Differential whine?
Differential whine?
Author
Discussion

phillpot

17,437 posts

205 months

Tuesday 16th August 2016
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Sounds more like gearbox to me scratchchin


Checking the oil level would be a good start, but maybe too late!

John042

903 posts

191 months

Tuesday 16th August 2016
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I have a similar problem in trying to identify transmission noise. Mine seems to be in the gearbox area. Basically a continous mechanical noise not increasing or decreasing with acceleration. First thought was front wheel bearings, replaced to no effect. On advice oil levels gearbox/diff checked and additives put in to see if it made any difference: not really! Rear wheel bearings? No difference when cournering?? Another TVR owner did point out that you are virtually sat on top of the transmission so should expect some noise. Another opinion was that it might be the first motion shaft bearing in the gearbox. So I guess after carrying out the above I've discounted the diff' and will leave the rest until it gets worse. Try some additives Adam in the gearbox or diff and see if it makes any difference to aid identification but whining does indicate diff' I'm afraid. J C.

phillpot

17,437 posts

205 months

Tuesday 16th August 2016
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As a general rule gearbox noises are far less in top because the drive is straight through, no "sideways" load on the bearings.


from my experience diff noise comes in at a particular speed, you can then "play a tune" by going on and off the throttle!

900T-R

20,406 posts

279 months

Tuesday 16th August 2016
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^^^^ This. thumbup

Some noise is to be expected, changing diff oil can't hurt though if it's been awhile (looking at the oil that comes out will give you a rough indication of wear, too).

mrzigazaga

18,742 posts

187 months

Tuesday 16th August 2016
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Hi mate.

Clutches whine as well...Does it stop when you depress the clutch but start again when on the loud pedal...Or is it only on de-acceleration?

Number 7

4,111 posts

284 months

Tuesday 16th August 2016
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If it's bad enough to warrant attention, usually better to get your own diff rebuilt. Depending on what's wrong, for a Salisbury 4hu Powrlok (lsd) I think you'd be looking at £300-500. That's if you take the diff. Out yourself.

RCK974X

2,521 posts

171 months

Tuesday 16th August 2016
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Whines and squeaks can be really difficult to find and diagnose, so don't just assume it's the diff, although checking oil and its condition never hurts, and gearbox as well.

Try seeing if noise changes when you put clutch in, decelerate/accelerate, is there a whine when stood still, does it change/stop if clutch pressed ? Turn left and right also.... All that kind of thing.

Hopefully that will give you some more clues and help confirm.

From what you said, noise seems to gradually quieten as you go up the gears, I'd be suspicious of the gearbox (but I would still do the checks)

Ford boxes tend to do that when layshaft bearings wear out, don't know about LT77/Rover - I would assume it's similar.

I thought 4HU diffs tend to rumble rather than whine ? Or is that not true ? (i.e. lower rotation rate than gbox ?)

Edited by RCK974X on Tuesday 16th August 23:35

mrzigazaga

18,742 posts

187 months

Wednesday 17th August 2016
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Check your gearbox oil level....And for that matter the diff oil and also grease up all the UJ's while you are under there...Should be done every 6 months really if you use the car most days....

Ziga

Wedg1e

27,002 posts

287 months

Wednesday 17th August 2016
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4HU diffs are not prone to oil leaks unless the output shaft seals are shot, which can happen due to overheated brakes. They'll also tolerate a lot of abuse. I stripped my PowrLok at 122,000 miles (to replace the oil seals due to the aforementioned cooked brakes)and could detect no wear or damage in the bearings, the oil had minimal metal particles and the gear wear pattern was as shown in the Salisbury manual - and my car hasn't been driven by Granny for 29 years.
So if it has oil, there's no play in the bearings and the seals don't leak it'll probably go on for years even if it is noisy biggrin

More likely is that you have tired UJs, they create a vibration that increases with road speed and diminishes a bit if you dip the clutch whilst rolling (as the load comes off). Thay get a lot of stick on the Wedge as the half-shafts also act as the suspension upper link.
People sometimes grease the half-shaft UJs but forget about those on the propshaft (which spins faster although it displaces less from its axis).