Outer Limits 4x4 Board

First post.

Recently acquired a shorty GQ. Very fresh to this 4wd stuff. Done a fair bit of reading. Great forum!

The car is great, apart from an annoying whine above 80kmh. It's quite loud. It could only be: one of the diffs, auto box (unlikely), trans case or tailshaft. I'm sure someone could tell me, if I describe the symtoms.

About the car: Auto TB42S GQII. 2" coil lift, 33" AT tyres, gearbox spacers. Stock everything else AFAIK.

Under acceleration or load there is a whine from under the car. It sounds like it's from mid to front of the car. Obviously, this is in 2H.
If I back off so there is no load on the drivetrain (decel) it goes away. It comes on from 80kmh and increases in pitch as I go faster.
Also it seems to be louder with light throttle input than giving it, say, mid throttle.

I have changed diff oils, trans fluid, trans case oil using manufacturer spec oils. No noticeable difference after fluid changes.

No difference before or after the rear tailshaft unis were greased.
There was a "braap" sort of vibration on decel from the rear tailshaft, but that has all but gone after greasing the slip joint. I know this is a separate lifted SWB GQ problem in some cases.

Questions/thinking out loud:

It's not tyre noise.

It couldn't be the front diff because it's not driven in 2H.

Is it possible/dangerous to disconnect the rear shaft, put it in 4H and drive it by the front wheels to 100kmh? That way I can at least pin point if it is tailshaft back.

When transfer cases fail, how do they fail?

I know it's a process of elimination, but eliminating the right one first is the key.

Once I get this sorted, I'll be happy, get dirty, then do some mods.

ive got a similar kinda thing in my diesel shorty, cept it's more of a humming noise. Been there for a while now, doesnt seem to affect anything, though i do have hole in my muffler so that could be it

hi mate

its probably likely that your pinon nut is Overtorqued.
pull your tailshaft off and see if teh nut has been removed before.
if it hasnt then you may need to pull the diff out and check the gear surfaces and replace bearings.

Jes

try a thicker oil in your gearbox, or some gear oil stabiliser

get ya selfa better stereo

Or a louder more annoying girlfriend

chops wrote:try a thicker oil in your gearbox, or some gear oil stabiliser

Its auto, so just stick with the recomeneded auto oil.

Layto....

Sorry to bump an old thread but I have a loud, annoying whine in my 5 speed GQ SWB when going at speed as well.

I cant tell if its the gearbox or rear diff. It happens in 2WD. It goes away when I put the clutch in.

Is running it in 4H without the rear tailshaft an okay way to test?

If it is my gearbox or diff what is the best way to fix the problem? Do they need to be completey rebuilt or just parts of them fixed up?

I have changed oils in both to no avail.

Possibly could be the throw out bearing in your gearbox..

dansedgli wrote:Sorry to bump an old thread but I have a loud, annoying whine in my 5 speed GQ SWB when going at speed as well.

I cant tell if its the gearbox or rear diff. It happens in 2WD. It goes away when I put the clutch in.

Is running it in 4H without the rear tailshaft an okay way to test?

If it is my gearbox or diff what is the best way to fix the problem? Do they need to be completey rebuilt or just parts of them fixed up?

I have changed oils in both to no avail.

sounds like worn crown wheel and pinion.
it goes away when you clutch in because there is no load on the diff. im guessing it is quite loud especially on over-run?

it can be fixed by lapping, if its not too badly worn. but thats no garrantee it will be quiet.
best fix is new crown wheel and pinion and getting diff set by a diff shop. depends how deep your pockets are. i did this in my weekend car, spent 1200 on the diff, and a week later its whining again, just to a much lesser extent.

i have driven/clutch kicked a car with a whining diff and rumbling wheel bearings for 50,000 km and had no issue until getting a roadworthy. with diffs, if its whining when you buy it, leave it alone til you break it. coz its not really worth trying to fix the problem. just service it how you normally would, to prolong the suffering.
my guess is you will never have an issue from this. if you do, you will take all the tips of the teeth off the crown wheel. but you would probably have replaced it anyway, so why not risk it

Thanks guys.

Is disconnecting the rear drive shaft safe to do to isolate the noise?

Whatever it is I want to have it fixed ASAP.

Ive got a broken factory rear locker atm so if its the diff I will get another complete rear end to replace it. LSD or another factory locker will be good.

If its the box I will try to fix that first. Its really loud and although I only drive the car on the weekends its really giving me the shits.

Is it possible/dangerous to disconnect the rear shaft, put it in 4H and drive it by the front wheels to 100kmh? That way I can at least pin point if it is tailshaft back.

It is possible to remove the rear shaft to try and isolate the noise, just be ready for some strange handling characteristics, a bit like driving an oversized mini.

Sounds like when i had a worn pinion bearing in the rear diff/dry worn out tailshaft. Try moving the pinion up and down when there is no load on it and grease the tailshaft

Rob

badger wrote:get ya selfa better stereo

X 2 WHAT NOISE ?? ( while turning up stereo )

Thanks for that Tuff rangie, Ill check it out on the weekend.

Hopefully its an easy fix.

im selling a good GQ rear LSD centre for $200 in brisbane replaced by locker

Did your axles fit up to both centres? I read on here that the locker axles are different to the LSD axles.

I thought it was strange.

I took out the tailshaft, locked the hubs, went for a drive and the noise is gone!!!

There seems to be a lot of freeplay in the diff flange, im guessing this is the cause of the noise?

A replacement lsd is $400 and another factory locker is $750.

Would an air locker fit into an lsd center?

I think I will get an LSD and front locker before doing the rear.

Opinions?

replacement crownwheel and pinion would solve the noise im quite sure. and depending on the wear a $90 lap job of crown wheel and pinion "might" get rid of it. then you just have to get the preload set properly again. the play is due to the preload being sloppy, and the noise is caused by the pinion running right on the top edge of the crownwheel teeth and wearing them.

cheers, andrew

Thanks Andrew.

I called a wrecker and asked a few questions and I am picking up an LSD center for it next weekend once he removes it from a car. It seems like the cheapest and most reliable option.

Any ideas what a diff joint would charge to shim it up so it is nice and tight if I give them the centre?

they will charge by the hour. about 80 an hour, and depending how much more they have to. but just to shim it up, should only be an hour. but you never know, it may be three.
if you swap the whole lot as a unit it may not need setting, as it shouldnt have changed. depends what you are changing.
did you ask if the wrecker will swap if this one whines or is damaged upon inspection by diff shop?

not sure what area you are in, but i like diff lapping in brisbane