This thread consists of two different questions. Firstly on the question of what was actually the cause of the brake master cylinder problem. Putting on my former production engineer/industrial designer hat I can say you will never know, or at least from formally from MMC. Due to the string of companies involved in the production of the master cylinders, metallurgical suppliers, casting companies, rubber compound and seal manufacturers etc there are a number of avenues where production could have gone wrong. It is most likely that MMC have accepted settlement containing a “gagging” order and would have been advised not to make any further disclosures. It is normal industrial business. Morgan dealers would have been also told not to make statements as to the causes. So basically on TM you may as well drop the question.
Secondly on the matter of the Plus Six brakes the experience with our car is very real. The brakes on ourP6 were disappointing, frightening from Day One. Excessive pedal travel, soft feeling, and more worrying pedal travel that increased and brake fade after a long (100 mile plus) trip. Our car was one of the few that actually experienced failure of the master cylinder seals and subsequent damaging of the brake booster unit in less than 7000 miles. So the problems I had were more than just needing proper brake bleeding.
The car had the master cylinder and booster replaced and a complete service of servos, ABS unit, hydraulic lines and wheel cylinders, however we still had excessive (60mm plus) brake travel, and more telling a brake pedal that could be pumped up to 40mm travel. All this pointed to air in the system and the need for a more sophisticated brake bleeding. Power bleeding that involved pumping fluid into the brake cylinder reservoir, and vacuum bleeding removed all the air from the whole system. Yes the P6 brake system is notoriously difficult to properly bleed, but it can be done with the right equipment. So yes Barry is right. If you are still experiencing excessive brake pedal travel and a soft brake pedal with your upgraded system you are most likely to need proper brake bleeding - difficult but it can and should be done.
Well the car is back on the road and while I have yet to do a really long tour, I can report that the brake pedal travel is now about 40mm, the brakes feel a lot firmer and the brake “bite” is vastly improved. It feels great! Kerry
2019 First Edition Plus Six Moonstone Blue Prev 2017 Plus 4 Auto Ivory 2011 4/4 Grey 1939 4-4 Blue
