Ayc whats it all about?

[petbeemer]

Ever wondered how Ayc worked and what was inside the rear diff on the latter evo's i have so............
Here it is!
Basically its a bike clutch! well actually 2 that are pressed together via hydraulic oil from a pump and a pressure switch controls how much force is used to apply the pressure to the plates,the other side is just an average open type diff unit!
very similar to LSD but without the use of springs to apply the pressure

[kat]

Nice one Pete

[Jabberwocky]

how come the clutches dont wear out it they are constantly slipping?

[petbeemer]

Originally Posted by Jabberwocky

how come the clutches dont wear out it they are constantly slipping?

who said they don't?

[UKV]

Nice one mate.

I wonder if you could answer a question about the AYC ? My AYC light came on last week on my 5 when we were on our way back from hol. I had the unit checked out - the guy replaced the oil and re-bled the system - The light,while the car was at the garage went out and stayed out after first starting the car. He said to me that it may be a slight fault with the pressure switch - If it happens again he said that he could replace the switch with an aftermarket one as the stock one is part of the AYC which is £1800 to replace!!! :shock: . May it be the switch that was the problem and if it does happen again can it be done as the guy told me?

[Jabberwocky]

Originally Posted by petbeemer

who said they don't?

I have just never known then to go... or is it a complete diff change if it does?

[petbeemer]

Originally Posted by UKV

Nice one mate.

I wonder if you could answer a question about the AYC ? My AYC light came on last week on my 5 when we were on our way back from hol. I had the unit checked out - the guy replaced the oil and re-bled the system - The light,while the car was at the garage went out and stayed out after first starting the car. He said to me that it may be a slight fault with the pressure switch - If it happens again he said that he could replace the switch with an aftermarket one as the stock one is part of the AYC which is £1800 to replace!!! :shock: . May it be the switch that was the problem and if it does happen again can it be done as the guy told me?

Dont quote me on this because it is a complex unit that does very little in my opinion but..........
Changing the fluid will do very little a bit like changing gear oil every 4500k(you dont feel any benifit), if any problems occur i would say its in the pressured side of the system meaning switch/pump which is all there is, so for the light to be flickering/on i would presume its more than likely to be the switch as thats a more 'wearing part' than the pump.

[petbeemer]

Originally Posted by Jabberwocky

I have just never known then to go... or is it a complete diff change if it does?

from what i can work out from stripping a unit(and a little agricultural knowledge) the drop gears which are the 3 small gears slow the clutch basket down so it doesn't rotate the same speed as the rest of the diff unit, plates that big would obviously take some pressure to hold together at higher speeds/torque figures so to decrease torque load they have put in the drop gears to slow the whole lot down, thus if the whole clutch unit is going relativley slow compared to the rest of it you should get thousands of miles before it wears out completly on the clutch side of things,but it is wearing and dependant how its driven i would presume is how long they can last!
What i dont understand is why everyone looks out for RS diffs(rare) when you can just strip out the internals of the AYC and use an LSD instead of the open normal diff,which is what weve found in a unit a m8 bought off ebay the other day!
The other thing is the 'bleeding' of the AYC, what actually are you bleeding? not a lot!
So why the fook do Mitsi charge so much for it?

[Jabberwocky]

I thought the light on the dash board is controlled by the AYC ECU, and that will say on or off and not make it flicker?

I think the whole RS Diff thing is to just say that you have it from an RS to make it sound better than, I got the GSR on and B@stardised it. TBH if I ever felt the need for an LSD I would not go down the RS route.

As for the bleeding, I always accumed it was the Hyrolics (spl) for the clutch control that where being bleed?

[petbeemer]

Originally Posted by Jabberwocky

I thought the light on the dash board is controlled by the AYC ECU, and that will say on or off and not make it flicker?

I think the whole RS Diff thing is to just say that you have it from an RS to make it sound better than, I got the GSR on and B@stardised it. TBH if I ever felt the need for an LSD I would not go down the RS route.

As for the bleeding, I always accumed it was the Hyrolics (spl) for the clutch control that where being bleed?

As far as i can see for bleeding,its only the pipes that need it,the ayc diff has air at the top of it so any air trapped between the plates wouldn't be for very long