VW Gear Ratios (originally from the EM Sport webpage, visit them at EM Sport
Codes located at bottom of Bell Housing
Tranny Code Final
Drive		 1st 2nd 3rd 4th 5th    
FO (11/78-5/79) 3.89 3.45 1.94 1.29 0.91 0.71 RPM/Speed calculator  
Tire size:  
width (mm)   
sidewall ratio    
rim size (in)   

Final Drive:    
Gear ratio:    

Option 1:   
RPM    
   

Option 2:   
speed    
kph or mph?    
   

example:

for 
195-50-15 
tires

width = 195
sidewall = 50
rim = 15

fd = 3.89
gear = .89

RPM = 3600
gives: 
speed = 112kph, 
       70 mph

speed = 140
kph/mph = kph
gives: 
RPM = 4464rpm
FN, FF, FH (most to 7/80) 3.89 3.45 1.94 1.29 0.97 0.76
FN, FF, FH, FJ (most from '81) 3.89 3.45 1.94 1.29 0.91 0.71
4Y, 9A, ACD, AEN (8v Close Ratio) 3.67 3.45 2.12 1.44 1.13 0.89
4S 3.94 3.45 1.94 1.29 0.91 0.75
7D, 7A 3.94 3.45 1.94 1.29 0.91 0.71
IS 3.94 3.45 1.94 1.29 0.91 0.75
FK, FM, FD (Close Ratio) 3.89 3.45 2.12 1.44 1.13 0.91
2H (83 GTI Close Ratio) 3.94 3.45 2.12 1.44 1.13 0.91
4K 3.94 3.45 2.12 1.44 1.13 0.89
ACH ('85 1.6 Diesel) 3.94 3.45 1.94 1.37 1.03 0.89
AOP (Late 80's G/J) 3.94 3.45 1.94 1.37 1.03 0.75
ASF, AON, ACN, ACL (8v) 3.67 3.45 1.94 1.37 1.03 0.75
AGS (86-90 1.6 Diesel) 3.94 3.45 1.94 1.29 0.91 0.75
AGB, 2Y (16v Close Ratio) 3.67 3.45 2.12 1.44 1.13 0.91
AUG (1.8 8v 90's G/J) 3.67 3.45 1.94 1.44 1.13 0.89
AWY ('90 Diesel) 3.94 3.45 1.94 1.44 1.13 0.89
AMC, DFQ, CHE (from '93 115hp) 3.67 3.45 1.94 1.29 0.97 0.80
ATH, DFP, CHD 3.67 3.45 1.94 1.29 0.91 0.75
APW, DFN, CHB 3.67 3.45 1.94 1.37 1.03 0.85
AVX 4.25 3.45 1.94 1.29 0.91 0.75
ACL 3.67 3.45 1.94 1.37 1.03 0.75
APW (from '93 1.8) 3.67 3.45 1.94 1.37 0.97 0.85
VW Motorsport 8V ???? 2.50 1.79 1.42 1.17 1.03
VW Motorsport 16V ???? 2.72 2.06 1.68 1.43 1.26
GP (3+E from '81) 3.89 3.45 1.75 1.06 0.71  
GY (3+E 8/82-7/84) 4.17 3.45 1.75 1.06 0.71  
GC (to '80) 3.89 3.45 1.94 1.29 0.97  
GC (from '81) 3.89 3.45 1.94 1.29 0.91  

VW MotorSport Ring & Pinions (small input shaft, 8v): 4.20, 4.46, 4.64, 4.81, 5.07
VW MotorSport Ring & Pinions (large input shaft, 16v): 3.32, 4.20, 4.46, 4.64, 4.81, 5.07

Via Drew MacPherson (on the scirocco mailing list):

    Here's a chart of transmission code and axle flanges (A2 transmissions) from the VW parts catalogue. There may be some aaplications missing, butI tried to cover most of them. I did not specify gas vs diesel, but I think as a ROT most gas transmissions in Dijifant applications (ie 100hp and up) are 100mm flanges, while most CIS and Diesel applications (85-90 hp) are 90mm flanges. The obvious exception to this that I've found are of course 85+ Sciroccos and Cabs, and some early A2 Jetta GLs. YMMV.

90 mm flange
Code     (Application)
++++    ++++++++++++
ACN     (07/84-09/86 GOLF)
             (08/84-07/85 JETTA)
ACH     (07/84-09/86 GOLF)
             (08/84-07/85 JETTA)
AGS     (08/86-07/87 GOLF)
             (08/86-07/87 GOLF)
AOP     (08/88-07/89 GOLF)
             (10/87-07/88 JETTA)
AEN    (11/87-07/88 JETTA)
ASF      (09/87-05/88 GOLF)
             (09/87-05/88 JETTA)
4S         (08/87-08/88 JETTA)
AWY   (08/89-07/91 GOLF)
             (08/89-07/90 JETTA)
AVX    (01/91-07/92 JETTA)
100 mm flange
Code     (Application)
++++    +++++++++++++
9A         (08/84-07/85 GOLF)
              (01/85-07/85 JETTA)
              (07/84-07/84 RABBIT)
             (07/84-07/84 SCIROCCO)
2Y        (09/87-05/88 GOLF)
             (10/87-05/88 JETTA)
             (07/87-07/88 SCIROCCO)
ACD     (09/87-05/88 GOLF)
             (10/87-10/87 JETTA)
AGB     (09/87-09/87 GOLF)
             (02/87-07/87 JETTA)
             (02/86-07/89 SCIROCCO)
ACL     (08/87-09/87 JETTA)
AON    (09/87-10/87 GOLF)
             (09/87-05/88 JETTA)
AUG    (08/89-07/90 GOLF)
             (08/89-07/90 JETTA)
 


   Here is a great Excel spreadsheet by Ron Pieper that has a table of transmission gears / ratios and a speed -vs- RPM calculator graphing utility. Ron collected the info from official VW sources and this table above was updated based on the information contained in Ron's sheet. Nice tool, thanks Ron!

Get It! (click to download)

   Download a DOS program written by Drew MacPherson that allows you to interactively cycle through transmissions, gears, MPH / KPH and tire sizes. Comes with control files to add new tires, & gears. Fun for the whole family!

Get It! (click to download)