Could be clutch fluid overheating rather than gearbox ..stuart wrote:I reckon that's pretty much a foregone conclusion Mr Fletcher. Most of the Britcar BMW's use a gearbox or diff cooler. I know I'm not anything like Britcar level but sustained laps on the circuit or ragging around sideways (spinning more like) mean that the gearbox gets hot quite quickly and then the ambient temps mean it starts getting difficult to select gears, especially first.
As Jason said I would fit a sensor first before fixing a problem that might not exist or at least have a before/after comparison for what the cooler is doing.