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408 and later brake servo/booster help needed.

My 408 has been modified to split the braking circuit in two for safety. There's a dual master cylinder that activates two separate servos/boosters. One servo powers the front calipers and the other powers the rear. The servos are rated at 1.9:1 boost. I am happy with the braking distances but the pedal effort is very high. I believe the 408 and 409 had single circuit/one booster setups but the 410 introduced split circuits with two boosters.

Does anybody know, or have experience, of what boost ratio should be used for each of the two circuits? Should I be looking at 3x or 4x boot? Should the front be boosted more than the rear? The current servos are Moss Motors part no. 117-312. They are by Powertune whose part number is RLE72696 (made in China!) If I need to replace them, what exact product numbers should I be looking at buying, please? LR18230 available from JustJags have been suggested by a fellow owner.

Thanks for any help.
David Womby

For the record, I fitted a 4.25x boost brake servo (Lockheed LR18230) to the front brakes and left the 1.9x servo on the rear brakes. After days of fiddling to stop a fluid leak at the caliper, I finally put it back on the road today and took a VERY slow drive down the street to test the brakes still worked at all! It seemed ok so I took it for 30 minutes on the back roads.

The new servo for the front brakes gives over twice the boost the old one did and it really makes a huge difference. The pedal effort to stop the car is now similar to our modern Mazda and the stopping power is impressive for a car of this vintage and weight.. I'm really glad I made that change.