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Joji Tokumoto's Remove Brake Booster Documentation:
Overview of the Europa brake hydraulics
Before removing the brake lines from the booster, it would be best to mark and tag the lines to and from the boosters both from the PDWV and to the connections at the “manifold “(the collection of fittings on the top left frame rail) as front brake circuit or rear brake circuit. I’ve also included the federal dual brake system diagram for reference, Pic 1. It has been colorized to make it easier to follow the convoluted mess. Since the replacement master cylinders are usually single bore 0.70” 0r 0.75”, it may not matter if the connections are swapped. However convention should be followed by maintaining the stock configuration.The only exceptions are if using the S2 tandem master cylinder. Stock configuration must be maintained.
Following the diagram, this is the flow path of the front and rear brake circuits from the master cylinder, to the boosters and back to the front and rear brakes. The front circuit has been colored in RED and the rear in Yellow.
The brake lines from the master cylinder are continuous until they terminate at the area I call the “manifold” on the top of the left frame rail where the lines transition to two female tube nuts coupled by a double male connection. At this point determine the lines for front and rear brake circuits. On my TCS the two bottom lines came from my master cylinder. Physically tracing the lines determined that the second line from the bottom was the front circuit and the bottom line was the rear circuit, Pic 2. Both lines continue to the PDWV, Pic 3.
At the PDWV, the lines for the front circuit enter the rear port at the bottom of the PDWV and the rear circuit enters the front port. Both lines exit the respective top ports of the PDWV and connect to the boosters above. The bottom servo serves the front brake circuit and the top servo, the rear brake circuit, Pic 4.. The PDWV maintains the difference in thread size for front and rear brake circuits, ⅜-24” threads for the front port (rear circuit) and 7/16-20” threads for the rear port (front circuit).
The outputs from both servos return to the “manifold” on the left frame rail. The line for the rear brakes connects to a four way junction where the lines split up to supply the rear brake drums and a brake light. The front line connects to a double male coupler where the line continues to the front of the car to supply the front calipers via a three way junction on the front “T“ section of the chassis, Pic 2.
Running the jumpers:
There are a couple of ways of running the bypass jumpers, either keep the PDWV in the system or totally get rid of it. Although I decided to keep mine and the directions are for this method, I’ll also describe how I would run bypass jumpers with the PDWV removed.
In bypassing the boosters, the brake lines exiting top ports of the PDWV to the boosters and the lines exiting the boosters to the “manifold” are disconnected and removed .Measure, cut and bend enough tubing to reach from the PDWV ports to the respective line connections for the front and rear brake lines at the “manifold”. As stated in the intro above, the line from the front port of the PDWV connects to the rear brake four way junction while the rear port connects to the single line connector going to the front of the car, Pics 5,6,7..
The hardware required are:
(1) male tube nut, 3/8-24 with a bubble flare on the PDWV end
(1) male tube nut, 7/16-20” with a bubble flare on the PDWV end
(1) female tube nut, ⅜-24 with a double/inverse flare on the “manifold” end
(1) male tube nut, ⅜-24” with bubble flare on “Manifold” end
Appropriate lengths of 3/16” Cunifer or steel brake tubing
Keeping the PDWV in my view makes for a neater looking engine layout and arguably maintains the brake failure warning light feature. Others however may prefer to bin it for simplicity and fewer complications. I see a couple of ways of doing it this way. First way is to run jumpers from the couplings on the incoming front and rear circuits directly to the outgoing front and rear circuits on the “manifold”, Pic 8. If using jumpers at the “manifold”, the front brake circuit jumper will require two ⅜-24” female tube nuts. The 3/16” tube on both ends will need to have a double/inverse flare to mate with the male couplers in the existing line. The rear brake circuit jumper will require one ⅜-24” female tube nut with a double/inverse flare on the existing male coupler end and a ⅜-24” male tube nut with a bubble flare on the four way junction end. I would recommend making the jumpers long enough to allow a gentle bend on the tubing without kinking.
The second way is to connect the fittings at the PDWV with unions, Pic 9,10. This may be the easier option if removing the PDWV. The original fittings and lines use bubble flares at the PDWV. Ensure that the unions also use bubble flares. The rear brake lines uses the ⅜-24” fittings. The front brake lines unfortunately use the 7/16-20” fittings at the PDWV. Finding unions using 7/16-20” fittings for 3/16” lines may be difficult. If unable to locate the correct union, the only option may be to convert the front brake line circuit to and from the union to ⅜-24” fittings with new brake lines.
Final thoughts. I traced the lines from the master cylinder back to the rear "manifold", the PDWV, boosters and back to the "manifold" on my TCS and I'm fairly confident that I did not cross lines but who is to say that I didn't make a mistake. I really urge anyone doing this modification to trace the lines back personally to ensure that the info on this write up is accurate.
Please take extreme care when modifying the brake lines. When forming flares, use the proper tools to ensure that the cuts are straight and square and that the ends are deburred properly. Doing that and using a good quality flare tool should allow you to make acceptable flares. Also please make sure that you are using the proper flare for the proper application, bubble vs double/inverse For fittings and cunifer brake lines RD Enterprises and Fedhill USA are good places to check. For flaring tools, a good quality tool and an “on car” flaring tool sold by several vendors is the only way to go. I used the one sold by Eastwood although Amazon has several similar ones.
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