Bosch Alternator 12V 120A 1986A00558

The Bosch Alternator 12V 120A is a new rotating electrical unit with internal regulation, a 120 amp charge current, and a 6 groove pulley. It suits Bosch applications and carries part number 1986A00558, so the matching specification should be checked carefully before ordering.

Key mounting details include an inside mounting legs measurement of 60mm, a mount centre-to-centre dimension of 127mm, and an M8 x 1.25 pivot hole diameter. The alternator uses a quad leg mount and double pivot lever fastening type, which makes the physical mounting arrangement an important part of the identification process.

This unit is supplied with a free-wheel belt pulley, rotates clockwise, and is listed as alternator type excl. vacuum pump. If the vehicle requires a different pulley style, mounting pattern, or belt arrangement, those details need to be confirmed against the original part and application before fitment.

Bosch lists this alternator as manufactured in South Africa and covered by a 12 month warranty. It is a 12 volt unit with B1+(M8), L, and DFM clamp configuration, so the electrical connections should also be matched to the vehicle’s charging system requirements.

Key Features

• 12V alternator with 120A charge current
• New unit, not remanufactured
• Internal regulator type
• 6 groove pulley with free-wheel belt pulley
• Quad leg alternator mount
• Clockwise rotation

Specifications

• Brand: Bosch
• Part No.: 1986A00558
• Voltage: 12V
• Power rating: 120A
• Alternator charge current: 120A
• Alternator type: excl. vacuum pump
• Pulley outside diameter: 56mm
• Pulley section: 6 groove

Fitment guidance

• AUDI A3
• AUDI TT
• SKODA ROOMSTER
• VOLKSWAGEN BEETLE
• VOLKSWAGEN BORA
• VOLKSWAGEN CALIFORNIA
• VOLKSWAGEN GOLF
• VOLKSWAGEN LT 28-46

Application and Buying Notes

Before ordering, match the part number 1986A00558 and confirm the mounting dimensions: 60mm inside mounting legs, 127mm mount centre-to-centre, and M8 x 1.25 pivot and adjusting holes. Those measurements are often the quickest way to confirm whether the alternator will physically interchange with the original unit.

The pulley and drive arrangement also matter. This alternator has a 56mm pulley, 6 grooves, and a free-wheel belt pulley, so the belt type and pulley style on the vehicle must align. Bosch also lists the unit as excl. vacuum pump, which is an important check where the original alternator is part of a different engine accessory setup.

Electrical connection detail should be checked as well. The clamp configuration is B1+(M8), L, DFM, and the regulator is internal. That means the vehicle plug and charging control arrangement need to match, especially on applications where the original unit uses a different terminal layout or control signal.

If you are comparing against the removed alternator, check the rotation direction, which is clockwise, and confirm the alternator mount style is quad leg with double pivot lever fastening. These are practical identification points that help avoid ordering a unit that looks similar but mounts differently or drives the belt incorrectly.

Before supply, the safest approach is to confirm the original unit details against the listed part number, voltage, output rating, mounting arrangement, and pulley configuration. That checking process is standard practice in the parts trade because visually similar units can still differ in service-critical ways.

For workshop, fleet, and equipment applications, accurate identification of part number 1986A00558 helps avoid unnecessary freight, additional labour, and vehicle or machine downtime. Where the application is not straightforward, the original unit, OEM reference, or workshop records should be used as the primary confirmation point.

Relevant published details for this unit include Type ALTERNATOR, Unit of Measure EACH, Warranty 12 Months, Inside Mounting Legs 60mm, Pivot Hole Diameter M8 x 1.25, Pulley Outside Diameter 56mm, Regulator Type Internal, Suits Unit Make Bosch, Alternator Mount Quad Leg, New / Reman. New.

Additional published details for cross-checking include Fastening Type Double Pivot Lever, Pulleys with free-wheel belt pulley, Number of grooves 6, Recommended additional repairs V-Belt/V-Ribbed Belt, Packaging width 20, Manufactured in South Africa, Product Group 1 ROTATING ELECTRICAL, Part No. 1986A00558, Brand BOSCH, Description Bosch Alternator 12V 120A.

Bosch Alternator 12V 120A. Part number 1986A00558 should be checked first. Listed voltage is 12. Listed output rating is 120. These details form the core reference points used by parts interpreters when confirming the correct replacement.

Mount style is Quad Leg. Regulator type is Internal. Pulley configuration is 6 Groove. Those physical and electrical details should line up with the original unit before the replacement is approved for fitment.

For part number 1986A00558, the normal identification sequence is part number, electrical rating, mounting arrangement, connector or terminal style, and pulley or drive details. Using those checkpoints helps confirm that the listed unit matches the service requirement rather than only looking similar.

For a alternator in workshop, fleet, trade, agricultural, or construction service, the listed voltage 12 and output 120 should be checked carefully. Incorrect selection can affect installation time, return freight, and equipment availability.

Available application references include AUDI A3, AUDI A3 1997, AUDI A3 1998, AUDI A3 1999, SKODA ROOMSTER, SKODA ROOMSTER 2008. Even with application listings, final confirmation should still be based on the exact unit being replaced and the service requirements of the vehicle or machine.

Compatibility note: Confirm fitment by matching part number 1986A00558, the 12V 120A specification, and the mounting, pulley, and clamp details against the original alternator and vehicle application before purchase.

FAQ

What type of alternator is this?

It is a Bosch alternator, new, 12V, 120A, with an internal regulator and a free-wheel belt pulley.

What is the part number?

The listed part number is 1986A00558.

Does this alternator use a vacuum pump?

No. The alternator type is listed as excl. vacuum pump.

What pulley details should I check?

Check the 56mm pulley outside diameter, 6 groove pulley section, number of grooves, and that it uses a free-wheel belt pulley.

What mounting measurements are provided?

The listed mounting details are 60mm inside mounting legs, 127mm mount centre-to-centre, and M8 x 1.25 for both pivot and adjusting hole diameters.

Which vehicles are shown in the fitment guidance?

The fitment guidance includes AUDI A3, AUDI TT, SKODA ROOMSTER, and several Volkswagen applications including Beetle, Bora, California, Golf, LT 28-46, Multivan, New Beetle, Polo, Touareg, Transporter, and Transporter / Caravelle.