How-To:

V4 Gear Ratio Comparison

During the heyday of the 96, The Saab Competitions Department made available a number of gear sets and final drives (ring and pinion) for off-road and race purposes.  The gear sets are known as Special I and Special II (although I recently heard there was a Special III ).  The final drives are known by ratio rather than name.

To optimize gearing (not that there really is such in the Sonett) you need to consider engine performance along with total gear ratios  (tire size and intended application also figure in).  For instance, an engine with a narrow power band will work better with tightly spaced gears (close ratio), whereas a broad power band may work better with wider spacing.

The Special I and II gear sets are both close ratio sets.  Special I uses the standard 1st and 3rd gears, and provides closely spaced 2nd and 4th gears.  Special II goes a step further, and replaces all forward gears, and compresses the entire range (1st is higher, 4th lower). 2nd and 4th gear are the same in each set.  NB: the Orange Competition book is inconsistent in its nomenclature, it refers  to Special I in Section 2 as a two gear set. In Section 6, however,  it is described as a three gear set.   Perhaps  Special III  was added to describe this latter alternative.

All of the competition ring and pinions offer  numerically higher ratios than the stock V4 or Sonett box and were intended for  off-road rallying.

The table below presents selected gear sets and ring and pinion combinations.   Speeds noted  are in mph at 1000 rpm with 155/15 tires (300 mm tire radius).   Special I  is the 2 gear version.

  • Ring & Pinion Gear Set 1 2 3 4 9:42 (4.66)   Sonett Standard 4.3 7.2 11.6 18.0 8:39 (4.87)   95/96 Standard 4.1 6.9 11.1 17.2 9:42 (4.66)  
  • Sonett Special I 4.3 9.4 11.6 16.5 8:39 (4.87)   95/96 Special I 4.1 9.0 11.1 15.8 7:36 (5.15)   Rally Special I 3.9 8.5 10.5 14.9 7:38 (5.43)  
  • Rally Special I 3.7 8.1 10.0 14.2 6:35 (5.83)   Rally Special I 3.4 7.5 9.3 13.5 9:42 (4.66)   Sonett Special II 5.7 9.4 12.7 16.5 8:39 (4.87)  
  • 95/96 Special II 5.5 9.0 12.2 15.8 7:36 (5.15)   Rally Special II 5.2 8.5 11.5 15.0 7:38 (5.43)   Rally Special II 4.9 8.1 10.9 14.2 6:35 (5.83)  
  • Rally Special II 4.5 7.6 10.2 13.2 9:42 (4.66)   Sonett MSS Special 5.7 7.2 12.7 18.0 NB:

    The calculated road speed (mph) is based on a rolling radius of 300mm (155/15), tire size other than this will have a multiplicative effect on all speeds listed.

  • To the top