rear diff

[craig82]

i was driving back from work when i heard a rumblin sort of sound i thought it was the exhaust thats what it sounded like when all of a sudden at about 60mph BANG CRUNCH and a lot of grindingi was like WHAT the f**k was that, i had to carry on a few hundred yards to some were safe to pull up , i got out and looked under my baby and there was OIL everywere and that horrible stench of gear oil
, i opend up the inspection cover on the diff today and loads of metal and crud came out it is deffinatley FUBARD, i dont no just how much damage is done to anything else yet till we strip it out. im absolutley gutted my pride and joy is off the road.ggggrrrrr
any help or advice i will be truely gratefull

[Nick Mann]

You aren't the first and you won't be the last!

The diff is fundamentally the same as in the Evos. Later Evos (8&9?) have a slightly stronger diff, which also shunts more power around on the AYC. It is not too hard to adapt it to fit, but the fluid fill plugs are not quite in the right place so servicing it is a bit harder. Having said that, the strength and handling improvement could outweigh that.

You can DIY the job with a handfull of basic tools. I'd recommend joining as a full member though, to gain access to the members articles on how to do it.

You aren't that far from Eurospec, who are the best people in the country to look after your car.

[aboo]

If you look for the thread Nev put up not so long ago you will get a few useful tips of that.

[craig82]

You aren't the first and you won't be the last!

The diff is fundamentally the same as in the Evos. Later Evos (8&9?) have a slightly stronger diff, which also shunts more power around on the AYC. It is not too hard to adapt it to fit, but the fluid fill plugs are not quite in the right place so servicing it is a bit harder. Having said that, the strength and handling improvement could outweigh that.

You can DIY the job with a handfull of basic tools. I'd recommend joining as a full member though, to gain access to the members articles on how to do it.

You aren't that far from Eurospec, who are the best people in the country to look after your car.

yeah i think i will join cheers chaps

[VR4WGN]

another AYC Destruction guys???? Non AYC??????? i still havent blown a non AYC yet...

[scott.mohekey]

another AYC Destruction guys???? Non AYC??????? i still havent blown a non AYC yet...

There's quite a few people on here that can say they haven't blown an AYC yet either..

[Turbo_Steve]

AYC is a known weak point on the VR4s Q, justs as it is on the Evos.
Most people will never have a problem, though.

It has to be said that launches or big power seem to be the most likely way of killing it.

[VR4WGN]

i know what your sayn guy but im very fortunate that the nons seem to handle their stuff well.its hard to find an un damaged ayc these days tho..

[TAR]

It has to be said that launches or big power seem to be the most likely way of killing it.

I disagree with this statement!

I agree that big power may cause premature failure, but the number 1 killer of rear diffs is.....Lack of correct maintenance, including use of the wrong oil/atf in the wrong holes.

[Kenneth]

Agree with Tim (in that the #1 cause is the diff being serviced poorly in its lifetime). I have always driven my cars hard and have yet to blow a diff.

Rule #1: full fluid change directly after buying the car

After that, hopefully the one you bought hasn't been too badly looked after... The number of cars out there vs the number of diffs which blow up still is very much in favour of the diffs.

In NZ, VR-4s get wrecked faster than their diffs and gearboxes which is why we have such a good parts market. Unfortunate for the UK members that VR-4s are relatively rare, though I can't recall anyone having significant issues getting replacement 2nd hand diffs and gearboxes (other than manual conversions)... Correct me if I am wrong.

[White Lightning]

Another Berkshire member. Welcome. I am just up the road from you in Bracknell. And good to see you got a VR-4 with the best gearbox

Sorry to hear about the diff. If it makes you feel any better I am most likely going to have to replace mine soon!

[Nick Mann]

I've killed one. It was only serviced with amsoil for three years before it exploded. I am running just under 370 lb/ft.

Sorry, Tim, I'm not intending to argue with you, as I think that you have a valid point - my diff was high mileage with the majority probably not on Amsoil, but the fact is I did maintain mine pretty well prior to it dieing.

[TAR]

Nick, I've experienced your driving so I know exactly how you could break one!!

[Nick Mann]

PMSL!

[craig82]

Another Berkshire member. Welcome. I am just up the road from you in Bracknell. And good to see you got a VR-4 with the best gearbox

Sorry to hear about the diff. If it makes you feel any better I am most likely going to have to replace mine soon!

alright mate im from bracknell but living in sandhurst now

[Kenneth]

Nick, my car was doing the same sort of torque. Difference I guess was that I got mine after it had only done just under 50,000 miles (80,000km)

I have to re-tract some of my agreement though, as I am sure launching does stuff them, especially if you do it with high torque.

Taking apart 2 transfer cases yesterday, I did notice that the bolts weren't as tight in the VR-4 transfer case. It makes me wonder if it is worth while re-torquing the bolts in all drive train components, as this could directly affect the durability of diffs and transfer cases.

[Nick Mann]

I've recently been told that some Evos have had uprated bolts put in their rear diffs. I've no idea which bolts or who or why yet, but I suspect someone thinks it is a way of delaying the inevitable bang on a car with stoopid torque.

I neglected to say in my earlier post, mine died whilst launching.

[Nutter_John]

The uprated bolts on the evo's goes in the front diff , there is an issue withe them snapping

[Kenneth]

One of the accepted reasons for failure is that the Aluminium casings flex which causes the gear contact to go out of specification and cause breakage.

It is also accepted that going from M10 to M12 bolts in the case housing reduces this flex to the point that the diff will survive a fair bit more abuse.

I have read of this being done a fair bit in the transfer cases, but not in the rear diffs. I expect it could work just as well though, and was definitely considering looking into it.

[Turbo_Steve]

Tin does have a point, if your diff hasn't been looked after then it's only a matter of time, so fair comment.

My point still stands, though, that big power or hard launches will, eventually, break the diff: which fits with casing flex.
Hard Launches and big power definitely seems to be something of a recipe for failure.

The worst part about all this is that the damage could be already done and not manifest itself for miles. A little flex can overstress a tooth, putting stress cracks in it that won't manifest themselves as a proper chewed up diff for miles and miles: if ever.