Final drive (differential)

Final Drive Assembly
You will need to establish several things before embarking on a rebuild of your final drive:

The first thing (and the easiest) is to work out which drive shafts your Mini has. Rubber coupling (or 'Moulton') drive shafts were used on most Minis up
until 1973. The exceptions were the Cooper S and automatic transmission models, which used universal joint (or 'Hardy Spicer') drive shafts up until that
date. From 1973 onwards, all Minis used offset sphere (or 'pot joint') drive shafts. The designs of the final drive output shafts and their covers depend
on the drive shafts fitted. While rebuilding a final drive on a rubber coupling Mini, you can easily convert it to take 'pot joint' drive shafts if you wish by
fitting a pair of DAM3114 output shafts and 22G2688 circlips.

The final drive gear also needs to be identified. This may be achieved by counting the number of teeth on the final drive gear and if you divide that number
by the number of teeth on the corresponding final drive pinion in the gearbox, you'll get the final drive ratio. If you are unsure that the age of your Mini's
transmission matches the age of the car, you will also need to work out whether you have pre-A Plus or A Plus gears. A Plus gears were introduced
on the Mini round about 1982 (at different times on different models...), and have a sharper tooth angle and different pitch making them quieter than, but
definitely not interchangeable with, the earlier gears. Looking in the gearbox, A Plus gears can be identified by the presence of a circumferential groove in
the centre of the teeth, and the final drive pinion on the gearbox mainshaft is machined flush on both sides.

The only exception to this rule concerns cars with the 3.444:1 final drive ratio, which received A Plus final drive gears in 1979, a full 3 years before they
got A Plus gearboxes. So, if you have a 3.444:1 final drive Mini with a pre-A Plus gearbox containing the larger idler gear and 1st/3rd motion shaft bearings
introduced in 1979, the chances are you will have A Plus final drive gears.

Lastly, you will need to identify your differential case. The case was redesigned in the early 1980s to combat the problem of spinning pinion thrust washers
wearing through it: notches were added to the case to locate anti-rotation tabs on redesigned thrust washers.

For those owners indulging in modified or cometition Minis, several flavours of limited slip differential plus a strong cross pin differential are available, to
special order. Please contact us to discuss your requirements.

Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
1	BTA145	CASE, differential	1	Use with plain pinion thrust washers.
	DAM6027	CASE, differential	1	Use with anti-rotation pinion thrust washers.
2	ATA7378	BUSH, differential case	1	Included in differential case.

Final Drive Gears, Manual Gearbox
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
3	22G443	GEAR, final drive, 65 teeth	1	4.333:1 ratio (with 15 tooth 22G99 pinion).
	22G370	GEAR, final drive, 64 teeth	1	4.267:1 ratio (with 15 tooth 22G99 pinion).
	22G101	GEAR, final drive, 62 teeth	1	4.133:1 ratio (with 15 tooth 22G99 pinion).
	22G340	GEAR, final drive, 63 teeth	1	3.938:1 ratio (with 16 tooth 22G338 pinion).
	22A401	GEAR, final drive, 64 teeth	1	3.765:1 ratio (with 17 tooth 22A399 pinion).
	22G940	GEAR, final drive, 62 teeth	1	3.647:1 ratio (with 17 tooth 22A399 pinion).
	22A411	GEAR, final drive, 62 teeth	1	3.444:1 ratio (with 18 tooth 22A413 pinion).
	DAM3645	GEAR, final drive, 65 teeth, A Plus type	1	4.333:1 ratio (with 15 tooth DAM3647 pinion).
	DAM3216	GEAR, final drive, 63 teeth, A Plus type	1	3.938:1 ratio (with 16 tooth DAM3218 pinion).
	DAM4779	GEAR, final drive, 64 teeth, A Plus type	1	3.765:1 ratio (with 17 tooth DAM4131 pinion).
	DAM4162	GEAR, final drive, 62 teeth, A Plus type	1	3.647:1 ratio (with 17 tooth DAM4131 pinion).
	DAM2677	GEAR, final drive, 62 teeth, A Plus type	1	3.444:1 ratio (with 18 tooth DAM2679 pinion).
	DAM2806	GEAR, final drive, 61 teeth, A Plus type	1	3.211:1 ratio (with 19 tooth DAM2808 pinion).
	DAM6327	GEAR, final drive, 59 teeth, A Plus type	1	3.105:1 ratio (with 19 tooth DAM2808 pinion).
	DAM5925	GEAR, final drive, 59 teeth, A Plus type	1	2.950:1 ratio (with 20 tooth DAM5927 pinion).
	TCB10004	GEAR, final drive, 58 teeth, A Plus type	1	2.762:1 ratio (with 21 tooth TCC10001 pinion).

Final Drive Gears, Automatic Transmission
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
	22A1003	GEAR, final drive, 72 teeth	1	3.273:1 ratio (with 22 tooth 22A1300 pinion).
	DAM7362	GEAR, final drive, 72 teeth, A Plus type		3.273:1 ratio (with 22 tooth DAM7365 pinion).
	DAM4130	GEAR, final drive, 69 teeth, A Plus type	1	2.760:1 ratio (with 25 tooth DAM4128 pinion).
4	ATA7378	BUSH, final drive gear	1	Included in final drive gear.
5	ATA7043	BOLT, gear to differential case	6
6	ATA7385	LOCK TAB, bolt	3
7	BTA154	BLOCK, thrust	1	Optional in DAM6027 differential case.
8	DAM6624	PINION, differential	2
9	2A7062	WASHER, pinion thrust, plain	2	Use in BTA145 differential case.
10	DAM5071	WASHER, pinion thrust, with anti-rotation tab.	2	Use in DAM6027 differential case.
11	22G2583	CROSS PIN, pinion	1
12	RPS1418	ROLL PIN, cross pin	1
13	22A373	OUTPUT SHAFT AND GEAR	2	For rubber coupling ('Moulton') drive shafts.
	22A1151	OUTPUT SHAFT AND GEAR	2	For universal joint ('Hardy Spicer') drive shafts.
	DAM3114	OUTPUT SHAFT AND GEAR	2	For offset sphere ('pot joint') drive shafts.
14	BTA101	WASHER, output gear thrust	2
15	AHU1856	BEARING, differential	2
16	2A3535	SHIM, bearing, 0.002" (0.0508mm)	A/R
	2A3534	SHIM, bearing, 0.003" (0.0762mm)	A/R
	DAM3108	SHIM, bearing, 0.006" (0.1520mm)	A/R
	DAM3109	SHIM, bearing, 0.010" (0.2540mm)	A/R
	DAM3633	SHIM, bearing, 0.020" (0.5080mm)	A/R
17	88G477	DISTANCE PIECE, with bush	1	Automatic transmission models; for universal joint ('Hardy Spicer') drive shafts.
	CHM166	DISTANCE PIECE, with bush	1	Automatic transmission models; for offset sphere ('pot joint') drive shafts.
18	22G421	BUSH, distance piece	1	Automatic transmission models; for universal joint ('Hardy Spicer') drive shafts.
	2A3538	BUSH, distance piece	1	Automatic transmission models; for offset sphere ('pot joint') drive shafts.

Final Drive Output
Rubber Coupling ('Moulton') Type
All Manual Gearbox Models Except Cooper S, 1959-73
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
19	CHM85	COVER ASSEMBLY, with bush	2
20	2A3538	BUSH, cover	2
21	ADU5738	OIL SEAL, cover	2
22	GUG705567GM	GASKET, cover	2
23	SH505101	SCREW, coarse thread, cover to gearbox	10
24	LWZ305	WASHER, locking	10
25	22A374	FLANGE, output	2
26A	FNZ810	NUT, output flange to shaft	2
26B	ZPS415	SPLIT PIN, securing nut	2
27	PWZ110	WASHER, plain	2
28	GCD101	RUBBER COUPLING KIT, output flange to drive shaft	2	Includes one rubber coupling, plus U bolts and nuts.
	QL5000	NYLON COUPLING KIT, output flanges to drive shafts	1	Uprated; includes two nylon and needle roller couplings, plus U bolts and nuts.
29	22A132	U BOLT, coupling to output shaft and drive shaft	8
30	LNZ205	NUT, locking	16

Universal Joint ('Hardy Spicer') Type
Cooper S, 1963-71; All Automatic Transmission Models, 1965-73
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
31	22G419	COVER ASSEMBLY, with bush	2	Cooper S.
32	22G421	BUSH, cover	2	Cooper S.
33	AHU1082	OIL SEAL, cover	2	Cooper S.
34	GUG705567GM	GASKET, cover	2	Cooper S.
35	SH505101	SCREW, coarse thread, cover to gearbox	10	Cooper S.
36	LWZ305	WASHER, locking	10	Cooper S.
37	88G476	COVER ASSEMBLY, with bush	2	Automatic transmission models.
38	22G421	BUSH, cover	2	Automatic transmission models.
39	22A1616	OIL SEAL, cover	2	Automatic transmission models.
40	22A1612B	GASKET, cover	2	Automatic transmission models.
41	SH505081	SCREW, coarse thread, cover to gearbox	8	Automatic transmission models.
42	LWZ305	WASHER, locking	8	Automatic transmission models.
43	22A1152	FLANGE, output, with bolts	2
44	22A1139	BOLT, output flange to drive shaft	8
45	LNZ405	NUT, locking, output flange bolt	8
46	22A1104	SCREW, output flange to output shaft	2
47	WE600101	WASHER, shakeproof	2
48	22A1201	WASHER, plain	2
49	88G493	COLLET, output flange	4
50	22A1566	RING, sealing	2

Offset Sphere ('Pot Joint') Type
All Models, 1973 On
Ill. No.	Part No.	Description	Qty. Rqd.	Remarks
51	CHM85	COVER ASSEMBLY, with bush	2	Manual gearbox models.
52	2A3538	BUSH, cover	2	Manual gearbox models.
53	ADU5738	OIL SEAL, cover	2	Manual gearbox models.
54	GUG705567GM	GASKET, cover	2	Manual gearbox models.
55	SH505101	SCREW, coarse thread, cover to gearbox	10	Manual gearbox models.
56	LWZ305	WASHER, locking	10	Manual gearbox models.
57	CHM167	COVER ASSEMBLY, with bush	2	Automatic transmission models.
58	2A3538	BUSH, cover	2	Automatic transmission models.
59	ADU5738	OIL SEAL, cover	2	Automatic transmission models.
60	22A1612B	GASKET, cover	2	Automatic transmission models.
61	SH505081	SCREW, coarse thread, cover to gearbox	8	Automatic transmission models.
62	LWZ305	WASHER, locking	8	Automatic transmission models.
63	22G2688	CIRCLIP, output shaft	2
64	GCV1102	OFFSET SPHERE C.V. JOINT ASS'Y	2	'Pot' joint.
65	GSV1073	GAITER KIT, offset sphere joint	2	Includes one gaiter, clips and grease.
66	AKF1457	GREASE, sachet, offset sphere joint	A/R

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Final drive (differential)

LOCK TAB-CROWNWHEEL TO DIFF CAGE BOLT

BUSH-DIFF CAGE,CROWNWHEEL & OUTPUT SHAFT

BOLT-DIFF CROWN WHEEL TO CAGE

BEARING- DIFFERENTIAL

OIL SEAL-DIFF SIDE COVER-COOPER 'S'/HARDY SPICER

OIL SEAL-DIFF SIDE COVER-NOT HARDY SPICER

COLLET-FLANGE TO DIFF OUTPUT SHAFT-HARDY SPICER TYPE

DISTANCE PIECE WITH BUSH-DIFF-AUTO WITH HARDY SPICER JOINTS

COVER-DIFF SIDE-AUTOMATIC

WASHER-THRUST-DIFF PINION NO ANTI-ROTATION TAB

BUSH-DIFF SIDE COVER-SUITS RUBBER & POT JOINT SHAFTS-GENUINE

SHIM-DIFF BEARING .002'' (0.0508mm)

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