Not been exposed to a car that's had a dodgy diff so I wondered what the symptoms were? (4x4 saph)
The car is driving great and properly fast so I'm happy, but last night I noticed when slowing down that there's a droaning kind of noise coming from somewhere, it seems to be a lot more prevelant when off throttle but the exhaust note is very loud inside the car when driving so I cannot say for sure it's not there all the time.

I've had wheel bearings go out on me before and checked these very recently, it doesn't sound like a wheel bearing type of noise. Loving the T4 power but it's definately testing the rest of the car!

 

i had a knocking noise from the rear diff but only when pulling off

planet gears i was told

check the oil and levels in them

are you sure the prop went back on in the same position when the box was changed

 

No idea, so probably not.
It doesnt knock, but when you drive away you get this really weird nosie like the revs/exhaust note are going up and down when it's not, strange indeed!

 

Worn bearings in the diff usually make a whining or grinding noise.

Or if the gears are slightly worn, you'll get a bit of play, making the car feel jerky if you let off or step on the throttle.

Does the car vibrate like it's on badly balanced wheels?

When you say 'droaning' noise, are you sure it's not just the exhaust catching somewhere?

 

Deffo not exhaust catching, you would hear it banging and vibrating on the car. Yes it vibrates like there's a wheel issue.

 

If it is fucked, put a 2wd diff back in with the bigger shafts as well, all bolts in easy peasy, you just have to take a small bit off one of the 7.5" diff mounts to fit into the 4x4 beam.

 

I fail to remember the english name for it but theres a rubber plate between gearbox and propshaft. If its fubarred you will get all kinds of vibrations. Had it on a mk3 granny once and he whole car.was shaking. Only got better when you floored it.

 

Propshaft donut... Make sure it is perfect or death is highly likely! Will post pics later

 

Yes it's all good, it's the guibo joint you're talking about, both that and the centre bearing are new.
Thought about the 7.5" diff, think it's probably a worthwhile addition, but I think I'll break it again by next week as I'm about to have more boost! The only thing I have never touched in this car in 12 years is the rear diff, last week the box was changed for a 2nd hand standard one which seems nice, it's predecessor was brand new from Ford and only lasted 4k miles, it always drove like crap and seems a pig to get into gear.

 

The 2wd diff will be much stronger, don't forget it is only seeing 66% of the power in a 4x4. I would highly reccomend a front diff steel sandwich plate as well, cheap & easy upgrade for mucho strength.

 

***What kind of noises to bad diffs make?***

RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRrrrrrrrrrrrrrrrrrr rrrreeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeekkkkkk kkkkkkkkkkkkkkkkkk clunk clunk ssssssssssssssssccccccccccccccccccccceeeeeeeeeeerr rrrrrrrrrrrrrrrrrrrrrrrreeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeccccccccccc ccccccchhhhhhhhhhhhhhhhhhhhhhhhhh chunk clumk weeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee crunch eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeekkkk

or similar

 

thats exactly what i was about to do

 

I'm convinced the diff is fucked, it doesn't clunk or make a racket like that, only a droaning noise, and that stupid exhaust noise i get that I can't figure out. Whatever it is, i will break it by next week when i add more boost, then I'll know what the cause was.

 

RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRrrrrrrrrrrrrrrrrrr rrrreeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeekkkkkk kkkkkkkkkkkkkkkkkk clunk clunk ssssssssssssssssccccccccccccccccccccceeeeeeeeeeerr rrrrrrrrrrrrrrrrrrrrrrrreeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeccccccccccc ccccccchhhhhhhhhhhhhhhhhhhhhhhhhh chunk clumk weeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee crunch eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeekkkk

I think you will find that there should be 5 k's at the end

 

LOL!!!

 

Whine..whiiiinnneee.....whhhhhhhiiiiiiiinnnnneeeee eeeee.....bbbbbbb BANG!!

 

dovboy, stop posting you're making me want another 200sx

 

A little vid of me diff testing for you
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Chizfab + Chums on Vimeo

 

It wouldnt really matter how good the standard 4x4 box is,it's going to struggle with a t4 roj.
Is the clutch a heavy duty unit?