Gearbox Servicing and Overhaul

To complement our work on engines we perform basic servicing on manual and automatic (torque convertor) gearboxes. We also overhaul manual gearboxes. It is our intention to offer an overhaul service for automatic gearboxes (torque convertor) as well in the future.
A typical gearbox overhaul comprises assessing the condition of the internal components for wear or damage. Where needed, we replace:

• Bearings
• Damaged or worn gear teeth
• Synchromesh assemblies
• Shift rod bushings

We can also change the gear ratios if desired.

To complete the service, the gearbox casings will be cleaned of oil and debris, all gaskets and seals will be changed and new gear oil added.

Below are a few samples of our workmanship on gearboxes:

Porsche 911/914

The 911 and 914 gearboxes are of a transaxle design. That is, the final differential is incorporated into the gearbox housing. They are constant mesh gearboxes – that is, the layshaft is always connected to the main shaft. The gears are always meshed.

The 911 and 914 gearboxes are very similar in design – they both have 5 forward gears with synchromesh on all forward gears and a reverse gear with no synchromesh. The gearbox is mid-mounted in a 911 but rear-mounted in a 914. Consequently, the crown gearwheel on a 914 gearbox sits on the other side of the differential housing to the 911, otherwise the 914
would have 1 forward gear and 5 reverse gears!

The early 911 gearbox is a type 901 and the housing is made from aluminium. In the early 1970’s this was changed to a 915 type that could handle more torque. By the late 1980’s the G50 type gearbox was in use. By 1990 an automatic gearbox (4 speed) designed by ZF and called Tiptronic was available.

The 914 gearbox housing is made from magnesium and is a shared VW design. Early 914’s had a tail shift design carried over from the 911 but by 1973 this was changed to a side shift mechanism to improve the gearchange as there was too much play in the tail shift mechanism.

Jaguar E-Type 5.3 litre V12

The gearbox has four forward and one reverse gear. All forward gears are fitted with a synchromesh mechanism. The gearbox is a constant mesh type. The differential is contained within the final drive unit which is separate to the gearbox. The bellhousing (for the flywheel and clutch mechanism) is made from lightweight aluminium but the gearbox housing is made from cast iron for durability.

Mercedes-Benz 190 SL

The 190 SL has a conventional gearbox of four forward gears and one reverse. The forward gears have synchromesh and the gearbox is a constant mesh type. As the car is rear wheel drive, the differential is not contained within the gearbox but within the final drive unit. The gearbox housing is made from cast iron but the bellhousing (for the flywheel and clutch mechanism) is made from aluminium to save weight.