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All varieties of
the Land Rover 109 have drum brakes. My 1960 109 came with a single
hydraulic system and no power booster. This design has been improved
by the factory over time. The most advanced brake system designed
specifically for the 109 Land Rover came on the 1984 109 Land
Rover. This system has dual circuit power brakes and larger front
brake shoes.
I choose to upgrade the Green Rover's brake system to 1984 109
factory specifications. I decided to stay with the factory specification
because the engineering was performed by professionals and thoroughly
tested to work properly as a system.
An overview
Upgrading The Green Rover's brake system upgrade required:
- Fitting a new brake pedal pedestal with a power booster.
- Cutting the left front wing for clearance (you can use a
SIII inner wing panel instead).
- Adding a 109 dual master brake cylinder, a PDA and routing
brake lines.
- Switching to the series III master clutch cylinder.
- Rerouting wiring for the stop lamp switch.
I choose to replace my entire brake system with all new parts at
this time. The Green Rover had already suffered brake failures twice
from pinhole rust though leaks in the steel tubing and I wanted
to have everything new.
Clearance on the wing
Parts of the front left wing needed to be cut away to make space
for the new brake booster. I carefully measured the cut out
on a series III wing and cut my own wing as closely as possible
to match. Before I cut the wing, I drew a line where the bonnet's
outer side edge meets the wing. This provided the absolute
outer boundary for the cut. There is a flage on the underside
of the wing top for mounting the splash shield. Your cut should
end before reaching the flange so you can reinstall the splash
shield.
There is a mounting bracket on the bulkhead that supports the rear
of the wing. I needed to cut part of the top of this bracket off
to provide clearance for the series III clutch reservoir. I cut
the top part of the bracket off to match the wing cut. This left
me with one bolt mounting hole left on the bracket.
The brake pedestal
I used a brake pedestal from a late series IIA or series III Land
Rover. The pedal on a booster pedestal is hinged on the opposite
side as the pedal on a pedestal without a power booster. This means
I needed to elongate the hole in the bulkhead for the pedal. The
mounting holes stayed the same. The late pedal uses dual side return
springs. I had to file the pedal slot a little wider to keep the
springs from rubbing on the bulkhead. Once I was sure of the fit,
I smeared RTV along the base of the pedestal and bolted it into
place. Once the pedestal and booster were fitted, I added a vacuum
take off fitting to my intake manifold and routed a hose to the
booster.
The Servo unit
Here is a listing of the different 6 inch boosters Land Rover
used for Series power brakes.
LR |
Kit |
Servo |
Boost Ratio |
88 |
LE72696 |
LR17818 |
1.90:1 |
|
109 |
LE10118 |
LR15248 |
2.00:1 |
|
109 |
LE10117 |
LR15248 |
2.00:1 |
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If you could use a little Extra boost, Heystee
Automotive in The
Netherlands offers larger 8 inch Sanatana power brake boosters.
The master clutch cylinder
I used a master clutch cylinder from a series III Land Rover that
has its own built in fluid reservoir. It bolted to my old clutch
pedestal and clutch hydraulic line.
The master brake cylinder
I installed a 109 master brake cylinder. The one that is common
in the United States is designed for the 88 and will not work
properly. The 109 has dual front wheel cylinders on each side.
The 88 has a single wheel cylinder on each wheel. The master
cylinder supplying fluid to the front brakes needs to be capable
of pumping more fluid than the 88 master cylinder pumps. Disc
brake conversions have different master cylinder requirements.
Here is how to tell an 88 Master cylinder from a 109 master cylinder
by looking at their profiles:
This is a new 88 master brake cylinder
This is a not so new 109 master brake cylinder
The 109 master cylinder is connected so that the tubing for the
front brakes is connected to the larger diameter cylinder, located
closest to the booster. The tubing for the rear brakes is connected
to the front most cylinder.
This is opposite
the connections on an 88. The 88 master cylinder
has the front of the cylinder going to the front brakes.
The fitting for the rear brake line is
larger diameter than the fitting for the front brake line.
PDA
The 88 master cylinder has the same diameter bore for both cylinders
and an internal part that allows the rear brake piston to
push the front brake piston in case the rear brakes fail. Model
88 dual brake Land Rovers do ot use PDAs.
The 109 dual master cylinder has different diameter offset circuits.
The rear brake piston is activted by fluid pressure generated
by the front brake piston. There is no internal mechanical
linkage. If
the rear brakes fail, the front brakes will continue working but
if the front brakes fail there is nothing internal to the master
cylinder to keep the rear circuit working (no brakes!). 109
dual brake systems came with a special PDA that blocks off the
front brake circuit in case of front brake failure. This
keeps enough fluid in the front circuit for the master cylinder
to operate the rear brakes. There are many different varieties
of PDAs each designed to work with specific brake master cylinders.
You need one specific for a Land Rover 109. I purchased
a new PDA for a 1984 109.
According to the Stage I workshop manual" the PDA that is fitted
to the 109 blocks off an open brake system, keeping fluid in the
master cylinder, and activates a warning lamp that lets you know
that one of your brake systems has failed".
I mounted mine on the unused right side steering box support just
above where the five way junction went.
I routed new brake lines between the Master brake cylinder and
the PDA using the original line routing.
Rear Brake line routing
I installed all new brake tubing from the PDA to the rear brakes
using the stock routing.
Front brake routing
I never liked the factory routing for the
front left brake. It has too many places to trap air bubbles.
I routed the front brake line along the top
of the frame to the front right brake. There I used the same 3 way
connector that comes stock for the rear junction. One side went
to the front right brake. The other side continued along the top
of the frame, around the front of the radiator to the front left
brake. The run from the PDA to the front left brake is very close
to level with no place to trap air bubbles.
Brake lights
When I removed the five way connector, the
brake light switch went with it. The power brake equipped Land Rovers
have a brake light switch mounted on top of the brake pedestal.
I just routed two wires from the new brake light switch to the old
wires.
I was done
Safety Considerations - Please read
A car's brakes can save your life and the life of others if they
are in proper working condition. I recommend that any modifications
to a braking system be performed by experienced brake professionals
and that any design used be tested thoroughly as a complete system.
If you decide to modify your Land Rover's brake system please be
very careful. Any mistakes can lead to brake failure. I do not in
any way recommend that you make modifications to your Land Rover's
brake system, nor do I claim that this story is accurate or complete.
Please read the copyright notice attached to this web site and accessible
from a button at the bottom of this page.
If you do decide to make any modifications be very sure that you
use the correct fittings and the correct tubing flares, properly
made.
American brake fittings and British brake fittings are different
and incompatible. They will interconnect but are not safe to use.
The British male fitting has a long snout ahead of the threads.
The American one does not.
When you screw an American male fitting into a British female fitting,
the flare will not seat.
When you screw a British male fitting into an American female fitting,
the flare will seat with only one or two threads holding the parts
together.
Also be aware that Land Rover started converting to metric in
1981 so bake parts intended for newer Land Rovers and some aftermaarket
parts may require metric fittings.
Dual master cylinders designed for the 88 will not work properly
on a 109 brake system. The 109's front brakes have two cylinders
per side while the 88's has only one. The 88 master cylinder will
not push enough fluid to properly work the 109's brakes.
Always use new brake fittings and the proper brake fluid. For British
brake systems this is DOT4 or DOT5.
Steel brake lines should be clamped to a surface. Unsupported lengths
of rigid tubing vibrate and eventually will get fatigue cracks at
the fitting junction.
There are probably more safety concerns that I have not mentioned.
Please just be careful when working on your own brakes.
Master brake considerations for disc brake conversions
This advice comes from Paul Heystee of Heystee
Automotive Components. Paul recommends using using a
Defender master brake cylinder with a disc brake conversion. The
1993 D110 master brake cylinder available in North America
would be a good choice for a Series Land Rover that has front
disc brakes and rear drum brakes. Here is what Paul has
to say:
"The reason for changing to an early Defender master cylinder
is because these designed specially for discs/drums set-up. Master
cylinders designed for drum brakes have a so called "remainder
pressure" that keeps the shoes close to the drums. Using this
type of MC with a disc/drum or disc/disc set-up will push the pistons
constant to the disc wearing out the pads quickly ("in no
time"). Also the disc brake set-up requires less volume
to work but this is not an issue because the LR pedal has already
a long travel and a short travel is welcome. The tandem set-up
will allow to keep pushing fluid to the rear although the front
is saturated."
"The small valve that is fitted to many Series IIIs was a
safety device and caused more problems and actual safety. I remember
trying to bleed the system for 2 days due to this valve (!) I
recommend to separate the front and rear directly form the MC
and if required you can put a G-valve in the rear line to limit
the pressure on the rear drums when going down a hill or when
decelerating form high speeds. Due to a small mass inside this
valve which activates when it's moved under G force, hence the
name. It is found on many 110 Defenders."
"The Santana PS10 has a load depending valve which is
better when the load variations are big and especially when it's
fitted with parabolic springs (more movement compared to the
rigid multi leaf springs). However, the coil springs form the
Defender make more movement then still they had this G-valve.
It's my favourite also because it is not connected to the axle
which is prone to break off in heavy conditions."
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