Poor brakes with no feeling

[Bob Culver]

Hi Tony
The self servo leverage about the pivot is generated largely by the leading edge of the leading shoe and increases as the leading edge is advanced and the angle of thrust changes. So cutting it back reduces the effect. The effect is increased with older high friction linings.
It is not suggested in this case  but many materails of the last 50 years intended for assisted brakes are very poor on older cars, including hydraulic.

[squeak]

A reduction in lining area for the desired amount of retardation will raise the lining temperature. 
Taking lining  material from the actuator end of the shoe will cause an unnatural bending moment in the shoe.
The pedal travel will be increased as will feel.
Higher temps may result in brake fade at a point where lockup was previously experienced.
Racing may incur short frequent heat cycles but I would not like to come down a long mountain with reduced lining.
Well come to think of it I have

[Rogerfrench]

Thank you Bob, saves me explaining.
Squeak, you are right about the bending moment but I'd suggest the shoes are sturdy enough for it not to matter, and the increased feel was welcome. Brake fade wasn't an issue.

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To get back to the original question, wooden brakes can be a result of over-hard linings too. It would be good to know if the brakes were always like this, or is it a recent change.
If recent, has anything changed, apart from bleeding etc? If they have always been like this and all wheel cylinders are working correctly, it's either linings or m/c size. I'd try a smaller m/c diameter first.

[Terrytuned]

Having done several hydraulic brake conversions the MM master cyl is not suitable for a Seven apart from being cast iron and over weight its too big, we use a Girling alloy cyl 3/4" bore. the rear brakes are best setup as trailing (cyl handbrake levers at the rear pointing down) this stops the rear brakes locking under heavy braking. Silicon fluid prevents w/cyls seizing as well as silicon grease around the cyl pistons, std MM lining seem OK on 2 leading front setup you can lock the fronts or brake lightly in the wet there is plenty of feel. Terry

[Charles P]

Having done several hydraulic brake conversions the MM master cyl is not suitable for a Seven apart from being cast iron and over weight its too big, we use a Girling alloy cyl 3/4" bore. the rear brakes are best setup as trailing (cyl handbrake levers at the rear pointing down) this stops the rear brakes locking under heavy braking. Silicon fluid prevents w/cyls seizing as well as silicon grease around the cyl pistons, std MM lining seem OK on 2 leading front setup you can lock the fronts or brake lightly in the wet there is plenty of feel. Terry

I agree Terry. 
I have a 3/4 bore cylinder mounted on the rear cross member, actuated via a hefty bell crank mounted in the chassis member. The pedal pull rod works as normal and the crank arm converts this into a push on the master cylinder. A bonus is that you have some adjustment of leverage available via the postions that the rods connect with the arms of the bell crank. 

Charles

[Rogerfrench]

Surely the rear brakes are one leading, one trailing?

[shane]

Thanks for the suggestiond I will let you know what I find

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Even the suggestions

[Terrytuned]

In case anyone does not understand the rear setup wheel cyls normally operate in the direction of rotation of the brake drums, by fitting the back plates so the wheel cyls are operating against the rotation it reduces the effect of the self servo action so the rear brakes are less effective, it works in practice anyway.
Terry.

[Colin Reed]

HI Terry,
I am one who does not understand,
normal rear drums have one cylinder operating both shoes and one common pivot so you have one leading and one trailing shoe
the only way to have two trailing or leading shoes on the rear is to have twin cylinders.

Colin 
NZ

[Bob Culver]

Most other cars have a single cyl with two pistons so, assuming the pivot is symmetrically placed, direction is the same. I gather Seven conversions commonly use the single piston type assembly with the body of the cylinder floating on the backplate, so it behaves like two pistons..  Also with these direction should not much matter. I have no experience of Sevens but with  the type on other cars can get situations of wear or mismatched shoes where the cyl body reaches limit of travel, then more or less  becomes single shoe and direction matters. The conditon is not always very obvious.