Codes pour la transmission et pont

Diff Codes

 

The “Trans” code is your Gearbox identifier. And with Classic Celica’s there were not that many options. Before 1975 each gearbox option had a code and the Three codes are listed below.

3FC – 3 speed auto, floor shift
5F1 – 5 speed manual, floor shift, option #1
5F2 – 5 speed manual, floor shift, option #2

5F1 means the first in the series of 5 speed manual gearboxes offered on that car and engine.
On a car with a T series engine it means a T50 and on a car with an R series engine it means a W50.
5F2 means the second in the series of 5 speed manual gearboxes offered on that car and engine.
On a car with an R series engine it means a P51.

After 1975 things got a lot easier, instead of a code number for the gearbox, the actual gearbox identity was listed instead.
E.g. T50, W50, P51, A30, A40,  etc

Diff codes appear in the TRANS section on the build plate (typically rivetted to the firewall in the engine bay).
They look like T292 (6.7" crown wheel, 4.100 ratio, 2 pinions, no LSD), F314 or similar.
The letter shows the crown wheel size, the next 2 digits show the ratio and the final digit shows the number of pinion and whether LSD is fitted.

Series letter

The ring gear is also known as the crown wheel.
Ring gear sizes are measured by the outside diameter.
All Toyota ring gears of the same size or letter code are interchangeable as long as the matching pinion gear is swapped at the same time.
Also, the LSD mechanism can be removed from one diff and put into a diff with the same series code.
In some case the axles need 5mm removed from the inner end to clear the LSD mechanism.

TOYOTA
  MODEL A-RA28-MQGU-GG
  ENGINE 18R-GU 1968cc/120.0cu.in.
o FRAME No. RA28-020580 o
  COLOR/TRIM 023 FP23
  TRANS/AXLE P51 F312 O-12
  PLANT/G.V.W. A41

 

ENGINE   TOYOTA MOTOR CO.LTD.  
22R   JT2RA42CXB3123456  
2366cc
144.4
cu.in.		      
o     o
       
       
MODEL   RA43L-BCMSSA  
C/TRA/TM   033 FB11 T312 W50  

 

Code Size
A 138mm
B 145mm
C 6.25"
D 6.62"
E 7.1"
F 7.5"
G 8"
H 9"
J 9.25"
K 9.5"
L 10.5"
M 12.5"
N 13.5"
P 14"
R 162mm
S 6.38"
T 6.7"
U 6"
V 10.6"
W 15.5"
X 142mm
Y 158mm

Ratio codes

Code Ratio Teeth
01 3.30
02 3.36
03 3.545 39 11
04 3.556 32 9
05 3.70 37 10
06 3.889 35 9
07 3.90 39 10
08 4.111 37 9
09 4.222 38 9
10 4.375 35 8
11 4.444 40 9
12 4.625 37 8
13 4.79
14 4.875 39 8
15 5.125 41 8
16 5.286 37 7
17 5.60
18 5.714 40 7
19 5.833 35 6
20 6.167 37 6
21 6.667 60 9
22 6.78
23 6.833 41 6
24 7.64
25 4.556 41 9
26 5.571 39 7
27 3.364 37 11
28 4.30 43 10
29 4.100 41 10
30 3.727 41 11
31 3.909 43 11
32 6.591
32 5.583 67 12
33 7.503
33 5.583 67 12
34 6.781
34 4.786
35 7.636
35 5.60
36 4.778 43 9
37 3.583 43 12
38 3.417 41 12

LSD and pinions

Code Pinions LSD
2 2 -
3 2 LSD
4 4 -
5 4 LSD

 

Ring and pinion ratios for 1970-1975 Carinas/Celicas

 

Ring gear size Gear Ratio Ring teeth/Pinion teeth Standard on
6.7" (T series) 3.7 37/10
RA20L
RA21L
? 3.9 39/10
TA12-S
TA20-K
TA22-K
? 4.111 37/9
TA10
TA12L-KA
TA20
TA22
? 4.300  
TA12L-HA
? 4.375 35/8
TA10-Y