Contact Breakers - New Replacements by Alphamet & Schmittparts
Messerschmitt (SACHS), engines were fitted with two different types of contact breakers. 1 type is SIBA fitted to all engines up to 1958 and fitted with SIBA starter system (up to chassis number 68254). The later type BOSCH equipped engines had a different contact breaker system. Both types are interchangeable by using the appropriate contact breaker mounting plate.
Schmittparts offers new Alphamet back plates fitted with new SIBA contact breakers. These come complete with a new felt pad that should be lubricated with BOSCH grease or high melting point grease to prolong the life of the Crankshaft cam and the contact breaker heel. BOSCH contacts have been unavailable as proprietary items for more than 40 years.
Contact breaker units as used in British Villiers engine with new back plate. The forward assembly is fitted with a black cable and the reverse is fitted with a red cable. These are interchangeable with each other. There is ample space within the contact breaker cover to fit the connectors. These contact breakers can be used with the above SIBA backplate, to convert a BOSCH contact system to SIBA.
SIBA Contact breakers originally fitted including a retaining clip for holding the coil wire as it passes through the clutch housing. Forward direction is marked 'V' (German - Vorn = forward). These are interchangeable with the reverse assembly marked 'R' (German - Rueckwarts=reverse). The R or V is upside down if the two types are transposed. This does not affect operation. The Black wire connects to 'V' on the right-hand set of contacts. The Red wire connects to 'R' on the left-hand set of contacts.
When setting the contact breakers, note that the time/position that the contact breakers open is the most critical part of the setting. The single lift cam has adequate time for re-charging the coil voltage at almost any gap setting. It is often not possible, (due to a worn cam), to set the gap to the correct specification together with the correct opening point. In this case, set gap as near as possible to the specification with the opening point at 4.5mm to 5.5mm before TDC. For the reverse timing, the gap is always a compromise and adjusting the gap is the only way to achieve the correct opening point of 3mm to 4mm before TDC. The reason for this is that many cams are seriously worn from previous neglect of the felt pad and failure to use BOSCH grease.
BOSCH Contact breakers originally fitted including a retaining clip for holding the coil wire as it passes through the clutch housing. Forward direction is marked 'V'. These are not interchangeable between forward and reverse. Reverse direction is marked 'R'. New BOSCH mounting plates are not available. If your contact breakers are worn out, you should convert to SIBA type with a new backplate.
The Alphamet (Siba) ignition points base unit has been precision manufactured using high quality materials. Extra ignition timing movement is built into the design if needed, for those who tune their engines. These Alphamet ignition points bases have been sold worldwide since 2004.