This is a common issue on the 2021 Volkswagen T-Roc models equipped with the 6-speed manual transmission (Gearbox code 'UFH') The problem is a direct result of a fault in the 3rd and 4th gear synchronizer rings.
Symptoms of the Fault
Drivers typically notice a grinding noise when shifting into 3rd or 4th gear, along with difficulty engaging these gears. In some cases, the gear lever can get stuck during the shift.
The Repair Process
Repairing this fault can be a complex procedure. First, the gearbox must be removed from the vehicle. Then, you need to carefully dismantle the entire gearbox, including the input shaft. The photo attached below, with the location marked in red, shows where the 3rd and 4th gear sets sit on this shaft.
To access these components, you must first remove the 6th and 5th gear sets by carefully pressing them off the shaft. When doing this, it's important that the shaft is not tightly clamped or hung to avoid damaging other gearwheels or synchronizer rings.
Once the new synchronizer rings are installed (Both of these rings are identical and share the same part number), be sure to correctly place the wave springs between each synchronizer ring and its cone during reassembly.
