Rear Diff has gone bye bye!!! New rear diff required (I think)

[Ghost_2008]

Hi Guys,

Finished work this evening got in the car and pulled from a layby into a fairly large gap in traffic only for a fairly loud bang followed by a series of "bumps".... stopped and hazards on!!!! Wasnt at this point surprized, I noticed a hum from the rear of the car, I thought it was exhaust related, I thought wrong..... so I put the car in nuetral and allowed the car to roll back into the layby...... the bumps continued but were a lot less severe in neutral or at least seemed to be than in reverse......

Jacked the car up to find the rear diff fluid dropping all over the road.... further in vestigation seemed to show a crack in the diff casing......

IMAG1009.jpg

In the above image it seems to run in the left hand section of the diff casing from the bolt.......

I'm assuming that I need to replace the unit alone..... is this the case, is it likely that the drive/prop shafts are damaged?

I looked at a few threads on here and there seems to be a few options available.....

I currently have/had the AYC type S diff..... I could replace with, type S AYC diff (like for like), type V non-AYC, STR non-AYC, SAYC from an EVO 8, AYC diff from an EVO 4-8, type v or STR diff with evo internals.......

Now I was under the impression that the AYC diff was the better handling, but evidently it doesnt handle the use/abuse...... essentially I want the car back on the road, handling as well as it did if not better.......

I cant afford for the car to be off the road for long as it's my daily driver... so ideally whats floating around here or in peoples garages...... anything considered and any advice will be appreciated........

[aboo]

Drive shaft should be fine. I know Nick Mann has a couple of standard VR4 diffs cause he was going to sort me out with one when I thought mine had gone the other week. Drop him a pm.

[Ghost_2008]

Cheers Aboo.... I'll drop him a pm and see whats what..... thanks for the heads up......

[Nick Mann]

Your options above are good I think. For information, I think general opinion puts the stock AYC diff as the weakest on that list. (Not many stock VR4's destroy their rear diffs though, so it isn't a true weak link for the majority of cars out there.) SAYC is stronger due to fewer larger teeth on the crown and pinion and also moves more torque around, which makes it feel more like a rear wheel drive car. Type V or STR diffs are open diffs so handle worse, but I understand that the diff is in a steel casing which is less prone to flex - thus stronger that AYC. Evo internals in afore mentioned steels cased diffs are usually limited slip, which should give good handling and strength, but is without doubt the more costly option.

Choices, eh?

Hope you get it fixed soon.

[Gly]

LSD conversion has cost me not much more than a stock replacement ayc has....
(ayc are around $4-500 + fluids)
my lsd conversion cost me $550 inc new shaft seals, fill and drain bolts, paint for a spruce up and fluid

sayc here costs 2-3x as much as ayc

[Ghost_2008]

Ideally I would have a fully adjustable set up, a cusco jobbie, unfortunately I simply do not have the funds or time..... I have however managed to locate two ayc diff's and should be able to get one of them to Eurospec by Wednesday, car should be with them by Tuesday and hopfully sorted by the end of the week....... fingers crossed......

Hey carston, I saw the thread your started about the 4th diff in 4 years..... mine seemed to crack in the exact same place, on previous diffs was th damage similar?

The end result looks excellent by the way, how is it to drive?

[Gly]

yeh pretty much the same,

the first only blew the pinion gear,
2nd and 3rd are pretty much the same, (2nd was so bad the diff locked up and i got stuck in the middle of a busy main road)....

lsd is fun misses isnt impressed with the round-about skids LOL,

you all sorted now?

[Benja]

Hi ghost 2008, can you tell me what you paid for your diff and where to look for one. Mine went last friday resulting in 2 hours stood at the side of the cold wet motorway! I have a pfl with Ayc, do you know if pfl and fl diffs are the same. Many thanks.
Ben

[Gly]

the vr4 ayc diffs are all the same, auto or manual, pre or post facelift, does not matter

[Nick Mann]

Hi ghost 2008, can you tell me what you paid for your diff and where to look for one. Mine went last friday resulting in 2 hours stood at the side of the cold wet motorway! I have a pfl with Ayc, do you know if pfl and fl diffs are the same. Many thanks.
Ben

Bummer, Ben. You have a PM.

Carsten is right, they are all the same. The only difference I have ever found is that they changed the gear oil fill bolt and the clutch pack drain bolt to match the rest of the car with the facelift. I have put facelift diffs in prefacelift cars and vice-versa without a problem.

[amsoil]

Just make sure the replacement diffs, get the best diff oil to give the best chance to what appears to be a problem area.
There are only 2 worthy contenders here Amsoil SVG and Castrol SAFX, no others, dont care what it says on the tin there are no others, Dont care if your mechanic has used x y or z for centuries without problems THERE ARE NO OTHERS, Promise you.
F1 teams visit us pay full list and require 'no invoices' when sponsored by other oil companies, for a reason!

[Ghost_2008]

Well the car was road worth before last weekend thanks to the hard working crew at eurospec and nick Mann who supplied the diff...... he has another if required......

Unfortunately I couldn't get to guilford until Tuesday, so a small road trip with my mate later we arrived at eurospec and we put the car on the dyno..... very pleased she put a very healthy 285bhp at the crank........

It's also an eye opener having nearly two weeks out of the vr4..... its awesome to have it back....

I'll post up the graphs when I get chance.....

Big thanks to everyone .....

[Nick Mann]

Glad you are sorted, Adam!

[aboo]

Well the car was road worth before last weekend thanks to the hard working crew at eurospec and nick Mann who supplied the diff...... he has another if required......

Unfortunately I couldn't get to guilford until Tuesday, so a small road trip with my mate later we arrived at eurospec and we put the car on the dyno..... very pleased she put a very healthy 285bhp at the crank........

It's also an eye opener having nearly two weeks out of the vr4..... its awesome to have it back....

I'll post up the graphs when I get chance.....

Big thanks to everyone .....

Glad the Mann could sort you out. What was your ATW power?

[Benja]

Thanks for the advice everyone, much appreciated. Nick Mann, I will pm you monday when I've had a chat with my mechanic, your old diff sounds just the job!
Once again many thanks everyone.
Ben

[Ghost_2008]

Glad the Mann could sort you out. What was your ATW power?

ATW power was 205bhp give or take.....if it was a manual the cranck figure would have been about 265bhp, but being an auto it soaks up that bit more..... the torque at about 2200 rpm was over 400 which I was really impressed with..........

[aboo]

Wouldn't the 400 torque at 2200 rpm not be the torque converter loading up though Adam? Nice figures though

[jayp]

At that rpm it would be, I got roughly 395 at Eurospec last year, it's why autos seem so much mor brutal off line in my experience.
I'll Never forget when I gave a biker friend a lift in my auto and made feel physically sick when I floored it from a standing start!
The tongue curve for autos starts after the peak and trough of the tc on a dyno print as far as I'm aware

Sent from my HTC Desire S using Tapatalk 2

[Scanny]

that looks like the same place that my diff cracked and i am now waiting for a txt to collect a non AYC diff almost 5 weeks later. whether i stick with it or seek something in the future depends on opinions. i think going for strength rather than ability is the way to go judging by the comments on this thread. ok, higher price but having my car off the road is costing me £100 per week on a hire car so spending a bit more to not have the same problem may well be worth the investment

[amsoil]

It may well be that there is absolutely nothing wrong with the strength and design of any of the variants of diffs here. The teeth on the CWP actually flex as pressure is applied to them during driving. The flex is absolutely minute and happens near the root of the teeth. Over time the flexing eventually leads to micro cracking on the surface again near the root. This cracking leads to material being lost near the root and as more material is lost as the cracks deepen and join up the teeth are weakened and flex more. Finally the / a tooth will come loose, it will usually get caught on the very next rotation; then its major failure time as there is not enough room for the crown wheel and pinion to continue to rotate; Bang. Even if the lost tooth is thrown clear the result is the same, the pinion may thump the tooth next to the gap with such force that the inevitable Bang occurs or the additional wallop may be enough to break off that tooth and then the next and then the next stripping the crown wheel. Whilst this is actually the best case (pun intended) scenario as the casing is saved on a road car it is nearly always more practical to just change the unit. The things that affect the creation of these micro cracks are number of rotations pressure applied and heat. So if you think about it what is now a 'known weakness' may actually not have been at all but 10 or 15 years on and with extra boost added these units are getting to the grey area known as 'Time Served' The only true way out is a new Crown Wheel and Pinion, but there is of course a cost implication here. Yes you may extend the life by using the very best oil available which is Amsoil SVG or No2 Castrol SAFX but failure is inbuilt from the very nature of the beast.