How to run dual power brake lines - question

[GeniusAndHisAssistant]

Since the 5-way junction is no longer available for the brake lines, can anyone tell me how to run two separate lines? Since one line coming out of the master cylinder is bigger than the other, I am curious if one goes to the back and one goes to the front. Could we run one line to the rear brakes and the other one to a t-fitting, and each end of the T would go to one of the front brakes?

Thanks in advance

[SafeAirOne]

What's wrong with the existing 5-way junction?

BTW, I've got single-circuit brakes, and I having trouble imagining how a dual circuit braking system would make use of a 5-way junction:





Perhaps you are referring to the PWDA valve?:

[I Leak Oil]

Common to just run the rear brake port off the master directly to the rear flex line. Run a line from the front brake port to a 3 way junction, then a line out to each front brake. Depends on what master cylinder you have as to what port goes to the front.

[darbsclt]

Common to just run the rear brake port off the master directly to the rear flex line. Run a line from the front brake port to a 3 way junction, then a line out to each front brake. Depends on what master cylinder you have as to what port goes to the front.

My plan, when/if I get around to a disk brake conversion, was to do this ^^^...

The only difference being, rather than adding a 3-way for the front circuit, I thought I would make use of the existing 5-way junction and blank off the unused rear port. I'd keep the brake light switch on the 5-way instead of using one on top of the pedal tower.

(If there's an issue with this logic, I'm all ears...)

[TeriAnn]

Since the 5-way junction is no longer available for the brake lines,

Not needed for the dual brake system on your 1970 88.

can anyone tell me how to run two separate lines? Since one line coming out of the master cylinder is bigger than the other, I am curious if one goes to the back and one goes to the front.

2. Both the front and rear brake lines are are the same diameter. The connectors to the master cylinder are different diameter so that you do not mix them up.

3. Yes one line from the master cylinder goes to the back and one line from the master cylinder goes to the front.

1. I can tell you how I plumbed my lines when I switched from a single circuit system to a dual brake system. The factory routed the brake lines on the frame as if all Land Rovers were right hand drive (RHD). For a LHD truck they routed the lines along the top of the firewall (bulkhead) to the right side then down.

My truck, like yours is LHD. I ran the rear tube straight down from the master cylinder to the frame. The across the back of the under bulkhead frame cross member to the right side then on top of the right side rail to the rear end. I chose to follow the factory route for the rear to keep the line away from the heat of the exhaust system.

For the front I ran the line down to the frame and forward on top of the frame to the front left brake. I added a 3 way junction to feed brake fluid to the front left brake. I continued the brake line across the top of the front frame cross member in front of the radiator to the right side front brake.

When you source parts you need to know a little about brake fittings. 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. Last time I looked Rovers North carried the correct British fittings.

What I did was go to my local auto parts store & buy pre-made brake lines. These are straight assemblies with flares and American spec fittings on both ends. I would cut the flare off one end, remove and discard the American spec fittings, place a new UK spec fitting at one end, bend the tube to shape using a brake tube bender, cut to length if needed, add the other UK spec fitting and make a new flare at the other end.


A couple other things:

First it is a really good idea to purchase an owners manual. The manual tells you what all those switches and levers do and how to use the levers without killing the gearbox. It also has the factory recommended service list telling you what to check after so many miles and very importantly it gives clear step by step instructions on how to perform a tune up on the vehicle and check whatever needs checking. When you are new to these vehicles the owners manual is well worth the price.

Second, replace all six of the 90 wt oil fluid reservoirs with new gear oil & lube all the grease fittings before you get going.

Third, if the engine has been sitting for a while with coolant it would be a good idea to flush the cooling system.

Fourth, if you have not done it already it is a good idea to do a compression check just to see what condition the engine is in. If the compression is low it is OK as long as all cylinders are within a few lbs pressure of each other. if one or more cylinders are low it is time to buy the factory workshop manual and do a valve job.

And last have a good time resurrecting your barn find. Series Land Rovers are very good for learning the basics.

[TeriAnn]

My plan, when/if I get around to a disk brake conversion, was to do this ^^^...

The only difference being, rather than adding a 3-way for the front circuit, I thought I would make use of the existing 5-way junction and blank off the unused rear port. I'd keep the brake light switch on the 5-way instead of using one on top of the pedal tower.

You are making the system more complicated than it needs to be. It is always a good idea to simplify and make changes look more like the factory did it whenever you change things. Otherwise you end up with a mess that is hard for others to figure out or for you to remember 10 years from now.

Try picking the old wires out of the harness and rerouting them to the back of the brake tower. If you can't move the old wires the circuit is 12V-> brake light switch. Brake light switch to a 4 way electrical connector that has the wires going to the brake lights.

[darbsclt]

You are making the system more complicated than it needs to be...

Gosh!... and I was under the impression that I would be making things more simple!!... something I was sure you could appreciate!

The thought of switching out junctions and hunting through a new(ish) wiring harness to relocate the brake light switch seems over-necessary, especially when perfectly usable bits are already there, wired/plumbed and functioning. Perhaps simply placing a some detailed notes in my GB would be a less intrusive solution.

Furthermore, if I was to sell her later on & the new owner wanted to go back to drums (for whatever reason), the original fittings would already be there. They'd just have to look past the bulkhead/wing cuts.

Am I missing something???

[TeriAnn]

Am I missing something???

Different people have different ideas of what is best and there is more than one way to successfully do things. It is always a good idea to pick the path that works best for you. Best of luck with your project.

[o2batsea]

Gosh!... and I was under the impression that I would be making things more simple!!... something I was sure you could appreciate!

The thought of switching out junctions and hunting through a new(ish) wiring harness to relocate the brake light switch seems over-necessary, especially when perfectly usable bits are already there, wired/plumbed and functioning. Perhaps simply placing a some detailed notes in my GB would be a less intrusive solution.

Furthermore, if I was to sell her later on & the new owner wanted to go back to drums (for whatever reason), the original fittings would already be there. They'd just have to look past the bulkhead/wing cuts.

Am I missing something???

The Girling line fitting nuts are 3/8-24 UNF. Just run a proper size bleed screw into the unused hole on the 4-way fitting, making it a 3 way.