PROPSHAFT LENGTHS

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