Diff's...... Tip owners look away now

[Gowf]

Right, as i can't be arsed raking through the reels of info on dif bits and bobs im looking for some definitive answers.

Firstly, has anyone fitted any mechanical diff's to their car? Im looking at changing the rear for just now, but unsure what to go for. I know you can get cusco or Kaaz, for the evo4 gsr's and the RS's. but do we definately have the same rear diff? Does anyone have the part number? Also, does anyone know how you would install one to the original casings? Would it have to be a rs casing (ie no ayc)?

The same also goes for the front and centre viscous. Are they both situated in the transfer box? If so can you change them both in the transfer box, or do you instal the front one in the gearbox, remove the one from the tx box and replace the VC?

Not sure if anyone will be able to answer the specifics, but can we clarify exactly what boxes we have? Is it identical to the evo 4 apart from the bell housing?

Sorry for all the questions, but as it looks like im about to head into the world of major investment yet again, i need to get it right first time!

[Kenneth]

Front diff and viscous coupler are both in the transfer case, centre diff is in the gearbox.

That is fact, if anyone tells you different steer clear.

My understanding is that the EVOs usually break the spider gears in the front diff due to wheel hop on launches.
I haven't researched centre diffs a huge amount, but I haven't heard of the centre diff causing any issues.

[Kenneth]

Oh, and while I am thinking about it...

If you have the transfer case out and are putting in a stronger diff (or anything really) you might want to shore up another potential weakness.

Apparently Evos blow the transfer case due to the bolts not holding it together well enough and allowing movement of internal components, which then results in damage.
The solution is to re-drill and tap the holes and use bigger bolts. IIRC this makes quite a significant difference to the durability of the transfer case.

[Gowf]

Yeah i was just reading that the changing the centre and the front means you can do away with the vc. may have to do it if i keep braking the vc. This is why i need to know exactly what we have in the boxes.

But of more concern is the rear diff at the moment, and how the diff is fitted in that.

[Kenneth]

Short of having done the conversion myself, I believe the diff can be placed in the AYC housing.
Put it this way, if it were me I would go for it, but giving advice to another without being 100% sure just doesn't work for me.

Of course the benefit of using a RS housing is that you reduce the weight some. Down side is you would have to have different length half shafts.

I am not sure what you want the car for, but personally I would go with a helical (Torsen) LSD over plate.
In saying that, it seems quaife do a LSD called a wavetrac which is essentially both. It is a helical in operation, but has a binding disc which gives it positive lock up like a plate, should things get out of hand (or you lose 100% traction with one wheel)

[Adam.Findlay]

Hmm my AYC blew up and from all the research I have done it I have come to the conclusion that the gears are not the weakness its the fact that the casing is made from a alloy which is weaker then the cast iron casing of VR4 type V open diffs and evo RS VC LSD'S, this weakness in the AYC casing caused the casing to twist under heavy load (launches, increased horsepower) which means the pinion moves away from the crown wheel causing more torque to be exterted on the base of the gear teeth (Torque=force*distance. Increasing the distance for a given force increases the torque at a point). Having said this it may seem a bit off topic but my point is dont use a AYC casing for any LSD rebuild.
Furthermore changing the rear diff to a VR4 Type V open diff is easy enough (and Gwof I am Sure you are capable having seen your work on the intercooler thread).

Now we both know that ayc from evo and VR4 are the same right?
they have 3 bolts on either side of the pinion part that bolt to flanges which connect to the subframe, and two subframe bolts at the back as shown in the link below.
http://www.lancerregister.com/attach...1&d=1159037961
The Vr4 type V diff has the cast iron casing with the exact same bolt patern as an AYC diff so all you have to do is change the half shafts to different lengths and bolt the new diff up .
I beleive it to be the same for a evo rs rear diff (where some people say the evo rs subframe must be swapped in to fit the rs diff), BUT the wings on the rs diff that use the 3 bolts on either side of the front of the diff, ARE different in a evo compared to a vr4, this is because evo's have different subframe mounts. so just use the vr4 wing mounts and you are away laughing.
Here is a evo rs lsd for comparison sake
http://zevo.se/temp/RS_Parts.jpg
But saying that I dont know if the rs diff has the rear two subframe bolt holes like the VR4 Type V diff has.

One last thing I know you can get LSD packs for the evo rs diffs to replace the VC but am unsure if these kits will fit the type V diff, I think they will fit both evo RS diff and VR4 Type V diff but am not sure as I have never had the two diffs apart to compare.
Hope that helps?

[Gowf]

Well... As just said the RS diff is heavier due to the casing than a gsr diff apopting a mechanical set up. They dont have issues that i have heard of through the rally world. Now, changing the rear diff is not what i was on about, as bolting a diff on isnt exactly difficult ( i think ive done a fair bit more than bolt intercoolers on in the past.) butwhat i need to know is how to install in the casing. Are they pressed in? or can the assembly be easily placed in without the need for pressing new bearings on etc.

Ken, Its going down the strip in some savage fashion, so a plate is really what i am after. I know what your saying though, as the helical's are a lot more friendly and pretty much maintainance free.

[Gowf]

Just spoke to coordsport. Can get a cusco rear ayc replacement for just over £1k. They will do me a deal on them if i buy all 3 diffs. If only i had more than 20p left! Looks like i may have to put a standard diff on and see how long it lasts, place your bets now!

[elnevio]

Just spoke to coordsport. Can get a cusco rear ayc replacement for just over £1k. They will do me a deal on them if i buy all 3 diffs. If only i had more than 20p left! Looks like i may have to put a standard diff on and see how long it lasts, place your bets now!

I think the diff will look at the car, and just break out of fright in your hands before you even fit it!

[Gowf]

Its odd that you say that, When i arrived at my car's resting place last night it did let out a sigh, as though it was thinking, not again

[Louis]

Roger Rally, puts cusco etc diffs in VR4 casings, (removing all ayc bits etc) someone on here has one. (£1k)

The evo centre will shear the bolts when pushed, you can replace these with higher tensile steel bolts (of the same size), available on the MLR forum.

S-AYC is a totally different internal set up and much stronger, (looks nore like an LSD when removed)

Evo RS is cast iron and very durable, but, very expensive second hand bout £2k.

A russian guy has fitted a 6 speed evo box, by drilling a couple of holes in the bell housing, and is mates to the V6 VR4 block.

[Gowf]

The plan is eventualy to have a dog box in there, with plate lsd's all round. Will make it oversteery as hell, but awsome in a straight line. At the end of the day, sideways is the new forwards anyway

[miller]

sideways is the new forwards anyway

Style, as always Gowf!!!! love it!!


Rubbing is racing......

[Gowf]

well you know, for those 13s or more... Im free

[White Lightning]

If you are going to just fit another standard diff for now, does it not make sense to fit one from a Type V if they are stronger?

[Gowf]

They are open dif's though, so not going to help with traction issues

[psbarham]

get a type 'V' one and weld it you pussy

[Kenneth]

get a type 'V' one and weld it you pussy

Agreed! If straight line or sideways is your motto, this is as good an idea as any and the cheapest by far!

[psbarham]

Agreed! If straight line or sideways is your motto, this is as good an idea as any and the cheapest by far!

yup, it works perfectly on the rear diff of our pug 205 (yes rear diff )

[Nutter_John]

And how many type V diffs are there for sale in the uk at this point in time ?