[Scrawny]

I knew it had Greg's mount but couldn't remember if they were lifted or not. How closely have you looked at the rear diff? Can you grab another one from your supplier to try? That would eradicate another component

[Bruce]

I don't have a rear and I'm sure Greg does not either. But one would think it would do it in 2wd. As stated before you can drive in 2wd and all good and when you put in in 4x4 (on the fly as well) the noise come back. Then you can go from 4x4 to 2wd and it's gone.

[Scrawny]

Stranger things have happened, just trying to rule out another possibility.

[Bruce]

I know mate it's frustrating the shit out of me.
I'll see who has a rear NT diff but I don't think it's that.
I'll do what Royce said and loosen the mounts a little and see. I have taken the boot off as well but don't think it's that as it was not a prob before hand but I'll try anything now after changing all what I did on the weekend.

[steak_knife]

Let me drive it......

[Bruce]

steak_knife wrote:

Let me drive it......

Sure you can come drive it. But I need to be in the car. I've seen pictures of your driving habbits.

[steak_knife]

[coily96]

Has the balance weight fallen off the front shaft? at low speeds its out of balance at high its ok? from what you said has been changed it narrows down to that shaft.

[Bruce]

To my knowledge the weights have not fallen off. I will look at that thanks. Does it a low or high speed in 4x4.

[coily96]

also if it helps. Rotating the front shaft 1/4 of a turn and re-fitting can fix balancing issues. But in you case it wasnt from re-fitting the shaft.

[Bruce]

Had another chance to play with the NT today after work. I did what Royve said and backed off the T/case mounts and took the T/case boot off. THis made no diffence. But it did make it easier to work out what I think is the prob. It seems to be coming for the spline on the front shaft.
I went back home and FILLED the shaft with grease. Some thing I normally don't do, I normally just put a little grease in there.
Anyway, went for another drive and it was a little better. SO I think it;s play in the front shaft in the front tailshaft.
I think that it may be because I have fitted a 2" spring lift into the NT which raised it about 65mm. This is because the old springs were stuffed and were flat. So I'm thinking that becasue of the lift it has changed the Uni angle. Now I know lots of other zooks have 2" lift and I guess they don't have the noise I am having.
I know the uni's are good with no play.
I guess I just need to live with it unless others have more suggestions?

[Scrawny]

I was thinking about this today

Did you grease the rear shaft too? How much grease did you pump in? I thought you swapped shafts and it didn't make any difference?

[Bruce]

I pumped the rear as well Scrawn. Yes I did swap front shafts. It made no differance.

[mrw82]

it might be worth replacing the uni's, or atleast pulling them apart and manually greasing each bearing cup. I know the unis have a grease nipple on them, but if one of the ports that the grease flows through is blocked (or even partially blocked) then the grease will fill the easiest passage (path of least resistance), likewise if one of the cups has a buggered seal, the grease will spew out of the seal before having enough pressure to get to the other bearing caps and you could still have a dry bearing cup in one of the unis.

[christover1]

I had to fit a tailshaft spacer to front of my lifted sierra,
because tailshaft spline was too loose, that fixed my probs.
Spline could be past its best, or could be ok with shaft up further into it.

[Teracis]

I have a noise that only comes on in 4wd, though it also happens when I lock the front hubs and have it in 2wd.

It disappears when I take out the front shaft though so that leads me to believe the front shaft is badly out of balance.

Have you tried with NO front shaft?

Oh and for the competition, like my first post implied, front shaft?

[Bruce]

Thanks heaps all for your thoughts. I've not had a real lot of time this week but I should get time to play again this weekend.

[skyman]

So the lift cause the driveshaft to pull apart just enough to cause some slop, it doesn't take much to accelerate wear, and make it even more loose than it was before.

The noise those front splines make when they are loose is an awful racket. it really sounds like a front bearing in the t-case. The first time I heard it, I was coming onto the gravel and started to pick up speed. I thought "great there goes a front bearing".

So I replaced the front female splined shaft with a new one. Within 25 miles the new shaft had worn out, no joke. It only got better when i moved the axle back towards the case an inch to make the spline fit better.

A 1" extended shaft would have fixed it as well.

Whenever I hear a mystery grinding/bearing noise and nothing is immediately suspect, I always grab the driveshaft(s) and check for play. It's easy to diagnose.

[Bruce]

skyman wrote:

So the lift cause the driveshaft to pull apart just enough to cause some slop, it doesn't take much to accelerate wear, and make it even more loose than it was before.

The noise those front splines make when they are loose is an awful racket. it really sounds like a front bearing in the t-case. The first time I heard it, I was coming onto the gravel and started to pick up speed. I thought "great there goes a front bearing".

So I replaced the front female splined shaft with a new one. Within 25 miles the new shaft had worn out, no joke. It only got better when i moved the axle back towards the case an inch to make the spline fit better.

A 1" extended shaft would have fixed it as well.

Whenever I hear a mystery grinding/bearing noise and nothing is immediately suspect, I always grab the driveshaft(s) and check for play. It's easy to diagnose.

Hummmmmm What you say makes a lot of sense. Might look at putting a small tailshaft spacer in and see.

[skyman]

The easy check is to grab that driveshaft and shake it. If there is play, then there will be a source of vibes.

Make sure the shaft spins freely (hubs unlocked 2 wheel drive), sometimes the shaft gets in a bind and will fool because the shaft ahas tension on it.

I really hope it is something as simple and cheap as an extra female slip yoke armsup

[Bruce]

skyman wrote:

The easy check is to grab that driveshaft and shake it. If there is play, then there will be a source of vibes. There is play but only just a little but I see what you mean
Make sure the shaft spins freely (hubs unlocked 2 wheel drive), sometimes the shaft gets in a bind and will fool because the shaft ahas tension on it. It spins free.
I really hope it is something as simple and cheap as an extra female slip yoke armsup

It would well be. Thanks again.

[Bruce]

Well today I fitted a front tail shaft spacer (13mm) and it made no diffance so I'm going to replace both uni's on the front shaft and see.
If that don't work I have no idea and I guess I'll have to live with it till something goes BANG
Once I have replaced the Uni's I'll let you all know.

[Teracis]

I just went and checked the play in my front driveshaft spline (after the advice here) and the thing will move +-5mm...

Guess that explains my problem, I'm glad I didn't change the uni's in it!

Doesn't make a grinding noise though, more of a vibration.

[skyman]

when they start they are more of a vibe, but can make more of a bar bearing sound as they wear.

Jut a FYI, speed over 15-20MPH will greatly accelerate wear. I had a new yoke with good splines wear itself out within 25-35 miles. The other one took almost 4 months to show a problem, the only difference was that I had been wheeling in 4x4 at speed with the second one.

I really need to extend my front driveshaft by an inch or o and eliminate the probem altogether.

[Bruce]

Ok update.
I have replaced the front diff, different front shaft complete with new uni's, replaced the jack shaft (cause I could). Put a front tailshaft spacer in. Replaced the t/case 2 times with differant ones (and I know they were good) There is no play in the slip shaft and the noise is still there when under slight load but nothing when in 2wd. Has me stuffed now. I guess I'll drive it till something goes bang, then I'll know.

Skyman, it's not a vibe at all, it's like a grinding noise. The faster you go the faster the noise is.

I guess I'm just lucky it's just a weekend beach car really and I don't drive it alot.

[Bruce]

Scrawn wrote:

Have you tried all four wheels off the ground on axle stands with Royce underneath listening? If it'll do it unloaded like that then you'll be able to pinpoint it a bit better

This is about the only thing I need to try.

[Teracis]

Which way does the transfer try and turn when it loads up?

Could it be twisting slightly (are you using the same mounts when you swap cases) under load and rubbing on something? If it's only happening in 4wd maybe something to do with the lever rubbing on the body?

Haven't heard the noise so it's hard to guess now.

[Bruce]

Teracis wrote:

Which way does the transfer try and turn when it loads up?

Could it be twisting slightly (are you using the same mounts when you swap cases) under load and rubbing on something? If it's only happening in 4wd maybe something to do with the lever rubbing on the body?

Haven't heard the noise so it's hard to guess now.

It only happens under slight load and is not there when you load it up so I don't think it would be that as you would think it would happen when under more load. And also you can hear it when you completly decelerate.

[Teracis]

Bruce wrote:

Teracis wrote:

Which way does the transfer try and turn when it loads up?

Could it be twisting slightly (are you using the same mounts when you swap cases) under load and rubbing on something? If it's only happening in 4wd maybe something to do with the lever rubbing on the body?

Haven't heard the noise so it's hard to guess now.

It only happens under slight load and is not there when you load it up so I don't think it would be that as you would think it would happen when under more load. And also you can hear it when you completly decelerate.

There has to be a common part that you've been re-using even though you're swapping cases and shafts, I can't think of anything else unless you forgot to put oil in all the cases!

[christover1]

My sierra had a small dent in the metal sleeve thingy,
and was occassionaly rubbing on diff housing. Was hard to find.
Tho you probably changed that with the diff.

Yeah just drive it till noise stops,
and whatever falls off was it.