Bosch VW Starter - 12 Volt - Manual Transmissions - New

Upgrading 6 Volt to 12 Volt electrical systems:

Keeping a 6 volt Starter.

When upgrading from a 6 volt system to a 12 volt system, contrary to popular belief, the 6 volt starter can be retained, meaning it is not a requirement to install a 12 volt starter.The stock 6 volt starter & 180mm flywheel will work on a 12 volt system.The result is an engine that will spin twice as fast during starting, making it mucheasier/faster to start your engine!

When using a 6 volt starter on a 12 volt system, it is important to only use it in shortbursts- meaning if the engine is not starting right away, do not continuously run the starter, give it a break! 5 to 10 seconds should be PLENTY of time to start an engine when a 6 volt starter is used on a 12 volt system.

Switching out for a 12 volt Starter.

If you do decide to remove your 6 volt starter, you will also need to remove your 180 mm (known as a 6 volt) flywheel, as the number of teeth are different making them incompatible with a 12 volt starter. This does lead to other hurdles.

A 12 volt flywheel will not fit 1100cc (25 horse), 1200cc (36 horse) or 1200cc (40 horse) engine directly. The mating surface of the flywheel is different.The 12 volt flywheel diameter is larger than a 6 volt, and may not fit inside of the bell housing of the 6 volt era transmission.This means you will need to grind the bellhousing out in various locations to make room for the larger flywheel. Furthermore,when installing the new flywheel, it is IMPERATIVE that the end play be set, or fatal damage can occur to the engine block. An advantage to the 12 volt flywheel, is that it does require the use of a larger clutch disc and plate, which can allow better grip for performance applications. This does mean of course, that the clutch and pressure plate also need be replaced when exchanging the 6 volt starter out for the 12 volt starter.

So what's the right choice?

Obviously it is much cheaper and simpler to simply retain the 6 volt starter, however in racing applications where clutch grip is a question, the 12 volt starter may be the way to go.If you are changing 6v Starter to a 12v Starter you would need the conversion bushing.