Differential Gears

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Japanese

Early corollas (KE1x, 2x, 3x) all had banjo-type front-loading differential centers, commonly called the Jap diff. KE1x and some 2x had 5.7" ring gears, other KE2x and 3x had 6". There are two different pinion flanges for these diffs, but the tailshaft unis are the same, so it's no big drama if, for example, you put a 6" KE30 center in your 6" KE25 diff and the pinion is different.

I am pretty sure you can put a 5.7" center into a 6" housing as well. The difference is in the ring gear only, not the carrier.

Borg Warner

1977, 1978 KE3X, KE5x and 7x Corollas in Australia had Borg Warner differentials, you can't change these centers as easily as in a Jap diff. KE5x have 6" ring gears, KE70s have 6.38". Apparently some KE1x cars had a Borg-Warner type diff as well, limited info available on these. KE20s have Borg Warner diffs from when they were made in Australia. All KE25s were imported, so they all have Jap diffs.

Comparision

So which is stronger? It really depends who you talk to. I personally would prefer a Jap diff, because even if you do destroy a center, it's bloody easy to change. I have seen both types of diff stand up to a decent amount of punishment (traffic light launches, weekend racetrack action, etc) behind a 96kw 4AG in a KE30.

Both factory diffs take 1L of oil. A common trick is to park your car on a downhill slope, so you can put more oil in, useful if you have a worn center or are running thinner oil or are just giving your car a hard time.

Upgrades (different housing)

Common upgrades are a Celica/T18/Corona T series 6.7" diff (clutch-type TRD LSD centers available AU$1200 ex-Japan, Cusco and Kaaz also available for more money), R31 Skyline diff (factory 4-pinion clutch-type LSD and disc brakes), 8" Hilux diff (many ratios and LSD available, rumored to be quite heavy), Mitsubishi Scorpion (LSD and good ratios available out of some L300 vans, but rare), even live-axle Datsun 1600 (wagon).

Depending on the car you are putting it into (obviouly KE3x, 5x and 7x are a bit wider than KE1x and 2x) just about any bigger diff you want to use is going to have to be shortened and have leaf mounts welded onto it. If putting into a KE3x, 5x or 7x, then Celica/T18 diffs will fit without shortening, but with the correct mounts welded on. With any of these, you'll obviously need to do something about your tailshaft.

Limited Slip (without changing housing)

Yes, there is a limited slip center that bolts into a Corolla housing, they were used in American KP Starlets. Sometimes you can find them in 4.1 or 4.3 ratio, more often than not they are the ridiculously low 2.928. Option1Garage on the Gold Coast import these for around $880. There are also people who "make" a sortof limited slip conversion, one such company in America is Phantom Grip. Tayell Automotive in Bentleigh East (Vic) advertise a similar service for around $250.


Ratios

Borg Warner diffs have the ratio written on a plate at the bottom of the diff center, facing the rear of the car. For Jap diffs, read the plate on your firewall, and relate to the list below. Most are U292 or U282, sometimes U209 or U211, rarely U231.

From Helene & Matti's page

First digit: ring gear diameter

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"
Q 12"
R 162mm
S 6.38"
T 6.7"
U 6"
V 10.6"
W 15.5"
X 142mm
Y 158mm
Z 202mm
No ring Gear FWD

Second, third digits: gear ratio

01 3.30
02 3.36
03 3.545
04 3.556
05 3.70
06 3.889
07 3.90
08 4.111
09 4.222
10 4.375
11 4.444
12 4.625
13 4.79
14 4.875
15 5.125
16 5.286
17 5.60
18 5.714
19 5.833
20 6.167
21 6.667
22 6.78
23 6.833
24 7.64
25 4.556
26 5.571
27 3.364
28 4.30
29 4.10
30 3.727
31 3.909
32 6.591 or 4.807
33 7.503 or 5.583
34 6.781 or 4.786
35 7.636 or 5.60
36 4.778
37 3.583
38 3.417
39 3.154
40 5.375
41 3.308
42 6.500
43 3.550
44 3.214
45 3.533
46 2.928
47 3.944
48 3.356
49 3.729
50 3.400
51 3.736
52 3.722
53 3.250
54 3.941
55 3.333
56 2.821
57 4.058
58 3.238
59 3.234
60 3.519
61 2.724
62 2.892
63 2.655
64 4.312
65 3.837
66 3.071
67 3.526
68 3.095
69 4.176
70 5.857
71 2.962
72 3.949
73 4.285


Fourth digit: no of pinions, ltd slip-yes/no

Code pinions LSD

2 2 no
3 2 yes
4 4 no
5 4 yes

Application guide

Based on a table from Helene & Matti's page

5.6" (X)

Starlet KP61 81-82

5.7" (B)

Corolla KE1x Corolla KE20,25,26 70-74

6.0" (U)

Corolla KE2x (some) KE30 77-79 Starlet KP61 83-84

6.25" (C)

Corolla TE21,27,28 (some) 71-74

6.38" (S or R)

Corolla TE21,27,28 (some) 71-74 Corolla TE31,37,38,71,72,75 75-82 Corolla AE71,72 83 Tercel AL10 80

6.62" (D)

Carina TA12 72-73 Corona RT62,72,63,73,83,93 70-72 Corolla TE27 (some) 74

6.7" (T)

Celica ALL 71-85 (RWD) Corona RT85,95,104,114,105,115,119,134,32,34,36 72-82 Corolla TE37,51 75-79 Corolla TE27 (some) 74 Corolla AE86 83-87 (?)


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