Transfer case whine - 96 Auto Disco I

I had to reply to this one as it happened to us - the 96 should have a cross drilled gear but I have seen 98's without

Anyway the input gear will only solve the clunking - worn shaft splines, but the whine are the gears not meshing correctly

The 230 is a swine to shim up = we put a set of Ashcroft high ratio gears in a 300 not so long ago and the output shaft (to the prop shafts) has so much play it was un true

We did the maths and had to fit a 0.60 inch shim to take up the play

When you have 2 x taper roller bearings on a shaft and very loose, then there is more play on the shaft, thus a lower contact area for the gear teeth - as the teeth are further apart and not correctly meshed hence the whine

Now we didn't have all the fancy tools you need to put the shim beneath the bearing seat, so we pulled the bearing off the shaft itself, and had a shim machined to suit - put it all back together and it was lovely!

Not rocket science, but a right prat about - even on the bench!

Mike

Britannica Restorations Ltd

Canada

Reply to
Britrest
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Scot Hi,

have you checked the front and rear axle bearings?

Take care Pantelis

Reply to
Pantelis Giamarellos

Not sure how to check them on this truck. Is it just like a car with trying to rock the tire on its horizontal axis? What I tried is to put the truck in neutral while rolling, which of course removes all of the sound so that means it is only under power, or braking. Then I tried to brake under power, which seems to bring the sound back a bit, then I tried to brake under neurtral, and I did not hear the noise. Problem is braking has its own noises and the decel noise is quite quiet anyways so its hard to say.

Bearings in the wheels would definitely be my favored issue! Much easier to pull the wheels/hubs and replace than removing the tcase.

Reply to
Scot Kight

Can you post up a bit more of a description of how to do this? Unfortunatly I have little to no experience with transmissions, so I wouldn't know where to start to look.

Thanks, Scot

Reply to
Scot Kight

Scot Hi,

A simple way to check the bearings on your front axle is to jack the vehicle up and check the wheel (with the rim and tyre still mounted) for play. Push/pull the wheel grabbing it from its upper and lower part. If you find play in there most probably it is from the bearings. If the play persists when you press the brake pedal then most probably you have play on the locating pins/bearings of the swivels. This testing procedure was posted sometime ago on this discussion group. I have not tried it but it sounds very logical.

As for the noise being audible when you apply power this is a VERY strong indication of a differential approaching its death.

Take care Pantelis

Reply to
Pantelis Giamarellos

I've seen slack in the pinion shaft where you can move the propshaft flange from side to side and that did howl

Reply to
George Spigot

Ok, how do I test to see if its the front diff vs the tcase? That could definitely be a possibility due to where the noise is coming from. I tried to move the diff lever left and right while driving as others say that should change the "note" a bit if it is the issue. No change whatsoever. If it is the diff, what then? Just save some pennies for a new one or can they be rebuilt? I am not looking at changing to lockers or anything drastic, my offroading is fairly limited and the stock system seems fine, I just need to make sure its quiet.

As for the pinion shaft, I am looking at the prop shaft part of the workshop manual and it doesn't say much (no suprise there.) What/how should I check for slack in the pinion shaft? Which flange should I be moving around? If it is loose do I need to get a new propshaft or do I need to do something else?

Reply to
Scot Kight

Scot Hi,

may I suggest something so that you check from which diff (front, center or rear) the howling may come.

Remove the rear propshaft, engage difflock on the center diff and drive the car for some distance until you can or can not listen any howling.

If you do not hear it then re-install the rear propshaft and remove the front. Do the same test.

In this way you will be able to establish whether the howling comes from any of the front or rear axle.

Reply to
Pantelis Giamarellos

Just got back in from testing this out. When I removed the rear propshaft, no difference in sound. Removing the front propshaft did reduce the sound just SLIGHTLY, but I think its more because of a pressure difference on the tcase than anything else.

So now the question is if the noise is constant and does not change with the gears, is the tcase the only remaining possibility? I guess it could be the transmission, but I would think that would change with the rpm and not the wheel speed.

Mike: I got the email, and while I think I have plenty of mechanical ability, I have no experience with transmission work so this might be best left to the experts. If I supply the LT230t to a shop off the truck, how much would you expect this kind of work to cost? Lets ignore the possibility of worn parts right now though I am sure a bearing or two will need replacement.

If I do get brave, does the haynes manual explain it better than the book? I understand some of what the book is talking about, but it does ask for special tools and processes, without much description.

Reply to
Scot

Scot Hi,

AFAIK if the noise is related to the transmission it must change WITH the WHEEL SPEED and not the engine's rpm. Unless you have a fault in your gearbox.

I remember you said that the noise gets louder when you accelerate and if you let the gas pedal it stops even though the car still moves. Am I right?

Take care Pantelis

Reply to
Pantelis Giamarellos

Yes. Only with power or under hard braking, auto transmission. Fluid on both transfer case and transmission are at proper levels.

Reply to
Scot

Scot I do not remember you saying anything about getting the whining noise when you are braking hard.

Have you checked your brakes system? Any chance of having stone chips between the pads and rotors?

Take care Pantelis

Reply to
Pantelis Giamarellos

Nope, its definitely not that, pads were just replaced by me and no change in the sound. It definitely appears to be either the transmission or transfer case. Only makes noise under braking when I have the truck in drive, not neutral. More and more it makes me think everyone is right and that there is a bad bearing in there at a bare minimum, which of course means a rebuild is required.

Reply to
Scot Kight

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