Brake size

[johnairey]

Is there any differences in the diameter of brake and width of drums between hydro and hydraulic brakes?

[David Kemp]

I am surprised no one has answered.
By rough calculation crawling through my foliage ,
The older mechanical drum seems narrower than the latter hydraulic.
I am waiting for a cyclone to hit, once it has passed I will get a better measurement

[johnairey]

Found in Javelin 2014 Feb. Magazine.
The width of linings are different Hydro-mechanical 1 1/4” & 1 1/2” full hydraulic 1 3/4”

[Keith Clements]

The technical data page of the Technical notes:
https://jowett.net/Parts/TechNotes-Part ... alData.htm

Braking System

Manufacturer Girling

Before E0/PB/10594:

Type – Front Hydraulic, with single hydraulic expander unit

Type – Rear Mechanical, with cable, compensator and rod actuation

Drum Diameter 9 in. (228.6 mm)

Drum Material Malleable iron

Lining Length 7.3125 in. (185.74 mm)

Lining Width (Front) 1.5 in. (38.1 mm)

Lining Width (Rear) 1.25 in. (31.75 mm)

Friction Lining Area 88 in2. (567.74 cm2)

Lining Thickness 0.1875 in. (4.76 mm)

Number of Rivets Per Shoe 10

After E0/PB/10594:

Type – Front Full hydraulic, 2 leading shoe

Type – Rear Full hydraulic, fully floating incorporating hand brake actuator

Drum Material Malleable iron

Lining Length 8.75 in. (222.25 mm)

Lining Width 1.75 in. (44.45 mm)

Friction Lining Area 123 in2. (793.55 cm2)

Lining Thickness 0.1875 in. (4.76 mm)

Number of Rivets Per Shoe 10

Wheel Cylinder Diameter (Front) 0.875 in. (22.23 mm)

Wheel Cylinder Diameter (Rear) 0.875 in. (22.23 mm)

Braking Effort (Front) 65%

Braking Effort (Rear) 35%

Brake Pedal Ratio 6 : 1

Brake Retardation at 30 mph (One up)

Pedal Pressure Stopping Distance

25 lbs. (11.3 kg) 130 ft. (39.6 metres)

50 lbs. (22.7 kg) 59 ft. (18 metres)

75 lbs. (34 kg) 43 ft. (13.1 metres)

100 lbs. (45.4 kg) 39 ft. (11.9 metres)

Brake Fluid (For Both Types) Castrol crimson brake fluid (authentic), Castrol Ultra-Stop

Colour – Amber. AS1960-1983 Grade 3.

Ford spec. ESW-FM6C-2, Leyland HBF-6

Brake Fluid Capacity 1 pint (0.57 litre)

Using Member Services Search Archive facility
download/file.php?id=7839

Bulletin Issue Date: September 1950
Item No. 26.
Four Wheel Hydraulic Braking System
Introduced with effect from Javelin car with Engine Number E0 PB 10594.

This for Bradford, using Member Services Search Archive facility
download/file.php?id=7385 page 18

Alteration To Brake Drums
In December 1947, the width of the brake drums was reduced from 2⅜” to 211/32” (60.33 mm to 59.53 mm), to avoid
any possibility of the drum fouling the back-plate. On early vehicles where this fouling has taken place, 1/32” (0.79 mm)
turned off the edge of the drum, should normally provide adequate clearance.
The width of the groove on the edge of the drum was increased to 5/16” (8 mm) and the depth increased to 7/32” (5.6
mm) to eliminate any possibility of water entering the brake drums at low speeds.
From Engine No. D8/CB/17009, the diameter of the brake drums was increased from 8” to 10” (203.2 mm to 254 mm).
The assemblies are not fully interchangeable as the modification involves alterations to the stub axles and to the rear
axle and flanges.

[David Morris]

Hi All,

I recollect that on the full hydraulic brakes used on the Javelin and Jupiter, that I was told that the shoes are the same as those used on the Mk. 1 Ford Consuls. You would have to check this against the extensive data given by Keith earllier in this post.

If this is the case, I am sure there would be a sizeable difference in price, with the shoes for the Ford being much cheaper on a stall at a car-based event!

Or, on the safe side, preferably you could use JCS, where I am sure you will find exactly what you are looking for!

All the best and do enjoy this great weather!

David