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What Makes a High Performance Transmission Mount?

Transmission Mount Basics

Your transmission's primary purpose is to keep the engine and wheels of your vehicle turning in sync. The transmission mount plays a significant role in keeping vibrations to a minimum.
A transmission mount holds the rear of the transmission, or tailshaft, securely to a crossmember. The crossmember is a support that is welded or bolted to the chassis. Typically, a transmission mount has a rubber or urethane bushing, which is bolted or welded to a bracket. The entire assembly securely fastens the transmission to the vehicle crossmember.
Once in place, the transmission mount also helps isolate and curb vibrations from the driveline by ensuring the linkages and driveshaft angles are correct. The number of transmission mounts needed depends on the vehicle.

G Force Transmission Mount line of products including our patented adjustable transmission mounts for GM and Ford.

Check out all of our transmission mounts and related parts—

What are the signs of a bad transmission mount?

When performing an engine swap, you might need a new transmission mount to secure the replacement transmission in place. Additionally, a transmission mount can go bad. The signs of a worn transmission mount include:
  1. Loud sounds from the engine

    If you hear noises like your engine is breaking when you put your car in gear or shut it down, that's a good indication that your transmission mount may be failing. The clunking and banging are the sounds of metal knocking into metal as the engine shifts and moves.
  2. Thumping sounds

    This sound usually happens when you go over a bump in the road. It's an indication that the transmission is shifting up and down while you're driving.
  3. Unusual vibrations

    Shaking so intense it's uncomfortable for passengers is another sign a it has gone bad.

If you are so inclined, you can check for a faulty transmission mount by inching beneath your car and moving the transmission tailshaft in all directions—up and down as well as back and forth. More than an inch of give in any direction is a good indication that the mount is bad. Experts recommend that if there is more than one installed, you should replace all of them simultaneously.

Are Rubber or Polyurethane Transmission Mounts Better?

This is a tougher question than it seems because which type you should choose is determined by a number of factors centered around the type of vehicle, how much you drive it, and the purpose of the vehicle. Rubber or polyurethane are used on transmission mounts to isolate vibration caused by the engine and transmission.

You could use a solid steel mount to secure the transmission, but all of that vibration would be felt by the driver. That’s fine in a race car, but if you’re driving much at all, you’ll want a rubber or polyurethane transmission type mount to reduce the engine and transmission vibration to make your drive more comfortable.

Let’s look at the two materials. Rubber is softer and will absorb more vibration than polyurethane making it the perfect material to isolate vibration in everyday or moderate performance vehicles where comfort is still important. It can be prone to tearing in high horsepower and torque applications as well as cracking over time, especially when it comes into contact with salt, oil or coolant.

Polyurethane generally withstands these materials better than rubber and will not usually crack. Polyurethane is more rigid than rubber, which is good and bad. More vibration is transferred through the mount to the driver, but it also means your transmission mount is stronger and won’t distort like rubber under torque. That translates to a more stable transmission mount that helps your transmission transfer power more efficiently.

Polyurethane is a great choice when you want some vibration isolation, but still want a high performance mount that can handle more horsepower and torque than rubber.

Transmission Mount Replacement

G Force GM and Ford Transmision Mount Collection | signs of a bad transmission mount

Usually, designed to fit the make, model, and year of your car as well as the transmission you are installing, a replacement is available from the automotive aftermarket. It is necessary to confirm the dimensions of the current one before purchasing a replacement.

Recently, G Force introduced our patented GM and Ford adjustable transmission mounts. Because it is adjustable, it allows for an offset of 1 inch to 2.5 inches and is perfect for LS swaps that require moving the transmission from stock positions. It also prevents the misalignment of the transmission and drivetrain. Plus, the bolt-in design simplifies installation.

The polyurethane bushing reduces vibrations, while the strong mounting hardware improves stability. The ability to adjust the placement before securing the slide bolt allows you to align your driveshaft and transmission quickly and easily. Accurate positioning of the assembly is a snap. Therefore, the adjustable mount fits most manual or automatic GM RWD transmissions and has an installed height of 1.75 inches.

What about the Crossmember?

 Because the transmission mount is secured to the crossmember, it stands to reason the strength and durability of it also is important. G Force is an industry leader in crossmembers.

Since they are crucial to body panel alignment, transmission mount stability, and proper vehicle handling, we engineer our crossmembers to hold up under the toughest loads. Independently tested and road-proven, the double-hump design allows ample space for factory and aftermarket exhaust. Plus, we guarantee it fits like your factory crossmember without modifying the installation location. In addition, they have a bolt-to-frame design that eliminates the need for welding or cutting to make the crossmember fit.

A G Force crossmember and adjustable transmission mount is a great combination for your next swap. Our team of experts is happy to guide you through your purchase.

Transmission Mount FAQs

Should I replace a worn, cracked or broken transmission mount? Yes! Having an unsecured transmission is not safe. Decide if you should use an OEM type replacement or upgrade to a more durable polyurethane version and replace the mount as soon as possible!   

Which transmission mounts are more expensive? Generally polyurethane transmission mounts are more expensive than rubber.

Do you offer an adjustable transmission mount? Yes – We offer Part Number GF-GMATM applications for most GM transmissions and Part Number GF-FMATM for many Ford transmissions. These transmission mounts are perfect when you want to keep the transmission crossmember where it is, but adjust for an engine swap or moving the engine and transmission forward or backward.

Do you offer transmission mount shims? Yes – Our GM transmission mount shim set for RWD vehicles includes four 1/8” thick shims that are perfect to adjust your transmission angle.

 Questions about our Transmission Mounts?

Chat with us or give us a call at 330-753-5300

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