Could someone help out with this problem?on a 1935 Austin Seven Ruby. When reversing and applying the brakes the foot pedal forces up towards you, normal braking is no problem.
What does it feel like if you drive down a bumpy track and brake?
The geometry on some cars is such that the cable lengthens and shortens as the rear wheels ride over bumps, normally you don't notice this on the road. It can quite disconcerting over bumps, though.
When reversing, the rear of the car rises - which I would have thought would make the pedal go down, which is why I would try the bumpy track braking to see if you are getting pedal movement, to help with diagnosis.
Or it is something else entirely....(waits for other people's inputs.....)
I assume you have cable brakes and you have checked the run of the cable: back from the cross-shaft, through brass guides in the chassis cross member (or over little brass pulleys) and connecting to downward pointing levers on the upper sector of the brake backplates.
The positioning of the levers is the subject of much discussion on this forum, having checked to see what you have, read up on it on here.
I think this is caused by the front axle moving under braking. When braking going forwards the axle moves back which tends to release the brakes. Going backwards the brakes pull the axle towards the front of the car which pulls on the cable and thence to the pedal.
The fixing of the radius arms to the chassis may be suspect. The ball on the cross member works loose on the rivets. If this is the case the rivets should be replace by high tensile bolts. The radius arms to the ball may be loose. Might just need tightening, but the special bolt and spring and the cups that fit onto the balls are available from the usual suppliers.
It will tend to happen to some extent even if everything is tight.
If the front wheels are very securely chocked, then with brakes off if someone pushes and pulls on the car whilst you peer underneath, movement at the radius rod mount should be apparent.
The brass cups need to be a neat fit in the radius rods and around the ball.