between mount halves

If there’s significant shaking when you “get on it,” it’s time to inspect your mounts.

A simple test is to gently apply force to the engine by hand (when safe to do so). Excessive movement or visible gaps between the mount halves may indicate failure. In some cases, you may need to support the engine slightly with a jack and wood block to safely inspect the mounts for cracks or separation.

Don’t Forget the Transfer Case Mounts

When one motor mount fails, the others are often not far behind. The additional stress placed on the remaining mounts accelerates wear.

While inspecting your Early Bronco engine mounts, it’s also a good idea to check the transfer case crossmember mounts for wear at the same time. A balanced mounting system keeps your drivetrain aligned and reduces unnecessary stress on components.

Upgrading Early Bronco Motor Mounts

If you’re converting from a 170ci or 200ci inline-6 to a Small Block Ford V8, you’ll need:

• V8 motor mounts

• Weld-on V8 motor towers

Upgraded or reinforced mounts are especially important if you’ve increased horsepower or frequently drive off-road. More torque means more stress on the mounting system.

Why Proper Motor Mounts Matter

Your 1966-77 Ford Bronco motor mounts do more than hold the engine in place. They:

• Maintain drivetrain alignment

• Reduce vibration transfer

• Protect headers, radiators, and fan shrouds from contact

• Prevent excessive stress on transmission and transfer case components

When motor mounts fail, it’s not just annoying — it can lead to damaged exhaust, broken fans, cracked radiators, or drivetrain misalignment.

Healthy Early Bronco motor mounts are essential for safe, reliable performance. If your engine is shifting, clunking, or vibrating more than it should, it’s time for an inspection. Replacing worn mounts restores proper engine stability and keeps your 1966-77 Ford Bronco running smoothly — whether it’s stock, swapped, or built for more power.