brakes

[Bob Culver]

The empirical rule seems to fail with brakes. Dunno why, possibly due heating effects or material change under pressure. Perhaps someone can explain.

[Paul N-M]

My understanding is: 
Linings have a co-efficient of friction which varies depending on material composition used. Also brake drum material has an affect. Cast iron in general being better than pressed steel. 
This changes with heat, hence the fall off in performance we call fade when brakes are heavily used.

Mechanical gain achieved from our foot to the shoes multiplies the pressure the shoes exert on the drums. The pressure is distributed accross the area of the shoe linings. The smaller the area the higher the pressure per sq. inch and conversely the larger the area the smaller the pressure per sq. inch for the same foot input effort.

So larger area shoes do not increase breaking effort for the same input they just dont heat up so much due to their greater area all other tings being equal. The obvious advantage is reduced fade though.

Hope this helps.

[Vancevr]

so just to be clear I need to jack the car up and have a friend hold down the brake pedal and then I should spin the wheel and it should be really hard to spin, if not then tighten it? Another question, my hand brake lever had been moved from the place near the gear shift lever. What does this mean? I can get a picture if you need.

[Andy Bennett]

I am at the lower end of skills here, but from my personal experience to where I am at now on my RP, which is quite happy, here goes.

Mine were not great at first so I worked from both ends replacing friction surfaces, cleaning up inner drums, replacing cables and putting in new gaskets between inner and outer hubs to prevent grease coming through, so was much more than just the set up. But on that point, it's also about balance left to right and front to back.
if you have straight coupled brakes then the fronts should auto balance through the centre but rears are separately adjusted through a clamp at the front end of the cable so are quite tricky to balance manually.
Worth checking for condition of cables and smoothness of the run through the central pivot point for fronts to make sure cables aren't catching. Mine were old and had a couple of kinks which meant that the pull was uneven and was pulling the kink straight first.
I set mine up with just 5mm of free travel on the pedal before you can feel it pulling on the cable.
Ultimately if a friend is pushing on the pedal hard you shouldn't be able to rotate any of the wheels by hand. but it is as much about what happens when you are half pushing on pedal where you can see how the balance is set.
Andy

[Reckless Rat]

I think before we give any more advice to Vancevr, we really do need to see photos of the underside of the car, the brake cross-shaft and handbrake arrangement as well as the linkages to front and rear wheels. We're fumbling in the dark if this car has an ad-hoc braking system, and it sounds to me like our friend really does need the help of someone local that knows something about our cars (or the US version).

[Dennis Nicholas]

"Handbrake leaver moved from normal position"
I wonder if hydraulics have been fitted?

[Vancevr]

They arnt hydrolic. I cant get pictures of the underbody because the car is in storage. I won't be able to get to it for a few days. I have an old pic from the top if that helps.(Probably not)

[Bob Culver]

Possibly 300 lb on the pedal proved inadequae so someone has arranged for a very effective supplementary pull. Probably about 100 keen Forumists eager to see underneath

[Jeff Taylor]

I've enlarged and rotated the image.

   

[Hugh Barnes]

Well, clearly a 'non-standard' set up...