I know there has been a lot of discussion on this topic on the Lancer Register with the UK spec EVO 7, however I have a US Spec EVO 9 MR. I only use it for track days and aggressive street driving. My 9 has minor suspension mods (works adj. rear swaybar) and no powertrain modifications at this time.

The next modification I'm considering is the Ralliart ACD ECU in hopes of shifting more power to the rear wheels to better balance the car under acceleration. I still get quite a bit of understeer in the Tarmac mode on dry tarmac.


Part-Box.com in the UK lists the part numbers as

RA580728K1 (Tarmac)
RA580728K2 (Gravel)

RalliSpec.com in the US lists the part numbers as

RMR-0728A (Tarmac)
RMR-0728B (Gravel)

Any experiences or suggestions?

 

The ACD is basically an open center diff with an electronically controlled hydraulic limited-slip clutch pack in it. It always sends power 50/50, and is an inherent limitation of the system.

Definitely *don't* get the "Gravel" ACD ECU, you'll end up with 3 gravel/snow modes for your ACD, and you won't be happy. Plus it locks the center diff the most of any of the ACD ECU's, so you could expect a reduced lifespan of the center diff running that ECU on paved surfaces.

 

It doesnt work with the US Spec Evos. The main ecu is different and i believe its made for the AYC models which we dont have.

 

We will soon be offering an ACD controller for the US spec EVO 8 and 9. We will have more information after this weeks PRI show in Orlando.

 

Check out this site:

http://www.btrprep.com/evo_7.htm

It seems while distribution is always 50/50, there are ways to improve the response time of the ACD (possibly by keeping higher pressure), which will improve the handling. However, component life and durability are sacrificed.

I don't know if it would be worth it or not?

 

Can you give us a brief description of the product and how it works?

 

Here are some additional details for the Ralliart ACD ECUs for those interested. I received the information from the website listed in my last post:

It can be used with US spec 8s and 9s.

The difference between the OEM ACD ECU and the Ralliart ACD ECU is response time. The Ralliart ACD ECUs activate the pump more, causing the diff to maintain higher pressure, and thus has more aggressive reaction times to inputs.

Both Ralliart ACD ECUs are for Tarmac, Gravel, and Snow despite their designations. The OEM ACD ECU is the least aggressive, the A is nice compromise for street and track, and the B (disregard the gravel designation) is for full on rally or competition use. The B will substantially decrease the life of the center diff components if used in a daily driver.

The only place I have been able to find them in the US is rallyspec.com

RMR-0728A (Asphalt)
RMR-0728B (Gravel)


The website recommends replacing the ACD ECU as one of the first modifications one should make to improve the overall handling of the EVO. They don't sell the parts - they just build rally cars.

 

You should check out the garage hrs Japan acd. Not sure if its compatible, but it doesn' hurt to check.

 

do think it will match perfect..

 

Sweet! I never knew about the Ralliart ACD. Keep us up to date on what you find, maybe a groupbuy could be made to lower the price?

 

nice

 

has anyone seen an improvement in handling in roadrace applications with the upgraded Ralliart ACD controller?

 

Will it work on an Evo 7 with AYC i have the three lights on and i dont know what to do with it....?

 

Want less understeer? Get a good coilver setup and have it properly tuned.

 

Your ACD unit is shot and needs to be fixed/replaced.

+1. After all that's been said and done, GSC center diff!