Short answer: A porch glider moves on four bearing arms, one at each corner, that hang the seat from the base like a swing. When a glider squeaks, sags, rocks side to side, or stops moving smoothly, the arms are almost always the problem: the bearings are worn, the arms are bent, or plain steel arms have rusted. Replacement is a one hour job. Measure the center to center distance between the bearing holes on an old arm (6-1/2 inches and 7-1/2 inches are the common sizes), buy four matching arms, unbolt the old ones, and bolt on the new ones in the same orientation. Choose 304 stainless steel arms if the glider lives outside; they are the part that fails first on painted steel hardware.
Bear Hollow Supply makes stainless steel glider bearing arms in the USA in both common sizes, plus a black powder coated version and an 80 piece bulk pack for builders. This guide covers how a glider works, how to diagnose it, how to measure for replacement arms, and how to install them. Browse all outdoor furniture hardware here.
How a glider mechanism works
A glider is a swing that does not need a frame overhead. The seat hangs from a base on four short arms, two per side. Each arm has a bearing at each end: the top bearing bolts to the base, the bottom bearing bolts to the seat frame. Because all four arms are the same length and mounted parallel, the seat moves in a flat arc front to back without tipping. That geometry is why the arms have to match: if one arm is a different length or mounted at a different angle, the seat binds or rocks.
The bearings are what make the motion smooth and silent. They are small sealed bearings pressed into each end of the arm, with a bolt passing through the center. When the bearings wear out or corrode, the glider starts to squeak, feel gritty, or develop side to side slop.
Signs the glider arms need replacing
- Squeaking or grinding that lubricant does not fix for more than a few days
- Side to side wobble when you sit down, which means the bearings have worn oversize
- Rust on the arms or weeping from the bearings. Painted steel arms rust from the inside out once the paint chips, and salt air finishes them fast.
- A bent arm, usually from someone standing on the seat or dragging the glider by one end
- The seat sits crooked or one corner is lower than the others
- Stiff motion that takes effort to start
If the wood or poly frame is sound and the problem is in the motion, new arms fix it. Replacing the arms is far cheaper than replacing the glider.
How to measure for replacement glider arms
The measurement that matters is center to center: the distance from the center of the top bearing to the center of the bottom bearing on one arm. This is the arm's effective length and it has to match the originals so the seat hangs at the same height and the four arms stay parallel.
- Remove one arm, or measure it in place if you can get a tape on it.
- Measure from the center of one bearing hole to the center of the other.
- Round to the nearest common size. Most residential gliders use 6-1/2 inch or 7-1/2 inch arms.
- Note the offset. Most glider arms are not flat; they have a bend so the top and bottom mounting points sit in different planes, which lets the arm clear the frame as it swings. Our arms have a 1-1/4 inch offset. If your original arms are offset, match the offset as well as the length.
- Check the bolt size that passes through the bearings. Ours use 5/16 inch bearings, which fit a 5/16 inch bolt.
If your existing arms are a size we do not make, or you are building a new glider from scratch, pick the arm length based on how much travel you want. Longer arms give a longer, slower glide; shorter arms give a quicker motion and sit the seat closer to the base.
Stainless vs painted steel glider arms
Plain steel arms with a black paint or powder coat look fine new and cost less. Outdoors, water gets into the bearings, the finish chips at the bolt holes, and the arm rusts. On a covered porch they can last years. In full weather or near salt water they can fail in a season or two.
304 stainless steel does not need a coating to resist rust, so there is nothing to chip. It is the right choice for any glider that sees rain, for coastal locations, and for poly lumber furniture, where the frame will outlast everything and you do not want to be replacing hardware every few years. Our stainless glider bearing arms are 304 stainless with 5/16 inch bearings, a 1-1/4 inch offset, and a choice of 6-1/2 or 7-1/2 inch center to center. A set of four is one glider. We also offer the same arm in black powder coated steel for covered porches and for matching black frames, and the stainless arms in an 80 piece bulk pack for shops building gliders in quantity.
How to replace glider bearing arms
Tools: two wrenches or a wrench and a socket for the existing bolts, a tape measure, and new bolts, washers, and lock nuts if the old hardware is corroded. Our arms ship ready to install; fasteners are not included because the bolt length depends on your frame thickness.
- Flip the glider on its back on a soft surface so you can see all four arms. Take a photo of each arm before you touch anything so you can match the orientation of the offset later.
- Buy new fasteners if needed. Use 5/16 inch stainless bolts long enough to pass through the frame and the bearing with room for a washer and a nylon insert lock nut. Stainless bolts with stainless arms means nothing rusts.
- Remove one arm at a time. Unbolt the top and bottom, slide the arm out, and compare it to the new arm. The center to center and offset should match.
- Install the new arm in the same orientation. The offset bend should face the same direction as the original. Put the bolt through the frame, a washer, the bearing, another washer, and the lock nut.
- Snug, do not crush. The bearing has to rotate freely on the bolt. Tighten the lock nut until the arm has no side play, then stop. If you cannot spin the arm by hand, back off slightly.
- Repeat for all four arms. Replace all four even if only one failed. Mixed old and new arms wear unevenly and the glider will not track straight.
- Flip it back and test. The seat should glide silently through its full travel and come to rest level. If it binds at one end, an arm is mounted backward or a bolt is overtightened.
Keeping glider arms working
- Once a season, check that the lock nuts are snug and the arms spin freely.
- A small amount of waterproof grease at the bearing faces keeps water out. Some customers pack the bearings with marine grease on installation for gliders in exposed locations.
- Do not stand on the seat. Bent arms are almost always from standing or jumping.
- Lift the glider to move it rather than dragging it by one end, which side loads the arms.
Building a new glider
If you are building from scratch, four bearing arms plus a seat frame and a base is the whole mechanism. Mount the top bearings to the base at the same height on both sides and the bottom bearings to the seat frame at the same height on both sides, all four arms parallel. For an outdoor build that never needs maintenance, pair the stainless arms with HDPE poly lumber; see our poly lumber guide for how it compares to wood. For swivel seating, our stainless outdoor chair swivel works the same way: stainless so it does not rust under the seat.
Frequently asked questions
How do I know what size glider arms I need?
Measure center to center between the two bearing holes on one of your existing arms. 6-1/2 inch and 7-1/2 inch are the two common sizes. Match the offset bend as well if your originals have one.
Why does my porch glider squeak?
Worn or corroded bearings in the glider arms. Lubricant quiets them for a while, but once a bearing is worn the fix is new arms. Replace all four at once so they wear evenly.
Do glider bearing arms come with bolts?
Ours do not, because the bolt length depends on the thickness of your frame. Use 5/16 inch stainless bolts with washers and nylon insert lock nuts, long enough to pass through the frame and bearing.
Should I buy stainless or black glider arms?
Stainless for anything that gets rained on, anywhere near salt water, and for poly lumber furniture. Black powder coated steel for covered porches or where you want black hardware on a black frame.
How tight should glider arm bolts be?
Snug enough that the arm has no side play, loose enough that the bearing still rotates freely by hand. A nylon insert lock nut holds that setting without clamping the bearing.
Can I replace just one glider arm?
You can, but you should not. The other three are the same age and will fail soon, and a new arm next to worn ones makes the glider track unevenly. A set of four is one glider.
What is the offset on a glider arm?
The bend in the arm that puts the top and bottom bearings in different planes, so the arm clears the frame as it swings. Our arms have a 1-1/4 inch offset. Mount replacement arms with the offset facing the same direction as the originals.
Will 304 stainless rust outdoors?
Not in normal outdoor use. 304 is the standard grade for outdoor hardware and holds up in rain, snow, and coastal air. It can show light surface tea staining in heavy salt spray, which wipes off and does not affect strength.