Somebody tell the owners of 03-04 usdm Evos that they aren’t awd and aren’t evos.

Seriously though, I feel like this comes up every year or so. It can all be avoided if people did some searching through all the wonderful resources we have here.

 

https://www.evolutionm.net/forums/ev...everybody.html

 

Those Evos have a Viscous coupling between the front and rear axles that limits the slip between them. Not as fancy as an active differential, but definitely better than an open diff. There are lots of other examples of viscous limited slip differentials out there.

 

You might want to give that a read yourself.

No pump = no clutch lock up. No clutch lock up = wheels will always slip/spin independently.

 

[size=16px]. What is the ACD?[/size]

[size=16px]*NOTE* If you are unfamiliar with how a Limited Slip Differential works, then please look that up first. Howstuffworks.com, answer.com, and even EvolutionM.net have many good descriptions and diagrams available. */NOTE*[/size]

[size=16px]The ACD is a bevel-gear type center differential with a front/rear torque distribution of 50:50. The differential is controlled by an electrically controlled hydraulic multi-plate clutch. For greater dependability, the clutches were made from steel. [/size][size=16px](1)[/size]

 

Thats right, someone give this guy a star!!

 

[size=16px]When the Lancer Evolution VIII model was released in the US in the spring of 2003, the Evo was outfitted without the ACD or AYC found in other markets. Instead, it was outfitted with the Viscous Coupling Unit (VCU) which distributes the torque evenly (50:50) to the front and rear wheels. This VCU was also equipped on the 2004 model year Evo in both the standard and RS models. [/size][size=16px](2)[/size]

[size=16px]1) All of this is over my head. What can I do to not be so stupid?[/size]

[size=16px]- SEARCH! All of the answers I provide in this guide were found searching on EvolutionM.net, SoCalEvo.net, NorCalEvo.net, & LancerRegister.com in a few hours. Digesting it took a bit longer though. If the issue is that you don’t understand the basics or basic terminology, then I would suggest starting at howstuffworks.com or picking up a copy of Car Hacks & Mods for Dummies by David V.

Ok, im done after this. And if this is wrong too, then tickle me pink and call me a moron.
Good night everyone!😃[/size]

 

I don't think this is super productive. If you're of the opinion that the ACD and pump don't offer any advantage to your car, you are welcome to ignore this information. I had intended this to be a heads up to people who also have an 8/9 that the single output pump is being discontinued.

 

Re: EUDM/JDM pumps, my understanding is that 3520A077 is also the pump used on the 8/9 RS in other markets, and I believe it is being discontinued everywhere. The non-single output version will probably be around for a while longer.

This is a good point about the evo X pumps. At least they were made in the last 10 years so hopefully the ACD pumps for them will still be around for a while.

 

The problem that the US cars will have in adapting other pumps is that US cars have a unique pump in the front of the car... Good thing is that all these cars have basically the same proportional valve in the pump so you can mix parts to fix your old pump. If you want to use evo X pump, you can use evo X RS pump, which is ACD only single output pump. Another, maybe better, option is Ralliart pump, which a cheaper car, and also uses single output pump.
As for adapting these to evo 8-9, the wiring harness will have to be modded a bit. and you may want to install it in the trunk, to keep away from dirt and corrosion. Only think I cant remember now, and would need to check is the electric compatibility of the pressure sensor.. IIRC it is different connector but works the same. Otherwise you would need to make an adapter to mount older pressure sensor on the X pump...

 

So do I’ve an evo or lancer? 🫨

 

Revived old thread. I'm dealing with this now on my new to me evo 8. I did a hard pull out of a turn in the rain and the rear did step out, so it is still AWD, but it definitely feels like front wants to break loose first on hard acceleration from a stop. I have until June to try to find a working pump, or I'll probably send my t-case to shep when I send my trans in for a rebuild.