Classic Square 3500 Series Heavy-Duty Replacement Sleeper Sofa Mechanism

Replace damaged, rusted, worn-out, or unsafe sleeper units with a new Made-in-USA Replacement Sleeper Sofa Mechanism which feature squared tubular construction that's safe, strong, well designed. When sleeper sofa mechanisms break, they can become uncomfortable, non-working, or worse, dangerous.  Wallace Flynn offers many different replacement sleeper sofa mechanisms. Repair it, don't replace it. 

If you're unsure, please contact us before ordering to ensure proper sizing. 

The strongest sleeper mechanism made, the Classic Square sofa sleeper system includes engineered low-profile linkage along with body-support tubes and wires for enhanced support. It eliminates sagging and the two-ply ballistic decking material enhances durability and visual appeal. The Classic Square Sleeper mechanism is a heavy-duty contract/residential sofa sleeper system with a number of features and benefits to ensure comfort and durability. The Classic Square is considered the easiest to operate in the industry and is engineered with low-profile linkage to keep all metal parts below the mattress line. Its all-square tubular frame construction provides a smooth and visually appealing look with improved safety (eliminated pinch points) and comfort in the seated position. The dual one-piece tubular legs also provide enhanced stability and strength, making this one of the highest quality products on the market.

When ordering a replacement mechanism for your sofa, finding the manufacturer and model number information for the existing mechanism is very important. This ensures that you receive the correct fit for replacement. This model replaces the Leggett and Platt 3500 Classic Square Series mechanisms. Alternately, if the label is difficult to read, you can measure the distance between the brackets where the unit mounts into the wooden frame inside the sofa. 

Please look for the Leggett model number sticker on your current mechanism and match it to the model number below. The model number of your current mechanism is the only accurate way to ensure a correct replacement. Please reference the chart below to find your model number.

Available in the Following Widths:
Size / Model
44" / 3544, 4435
48" / 3548, 4835
55" / 3555, 5535
60" / 3560, 6035
68" / 3568, 6835

Take Notice: regarding custom enclosures or custom builds for replacement mechanisms:
Screws or bolts for attachment are not included.

The mounting width is not the mattress size. Take away 8" from the mounting width for the correct mattress width.
Sleeper Mattress sizing differs from standard mattress sizes. Sleeper mattress sizes are:
Twin: 36 in. wide x 72 in. long
Full: 54 in. wide x 72 in. long
Queen: 60 in. wide x 72 in. long

When custom building, we encourage you to build around the unit once it's received. All measurements provided on the spec sheets are minimums. 

Please contact us before ordering to ensure proper sizing.  All sleeper mechanisms are made in the USA