[lump_a_charcoal]

Noice!

[abclarke]

Pictures of the process in my build thread

[Rossco]

good to hear! I had a good listen to the noise I'm getting. when I go slowly in in any gear the noise almost sounds like a vibration coming from the rear. sometimes I can feel it through the accelerator. then once you speed up it turns into more of a roar than a whine? does that sound like what you just fixed ab?

[abclarke]

Yeah similar, its really hard to describe though, but if you get a video of it ill know it straight away! Is it so loud inside the car you cant hear a radio or even yourself talking?

Take your diff plug out and see if the oil looks like mine did and if any metal comes out with it. According to the guy at the wreckers its a part that commonly goes on older models.

[lump_a_charcoal]

Guys, Zooks are fairly simple things, and great to diagnose.

Rossco, check your uni joints - If there is a vibe, they could be on the way out. Then check the pinion bearing (pointy bit of the diff) for side to side movement, or leakage.

After that, check the fluid like abc said.

[Rossco]

righto, I'm going to get a sound clip up tomorrow (I'll make it on my way to work tonight). and for sure they are easy to fix but unfortunately I really only have enough money to fix one of the several different things it could be. just want to fix the one that's causing the noise

[abclarke]

Yeah thats why i got my granddad to check it out first before i went splashing what little cash i have around. Youll know its the same thing as mine if anytime over 10kmh you cant hear the radio

[Teracis]

I rebuilt a uni on friday and couldn't work out why the hell I had vibration, I took the shaft out, checked it, put it back, drove it, took the grease nipple off the uni incase it was putting it out of balance, drove it, realised what was wrong, put the grease nipple back on and then...



I unlocked the front hubs!


I forgot that I'd locked them in to move it while I had the shaft out replacing the uni, I have a hell of a vibration from the front end.

So after that (read thismorning) I decided to remove the front driveshaft, lock the hubs and take it for a spin to see if it was the front shaft or something in the front dif.

Lucky for me, it's the front shaft, now I've just got to work out why, no play in either uni and the dots are lined up, must be out of balance?

[lump_a_charcoal]

Could be, but won't matter too much - most of the time you would be going slowly in 4wd...

[Rossco]

ok here it is http://www.youtube.com/watch?v=vDuixP5x7uc

the slow noise is at 0:14 and the fast one is at 1:28 or so. My computer makes the fast noise sound louder than it actually is. I don't think its quite as loud as your abclarke from what you are saying, but you do have to raise you voice a little to talk over it.

[lump_a_charcoal]

Is that in 4wd?

[Rossco]

nope 2

[lump_a_charcoal]

Damn, sounds like something is wak. Maybe the jack shaft could be bad...

[stocker]

that sounds bloody awful. are you sure your front hubs aren't engauging themselves???

[Rossco]

haha wonderful. its been going on for a couple months and it happens every time the accelerator is under load. so pretty sure its not the hubs. it kinda sounds like a bearing roar but then it would seem like it would be all the time. I don't understand why it only happens when the engine is under load.

[Teracis]

That sounds hectic,

Easiest way I can see to work out what it is is this:

To prove the jackshaft is ok, throw the transfer in neutral and handbrake on (you won't go anywhere but the jackshaft will spin, rev the engine up (whatever gear you like but don't blast the hell out of it because you don't/shouldn't need to), if you get the noise then because your jackshaft is the only thing spinning then it's probably that, or a bearing in the transfer but that's less likely.

If the noise doesn't present itself in the first test, move on to the second.

Remove the rear drive shaft, throw it in 4wd and lock the hubs, take it for a spin. If you don't get the noise then it's in the rear drive shaft, if you do then it's probably not in the rear shaft and might be in the rear dif (unless as you say it only does it under load, at which point you've proven it's not the shaft anyway so put that back in as it's most likely the dif)

I've not had a dif problem before so aside from checking the oil in it (you don't have to drain it, take the fill plug out and put your finger or a straw or something in and get a bit out, obviously while it's not moving...) or pulling the centre out I can't help.

Good luck and as to why it's only doing it under load, when you are free wheeling the wheels are turning faster than the engine (and driveline) wants to, so that means the wheels turn all the gears e.t.c and therefore they are running on the other side of the tooth. So if you've got heaps of wear thats causing the noise on any of the gears (or they are rounded on one side or chipped or something) then it will only show up under load (engine pushing so driving on the worn side of the tooth)

Hope that helps, I could be wrong but that's the way I understand it to work.

[Rossco]

ok first test done didn't get the noise but when I let the clutch out the engine whined like a bitch (my second problem).

definitely only occurs under load. I can be driving 60 down the road noise is there. lift off the accelerator.. immediately gone.

I like the diff idea if the last bit of your post was referring to diff gears. I doubt it has been replaced in the life time of the car.

[lump_a_charcoal]

Thrust bearing I reckon.

[Teracis]

Yeh, diff gears, transfer case gears, gearbox gears, they all work the same way.

I know for a fact that my new transfer case gears whined (as new gears do) and they quickly lost the whine under load (bit of highway work the day after the install) but it's taken a fair bit longer to get the whine of deceleration to quiet down because the gears don't a) have as much load on them in deceleration (you have the engine load as opposed to load of accelerating the vehicle) and b) it takes longer to accelerate the car than decelerate therefore the gears spend more time under load than deceleration.


So yeh, could be the dif, easiest way I can think of to test it is to jack it up and run it (not fast, just idle), but that is a touch dangerous unless you can fix it to the stands and make sure it wont come off/drop to the ground and take off!

Because while the wheels are in the air you can listen to the dif.

[Rossco]

ya I thought about getting it on a dyno but then again that costs money. theres a dead end on my street I'll just aim it down the road and have someone sitting in it. as long as my head isn't in the way should be fine. I'll give that a go next weekend. I reckon its either the rear diff or the transfer. the noise sounds like its coming from everywhere when your driving.

[abclarke]

Nah mate no where near as loud as mine, but similar sounding sound. Im thinking if you have anyone nearby with the same ratio diff centre swap em over and see if that fixes it if you dont want to spend the cash on a guess?

[Teracis]

It's easy to check the transfer, take the rear drive shaft out, whack it in 4wd and don't lock the hubs, it will still have a bit of load on it (bugger all but should keep it from just free spinning and not running on the loaded side of the gears)

I don't know if you should run it too long in 4wd with the hubs not locked in though, it says not to on that little sheet that sits beside the shifter, I'm wondering what it could do though to actually damage something?

I'm thinking it has something to do with the hubs? Can any of the guru's enlighten me?

[Rossco]

ok so just had a mate drive and I hung my head out the back next to the diff. definitely sound like where its coming from. another thing is that it seems to be very rhythmic. as in it gets louder and quieter, and if you drive at a constant speed it happens at the same interval. then when I speed up it gets faster until it just becomes a constant roar about 40-50 or so.

[abclarke]

Try a new diff centre i reckon, just to try and cancel that bit out. And if it doesnt work then you have a spare!

[Rossco]

ya I think you might be right. umm.. can I pull one out of a vitara? there are no sierras at any of the wreckers in townsville. I know on has two vitaras.

teracis I'll pull the drive shaft out next weekend when I have time to see if its the hubs.

[IN2DEP]

Rossco wrote:

ya I think you might be right. umm.. can I pull one out of a vitara? there are no sierras at any of the wreckers in townsville. I know on has two vitaras.

teracis I'll pull the drive shaft out next weekend when I have time to see if its the hubs.

Yep thats what mine sounds like rossco, but louder, and yes mine gos with the revs of the motor aswell, its ether transfer or diff gears, both is gona cost heaps to fix,

Im gona do my diff first, can I run vit diffs in a 95 sierra, and if I want to fit a arb locker do I need a sierra one or vit one

[Jason]

A thought...

If you can get the noise to come and go (under load/not under load) try holding the transfer lever as you make it do it/not do it and see if any vibration can be felt through the transfer lever.

[abclarke]

My transfer level vibrated a bit, but so was the rest of the car lol.

[Jason]

My mystery vibration only occured under load. Haven't looked at your clip but mine was LOUD as, lift off the throttle, instantly all gone.

Turned out to be a UNI joint, on the shaft between the gearbox and tranfer. Joint had seized a bit and had a point it would not rotate past at that angle so the shaft kicked up to rotate past that point.

[Jason]

At night the whole car shook so much that the headlights of the cars following made pretty pattern in my mirrors. Circles and spinning ovals at different speeds. at 82kmh it was pretty psychadelic man like a spirograph.