Gearbox/ transfer noise

[GURU]

G'day all,

I just finished fitting nissan disffs to my RR and went to drive home after connecting the front propshaft and drove about 5 kms then I heard this noise from the drivetrain, the sound of gears not meshed together fully. pull over, unlock the hubs and lock centre diff lock and the noise continued and got abit louder, noise has only appeared during cruise., full acceleration or full back off and no noise.

So I took the front shaft out again and noise went away. drove with front shaft out and free wheeling hubs locked and no noise.

connect front shaft and noise appears. I jacked all wheels off ground and got under and tried all the combo's I could think off, noise was apparent at all times including centre diff locked and no front shaft, but you can't hear it while driving. put front shaft in and you hear it under the rig and also when your driving.

Really annoying me I want to go wheel. what do you guys think ??

[up2nogood]

Front output shaft bearings in t-case?

Might be an unfortunate coincidence rather than anything to do with the diff conversion?

Bit hard to tell tho, can't hear it properley from here

[ISUZUROVER]

How much backlash and side-side play does the front output have?
How much backlash does the front diff have?
What is the diff nose angle like compared to the rover diff?

Often the driveshaft can transmit noise - i.e. noise from diff can be transmitted along the tailshaft so it sounds like problem is the t-case.

[red90]

Can you move either the t. case front output shaft or the diff linnion flange at all? They both should be very firm. I'm thinking diff pinion bearings. They are supposed to have preload, so there should be no play at all.

I assume you have had a good look at the propshaft.

[daddylonglegs]

If the noise only appeared after you fitted the nissan diffs then I would suspect that the front pinion angle in nowhere near the same as the Rovers and the UJ' angles are all wrong. you may need double cardens, even on both ends of the front propshaft.Or convert the transfercase to Part time 4wd
Bill.

[GRIMACE]

Bill is correct....
I have the same prob, new shaft with DC at Tcase end or re allighnment of the diff input drive flange, while your there check the bearings and seals cause the do get damaged, mine R farked

[red90]

Oops, need to read better. How about details of exactly what you have done.

Is this a full Nissan axle assembly?

What is the pinion angle?

Any change in propshaft length?

Pictures?

[GURU]

interesting thoughts guys.

It's a complete nissan axle assembly

front diff angle is the same as any GQ with 4" lift. but the pinion isn't dead inline with the TC has abit of a side angle, but nothing major.

Had to shortern front shaft by 40mm. shaft is out of a disco 1.

No play in pinion shaft, a very small amount of movement in the TC output shaft, but I mean small.

keep the idea's rollings

thanks

[ISUZUROVER]

In that case then my money is on either an out of balance front prop, the pinion angle or the misalignment of the pinion and the T-case.

[red90]

What did you do to adapt the shaft flange to the pinon flange? Is there machined centering surface to ensure both run concentric?

Is it a front shaft from a Disco? Are the u-joints out of phase?

How much lift? Can you attempt to measure the u-joint angle(s)?

The stock Rover set-up basically has the front pinon pointing at the t. case. How far off might you be? A photo might help.

[J Top]

Which Free Wheelingt hubs have you got.
The GQ FWHs that are both auto and manual have a problem like you are talking about when worn or over packed with grease.
Take off the hubs and drive again.
J Top

[J Top]

Reading through your posts again ,you seem to be saying that , vehicle
on stands,no front shaft ,the noise is still there ,but not as bad.
This would mean it is Transfer becauseno front parts are turning.
J Top

[GURU]

J Top, thats what I tought...although when driving I can't hear that noise at all in the vehicle, front shaft in and I can.

Also intresting thought about the FWH's mine are manual and I packed heaps of grease in them so that it didn't get dry as it will be in constant lock, might be the noise??

will take a pic tonight. there is a machined recess in the pinion flange to make it run true. disco shaft with out of phase uni's. 4" lift but I had a 3.5" lift when I had the rover stuff to begin with and no probs at all

[red90]

Sorry, I don't recall what the Patrol Diffs are like. Are the low or high pinion hypoid or spiral bevel? Just wondering if the offset (iff it exists) affects the alignment of the shaft.

With 3.5" lift, you might have been right on the edge with the Rover diff. The longer pinion and axial offset of the Nissan axle might be just enough change to push you over the edge of what works with single U-joints.

[derangedrover]

Since the offset of the patrol diff is different, the stock out of phase setup in the front shaft might be a problem. Try running the front shaft in phase properly, then if no good a spline either way.

What you're hearing might be 'chatter' in the cw&p or tcase differential as the front shaft runs at different speeds due to the phasing of the front shaft, since the noise got louder when you locked the centre diff lock (less available 'play' in the drivetrain) I think this could be your prob. The noise you hear with no front shaft and centre diff locked might be 'chatter' in the centre diff lock dog from the unloaded front output?

Whats your rear shaft angles like? Might be contributing, ie referred noise?

Like the others have said, check pinion angle and angle of uni at tcase, equal and opposite at either end @ ride height for an in phase shaft with no DC. With that much lift you will probably need a dc front shaft and then the offset misalignment between tcase and diff might become an issue since the diff end will have variation in rotational speed due to (small) misalignment in offset.


Cheers
Daryl