STROM
S58 / B58 Gen 1 / B48 Alternator Overrun Pulley
S58 / B58 Gen 1 / B48 Alternator Overrun Pulley
SKU:99.00183
24 in stock
Couldn't load pickup availability
An Overrunning Alternator Pulley allows the alternator to freewheel when the engine is trying to decelerate rapidly. This has many benefits by temporarily reducing drivetrain inertia. It saves your crank balancer from trying to tear itself apart which is a common problem on these engines . It also has the same affect as a lightweight flywheel on upshifts and allows for more rapid shifts and less wear on the transmission clutches on a manual or auto Trans. On some engines it even makes it run smoother! There is no downside to using it and it does not increase belt or alternator noise. See video at the bottom for an in depth explanation.
This part is also known as a OAD (Overrunning Alternator Pulley) or OWC (One-Way Clutch) Alternator Freewheel Pulley or a Dutch Pulley. It is not an OAD (Overrunning Alternator Decoupler) or IDP (Isolator Decoupler Pulley) which refer to pulleys with a one way clutch and torsional spring. The version we use does not have a torsion spring in it as that task is taken over by the crank balancer and belt tensioner. This simply allows the alternator to freewheel in the counter-clockwise direction and act as a solid pulley in the clockwise direction to assist with rapid engine speed changes in the deceleration direction.
FITMENT:
The best way to guarantee fitment for this pulley is to check if your current alternator has a 24mm nut holding the stock pulley on. If your original pulley has a small plastic cap or a 22mm nut then this is the wrong pulley for your car.
The images shown of the part installed are on a B48 engine.
There is an incredible amount of crossover between models and engines and alternators so please verify your fitment by looking up your VIN at realoem.com and matching the alternator part number with what we listed below. Or email info@strommotorsports.com with your VIN and we are happy to assist!
We have provided a list of what we know it fits but its impossible to correlate them all.
In every case we can find so far if you have a Bosch brand alternator on a B48/ B58/ S58 then you have a 24mm nut and you would use this pulley. If you have a Denso brand alternator and a 22mm nut then you would use the 99.00177 Pulley.
If your car already has an aftermarket alternator then there is no way to verify other than by checking the nut size.
There are many variations of the correct alternator. If one of the part numbers below is called out for your car in RealOEM, this pulley will fit. This list is not comprehensive — there are far too many alternator variants to catalog, so the pulley may still fit your car even if your part number isn't listed here. Engine codes, alternator part numbers and example models are listed independently within each group; a part number is not tied to the specific engine code beside it.
Confirmed fitment
verified against these alternators| Engine | Alternator P/N | Example models |
|---|---|---|
B58 Gen 1
|
|
|
S58
|
|
|
Other
|
|
|
THIS PART DOES NOT FIT (But we are working on parts for these):
- Gen 2 B58 and all B46/ B48 Inline OTHER than in the G30 - for that part Click Here
- First Gen B46/B48 and B36 in Mini / X1/ X2. Example alternator part numbers are: 12319845487, 12317646814, 12317640875. The pulley on these alternators is very short and does not have a shaft spacing out the pulley as seen on the new part.
- Does not fit any car with a 48V alternator 12318490540 - also known as Mild Hybrid.
Installation Instructions
