Hi. I bought an evo 9 a couple of months ago. The PO said it had an RS diff on it when he bought it and he seemed like a straight up bloke, family man and all that, and to be honest I did to have enough knowledge on Evo's to question it. I'm no mechanic. Anyway, I done a bit of homework and got under the car today and this is what I found





I'm fairly sure that's the standard diff with the pump removed. I've checked there's oil in it and it drives fine with no dodgy sounds, and still sticks to the road like glue, but what does this all mean? Why would someone remove the pump??

Thanks

 

So what your looking at in the first picture is where the evap canister used to be. The rear diff is a mechanical LSD as far as I know and looks fine if a little dirty.

Your ACD is the center diff with the pump located in front of the left front wheel (on LHD cars anyway).

I don't think 9's came with AYC even in non-USDM parts of the world?

Anyway the only thing I see missing is the charcoal canister from the evap system.

 

One reason people remove the acd is for drag racing where it wouldnt help anyway. Thats in the center not the rear though.

 

I've got the 'gravel, Tarmac, snow' lights on the dash and the 'acd' button, but they don't light up and the button doesn't appear to do anything which I thought was because of the supposed rs diff. I'm clearly just showing how little I know about the differentials on these things, I've just upgraded from a fwd leon cupra r.... Is this anything I should be worried about? Feel free to talk to me like a simpleton, in fact I encourage it lol

 

This is correct. Evap not AYC.. No AYC on Evo 9's.

 

Sell it for an 8 J/K Check out the Evo 9 ACD pump threads. Those pumps suck and like to not work for a bunch of reasons, all outlined by various frustrated owners. Some good tech guys in there though to get through it. GL

 

First thing is first. Evo 9s did come with AYC differentials in other parts of the world.

As for pump, this is for the center differential and not the rear diff, and by what you've described, it seems like you own a mechanical LSD which requires the pump to be removed as stated above.

 

I've heard of some people taking out the bulb in the dash to hide problems. Is that possibly why mine doesn't do anything? Basically are you saying something isn't right and I should look into why the acd button doesn't do anything?

 

The Evo 9 came with AYC and ACD in Europe, if its GSR.

Rather than guess, log onto MLR Lancer Forum, and visit one of the preferred Evo specialist in your area.

Your ACD pump which also works AYC, as in US Evo X...and as in Rest of the World (other than USA) Evo 7/8/9 GSR models and MR models (and RS2 models), but not RS models

If the lights do not change with switching the ACD button, something is wrong.
So check and find out what is going on.

In USA there is limited experience with AYC pumps and ACD/AYC pumps.

MLR Forum is plenty good for that.
And reputable Evo specialists in UK can sort you .

 

I'm not suggesting you have issues. If you don't see a pump anywhere for the front diff, then your diff has been replaced with a mechanical LSD and you can rest your mind.

If there is a pump though, then you'll need to find out what that's all about.

On USDM cars the ACD pump was in the engine compartment, driver side I believe. JDM models had them near the rear of the car.

 

Ok, thanks for the replies. My mechanic mate has got to replace a transfer box seal next week because it's leaking, so while he's getting stuck in I'll get him to find out what'd going ok with the diff too

Thanks

 

That is an AYC diff.

If you have no pump then you have an open rear diff, which isn't quite an RS rear diff. But I can see how someone would think that way.

A previous owner may have removed the pump because it had failed and decided to leave it as an open diff because pumps and related costs are expensive.

 

Would it still have the ACD button if it was ayc diff? And by them open hoses there are 1 or 2 connectors and it did cross my mind that a carbon canister wouldn't have any connections like that??

 

Wow. Lots of folks need to stay out of threads for non-USDM cars, it seems.

Anyhoo, my guess is that, when the PO said "it has an RS diff," he or she was saying that a Cusco RS was put in the OE AYC housing. (A Cusco RS can be run with or without AYC, but if you don't have a pump any more, then an RS is way better than an open rear.) My further guess is that the pump died and the PO didn't want to replace it, so he or she put in an RS.

It still has buttons because - again, another guess - the PO did the minimum work to get the car going again.

edit: my suggestion is take the car to AutoTorque in Aylesbury and see what they can do for you

 

Tbh I have no idea what I mean anymore. When I bought it I was told the ayc had been swapped for an rs diff. Then a friend tells me the housing isn't black which means it's not an rs diff, which I now know is a fair statement. Then you guys say it's acd, which makes sense because I've to an acd button, but the pictures I've taken aren't even of the rear diff?? I honestly have no idea what is going on lol if this is what they call a steep learning curve, I'm back at the bottom again lol