Bulldog GD400 garage door lock

£69.00 inc. VAT & Shipping

Before ordering please check the dimensions to ensure the bracket is suitable for your garage door panel.

  • Bracket (mm): 142H x 75W x 86D
  • Bracket Thickness: 6mm
  • Ground Tube (mm): 105H x 60 Diam
  • Hardened Steel Lock Bolt: 25mm Diam
  • Coach Bolts & Reinforcing Plate Supplied

Available on backorder

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SKU: AZ-BDGD400 Category: Tags: , ,
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Bulldog GD400 garage door lock

The GD400 Garage door lock by Bulldog is supplied complete with an angle bracket back plate & ground tube, fixings and Bulldog Super Lock Bolt. This lock fastens garage doors directly to the ground, which makes prising them open incredibly difficult. Please note, some excavation is required in order to fit lock tube.


  • To suit most metal, glass fibre, plastic or wooden garage doors
  • Bolt on ‘L’ shaped bracket to fit to either outside or inside of garage door
  • Supplied complete with angle bracket back plate & ground tube, fixings, and Bulldog Super Lock Bolt
  • Lock tube fits flush to ground
  • Excavation required to fit lock tube
  • Highly visible yellow powder coating

Fitting Instructions

Appropriate safety wear should be worn when drilling and cutting. Please ensure you wear gloves and goggles etc. Below is an eight step plan for fixing to most up and over garage doors. Adaptation may be required for fixing to other types of doors.

Fixing bracket to the door

1. First, fit the solid steel angle bracket through which the lock bolt is designed to be slotted. The optimum
position is at the midpoint of the bottom of the door, with the bracket being held no more than 25mm
above the ground for the marking of the four drill hole positions in pencil. This gap will allow the full
engagement of the lock bolt.

2. Center punch the hole centers and drill clearance holes through the door for the fixing bolts.

3. Using ‘blind’ coach bolts, fix angle bracket to the door.

4. A reinforcing plate is used at the rear of the door, the coach bolts being secured using the washers and
nylon locking nuts supplied in the kit.

Base Preparation

5. An area 150mm square and 150mm deep should be drilled and chiseled from the concrete garage floor or
drive directly beneath the angle bracket. You may wish to increase the hole size particularly in looser
tarmac to create a larger retaining ball of concrete.

6. A base of gravel, topped with sand, should be laid at the bottom of the hole and tamped down until
compacted. This provides support for the base of the lock bolt receiving ground tube during the
final stages of installation.

7. The ground tube is now surrounded in concrete. Use the Super Lock Bolt to accurately position the
ground tube whilst concrete sets. Fit the black dust cap to prevent concrete and dirt damaging the lock.

8. Once the concrete has set, the door can be opened and a final troweling off will ensure that the area
blends in with the surrounding floor slab. A dust cap is provided to prevent the ingress of dirt into the
lock, and should be fitted at all times.

Lock Lubrication.
IMPORTANT – To ensure free movement of the lock, spray lock mechanism & ball bearings with WD40 (or equivalent) minimum every four months.

Additional information



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Bulldog GD400 Garage Door Lock
Bulldog GD400 garage door lock
£69.00 inc. VAT & Shipping
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