FAQ Delco Moraine III ABS
Keep reservoir closed when applying the brakes! (otherwise brake fluid will spray around).
1/Depressurize the accumulator (=contact off +push pedal 30x), wait until the foam in reservoir clears up. Pressurize (=contact on, until pump switch off) and depressurize accumulator once more. Only little foam should appear. Wait until the foam in reservoir clears up and pressurize. (This part is not outlined in the Lotus manual, which explains why is it hard to bleed correctly: by not doing this, the foam gets back in the powermaster and brakelines...). Leave contact on.
2/First bleed the fronts in the standard way, first left, then right. Repeat if not ok. Sometimes they are hard to bleed: open the nipple on the caliper, connect hose and apply suction.
3/The rears: contact on, connect hose to nipple of left rear. Open nipple, press pedal, brake fluid will flow. Continue until the fluid is free of bubbles. Close nipple, then do the same on the right side. Pay attention to keep the reservoir at the appropriate level!
4/Switch contact off, apply brakes, switch contact on: the abs valves will be triggered. Do this 3x.
Your brakes are fully bled. Keep it safe.
An accumulator has a rubber bladder or diaphragm, which is slightly permeable to N2 (dried N2 is the gas utilized). It "leaks" N2 in the brake fluid in the accumulator, that is why the accumulators losses its charge, and has to be replaced after ca 10 years. This permeability increases with temperature and pressure. After pushing the brake pedal twice or more, the mixture of N2 and brake fluid will appear in the reservoir as foam. This has no negative influence on the brake fluid: the dried N2 contains no moisture, and so will not shorten the lifetime of the brake fluid. On the contrary, the escaped N2 will remain above the fluid in the reservoir, preventing air (with moisture) entering.
When the accumulator is depressurized, pressure is lower, so permeability is less, and the lifetime of the accumulator is extended. According manufacturer's information, leakage is 10x lower. So, when parking for an extended period and if you want to extent the lifetime of the accumulator, it is advised to depressurize the accumulator.
Although the N2 has no negative impact on the brake fluid itself, it compromises braking considerably: In some systems, the N2 accumulates in the system. When the spool valve opens to release the 160 bar brake fluid, it first has to compress the accumulated N2. Only after 1-4 s, pressure will build up in the system, and the brake assist and the rear brakes(!!) will start functioning. The brake assist also feeds the feedback system in the brake pedal... the pedal pushes back...
The accumulated N2 in the system disturbs the normal ABS functioning completely! In case of braking, brake pressure builds up only after 1-4s. In that scaring time (because of having only ca 60% of the brake power and no assistance), most people are pushing the pedal as hard as they can, and then suddenly, the assistance kicks in: the fronts and the rears block, the wheels slip, and the abs releases the build up pressure... losing assistance and the rear brakes. Again it takes 1-4 s to build up pressure, and again the abs releases the pressure. That is why disconnecting the abs valves gives a "better" braking (but still is poor, and not comparable to a fully working system).
Most probably because the accumulator has lost a part of its charge and replacement is imminent . Further events which proves this: 1/It is not blinking every time, sometimes things seem to be ok. 2/In case of a fast, hard braking (also at standstill, contact on, handbrake off), the handbrake/brakefluid indicator flashes on for a short time (which warns for a too low pressure in the accumulator). 1/ and 2/ will become more prominent as the accumulator degrades further.
Something in the abs system is broken, the ABS is shut down, but braking is still ok. It can be anything, a loose wire, a bad connector, broken wheelsensor, the switch on the brake pedal is broken (or dislocated - since it is not really well protected, accidental touch with feed is possible), broken ABS valve, brake controller failure,... Although seldom further damage will be caused, an early diagnosis is highly recommended.
This indicator lights up in 3 cases: 1/ handbrake on, 2/ brake fluid level is low, and 3/ too low pressure in the accumulator. Ref 3/: in case the accumulator has lost its charge, and basically lost his function as accumulator, pressure will drop immediately and deep, when the brakes are pushed. This means the accumulator needs to be replaced. In case this indicator lights up continuously, you have no brakes at all (because of loss of brake fluid) or you have no brake assistance and rear brakes. Probably the pump does not work anymore, or the fuse to it is blown, or the pressure switch/relay fails.
Yes, but they are very expensive, and do not fit in the available place. We spend much time to find, unfortunately...
The whole system is a nice piece of engineering, and was its time far ahead. That is the reason why Lotus and many other well known brands used it in the upper segment. It is a reliable principle, also used in industry (hence our experience) and some other vehicles, but is somewhat more complicated than the standard braking systems. (People referring to it as a "bad" system, just do not understand the working principles). It is just a matter of evacuating the N2 and preventing it from building up (this just happens in some systems), and that -together with other improvements resulting in a much lower pedalforce- is what has been fixed.
Your question is important to us: it may be about things we did not experienced yet, so please ask us.
The brakes of my S4 1994 felt like wood, the pedal was pushing back...and many said this was normal...? But Lotus and other well known brands, would not choose a bad system for their high end cars. The search for information started. But results were poor: there is a huge lack of know how concerning this system.
When the going gets though, the tough gets going... so the own research started. After lots of time, and many tests, about every part and aspect of the braking system, things were sorted out.
End of 2022, after 2 prototypes, the final design to fix things was ready, and after a long search for companies who were able and willing to make the (narrow tolerances) replacement parts (and additive), the first working prototype, with complete satisfaction, was fully functional in July 2023. The system is now performing excellent and reliable.