There is more than salt out there. Many states are using the other chlorides (mag & calcium) as di-icers & dust control. Those chlorides are more corrosive than salt (sodium chloride) in certain mixes

Also, IMHO, that YT rebuild vid looked somewhat sketchy & would not consider it a re-build but more of a band-aid fix

 

yeah, salt / chemcals.. I meant that just water will not do it..

as for the yt vid.. I'd like to know why it is sketchy?

.... as it did start the whole rebuild industry and made it possible for a lot of people to start doing it... as well as providing first real overhaul sets out there.. we did save a LOT of pumps that would have otherwise been scrapped..

what we have found while testing the fix in the field is that with propper sealing the pumps are pretty much bullet proof afterwards.. (as long as the valves are working..)

 

I have the three lights, sucks. Either fix will cost $$$. I plan on the rebuild since its a little cheaper, and also seems to have a better chance of longevity once it is fixed, with the added protection.

 

I don't have ACD and have never driven a car that does. Still, I don't understand how having ACD improves cornering since essentially what the ACD does is unlock for cornering.

 

thing is.. a car with an open central diff does corner better... having a fully locked central diff tends to promote understeer... but that is not the point..

passive transfer box has a viscous unit and that one has a certain preload and depends on axle speed difference to provide some "lock"..

ACD on the other hand will react momentarily to steering input, throttle, brakes, G sensors, etc...

We did some logging on ACD and AYC and it is fascinating how quickly it will react to driver input..

also, it can be tailor mapped to suit your driving style.. for example I did not like the somewhat instable cornering attitude when you are on full or close to full opposite lock (this is when we hoon around on snow covered roads) so with a few tweeks we changed the car, and now it is much more predictable on slippery stuff...

there is just no question ACD is better, it is used on all gn N cars after all..

 

some people do relocate the pump inside the car

 

yes,

I did run mine for 2 years in original location (behind rear wheel, since car is EUDM) to test the refurb work... now it is going in the trunk...

 

I'll share some good info I've found on the system function:

"How does the Active Centre Differential system work?

Mitsubishi ACD - “active centre differential system” ACD is the new major technical feature that distinguishes the previous Evo 4-6 models from the new Evo 7 ACD is an extension of the technology used in for the anti yaw control systems (AYC) employed in various previous Mitsubishi models in the rear axle position.

The ACD system comprises an electric motor, driving an oil pump which pressures an oil reservoir to a peak 16-bar pressure. This reserve of “SYSTEM PRESSURE” is fed to the piston of the ACD plate pack via a modulation (proportion) valve. The modulation valve is software controlled by the “ACD ECU (electronic control unit).

The control inputs for the ACD electronic control unit are
4 wheel speeds
G force both lateral and longitudinal
Throttle position – a variable value
Braking state - on or off
Steering angle – neutral position (straight ahead) and off centre position provided by 3 optical inputs generated by rotation of the steering wheel.
Handbrake state – on or off
System pressure – Hydraulic pressure state
Mode switch state – to select Gravel, Snow or Asphalt software strategy (maps)

We fitted a Motorsport logging system to the E7 RS test car during our 90 mile shakedown run of the new car (in the well knownYorkshire Forest complex) prior to the Network Q Rally GB. The test data from the ACD system has provided a full understanding of how the system functions and it’s efficiency.

The “Gravel” and “Snow” software strategies are similar; Gravel has the highest ultimate locking value of the two. In “Asphalt” mode a unique software strategy is employed

The system is technically far superior to the preceding Evo models VC centre differential systems. The centre differential performing well and able to limit front to rear axle “slip” on full throttle to a mean of around 0.6% on a slippery gravel surface. To put this in perspective, a good condition VC unit on a Evo 4,5 or 6 would struggle to be better than 30% aggregate slip value, which is traction going out of the window.
Pressure can be introduced and lost within the ACD system at speeds surprisingly close to WRC car standards, which has allowed Mitsubishi engineers to use a complex and sophisticated software control strategy."


As for rebuilding a failed pump - I tried that with mine, but the pump was so corroded I couldn't even get it disassembled to rebuild it. It looked like it came off the Titanic.

In my opinion, it's not only the salt, it's the moisture. I'm pretty good about rinsing all the salt off my car in the winter, and I remember I used to spray down the pump through the grille on my car, thinking I was helping prolong it's life.

In retrospect, I think I was doing more harm than good, as the pump is sealed so poorly I think I was just getting more water into the pump, leading to more galvanic corrosion.

So I think the moral of the story is to try to keep the pump as dry as possible, and if replacing, add grease / RTV / etc. to help keep water out.

 

That's what I thought, ACD is a traction device not a cornering device and this only becomes important on loose surfaces.

 

It's a cornering device to. When my ACD wasn't working because of a bad wheel speed sensor, my car pushed so bad it was horrendous.


Tuning the ACD, like the ER acd tune for example, greatly sharpens turn in response. And helps the car drive out of corners more like a RWD car with an abundance of grip. It greatly reduces understeer and really helps the car rotate on throttle.

 

Agreed

 

exactly.. after all, in a corner you always have difference betweeen front and rear axle speeds.. so by introducing controlled lock the ACD will influence the behaviour of the car regardless of the surface..

what was interesting to measure was that the ACD was quickest to react to the speed of steering input.. and not just the G forces... which also indicates that the ACD is essentially an important part of the whole dynamics of direction change..

 

Agreed. A flashed ACD makes a huge difference. I've had mine flashed since 2013ish.

I moved mine to the trunk years back when I had the new trans installed. It gets the pump out of the weather, out of the crash zone and moves some weight to the rear .

 

My pump failed twice already. Once at 50k and later at 70k. Car wasn't driven very often, unit coroded

 

yup, I've had mine flashed for at least that long as well. didn't get the response I was looking for from it until ER's ACD ECU though.

re: 2 corroded pumps - that is awful. is it a visible corrosion? I think if mine ever did corrode, I would relocate it to the trunk as well.