weird crack noise from under my gq.

[BLKWDW]

After our easter trip i have noticed a cracking noise from under the car. It happens worst when driving along and i back of you hear a crack. if i slowly take my foot of the pedal or let clutch in it doesnt do it only if i immediately lift my foot of the accelerator. I also found that whilst rolling backwards and jumping on and of the brakes everytime you let the brake of it would make the noise. i'm yet to have a real good look but from what me and my dad could determine on the trip it was coming from the rear of the car.


Any thoughts on the problem my 1st was gearbox but the noise is further back from that so maybe the diff backlash or something?

[threedogs]

Its not a rock caught between metal disc guard and rotor its self

Not sure that would make this cracking noise you mention

[happygu]

Any idea if it sounds like mechanical or body noise?

I had a cracking sound in my GQ and it was a broken weld and the metal had fatigue cracked (Mine was up the front though)

Mic

[BLKWDW]

It sounds mechanical. I checked the tailshaft for any free play thinking it might be it but seems ok.

[BigRAWesty]

Check all your bushes in the rear. Are you running rubber or neoprene bushes?

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[happygu]

Check your enine mounts too...4.2's have a habit of breaking them, and the sound could be transferring down the driveline.

[BLKWDW]

Rubber bushes. Well i think the only bushes that are not old are the ones in the new extended lower control arm i got from ss.

[BLKWDW]

Check your enine mounts too...4.2's have a habit of breaking them, and the sound could be transferring down the driveline.

But would that make enough movement whilst slowly rolling backwards on and off the brakes.

[threedogs]

Transferring weight. Might be a 2 person job ,one out side pin pointing area of noise then go from there
Its your term cracking thats throwing me

[Parksy]

Is the body sitting on extended mounts? Might be worth checking each body mount for cracking.

[happygu]

Is the body sitting on extended mounts? Might be worth checking each body mount for cracking.

Parksy could be on the money

[BLKWDW]

Transferring weight. Might be a 2 person job ,one out side pin pointing area of noise then go from there
Its your term cracking thats throwing me

We tried with 3 ppl and couldnt really pin point it except for it coming from the rear. its loudest wen you drive then back of the pedal straight away.


Is the body sitting on extended mounts? Might be worth checking each body mount for cracking.

It has no body lift

[Parksy]

Still worth checking though. It's more common when sitting on extended mounts.

[happygu]

You could see if it is the rear diff by putting it in 4wd and removing the rear tailshaft drive around and see if the truck makes the same noise

[BLKWDW]

Still worth checking though. It's more common when sitting on extended mounts.


You could see if it is the rear diff by putting it in 4wd and removing the rear tailshaft drive around and see if the truck makes the same noise

I'll check both of these once my battery charges up as its dead and cant move the car.

[BLKWDW]

Went for a drive and the noise is gone. All by itself. But now i have another concern. The same noise or similar but when i accelerate. If i quickly push the pedal down i get a clunk noise from under car hmm hope its not an expensive problem.

[93patrol]

Probably tailshaft backlash. Ie too much movement in the tailshaft to the diff or pinion gear to the crown gear in the diff


Just tap it in just tappy tappy tappy

[BLKWDW]

might pull the tailshaft of and see if the bolt is loose one the diff

[Dominator]

Also check your rear suspension bushes. If one of them is worn it could cause some movement.

[Parksy]

Park the car on a level surface and chock the wheels. Release the handbrake and try to turn the tail shaft. Might be able to replicate the noise. Also a good opportunity to check the u joints.