A set of metal door lock mechanisms displayed against a white background, including a central case and single spindle parts.
Diagram illustrating how to measure a Mila uPVC door lock centre case gearbox, showing the "Backset" (A) and "PZ" (B) dimensions for correct fitting.
A set of metal door lock mechanisms displayed against a white background, including a central case and single spindle parts.
Diagram illustrating how to measure a Mila uPVC door lock centre case gearbox, showing the "Backset" (A) and "PZ" (B) dimensions for correct fitting.
GU

GU Old Type Gearbox 30mm – Replacement Centre Case for uPVC Multipoint Door Lock – Single Spindle 92mm PZGU Old Type Gearbox 30mm - 92mm PZ

5.0 (3 reviews)
£29.99 SKU: HS2852
Order by 2pm for same-day dispatch
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Same-day dispatch on orders before 2pm

The gearbox is the most common part to fail on a GU multipoint lock — replace just this centre case, not the full strip, and save.Measure your backset before ordering.

Key benefits
  • Direct GU Old Type replacement - 35mm backset, single spindle
  • Restores multipoint lock function - no door alteration required
  • 92mm PZ standard fitting - measure your case before ordering
Product overview

GU Old Type 30mm Replacement Gearbox

The GU Old Type centre case gearbox (30mm backset) is the mechanism inside your uPVC door that is operated by the handle. It is the most common part to fail when a GU multipoint door lock stops working.

Replacing just the gearbox is far more cost effective than buying a complete new lock. The centre case re-attaches to your existing locking strip.

Key Measurements

The most important measurements are 30mm Backset and 92mm PZ. Other sizes on the product are provided for reference only.

This gearbox is non-handed, fitting both left and right-handed doors. Single spindle operation.
Delivery & Returns

How much is delivery?

UK Mainland Delivery is £2.99 on all items no matter how many you order!

Northern Ireland, Scottish Highlands, Channel Islands £6.00.

We do not offer International Delivery (Ireland, France, Spain etc).

When will my order be dispatched?

Orders before 3pm (Monday to Friday) are usually dispatched same day but may take up to 24 hours.

When will I receive my item?

We ship on 2 working day courier. Fully Tracked. Tracking will be emailed on dispatch. 

Special order items such as keyed alike locks will take longer to dispatch. Please refer to product description for lead times. 

I haven't received my item?

Please email us your name, order number and date of purchase.

We prefer email as it allows us time to research and respond.

Returns Information

We operate a 30 day refunds and return policy. 

If you change your mind you must return the product back to us within 30 days of delivery

Please include a copy of your invoice and a note stating reason for return. 

Additional keys, locks keyed alike or built to code are non refundable as they are personalised made to order goods.

Any refund, which is due to a fault or other defect, will include a refund of the applicable delivery charges otherwise not. 

It is the buyers responsibility to arrange the return of goods to us. We do not offer a collection service for returning items. 

Items must be returned including original product packaging and accessories.

We reserve the right to refuse any returns that do not comply with this policy.

Please post returns to the following address:

Home Secure (Online)

Unit 5, Brookfield Drive

Liverpool, L9 7AJ

United Kingdom

Frequently Asked Questions

A GU old type centre case gearbox is the internal mechanism of a multi-point door lock that controls the latch and locking points. It is specifically designed for older GU locking systems.

A 30mm single spindle refers to the backset measurement (distance from the edge of the door to the centre of the spindle hole) and indicates that the lock uses one spindle to operate both internal and external handles.

Signs include a floppy or stiff handle, the lock not engaging properly, or difficulty locking/unlocking the door. If these issues occur, replacing the centre case gearbox is often the best solution. For more insight into lock issues and risks, see Why Most Homeowners Don’t Upgrade Their Door Locks (And Why It Costs Them).

No, this gearbox is specifically designed for older GU multi-point locking systems. It’s important to match dimensions such as backset, spindle type, and fixing points with your existing lock.

Yes, with basic DIY skills you can replace the gearbox by removing the handle and lock strip. Following a proper step-by-step guide can help ensure correct installation and avoid damage.