Gearbox Upgrades

Almost all OEM gearboxes suffer the same problems when being used in race cars, be they circuit or drag or just fast street cars. The problem is the ratios are suited to the normal road application, ie first gear is way too low, and in the rally application, fifth gear is way too high. We can fix this by custom manufacturing a set of ratios that suit YOUR vehicle. We factor in, tyre size, diff ratio, engine RPM characteristics and your application. So in a rally car this would mean a much higher first gear, approx 75km/h, and generally a much lower fifth gear. Most rally cars are geared for a maximum of 200km/h.

In a circuit car, the same rules apply for first gear, but fifth is often only lowered a small amount . All the other gears are made to provide ever decreasing gaps as set by first and fifth ratio’s. We can also make almost any ratio that the customer requests.

Front wheel drive type gearboxes and their 4wd variants can also have custom diff ratio’s made.

We can also manufacture special gearsets to suit certain applications, these include removing synchro units and replacing with “crash” type engagement, this is essential for high revving engines as synchro systems will “baulk” over 7500 rpm preventing shifting from occuring unless excessive force is used. This can cause selector fork failure.

Also made are take apart type layshafts that allow easy changing of ratio’s to fine tune the car or setup for certain tracks.

Longer input shafts can allow optimum placement of the gearbox to keep the gear lever in the best place for cars with seats that are further back or for weight balance.

We manufacture adapter plates to let you fit engine/gearbox combinations from different vehicles or models, these can either be sandwich plates between the gearbox and bellhousing or plates between the engine and gearbox. Often a special flywheel is needed for these mixed units.

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