If you own a Garmin vehicle GPS and want to mount the existing cradle using a RAM Mount system, you run into a problem almost immediately: the two systems are not compatible out of the box. Garmin uses a 17mm ball socket on the back of their cradles. RAM Mounts use a 1-inch (25mm) ball on their arms and bases. That size gap prevents any direct connection, and no amount of force is going to change that. The good news is that a single inexpensive adapter solves the problem completely, and the resulting setup is significantly better than the stock Garmin suction cup mount that comes in the box.
What You Need at a Glance
| Component | What It Does | Mount Location |
|---|---|---|
| Arkon 25mm to 17mm Ball Adapter | Bridges the 1-inch RAM ball to Garmin’s 17mm socket | Between ARM and cradle |
| RAM Short Double Socket Arm (RAP-B-201U-A) | Adjustable 1-inch B-size arm, near-infinite positioning | Between base and adapter |
| RAM Twist-Lock Suction Base (RAP-B-224-1U) | 3.3-inch twist-lock base, windshield or dash mounting | Windshield or dashboard |
Why the Ball Sizes Don’t Match
Garmin has been using the same 17mm ball socket design across their automotive GPS line for well over a decade. Every Nuvi, every Drive, every DriveSmart — the cradle on the back of each one uses the same 17mm socket to connect to a mount. It is a reliable standard, and the Garmin mounting system works fine when you’re using Garmin’s own mounts.
RAM Mounts are built around a completely different standard. Their B-size ball, used across the vast majority of their consumer and professional vehicle mount lineup, measures 1 inch in diameter (25mm). That’s nearly 50% larger than Garmin’s 17mm socket. There is no way to wedge a 1-inch RAM ball into a Garmin cradle socket. People try. It doesn’t work.
The confusion usually comes from marketing. Some RAM cradles are designed specifically for Garmin units and use a G-ball, which is RAM’s term for a 17mm-compatible ball. These cradles connect directly to Garmin GPS units with no adapter needed. However, those cradles only work with specific Garmin models and do not give you the flexibility of keeping your existing factory cradle. If you want to use the cradle that came with your GPS, the adapter route is the right one.
The Adapter That Solves It
The Arkon SP25MM17 is a purpose-built adapter with a 1-inch ball on one end and a 17mm ball on the other. One end clicks into any standard RAM B-size socket arm. The other end pops into the 17mm socket on the back of your Garmin cradle. That’s the whole fix. There is no drilling, no modification, and nothing permanent.
Arkon has been making mounting hardware for GPS and mobile devices for a long time, and this adapter is one of their best-selling items for good reason: it solves a real problem cleanly. The build is compact, the fit is firm on both ends, and at its price point it is genuinely one of the better value-adds in the mounting category.
Building the Full Mount Setup
The adapter alone isn’t a complete mount. You need a base and an arm to go with it. Here’s how the full three-piece setup comes together.
The Suction Cup Base
The RAM Twist-Lock Suction Cup Base (RAP-B-224-1U) is the standard choice for windshield or dashboard mounting. It uses a 3.3-inch suction cup with a twist-lock mechanism that creates a strong, consistent hold on smooth, non-porous glass. You press it to the surface, then turn the lock to engage it. No wobble, no drop. It includes a 1-inch B-size ball built into the diamond base plate, so it connects directly to any RAM B-size arm.
The twist-lock mechanism is a meaningful upgrade over a basic push-lock suction cup. The Garmin stock mount uses a push-release vacuum button that works fine when it’s working and fails unpredictably when it’s not. The RAM version requires you to actively engage and disengage the lock, which adds a small step but eliminates the surprise failures. RAM backs it with a lifetime warranty.
The Double Socket Arm
The RAM Short Double Socket Arm (RAP-B-201U-A) sits between the suction base and the Arkon adapter. It has a 1-inch B-size socket at each end with a single adjustment knob in the middle. Loosen the knob, rotate the balls to the angle you want, tighten it back down. That’s how RAM positioning works, and it gives you a range of motion that a fixed-neck mount simply cannot match.
The short arm is 2.42 inches overall, which keeps the GPS close to the windshield and reduces leverage on the suction cup. If your dash layout or mounting position puts the windshield farther from the driver, the medium arm (RAM-B-201U) is the same design at 3.73 inches overall. Either works with the same base and adapter.
How It Goes Together
Assembly takes about two minutes. Attach the suction base to a clean glass surface using the twist-lock. Snap the short arm onto the 1-inch ball on the base. Insert the 1-inch end of the Arkon adapter into the open socket on the other end of the arm and tighten the knob. Finally, press the 17mm ball on the Arkon adapter into the socket on the back of your Garmin cradle. The cradle will click and lock in, same as it would on the stock Garmin mount. To remove the GPS, squeeze the release on the cradle as you normally would. The base and arm stay on the windshield.
Is This Better Than the Stock Garmin Mount?
In most cases, yes, and meaningfully so. The stock Garmin suction cup mount is functional but built to a price. The neck is fixed, so you get whatever angle the suction cup position gives you. If your windshield slope doesn’t line up with the viewing angle you need, your options are limited. The push-lock suction mechanism works well when new and degrades over time with temperature cycling — you’ve likely seen a GPS unit fall off a windshield in a hot car. The base is also sized down to be inexpensive, not to be robust.
The RAM setup gives you an adjustable arm, a more reliable suction mechanism, and a system built with a lifetime warranty. The modular design also means you’re not locked into one configuration. If you upgrade your GPS, the base and arm stay on the windshield. You either reuse the same Arkon adapter with the new cradle or, if the new cradle uses a different ball size, swap only the adapter.
For trucks, larger SUVs, and any vehicle where the windshield sits at an unusual angle or farther from the driver, the adjustable arm makes even more difference. The older Garmin dashboard adhesive mounts were actually more rigid and reliable than the suction version for this reason. The RAM system gets you that same stability with more flexibility.
When to Use a Dedicated RAM Garmin Cradle Instead
If RAM makes a model-specific cradle for your GPS unit, it is worth checking before going the adapter route. A dedicated cradle connects directly to a 1-inch RAM ball without any adapter, which reduces the number of connection points and can give a slightly more rigid hold. RAM’s model-specific cradles are available for a range of Garmin Drive, DriveSmart, and older Nuvi units.
The adapter approach works equally well and is more versatile, since it works with any Garmin cradle that uses the standard 17mm socket. It also future-proofs the setup: if you replace your GPS with another Garmin model that uses the same 17mm socket, the adapter carries forward. For dedicated Garmin handheld GPS units like the Montana, eTrex, and GPSMAP series, see our separate guide on Garmin handheld GPS mounts — those devices use different attachment systems entirely.
What to Avoid
A few things come up repeatedly when people try to piece together a Garmin-to-RAM setup and run into trouble.
Don’t buy components thinking they all connect automatically. RAM Mounts are modular, which means you pick each piece separately — base, arm, and end connector. A suction base alone does not include an arm. An arm does not include a cradle or adapter. Make sure you have all three pieces before you assume the setup is complete.
Don’t assume all RAM G-ball cradles fit your GPS model. RAM makes several model-specific Garmin cradles, and they are not universal. Verify the cradle lists your specific Garmin model in its compatibility before ordering.
Don’t buy off-brand “Garmin RAM adapters” claiming to fit all ball sizes without checking the dimensions. The Arkon SP25MM17 is the proven choice and is widely stocked. Generic listings sometimes describe themselves as 25mm-to-17mm adapters but ship 20mm or non-standard alternatives. Stick with the Arkon for this one.
For a broader look at how the Garmin mounting ecosystem fits together, the GPS car mount guide covers the full range of base mount options across the Garmin vehicle lineup.
