GR6 transmission - solenoids, clutch packs and retaining clips
£3,000–£12,000
The dual-clutch gearbox is the defining cost of R35 ownership. Debris circulating in the case jams the control solenoids, the clutch packs wear, and the retaining clips can pull away from the splines and take the oil pump and clutches with them. The early symptoms are subtle - harsh or delayed shifts at low speed - and easy to dismiss, which is exactly why cars get sold at that point.
Gearbox work on these is four to five figures depending on how far it has gone. A fluid service on the correct specification is a fraction of that and is the single most important line in the folder.
Typically bites
Driven by use and by fluid history rather than by age. Launch control use and long fluid intervals are both implicated.
Verified against 3 published sources.