this might help yu....
Land Rover, Converting to dual power brakes
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 and adding wiring for the PDA warning light.
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
LR Kit Servo Boost Ratio
88 LE72696 LR17818 1.90:1
109 LE10118 LR15248 2.00:1
109 LE10117 LR15248 2.00:1
LR Kit Servo Boost Ratio
88 LE72696 LR17818 1.90:1
109 LE10118 LR15248 2.00:1
109 LE10117 LR18221 3.00:1
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.
Here is how to tell an 88 Master cylinder from a 109 master cylinder by looking at their profiles:
Land Rover model 88 master brake cylinder
This is a new 88 master brake cylinder
Land Rover 109 master brake cylinder
This is a not 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.
Land Rove 109 brake lines
The fitting for the rear brake line is larger diameter than the fitting for the front brake line.
Series Land Rover 88 master cylinder
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 activated 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 installed a brake warning lamp and wired it to the PDA.
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 brake parts intended for newer Land Rovers and some aftermarket 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.
