Improving Austin Seven Brakes.


I am guessing that if you are reading this you have already discovered that your Austin Seven brakes are inadequate. What follows is not a chapter and verse manual on how to modify the system but rather an overview of the various solutions which work on Austin Sevens.

On the very first Austin Sevens the pedal operated the rear brakes only. In the case of a trials car it is an advantage to be able to apply only the rear brakes in order to maintain steerage whilst backing out of a section down hill, apart from that the system has little to commend it. In later cars front and rear brakes are coupled together.

On all Austin Seven models there is an obvious design error... On full left lock the left front cable end does not have enough range of movement, so the neck of the ball on the lever forces the cable end round so applying the front brakes and cutting into the lever. The same is true on the other lock The solution is to twist the lever about its vertical axis until the ball and neck axis is at 90 degrees to the cable end, thus giving equal movement each way. This modification will make only a small improvement but it costs nothing.

Another option is to fit a Bowden cable conversion to the front but, in my experience, the resultant internal friction and flexing of the various parts cancel out the theoretical advantages. In order to make the brakes suitable for competition or modern traffic more radical changes are needed.

In circuit racing it is essential to be able to lock the wheels because if the car spins with the brakes locked it will travel in a straight and predictable line until coming to rest. With the car slowing and the wheels turning they will eventually grip and the car will suddenly change direction, much to the consternation of those following!

In order to meet this objective there are three ways to go...

1. Modify the existing mechanical arrangements to achieve four wheel compensated brakes.

2. Scrap the existing system altogether and go for the new Pigsty developed method.

3. convert to hydraulic operation.

Method 1. is described in the 750 Motor Clubs 'Austin Seven Companion' and was previously in 'The Special Builders Guide'. Alex Myall at Pigsty has discovered a way to eliminate the resultant dangling front brake lever under the centre of the car. This method also makes front/rear bias adjustment easy.

Method 2. Which could be called a Pigsty Austin Seven brake follows Bugatti practice in having a continuous cable running from the rear brake lever around a crank, like that on a bicycle, in an 's' shape (nearside) and forward to the front lever. It is drawn in by a guide to clear the tyre on lock.

The crank (one each side) is on the end of a cross shaft. In a high chassis Austin Seven, such as an Ulster, the shaft passes under the side members. In a low, Pigsty height, Racing Austin Seven, the shaft passes through the car above the side members. In each case it is turned by a pull rod from the pedal. Front/rear compensation is automatic, bias can be adjusted.

Here is a side view of a Pigsty Austin Seven, so fitted, to clarify this description.

Pigsty Austin Seven Brake Modification

Both of the above methods, which contain no expensive parts, retain the standard single leading shoe in each brake.

Method 3. Hydraulic brakes. For this you will need semi Girling front stub axles. Early stubs have been changed to Girling pattern but even unmodified ones are prone to large cracks. Hacking metal off will not improve the situation.

One can machine the early rear side cases to accept Girling backplates, it is important to turn regisers to locate the backplate centrally.

Hydraulic conversion backplates can be purchased as complete assemblies with two leading shoes at the front and use all available early Morris Minor parts.The Minor master cylinder is, in my opinion, an abomination. I have used Sierra dual circuit parts and others of unknown origin.

It is important to avoid any solid metal pipes anywhere on the Austin Seven chassis, the vibration and twisting in the struture will eventually cause a pipe to fracture at the flare. I have seen one serious incident and two minor failures caused by just that.

It is worth mentioning that the last of the early steel drums are much thicker than even earlier examples and that the solid centre wheel will not fit over the Girling drum unless the latter is turned down on the outside.

Finally, remember that the retardation of your Austin Seven can only be as good as the grip of the tyres on the road. If you are running 3.25x19s, Hydraulic brakes may be seen as no more than conspicuous consumption.

Tim Myall