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AYC Fluid change (cure those donkey noises)

49152 Views 351 Replies 133 Participants Last post by  jhfozzy
Thought this may help some people who are having AYC sqwarking and grinding noses to try and cure it themselves.

This is a bit of a simple guide for people who are not familiar with the AYC clutch bath drain and fill procedure. Also I have covered the rear diff drain in this guide too.

I have just bought an Evo 5 with the classic sqwarking and grinding from the rear diff. It was quite a bad case and would even make a fair racket at slow speed turning. If you've got this problem then have a read.

Right, first off some tools you'll need..

17mm offset ring spanner
24mm socket (on wrench obviously)
oil drain tray (or container to catch oil)
refill bottle (old toilet duck bottle works a treat)
clear hose (to attatch to refilling bottle)

Also you'll need a litre (it takes less) of AYC fluid or Mitsubishi SP-III, if the car is making nasty noises I'd get a few lires of AYC fluid as you may well need to do more than one change to get it clean. I like to drain the AYC, refill with half a litre of new and drain again just to pull that dirt out.

If you're going to change the rear diff oil too you'll need a litre of regular gear oil 75w90.

Here we go then :naughty:

First, jack the car up at the back and secure on axle stands and chock wheels etc so it's nice and safe.

Get under the car and have a look at the rear diff area to get yourself familiar with the various drain and fill holes.

Here's what you'll see.

Note that the rear diff oil drain and fill IS NOT part of the AYC fluid system, it's regular gear oil.

Again another shot, note position of AYC fill plug.. it's at the back of the diff at the top and a bit fiddly to get to, not impossible though but just get your hand up there and work out how you're going to refit the plug when the time comes.

This pic was taken looking directly up at the diff.

I always like to remove the AYC fill plug before I do the drain (just incase) Please make sure you use a decent offset ring spanner (as picture) as they can be quite tight and risking destroying it with an open ended spanner is not worth it.

Once you've succesfully removed the fill plug then remove the AYC drain plug and the AYC clutch bath fluid will come out.

While I was under there I decided to put some fresh gear oil in the diff, this is not AYC related but the diff part, seperate fluid from AYC.. normal 75w90 gear oil.

You can see the refill hole

Once you've successfully drained the AYC fluid then you're ready to refill with new. I use a toilet duck bottle with a length of clear hose for this. You need to slip the hose into the fill hole at the top and squeeze away until the AYC fluid reaches the level of the fill hole (some will start to seep out the fill hole when full)

Here you can see my bottle :D

Once refilled then it's just a case of refitting fill plugs and you're good to go. As a matter of normal servicing of the AYC fluid you will only need to do a simple drain and refill


If you have noises from the rear diff I'd advise after draining to put the drain plug back and fill with half a litre of AYC fluid again then drain it again just to try and clean it out a bit more. Also if you do this and still have a slight noise after then I'd go for another change again in a week or so. From my experience it doesn't take much for the AYC clutch part to become noisey as far as dirty fluid goes! As you can see it's nice and simple, so no excuses.

Obviously the rear diff oil is a simple refill when drained and a lot easier to get to the refill hole.
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I'm pretty spanner averse, and I think even I could follow that. Well done mate :)

Love the action shots of the oil draining :D
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