[Bruce]

Ok here is some history. It's a 85 NT drover with std 3.9 diffs.
Had a funny noise in what I thought was the front diff only when in 4x4 on deceleration or under light acceleration. Sounds like a grinding noise.

Changed front diff. This made no difference, changed front tail shaft. This made no difference. For shits and giggles I changed the jack shaft. No difference.
Changed T/case to spare S1's I had in a case as a spare for the comp rig, this made no difference.

It's got the best of me now I not sure what it could be.
I can unlock the hubs and put it into 4x4 and it's still there.
Nothing is hitting anything so it has me buggered to what it is.
If I put the foot down there in no noise but is there when on deceleration or very light acceleration. It does not do in when in 2wd.

Come on lads and ladies, your 2 cents might throw some light onto this

[Teracis]

Does it do it if you remove the front shaft, put it in 2wd and lock the hubs?

That may help you find the problem.

[Scrawny]

Cv's?

[steve]

I think i had a similar thing once, it sounded like the gearbox/transfer case was vibrating in the transtunnel under deceleration. I think i replaced the car and that fixed it.

[Bruce]

Teracis wrote:

Does it do it if you remove the front shaft, put it in 2wd and lock the hubs?

That may help you find the problem.

Have not done that but I'll give that a go. (not today it's not daily driver)
CV's seem fine scrawn.

[zukmeista]

Brakes?

[Bruce]

zukmeista wrote:

Brakes?

It would do it when in 2wd then I would assume.

[royce]

Bruce wrote:

Teracis wrote:

Does it do it if you remove the front shaft, put it in 2wd and lock the hubs?

That may help you find the problem.

Have not done that but I'll give that a go. (not today it's not daily driver)
CV's seem fine scrawn.

doesnt make the noise with the hubs locked, shaft in and 2wd

[Bruce]

royce wrote:

Bruce wrote:

Teracis wrote:

Does it do it if you remove the front shaft, put it in 2wd and lock the hubs?

That may help you find the problem.

Have not done that but I'll give that a go. (not today it's not daily driver)
CV's seem fine scrawn.

doesnt make the noise with the hubs locked, shaft in and 2wd

Well that's true. Royce and I did that yesterday .

[TheRealCJ]

Could it be your CVs out of seat?

[Scrawny]

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

[steve]

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

That wont work, you need to get royce hanging under the car while bruce is driving down the road!! get some video for us too

[royce]

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

I doubt you would get the correct amount of load on it, its only really on cruise that it does it (if you arent always accelerating in a sierra you are doing it wrong)

Though it does it heaps in high 4 with the hubs unlocked, doesnt change if you hold the lever back or push it over to the lowrange gate

[Scrawny]

Can you tell where the noise is coming from or does it transmit through everything? What speed? Does it sound like metal on metal?

[FullyZooked]

Dry and worn Wheel bearings. Less load on them under acceleration-no noise. Cruise and under braking-grinding.

Worth a look.

[Bruce]

FullyZooked wrote:

Dry and worn Wheel bearings. Less load on them under acceleration-no noise. Cruise and under braking-grinding.

Worth a look.

Bearing are new and repacked. Good thinking tho.

Scrawn, the noise seems to be around the T/case stick area.


Now just throwing this out there. I just had a look at Casper's frontend and noticed that the front shaft had the little spline near the T/case. I looked at the manual and that's the correct way. I looked at the NT and it was the other way around in that the little spline part was at the front. I have just changed it to the other way. I don't think this will fix it but it might have been thowing the balance off?

[steve]

Bruce!! yeah i think i concluded that my vibration noise was the excessive play in the front shaft, the splines were worn and my shaft was floppy

[royce]

Scrawn wrote:

Can you tell where the noise is coming from or does it transmit through everything? What speed? Does it sound like metal on metal?

Its the transfer area, for sure isnt further forward

any speed, faster the speed the faster the noise, but only under light driveline load, heavy accel its fine

slop in the front output is the perfect reason but not across several transfers, next is the boot holding the stick somehow or something wrong with the mounts

[stockman]

Any chance you took out and refitted the same transfer case? Sounds stupid but it could happen.

[steve]

free Peace-out sticker

for the person that gives the correct diagnosis and solves this

"guess my problem game"

[Bruce]

stockman wrote:

Any chance you took out and refitted the same transfer case? Sounds stupid but it could happen.

LOL No.

[Bruce]

steve wrote:

free Peace-out sticker

for the person that gives the correct diagnosis and solves this

"guess my problem game"

[SuziBlu]

I would look to the rear, sound does strange things in cars, can be a noise in the rear, sounds like it is in the front, also the driver hears different to the passenger.

You have not spoken about doing any checks on the rear, shit in one of the brake drums, and the noise is traveling ?

[stockman]

I'm going to go with gear box and its a harmonics thing and can only be heard through the transfer case when it's in 4wd.

[Bruce]

SuziBlu wrote:

I would look to the rear, sound does strange things in cars, can be a noise in the rear, sounds like it is in the front, also the driver hears different to the passenger.

You have not spoken about doing any checks on the rear, shit in one of the brake drums, and the noise is traveling ?

No it only does it in 4x4. normal 2wd and it's all fine and any load of driving.
Have checked the rear shaft, brakes etc as normal checks and it is all good.
It 100% only happens when in 4x4. YOu can have the front hubs in and drive in 2wd, then as you are driving change to 4x4 and then the noise is there. You can also have the hubs free and put it in 4x4 high and it's there. It's really doin my head
And no I know the t/case is 1000% good. I only changed it out from my comp rig as I got S'2 so the s'1 were just sitting in the shelf as a spare T/case.

[whincup]

SuziBlu wrote:

You have not spoken about doing any checks on the rear, shit in one of the brake drums, and the noise is traveling ?

is possible, but as they've said its only in 4wd...

front shaft unbalanced? or my back diff used to make a similar noise only while decelerating, before i understood about diff breathers and mine was full of muddy water... just a thought...

[Scrawny]

Did you stick lifted mounts in or just the standard height? Is the crush tube in the mounts rubbing?
Can you describe the noise? Light metallic rubbing like backing plate? Harsh scraping like worn out pads?

[Bruce]

Std height mounts Scrawn. THey are the ones Greg sells
The noise I guess sounds like humm grinding LOL like metal on metal. It's like gears not meshing. I have taken the boot off and I'll drive it tomorrow when I get home and see. Strange thing is it has only just started to happen. I went to Bribie with Royce a few months ago and I heard it. Got home and thought it was the 1lt t/case I had in there. Changed the t/case to a rocklobster t/case from NFI. Did not do any 4x4ing till 3 weeks ago when again I went to Bribie. Same noise.

[royce]

loosen the transfer mounts off and try, do it now

[Bruce]

royce wrote:

loosen the transfer mounts off and try, do it now

Tomorrow. Too lazy now.