Strange noise?

Busdriver · Post by **Busdriver** » Fri Mar 18, 2011 8:31 pm

I think it sounds like my rear diff has developed a howl in the gears. I travel 25kms to work and back every day on a freeway. At about 100-110 it starts to whine like a worn set of diff gears, and when I lift off the pedal the noise stops and its straight back when I press down again. I swerve side to side a little to move the weight bias and the noise doesnt change, so its not a wheel bearing. Its a 91 L series wagon, so the diff should only be coasting in 2wd? I had a look under it, checked the diff oil, all good, removed the back wheels and drums, spun the hubs, smooth and quiet.Checked the unis and centre bearing, no play and no sign of that red rusty powder they get when their on the way out.
Anybody had anything like this before and what did it turn out to be?
Thanks.

YouTube · Post by **El_Freddo** » Sun Mar 20, 2011 12:36 am

Yeah I've had my rear diff do the same. Swapped it out for another diff of unknown condition, noise went away replacement diff still in L now. Hopefully it won't get noisy any time soon!

If you can't get a good replacement rear diff and you're not headed off road any time soon you can get away with it by removing the rear drive shafts (and diff + second section of the tail shaft if you want too), this will stop the diff from rotating and creating the noise.

If the noise is still there, remove the diff and 2nd piece of tail/prop shaft that connects to the diff - then if the noise is still there I'd start looking at either tyres or bearings

My bet is the diff as you've suggested.

Cheers

Bennie

Busdriver · Post by **Busdriver** » Sun Mar 20, 2011 4:21 pm

Thanks Bennie, so your saying that the noise in yours only came when you had your foot down and stopped when you lifted off too? Just want to clarify this point because it seems strange that this happens even though there is no drive being put through the rear diff.

YouTube · Post by **El_Freddo** » Wed Mar 30, 2011 11:54 am

It was some time ago. I think mine was just there all the time but can't be sure. I remember being super happy when I didn't have the noise!

The rear wheels drive the rear diff. So when you're accelerating the wheels are also making the diff accelerate. Make sure there is oil in the diff/it is in good condition.

I don't think a second hand diff is expensive and the job is pretty easy to do.

Cheers

Bennie

Busdriver · Post by **Busdriver** » Wed Mar 30, 2011 12:43 pm

Cheers Bennie! I will try changing the diff oil, and failing that I might go for the old banana skin remedy, but then again with the price of bananas at the moment a new diff might be cheaper! A new car is on the cards soon (Brand new! Woohoo!) and I dont wanna spend too much on the old girl, but I dont wanna see it fall apart either, so a trip to the wreckers might be in order.

SuBaRiNo · Post by **SuBaRiNo** » Wed Mar 30, 2011 2:34 pm

You could try removing both the rear axles and seeing if the noise goes away. Just to be sure it's not wheel bearings.

Dave

Busdriver · Post by **Busdriver** » Wed Mar 30, 2011 2:43 pm

Thanks Dave, I might, but being an old mechanic I hate working on cars these days, especially my own, so I will change the diff oil, and then remove the shafts if I have too.
I have had a lot of noisy wheel bearings and busted diffs in old holden "banjo" style diffs when I was a lad, and the noise sounds to me a lot like a noisy diff, but you never know. Also a bit funny how its not there until the diff has warmed up for a cuppla k's too.

YouTube · Post by **El_Freddo** » Wed Mar 30, 2011 10:31 pm

Or you could take out the rear diff and half of the prop shaft, the front half is supported by the centre bearing on the L series. Works a treat - I've done it before.

You have to basically remove the diff to remove the drive shafts. PITA. Shaved stubs are the way to go IMO.

Without the rear diff/drive to rear diff you will know if it is the source of the noise... No $'s spent either, just some time

Cheers

Bennie