Install Guide

Case Toilet Seat Adapter Installation Instructions

Product Overview:

The Case Toilet Seat Adapter Kit allows you to install modern toilet seats from brands such as Bemis, Mayfair, and others on vintage Case toilet models including Case 1000, 1100, 3000, 3200, Briggs 6000 series, and similar models. These toilets typically have mounting studs or bolts spaced 7 inches apart that mount through the front of the tank.

Recommended Toilet Seats:

  • Elongated: Bemis 1500EC
  • Round: Bemis 500EC

Make sure your chosen seat features the Stay-Tite or Easy-Clean & Change twist-lock mounting system and has a flat (not concave) bottom to properly accommodate the provided riser bumpers. These seats are widely available at hardware and home improvement stores in various colors and shapes.

Kit Includes:

  • 1 Adapter bracket
  • 2 Stainless steel carriage bolts
  • 2 Nylon washers
  • 2 Stainless steel nuts
  • 4 Raised seat bumpers (3/4" height)

Installation Steps:

  1. Remove Old Seat: Loosen and remove nuts from seat mounting studs inside the tank to remove the existing toilet seat.
  2. Install Adapter Bracket: Align adapter bracket holes with tank holes. Insert stainless steel carriage bolts through the front of the adapter bracket into the tank.
  3. Secure Adapter: Inside the tank, place nylon washers over bolt threads followed by stainless steel nuts (serrated side towards washers). Using a 9/16 wrench, gently tighten to approximately 1.5 ft-lbs torque. Do not overtighten to prevent damaging the tank or bracket.
  4. Attach New Seat: Ensure seat hinge twist locks are fully turned left (unlocked position). Press seat hinges firmly onto adapter studs until they snap fully into place. Confirm hinges are flush with the adapter bracket surface, then twist hinges to the right (locked position).

Install Riser Bumpers:

The adapter raises the back of the seat approximately 1/4 inch. Install included riser bumpers to level and support the seat on the toilet rim.

  1. Lower seat onto toilet rim.
  2. Slide new bumpers adjacent to existing seat bumpers, ensuring full rim support and no overhang. If no existing bumpers are present, place new bumpers about 2 inches from the back of the seat near the outer edges.
  3. Mark bumper positions on seat bottom with a crayon or erasable marker.
  4. Remove adhesive backing and firmly attach bumpers to marked positions. Close seat and apply pressure to ensure secure attachment.

Your seat installation is now complete with riser bumpers securely in place.

Installation Diagram