The ST200 was supposed to be treated to the Getrag F28 six-speed gearbox made famous by the Cavalier and Calibra Turbos, but this update failed to materialise. Instead, the F25 five-speed was used, although MSD revised the final drive to 4.45:1 and added an AP Suretec limited-slip differential for good measure. It’s a superb bit of kit, transforming the way the Vectra handles. It also helps to plant power. The same can’t be said for the revised gearing. Admittedly, the ST200 pulls marginally better in fifth than it would without the update, but the engine revs much higher than is necessary when cruising at the national speed limit, leaving you wanting to reach for the missing sixth.
The good news is that as far as maintenance and reliability is concerned, the F25 is rock solid. Much like the V6 up front, it’s a part fitted to a high number of front-wheel drive, V6-powered Vauxhalls. The clutch is a standard part, hydraulically operated and matched to a heavy, vibration-dimming flywheel. Many Griffin sixshooters have had their flywheels replaced by lighter, billet parts which enable high revs quicker, although they can make a racket and may be unforgiving at low speed. It’s a trade-off you can probably live with! If you are changing or upgrading the clutch or flywheel, be sure to replace the slave cylinder at the same time.