PROPSHAFT LENGTHS

In trying to source a propshaft for a 1930s A7, we came across a problem with the propshaft locking solid between the fabric joint and the carden block. Reading through many books, there appeared to be two lengths, long and short for the respective chassis lengths. On mentioning this to Vince Leek, he advised me that it was not that straight-forward, as it depends on the chassis/gearbox/back axle combination. We had the correct combination for a 1930s car, but the shaft would still not fit, so I decided to read through the Austin parts books and indexes and came across these index pages.

 The index pages show that there are four lengths of this type of propshaft where Austin adjusted the length as the car developed. Looking at the parts books, it became clear as to why the propshafts changed length for the correct combination of chassis/gearbox/back axle.

Year

Hand book

Chassis

Propshaft Ref

Gear box

Speedo

Axle

1926

Late

353j

Short

BP28

3 speed

Pulley on propshaft

Type 1

Case BO1

1928

Mar

353n

Short

BP28 &

BP73

3 speed

Pulley on propshaft

Positive drive on gear box

Type 1

Case BO1

Type 1

Case BO1

1930

Jun

670c

Short

BP73

3 speed

Positive drive on gear box

Type 2

Case BO100

1931

Jan

670d

Short

BP93

3 speed

Positive drive on gear box

Type 3

Case BO121

1932

Jan

888

Short

Long

BP93 &

BP118

3 speed

Positive drive on gear box

Type 3

Case BO121

1932

Nov

888a

Long

BP118

4 Speed Crash

Positive drive on gear box

D Type

Case BO143

 For images of the rear axle types see page 164 of the Austin Seven Companion.

1926 BP28 propshaft original length

1928 BP73 with the speedo on the back of the gear box the propshaft became shorter to accommodate the longer gear box

1930 BP93 the rear axle design changed the length of the torque tube requiring an increase in the length of the propshaft

1932 BP113 the chassis lengthened requiring the propshaft to increase in length

From the shafts I have been able to measure the lengths as follows:

1926 - 1928 BP28 20 measured from fabric joint end to carden pin

1928 - 1930 BP73 19.5 measured from fabric joint end to carden pin

1931 - 1932 BP93, not found one of these yet, does anyone know?

1932 - 1933 BP115 26 measured from fabric joint end to carden pin

 Thanks to Vince for the pointers and to Phil Whitter who measured his propshaft for me. Although it is now possible to get a modern propshaft made to measure for the Austin Seven with adaptor plates to suit the gear box/rear axle, we managed to pick up the correct propshaft from Beaulieu this year, although we did have a tape measure to hand to double-check the length.

Douglas Alderson DA7C