Antriebstechnik Schmidt
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Restored gearbox housing after water blasting

Porsche 911 Gearbox Rebuild

Rebuild to factory specification, limited-slip differential, drive shafts and motorsport options

From the early 911 to the G-model: we rebuild 911 gearboxes to factory specification, retrofit limited-slip differentials and machine the drive shafts and gear parts that can no longer be bought.

What we do on the 911 gearbox

  • Rebuild to factory specification
    fully stripped, measured, reconditioned — hypoid drive set up with original tooling, contact pattern checked, test-bench run included.
  • Limited-slip differential
    locking value 25–75%, direct swap for the standard differential, original bearings and seals stay in service.
  • Drive shafts and stub axles
    any length, any spline profile, machined from a single billet and heat-treated.
  • Motorsport options
    RSR-style spray-oil lubrication, gearbox oil cooling, uprated shafts.

Typical problems this solves

  • Second gear crunches, the synchromesh is finished
  • Howling final drive — contact pattern and backlash no longer correct
  • Inside wheel spinning at the limit: no limited-slip fitted
  • Standard shafts not coping with increased power

Why inquire here

The 911 is the centre of our programme — from a single gear wheel to a completely rebuilt gearbox. What the parts market no longer supplies is made on our own gear-cutting machines.

A different gearbox type?

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Made in-house

Parts for the 911, newly made

The 911 used the 901 gearbox until 1971 and the 915 from 1972 to 1986 — these parts fit. Made in-house, most in stock. Click to enlarge.

All parts in the catalogue →

915

Motorsport final drive 8:35

Porsche Motorsport final drive 8:35 in top quality, replacing the 7:31 whose tooth spread at the pinion head is unfavourable and damaged on almost every second gearbox.

In stock Newly made Enquire →

915

ZF clutch-type LSD with oil pump drive, 915/72

Porsche ZF clutch-type LSD with oil pump drive and Turbo stub axles for the Porsche 915/72 gearbox with oil cooler coil. No longer available from Porsche for a long time.

In stock Newly made Enquire →

901 / 904 / 906

Final drive 7:31, uprated

Porsche 901/904/906 final drive, uprated version, ratio 7:31, top quality.

In stock Newly made Enquire →

901

Ring gear 7:31, ground

Porsche 901 final drive 7:31, uprated version, ground to top quality.

In stock Newly made Enquire →

915 / 930 / 935

ZF clutch-type LSD internals

Internal parts of the ZF clutch-type limited-slip differential for Porsche 915, 930 and 935.

In stock Newly made Enquire →

901

Pinion, ground

Porsche 901 pinion, top quality, cleanly ground.

In stock Newly made Enquire →

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From the workshop

Common questions

01 Which gearboxes were fitted to the classic 911?

The early 911 has the 901 gearbox. From 1972 to 1986 the 915 followed, and the late G-series cars used the G50. We rebuild all three.

02 Can a limited-slip differential be retrofitted to a 911 gearbox?

Yes. Most classic 911s left the factory without one. Our clutch-type differential follows the ZF principle, has a locking value of 25 to 75 per cent and replaces the standard differential.

03 What does a rebuild to factory specification involve?

Complete strip-down, measurement and rebuild, setting up the hypoid drive with original setting tools, and a test-bench run before the gearbox is shipped back.

Inquiry

What is on your bench?

Gearbox type and a few lines about your request — that is all we need for a first assessment. A photo helps but is not required. The answer comes from the machinist, not from sales.

Send inquiry

Reply usually within 24 hours — from the managing director himself, no ticket system, no call centre. We call back on request.

or directly: 06628 9159093 · info@antriebstechnik-schmidt.de

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