Porsche 912 Transaxle Part Numbers: The Ultimate Reference

Finding the right part numbers for a Porsche 912 transaxle can be the difference between a smooth rebuild and a frustrating parts scavenger hunt. Whether you are restoring a 1965–1969 912 or maintaining a driver, understanding the original equipment numbers is essential. This guide covers the common transaxle types—901, 902, and 923—and provides specific part numbers for gaskets, seals, bearings, synchros, and more.

Understanding the Porsche 912 Transaxle

The Porsche 912 used a four-speed or five-speed transaxle derived from the 911 but with several internal differences. The most common models are the 901 (early four-speed), 902 (five-speed, mostly used in 911 but some 912s), and the later 923 (also a five-speed found in some 912s). All are non-synchronized first gear units with a distinctive side-shift mechanism. Knowing your transaxle type is the first step before ordering any parts. The type number is stamped on the bottom of the housing near the differential.

Common 912 Transaxle Part Numbers

Below are the most frequently needed part numbers for a 912 transaxle rebuild. Numbers are Porsche OEM unless noted. Always verify with your specific transaxle serial number.

Gaskets and Seals

• Input shaft seal: 901.103.115.00 – Used on all 901/902/923 transaxles. Fits the front cover.
• Output flange seals: 901.331.135.00 (left) and 901.331.136.00 (right) – for the axle flanges.
• Differential cover gasket: 901.301.105.00 – paper gasket between the main case and the differential cover.
• Shift rod seal: 901.303.133.00 – small seal where the shift rod exits the case.
• Side cover gasket: 901.301.115.00 – for the side shift cover (if applicable on early 901 boxes).

Bearings

• Input shaft bearing: 901.103.100.00 – a special ball bearing. Alternative: SKF 6205-2RS (but check dimensions).
• Output shaft bearing: 901.104.100.00 – roller bearing for the main shaft.
• Differential pinion bearings: 901.302.101.00 (inner) and 901.302.102.00 (outer).
• Differential side bearings: 901.302.115.00 (left) and 901.302.116.00 (right).

Synchro Rings

• 1st/2nd gear synchro ring: 901.302.211.00 (brass, early) or 901.302.211.06 (later steel).
• 3rd/4th gear synchro ring: 901.302.212.00 – note that 5-speed boxes use a different ring for 5th gear.
• Reverse gear synchro ring: 901.302.213.00 – if equipped.

Gear Sets

Individual gear part numbers are extensive, but common ratios include:

• 1st gear (9:28): 901.302.031.00
• 2nd gear (15:25): 901.302.032.00
• 3rd gear (19:22): 901.302.033.00
• 4th gear (22:19): 901.302.034.00
• Ring and pinion (7:31): 901.302.001.00 (4-speed) – 5-speed uses a different set.

Shift Components

• Shift fork (1st/2nd): 901.302.451.00
• Shift fork (3rd/4th): 901.302.452.00
• Shift rod (complete): 901.303.010.00
• Coupler (shift coupler bushing kit): 901.303.150.00 – includes the plastic cup and spring.

How to Identify Your Transaxle

Before ordering any part numbers, confirm your transaxle type. Look for a flat spot on the bottom of the main case near the differential. The type (901, 902, 923) and serial number are stamped there. Also check the passenger side of the housing for a small metal tag (often missing). If the tag is gone, measure the bellhousing pattern and count the number of bolts on the side cover. A 901 has a 4-bolt side cover; a 902 has a 5-bolt cover. The 923 has a cast-on differential cover rather than a separate bolted cover. You can also remove the fill plug and look for the gear ratio stamp on the ring gear.

Where to Find Part Numbers

OEM part numbers can be found in several places:

• Porsche PET (Parts Exploded Views) catalog – available online for free. Search by model (912) and then select the transmission section.
• Printed factory parts manuals – reproduced by publishers like Bentley or Pelican Parts. These list every original number.
• Specialty Porsche parts suppliers – websites such as Pelican Parts, Stoddard, or ourhost parts often cross-reference part numbers to OEM.
• Porsche classic centers – can look up numbers by VIN or transaxle serial number.
• Online forums – the 912 Registry, Early 911S Registry, and Pelican Parts forums have extensive threads with verified part numbers. Always double-check with a second source.

Cross-Referencing with 911 Parts

Many 912 transaxle parts are shared with early 911 (1965–1973) but not all. For example, gaskets, seals, and most bearings are identical. However, gear ratios differ: the 912 used a taller final drive (7:31 vs 7:30 or 7:29) and different synchro rings for 1st/2nd in later years. When ordering, specify “912” rather than “911” to avoid getting a 914 or 911S transmission part. If a part number supersedes to a newer number, note the change—e.g., the input shaft seal 901.103.115.00 has been superseded to 901.103.115.01. Always use the latest superseded number.

Practical Tips for Sourcing

• Buy gasket sets: A complete gasket set (e.g., Porsche 901.301.901.00) saves time and includes all paper gaskets, seals, and O-rings. Avoid aftermarket sets unless verified.
• Replace bearings in pairs: Even if only one bearing is worn, replace the matching counterpart (e.g., both differential side bearings).
• Inspect synchro rings: Brass rings wear quickly. If you feel grinding during shifts, replace all synchro rings and the hub sleeves.
• Consider a rebuild kit: Many suppliers offer a “master rebuild kit” for the 901/902/923 that includes gaskets, seals, bearings, and synchro rings. Compare part numbers to ensure completeness.
• Check the shift coupler: The plastic bushing in the shift coupler (901.303.150.00) is a common wear item. Replace it even if the transaxle otherwise shifts fine.

Final Recommendation

If you plan to rebuild your Porsche 912 transaxle yourself, start by confirming the type and serial number. Then compile a list of needed parts using the OEM numbers listed above. For most street restorations, a master gasket and seal set plus all bearings and synchro rings will restore smooth operation. For high-performance or track use, consider upgrading to a later 915 gearbox or installing a Quaife differential – but for originality, stick with the correct 901/902/923 parts. Always cross-reference part numbers with a trusted supplier or the PET catalog before ordering. A well-documented rebuild is the best insurance against mismatched parts and costly mistakes.