Porsche G50 gearbox (1987–1998)
The G50 is the Getrag-built manual transaxle Porsche fitted to the 911 Carrera 3.2 from 1987, the 964 and, in six-speed form, the 993. Club racers keep it for Porsche-based race cars, and kit-car builders use it behind V8 engines. Its hydraulic clutch, synchronised reverse and wide choice of ratios keep demand high.
History
Porsche replaced the 915 gearbox with the G50 for the 1987 model year. The new unit was built by Getrag, used Borg-Warner type synchromesh and was rated for 221 lb-ft of input torque 1. It brought a 240 mm hydraulic clutch 4. In a 2005 club discussion, one owner put it about 27 lb heavier than the 915 4. The same owners agreed it shifts better than a 915 in equal condition 4.
The five-speed box stayed in the 964 from 1989, with 3.6 litres of oil in the Carrera 2 8. The 1992 Carrera RS used a G50/10 with closer ratios, steel synchros and an asymmetric limited-slip differential 8. Forty-five US cars built for a cancelled US Carrera Cup shared that gearbox 8. The 1989 930 Turbo also got a G50, coded G50/50 1.
The 993 became the first 911 with a standard six-speed gearbox 9. Two road versions matter to buyers. The G50/21 carries the shorter ratios, while the G50/20 is the longer box 3. A Porsche Club GB member reported that US and Swiss cars always had the G50/20, and European cars moved to it during 1996 3. The Carrera RS used a G50/31 with modified ratios in the first three gears 9. Four-wheel-drive 993s use a similar box with a front driveshaft through the nosecone 1.
The G50 kept a second life outside Porsche. The Ultima GTR listed a five-speed Porsche G50 transaxle among its transmissions 10. One specialist calls the gearbox very reliable and says it often runs about twice the power it was designed for 1. Specialists such as Guard Transmission and RPM Technik still supply differentials, gears and rebuilds 1112.
Palmarès
Not a racing-results machine. The G50/10 served the 1992 964 Carrera RS and 45 US cars built for a cancelled US Carrera Cup 8. PCA Club Racing still names the G-50 as an allowed transmission for 1987–89 cars in its SP911 class 7.
What to check before you buy
Read the code stamped on the case and match it to the claimed donor car: The case stamp gives the version and serial, for example G50/20 on a 993 box 15; ratios differ by version 3. Confirm whether a limited-slip differential is fitted, and which type: Listings range from open differentials to factory LSD units, and prices follow 131718. Ask who rebuilt it, when, what was replaced and how many miles since: Sellers quote rebuilds such as 'late 2025' or 'under 600 miles since' without parts lists 1316. Ask which gear oil it has run on: Owners link thick oil to cold stiffness and early synchro wear in the G50 5. On 1987–89 units, check the clutch release fork and guide tube type: Early parts are superseded, and fitting later ones needs bell housing machining 6. For club racing, compare the ratios and final drive with your class rules: PCA Stock classes require factory ratios, and SP911 requires a 9:31 final drive with listed G50 gears 7. Make sure a 993 box is a two-wheel-drive unit if you need one: Four-wheel-drive 993 boxes carry a front driveshaft through the nosecone 1; RPM Technik offers a 964 4WD-to-2WD conversion 12.
Versions and evolutions
| Version | Years | What changed | How to identify |
|---|---|---|---|
| G50/00, G50/01, G50/02 (911 Carrera 3.2) | 1987–1989 | First G50 family, five speeds, hydraulic clutch; PCA's SP911 class lists G50 gears for 1987–89 cars 7. A G50/01 sold on PCARMARKET was described as best suited to 1987–89 911s 13. 13 | Code stamped on the case; 1987–89 cars with hydraulic clutch. |
| G50/50 (930 Turbo) | 1989 | Turbo version of the G50 for the last 930 model year; listed only for context 1. 1 | G50/50 code on the case. |
| G50/03 (964 Carrera 2) | 1990–1994 | Five-speed Getrag unit for the 964 Carrera 2; 1st 3.5, 2nd 2.059, final drive 9:31 (3.444) 216. 16 | G50/03 code on the case; 964 C2 donor. |
| G50/10 (964 Carrera RS and US Cup cars) | 1992 | Closer ratios, steel synchros and an asymmetric LSD 8. A forum member gave a 964 Cup G50/10-4 set of 3.500, 2.059, 1.407, 1.086, 0.868 2. 8 | G50/10 code; RS or Cup provenance should be documented. |
| G50/21 and G50/20 (993 six-speed) | 1994–1998 | G50/21 has the shorter ratios, G50/20 the longer ones 3. The G50/20 fitted to 1997 C2S cars was described as taller than the earlier G50/21 19. 3 | Case stamp begins G5020 or G5021, followed by the serial 15. |
| G50/31 (993 Carrera RS) | 993 Carrera RS production | Six-speed with a short shifter and modified ratios in the first three gears 9. 9 | G50/31 code on the case. |
Known issues
- Worn 1st and 2nd gear synchro rings and bearings — Gearbox noise and baulky changes; one owner found worn bearings plus worn 1st and 2nd synchros at rebuild 5. 5
- Synchro wear blamed on thick gear oil — Stiff changes when cold; a member argued thick oil stops synchro rings spinning freely and wears them early 5. 5
- Clutch release fork and guide tube problems on early G50s — Clutch release faults; later fork, shaft and bearings need the bell housing machined for new pivot bearings 6. £78 + VAT for a fork modification (2003); clutch kit about £600 (2015) 6 6
- Crunching changes after hard track use — After a fast straight one owner could not select several gears; 3rd still crunched once cool 21. 21
- Dual-mass flywheel failure on early 964 manuals — Clonking under power; flywheel strengthened on cars built after August 1991 20. about £1,000 for the flywheel, more with a clutch (2020) 20 20
- Tall gearing on G50/20 boxes for circuit use — Long gears; a quoted 5th-gear 80–120 km/h time rose from 7.0 s to 8.6 s on 1997 cars 19. 19
- Open differential on many road units — Inside-wheel spin out of slow corners; units are sold both with and without LSD 1318. 13
Checklist before you buy
- Read the code stamped on the case and match it to the claimed donor car. — The case stamp gives the version and serial, for example G50/20 on a 993 box 15; ratios differ by version 3. 15
- Confirm whether a limited-slip differential is fitted, and which type. — Listings range from open differentials to factory LSD units, and prices follow 131718. 13
- Ask who rebuilt it, when, what was replaced and how many miles since. — Sellers quote rebuilds such as 'late 2025' or 'under 600 miles since' without parts lists 1316. 16
- Ask which gear oil it has run on. — Owners link thick oil to cold stiffness and early synchro wear in the G50 5. 5
- On 1987–89 units, check the clutch release fork and guide tube type. — Early parts are superseded, and fitting later ones needs bell housing machining 6. 6
- For club racing, compare the ratios and final drive with your class rules. — PCA Stock classes require factory ratios, and SP911 requires a 9:31 final drive with listed G50 gears 7. 7
- Make sure a 993 box is a two-wheel-drive unit if you need one. — Four-wheel-drive 993 boxes carry a front driveshaft through the nosecone 1; RPM Technik offers a 964 4WD-to-2WD conversion 12. 12
Running costs 14
| Rebuild interval | No fixed interval published; one specialist advises changing the gear oil every couple of years 1. |
|---|---|
| Typical rebuild cost | No current published G50 rebuild price found. A fresh CMS-built unit was listed at $11,500 in October 2026 14. |
| Consumables | Gear oil, synchro rings, bearings and the clutch kit (about £600 in 2015) 56. |
| Spares availability | Specialist supply: Guard Transmission lists LSDs for the 1987–89 G50, RPM Technik rebuilds 5- and 6-speed G50s 1112. |
Where it races today
- PCA Club Racing · Stock classes — Factory ring and pinion and gear ratios only; coolers free; street-derived mechanical LSD allowed; synchros of any material 7. 7
- PCA Club Racing · Prepared classes — Ring and pinion ratio may be changed 7. 7
- PCA Club Racing · SP911 — 1987–89 cars may use the G-50 with Porsche synchros, a 9:31 final drive, listed gear ratios and an unmodified stock flywheel 7. 7
- PCA Club Racing · Vintage — All 1998 or older air-cooled 911, 930, 964 and 993 models are eligible 22. 22
Market prices
- Fresh CMS-built G50 five-speed, 0 miles (RCN asking): 11,500 USD (2026-10) 14
- Used 993 Carrera G50/20 six-speed from a running car (RCN asking): 8,000 USD (2026-09) 15
- G50/03 rebuilt late 2025, with LSD, half-shafts, pedals and conversion parts (RCN asking): 6,000 USD (2026-07) 16
- 964 Carrera 2 G50 with LSD (RCN asking): 10,345 USD (2025-10) 17
- 1989 Carrera G50, factory LSD, about 40k miles, blueprinted (RCN asking): 10,000 USD (2025-01) 18
- Rebuilt G50/01, open differential (PCARMARKET high bid, reserve status not shown): 5,500 USD (2022-05) 13
- Used G50 unit, UK club estimate: 1,800 GBP (2005-12) 4
In 2025–2026, RCN asking prices ran from $6,000 to $11,500, against a $5,500 high bid for a rebuilt open-diff unit in May 2022 131416. These are asking prices, not confirmed sales.
Reference prices are dated and sourced; live asking prices are in the listings above.
Frequently asked questions
Which G50 should I look for in a 964 or 993 track car?
For a 964, the G50/03 is the common Carrera 2 box, and the RS G50/10 adds closer ratios and steel synchros. For a 993, the G50/21 has shorter ratios than the G50/20, which suits circuits. Check the case stamp before paying, since the code tells you the ratios.
How much torque can a G50 take?
One Porsche gearbox specialist quotes an input rating of 221 lb-ft and says the box often runs about twice its design power. Kit cars such as the Ultima GTR used it behind V8 engines. Treat those higher figures as owner experience, not a factory rating, and budget for a strong differential.
Is a limited-slip differential worth paying for?
For racing, yes. Many road boxes left the factory open, and units with LSD are priced higher. Guard Transmission lists several LSD models for the 1987–89 G50. PCA Stock classes allow any mechanical LSD type that came in a street Porsche, but not a locked differential.
What does a used or rebuilt G50 cost in 2026?
On RCN in 2026, a used 993 G50/20 was listed at $8,000 and a fresh CMS-built five-speed at $11,500. A rebuilt G50/03 with conversion parts was offered at $6,000. These are asking prices, so ask for rebuild invoices and the parts list before agreeing a figure.
Can I use a G50 in PCA club racing?
Yes, within class rules. In SP911, 1987–89 cars may run the G-50 with Porsche synchros, a 9:31 final drive and listed gears. Stock classes require factory ratios but allow coolers and street-type LSDs. Prepared classes allow a ring and pinion change.
Sources
- Porsche transmissions (G50 section), Lufteknic (2026) — Getrag build, 1987 launch, Borg-Warner synchros, 221 lb-ft rating, 993 six-speed and 4WD, G50/50, reliability, oil change advice (page undated)
- Regear my G50/03 gearbox, Porsche Club GB forum (2011-05) — G50/03 1st and 2nd ratios, 9/31 final drive, 964 Cup G50/10-4 ratio set, Guard as gear source
- Why are the gear ratios on my Varioram 993 so long?, Porsche Club GB forum (2004-08) — G50/21 short and G50/20 long ratios, market split and 1996 change
- How better is the G50 box?, Porsche Club GB forum (2005-12) — Weight versus 915, 240 mm hydraulic clutch, shift quality, used unit price about £1,800
- Worn synchro rings, Porsche Club GB forum (2018-02) — Worn 1st/2nd synchros and bearings on a G50, thick oil debate
- Clutch, Porsche Club GB forum (2015-05) — G50 release fork and guide tube issues, fork modification and clutch kit prices (posts 2003 and 2015)
- 2026 PCA Club Racing Rule Book, Porsche Club of America Club Racing (2025-12) — Stock, Prepared and SP911 transmission rules, G-50 gear tooth counts and 9:31 final drive
- Porsche 911 (964), Wikipedia (2026) — Getrag G50 in the 964, G50/10 in the Carrera RS and 45 US Cup cars, gearbox oil capacity
- Porsche 911 (993), Wikipedia (2026) — First 911 with standard six-speed, G50/31 in the Carrera RS
- Ultima GTR, Wikipedia (2026) — Porsche G50 five-speed listed as an Ultima GTR transmission
- Limited Slip Differentials, Guard Transmission (2026) — GT2 Pro, GT3 Club and GT1 Pro+ LSDs listed for the 1987–89 G50
- Porsche gearbox rebuilds and upgrades, RPM Technik (2026) — G50 5- and 6-speed rebuilds, low-ratio crown wheel and pinion, 964 4WD-to-2WD conversion
- Rebuilt Porsche 911 G50 Gearbox, PCARMARKET (2022-05) — G50/01, single-cone synchros, synchronised reverse, open diff, $5,500 high bid
- Fresh CMS-Built Porsche G50 5-Speed Transaxle (0 Miles), Racing Car Network (2026-10) — Asking price $11,500, CMS rebuild, kit-car use
- Porsche 993 Carrera G50/20 Manual Gearbox / Transmission G50, Racing Car Network (2026-09) — Asking price $8,000, case stamp format
- Porsche G50/03 5-Speed Transaxle & Manual Conversion Components, Racing Car Network (2026-07) — Asking price $6,000, 1990–94 Carrera fitment, LSD, rebuild late 2025
- Porsche 964 g50 transmission, Racing Car Network (2025-10) — Asking price $10,345, LSD
- Porsche G50 transaxle, Racing Car Network (2025-01) — Asking price $10,000, 1989 unit with factory LSD, about 40k miles
- Gear ratios, Porsche Club GB forum (2006-01) — G50/20 taller than G50/21 on 1997 C2S, quoted 5th-gear 80–120 km/h times
- Porsche 911 (964): PH Used Buying Guide, PistonHeads (2020-11) — Dual-mass flywheel symptom, August 1991 change, about £1,000 cost
- G50 help/advice please, Porsche Club GB forum (2006-07) — Crunching and unselectable gears after hard track use
- PCA Club Racing Rules, Porsche Club of America Club Racing (2026) — Vintage class eligibility for 1998 or older air-cooled models
