311s SPEEDO-TRANNY-GEAR reprinted with the author's permission
Published 2007
Ross Mullen of Sports Imports writes:
The 4 speed and 5 speed transmissions in roadsters drive the speedo cable by the same method. A plastic toothed gear which is color coded and comes in variations 16-23 teeth. Each tooth variation gives roughly a 10% change in speedo readings. This gear is located at the transmission end of the speedo cable and can be changed with transmission in car. It is best to drain the oil before removing the gear which is held in place by a 10 mm bolt and small tab. before removing, estimate the inaccuracy by having someone pace you and measure what your gauge reads when they are doing 50 mph. If yours reads 55 then you are out 10%( 50 x 2=100 5X 2=10%) Most 5 speeds come with 18 tooth gear normally yellow. Dropping or adding a tooth will compensate to make your a speedometer a little closer to accurate.
5 speed transmission FS5C71A gear part numbers
- 32703-78100 16 tooth
- 32703-78101 17 tooth
- 32703-78102 18 tooth
- 32703-78103 19 tooth
- 32707-78000 sleeve for 16-19 tooth
- 32707-66300 sleeve for 20-23 teeth
- 32703-78104 20 tooth
- 32703-86401 21 tooth
- 32703-86402 22 tooth
- 32703-86403 23 tooth
4 speed transmission F4C63L gear part numbers
- 32703-22000 16 tooth
- 32703-22001 17 tooth
- 32703-21100 18 tooth
- 32703-78600 19 tooth
- 32707-14600 sleeve for 16-19 tooth
- 32707-14810 sleeve for 20-23 tooth
- 32703-14816 20 tooth
- 32703-25031 21 tooth
- 32703-16715 22 tooth
- 32703-19910 23 tooth
Increasing the tooth count on the pinion will decrease the MPH count. In other words, a 10% off 55 MPH reading with an 18 tooth pinion gear can correctly read 50 MPH by installing a 19 tooth pinion gear. Ross Mullen sports imports.
Ross is one of our vendors and has a wealth of information on his web site. You can email him at info@sportsimports.ca or visit his site here at Sport Imports-Ross Thanks for sharing Ross!