Just wondering if anyone could tell me what causes a diff to make a howling sound?

The diff in my EL futura makes a howling sound on deceleration and I am wondering why? I bought the car last year and it had 92,000km on the clock and now has 115,800km... I fondly remember my opt20 making this exact sound when I had the car, I got the opt20 off my dad and between us we did atleast 150,000km and the howling sound was always present on deceleration and never got any better or worse, the person we sold the car to still has it and it now has well over 300,000km on it and is still going strong, so what exactly is the howling sound?

Also wondering how often the diff should be serviced in an EL? I am wondering if mine had ever been serviced before I got it...

Also thought I might add that the sound is ONLY on deceleration and I can make it go away by droping the auto back to 3rd however the sound will come straight back when I put it back into drive (while still not accelerating)

Thank you in advance for your help!

I remember replacing diffs in them when they had only 20,000km on them, and under warranty.
I had a talk with an engineer from Timken ( the supplier of bearings to BTREng ), and he said it would have to be about the oil quality, and or cleanliness of the components when assembled.
I said the oil looked burnt usually when they were stuffed......oil quality????....Yep.

We always suggest to service diff and gearbox oils every 50 - 60 000Km.

Best to be safe than sorry.

I'm going to assume mine hasn't been touched so I will service it ASAP ... im not expecting the howling to go away but hopefully it will help the diff last longer than what it would untouched.

The howling or better know as whining . ( high pitched noise ) if from incorrect pinion preload . Basically your pinion gear isn't meshing with the crown wheel, within specs .
Either your pinion nut has came loose or something has worn .

I changed me pinion seal and it whined after it , marked eveything and installed the way it came out.
It won't damage your diff but in the long run the gears will wear quicker , so I've been told .

Only way to get rid of the whine is to rebuild the diff , new bearings, seals , crush washer and reset preload and backlash to factory tolorences .

That's what I'm doing with mine in a week or 2

Thanks for the info... sheds some light on the issue for me... how expensive is a rebuild for a falcon diff? (roughly) Is it even worth spending much money on a single pegger? of if s**t itself is it worth finding a LSD?

Expensive to rebuild , $600+.

Not hard to rebuild as long as you have a dial indicator , inch pound torque wrench, tools, bearing kit , work shop manual .

Not worth spending money on it .
Find a LSD and rebuild it while it's out of the car .

As above... You best find yourself a factory manual and have a read... Fairly involved sort of process... Takes a bit of getting your head around...

You have Toe & Heel adjustments and Face & Flank adjustments, plus everything is tightened to a preload and backlashes are measured to be within spec... Will require borrowing a full set of shims to keep sticking in an trialling until you get everything right and then just purchasing the ones your used... Every bearing change will require a shim change...

A diff is nearly set up to be within 1 thou of perfect... Very crucial... And as far as I was aware is once the diff starts making a pinion to crown noise the gears are knackered and need replacing... But if it is just a bearing noise then gears are OK?

Tools as above plus a spring gauge and diff spreader and gear blue and there is a special flange tool and thing like that too...

Considering you could buy a wrecked car for $100 like we have done on many occasions, that makes a cheap SS diff... And would be easier to swap the diff than rebuild it... And then you can get the body crushed for $80 a tonne of whatever steel is worth nowadays...

Cheers,
Tim

Hey Tim, at today's price of steel you might even make a profit on a $100 wreck.

Shano, often diff noise can be reduced or eliminated with Redline Synthetic 80W140 diff oil: http://www.redlineoil.com/product.aspx?pid=37&pcid=4
May be worth a try before spending significant money.