RUPES Backing Plate Washer for LK900E

LK900E Backing Plate Washer, RUPES 9.393

The RUPES LK900E backing plate washer (part 9.393) is the flat washer that sits under each backing plate screw on the RUPES LK900E gear driven polisher. The LK900E's plate bolts to the machine's aluminium support through six holes, and each of the six screws stacks with two washers: this 9.393 against the plate, and a 9.1808 contact washer between it and the screw head. On a gear-driven machine the plate is driven rather than free-spinning, so those six screws carry the full torque of the 900-watt motor, and RUPES's manual calls out placing the washers correctly before anything is tightened. The mount is the same for the LK900E's 125mm and 150mm plates, so this washer serves both.

A full plate mount takes six of each part. The RUPES backing plate screws (9.614) and the RUPES contact washer for the LK900E (9.1808) complete each stack, and the plate seats on a six-hole gasket, RUPES part 68.379, that's worth inspecting whenever the plate comes off. Body shops and detailers who swap between the 5" and 6" plates keep a few of each on hand, since hardware this small tends to disappear during a plate change.

What Makes it Great:

🔩 Sized for the 9.614 Screw: RUPES pairs this washer with the LK900E's backing plate screw, so the clamping load spreads around each of the plate's six holes instead of bearing on a narrow ring under the screw head.

🎯 Even Clamping, Square Plate: Six matched washers clamp the plate evenly against its gasket, which helps it seat flat and run without wobble.

🔁 One Part for Both Plates: The 125mm and 150mm LK900E plates mount the same way, so the same washer goes back in when you swap sizes.

🧰 Keeps Plate Swaps Moving: With spares in the drawer, a lost washer doesn't hold up a plate change or send the machine out with one screw short.

Frequently Asked Questions

How do you change the backing plate on a RUPES LK900E?

Unplug the polisher, loosen the six screws, and lift the plate off. Line up the six holes in the gasket with the new plate, set the plate against the aluminium support with its holes aligned, and refit each screw with both washers in place. RUPES warns not to tighten the screws until the plate is properly seated.

What is the difference between the 9.393 washer and the 9.1808 contact washer?

Both go on every plate screw. The 9.393 is the flat washer that sits against the plate, and the 9.1808 contact washer sits between it and the screw head. One doesn't replace the other, so a complete stack needs both.

Why does my LK900E backing plate wobble?

Start with the plate mount. A loose screw, a missing washer, or a plate tightened before it was seated can all leave it running off-center. Back the screws out, reseat the plate on its gasket, and tighten each screw with both washers in place.

Specifications:

Installation (Best Practices):