Why you need to replace both the running wheels and the GU lift lock on an old type lift sliding door
In older lift sliding doors, the door often runs heavily, closes poorly, or does not lift properly. Many people think that replacing only the running wheels is sufficient, but with old systems, that is usually not the case. For an old type lift sliding door, you often need to replace both the running wheels and the lift lock, especially when using GU parts, because modern parts do not fit well with the old mechanical system.
At Openingstechnieken.com you will find the right GU running wheels and lift locks for your lift sliding door.
The old system is one linked mechanism
In older lift sliding doors, the lift lock and running wheels are mechanically connected. At the bottom of the lift lock is a transmission mechanism that is directly connected to the running wheels.
With the old type lift locks GU 931, GU 933, GU 935, and GU 936, this system works as one unit. When you move the handle from top to bottom:
✔ The GU lift lock activates the transmission
✔ The door is lifted via the GU running wheels
✔ The door clears the rail
✔ The door can slide smoothly
The running wheels are therefore not only load-bearing — they actively form part of the lifting mechanism.
Old versus new GU parts
For old lift sliding doors, the wheels and lift locks are often of the following types:
✔Old type lift locks: GU 931, GU 933, GU 935, GU 936
✔New type lift locks: GU 934 and GU 937
In addition, the GU running wheels are divided into two heights:
✔Low type wheels with rebate height 45 mm → GU 937
✔High type wheels with rebate height 57 mm → GU 934
Note: the new type of lift locks and wheels do not fit the old mechanism, making it essential to replace the lift lock and running wheels at the same time.
Why replacing only the rollers is often not enough
When you only replace the rollers on an old system:
✔ The mechanical coupling does not fit properly
✔ The lifting mechanism works incompletely
✔ Operation remains heavy or stiff
✔ Accelerated wear occurs
✔ The door can pull crooked or keep sticking
The problem is temporarily reduced but not structurally solved.
Moving the upper locking cam on old doors
For most old lift-slide doors, after replacing the lifting lock and rollers, the upper locking cam must also be moved. This is necessary to allow the door to close correctly and to prevent it from getting stuck.
✔ Move the upper locking cam according to the manufacturer's instructions
✔ Always check if the door closes freely and evenly
📹 Watch our video about moving the upper locking cam: Video instruction
Why you should replace your GU lifting lock and rollers together
By replacing GU rollers and lifting lock as a complete set:
✔ The system closes mechanically perfectly
✔ The lifting movement works as intended again
✔ The door is fully lifted when operating the handle
✔ The door runs lighter and smoother
✔ Prevent recurring malfunctions
✔ Extend the lifespan of the entire lift-slide door
For old lift-slide doors, you replace for example:
✔ Lift lock: GU 931, GU 933, GU 935 or GU 936
✔ Rollers: low type 45 mm (GU 937) or high type 57 mm (GU 934)
This way you create a new, technically matched whole that works perfectly together.
Especially essential for older lift-slide doors
In older systems, parts are often:
✔ Mechanically outdated
✔ No longer available in original version
✔ Designed according to old tolerances and dimensions
✔ Less forgiving with partial replacement
That is why a complete replacement with GU parts from Openingstechnieken.com is more reliable than replacing individual parts.
Conclusion
In an old type lift-slide door, the GU lift lock (old types GU 931, GU 933, GU 935, GU 936) and the GU rollers (low type 45 mm = GU 937, high type 57 mm = GU 934) form one integrated system via a mechanical transmission. Modern types do not fit the old mechanism, making it technically necessary to replace both parts at the same time. In most cases, the upper locking lug must also be moved so that the door closes correctly and runs smoothly.
This ensures a smoothly running door, correct lifting action, and a durable solution.
Is your lift-slide door heavy to operate or not lifting properly?
✔ Replace GU rollers and lift lock together
✔ Check and move the upper locking lug if necessary
✔ Order the correct parts for GU 931, GU 933, GU 935, GU 936, GU 934 or GU 937 directly at Openingstechnieken.com
✔ Request free technical advice for your door
