Rear Brakes Locking

How many have experienced the rear brakes locking when going over bumps forward, and sometimes even whilst reversing?

Here is a list of problems observed by my experience:

1) Brake return springs too weak, due to age, Ask a spring manufacturer to make up new springs with the same tension and wire diameter etc.

2) Incorrectly ajusted brake shoes, clearance too tight, "I do not always go by the book manual" eg, set brake shoe clearance between 20 to 30 deg, I adjust 1 cam at a time until the wheel locks and then slacken off a bit, (more or less between the range of 20 to 30 deg), then rotate wheel again.

3) Brake hydraulic seals inside wheel cylinder sticky.

4) Handbrake sticky, (cable needs greasing), this will tension the leading rear brake shoe and decrease the brake shoe to drum clearance.

5) Air in brake lines causes uneven braking and sometimes causes wheels to lock

6) Brake hoses, (flexible rubber hoses) partially blocked, when the rear brake hose is partially blocked with age, during braking the brake fluid flows under pressure to the wheel cylinders, but cannot return properly when the brake pedal is released, (as a result both rear wheels can remain sightly blocked). The same applies to the front individual brake hoses.

7) During sudden extreme pedal braking: check the following

RHD FIAT 1100/1200 models the front right wheel will lock slightly before all the other wheels and for
LHD FIAT 1100/1200 models the front left wheel will lock slightly before all the other wheels.

The reason for this is that the master cylinder in these cars is close to the wheel, depending on LHD or RHD, and the length of brake pipe that attaches to the particular wheel, (from the master cylinder) is the shortest of all brake pipes. This means that there will be fewer losses due to resistance in hydraulic pressure flow.

I think it will be good to have an Italian version of this technical topic.

Regards Luigino

Thanks Luigino - very useful... I can translate or I'm sure one of the Italian technical gurus could put something together using all the correct terminology...

All the best, John.