Guide to the Automatic Transmission Mount for 1987-1989 GMC R2500
Stop the clunking and vibration by choosing the right new transmission mount for your classic GMC truck.
- A bad transmission mount on your R2500 will cause clunking noises when shifting and excessive vibration.
- For this truck, affordable aftermarket rubber mounts from brands like Anchor, DEA, or Pioneer are a suitable choice for normal use.
- Replacing the mount is a straightforward job for a DIYer with basic tools, but the transmission must be safely supported.
- While replacing the transmission mount, always inspect the two engine mounts for wear and tear.
Is Your Transmission Mount Failing?
A bad transmission mount on your R2500 will make itself known through distinct sounds and feelings. Because these trucks are over 30 years old, the original rubber has likely degraded from age, heat, and exposure to fluids. Here are the most common signs that it's time for a replacement:
- Clunking Noises: A loud "clunk" or "bang" when you shift from park into drive or reverse is the most common symptom. This is the sound of the transmission moving and hitting the frame because the mount can no longer hold it securely.
- Excessive Vibration: You might feel a new or stronger vibration in the cab, through the floor, or in the gear shifter, especially at idle or when accelerating. The old rubber is no longer able to absorb the normal vibrations from the drivetrain.
- Engine Movement: A worn mount allows the entire engine and transmission assembly to lurch forward or backward during acceleration and braking. In some cases, you can physically see the engine move more than it should when shifting gears with the brake applied.
Choosing the Right Aftermarket Mount
For a vehicle of this age, new Original Equipment (OEM) parts from GM are likely unavailable or very difficult to find. Aftermarket parts are the most practical and affordable solution. The brands available for your R2500 fall into two main categories:
Standard Replacement Mounts (Good Choice)
Brands: Anchor, DEA, Pioneer Cable
These brands produce standard, OEM-style replacement mounts. They use a rubber insert bonded to a metal frame, designed to restore the original ride quality and performance. For a daily driven or lightly used R2500, these mounts are a perfectly good and budget-friendly choice. Forum discussions show mixed reviews on quality between Anchor and DEA, with some users experiencing early failure. Pioneer is often viewed as a slightly better quality standard replacement. Given the low cost of the part, choosing any of these will be a significant improvement over a completely failed mount.
Pro Tip: When replacing the transmission mount, it's a good time to inspect your engine mounts as well. They are made of the same materials and are subjected to the same conditions. If the transmission mount has failed, the engine mounts may not be far behind.
Performance Mounts (Better for Heavy Use)
Brands: Lakewood
Brands like Lakewood often offer mounts made from polyurethane instead of rubber. Polyurethane is a much stiffer material. This results in less drivetrain movement, which is ideal for high-horsepower applications, towing, or heavy hauling. However, there is a trade-off.
Warning: Because polyurethane is stiffer, it absorbs fewer vibrations than rubber. Installing a polyurethane mount may lead to a noticeable increase in noise and vibration inside the truck's cab. This is a common trade-off for improved performance and durability.
Aftermarket Part Cost
| Brand Tier | Price Range (Part Only) |
|---|---|
| Standard Aftermarket (Anchor, DEA, Pioneer) | $7.93 - $15.18 |
| Performance Polyurethane (Lakewood) | $40 - $50 |
Frequently Asked Questions
How can I be sure the transmission mount is bad?
The easiest way to check is to have a helper safely sit in the truck with the parking brake set and their foot firmly on the brake pedal. Have them shift from Park to Reverse, and then to Drive, while you watch the transmission from the side. If you see the back of the transmission lift up or move excessively, the mount is bad. You can also visually inspect it for large cracks, torn rubber, or separation between the rubber and metal.
Is this the same as an engine mount?
No, they are different parts, but they do a similar job. Your truck has two engine mounts that support the engine at the front, and one transmission mount that supports the transmission at the rear. Together, they hold the entire drivetrain in place.
Can I replace just the transmission mount?
Yes. If your engine mounts are still in good condition, you can replace only the transmission mount. However, a failed transmission mount puts extra stress on the engine mounts, so it is critical to inspect them at the same time.
Will a new mount fix all my vibrations?
It will fix vibrations caused by the mount itself. However, vibrations in a truck can come from many sources, including tires, driveshaft, u-joints, or engine misfires. If the vibration persists after replacement, further diagnosis is needed.
Technical Specifications
OEM Part Numbers: 22188145
This is a single-bolt style mount that attaches the rear of the automatic transmission to the vehicle's crossmember. It consists of a metal bracket with a bonded rubber insert.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- GMC R2500: