The 1500cc engine and gearbox mountings are revised to suit the Triumph engine's different mass distribution and mounting geometry. The engine mounting brackets are specific to the 1500 and not interchangeable with the 1275cc items, though the same principle of rubber mounts on handed body-side brackets applies.
Gearbox Steady Bracket
The most important difference on the 1500 is the gearbox steady bracket. This restraint bracket with its rubber bushes prevents the gearbox from impacting the transmission tunnel under the torque reaction of hard acceleration or sudden deceleration. It was introduced shortly after the start of 1500 production and was not fitted to the very earliest cars.
Owners of early 1500s who experience a knock or vibration through the floor, particularly noticeable when pulling away sharply in first gear or when lifting off the throttle suddenly, should check whether this bracket has been fitted.
Steady Bracket Inspection
If the steady bracket is missing, the repeated impact between the gearbox casing and the tunnel causes progressive damage to both components. The bracket and its bushes should be fitted at the next opportunity when the underside of the car is accessible. The bushes themselves are a wear item and should be inspected periodically, collapsed bushes defeat the purpose of the bracket entirely, allowing the same gearbox-to-tunnel contact that would occur without the bracket fitted at all.