2 way differential whine around 45mph... Anybody else?

[az_240]

I've got a 2 way cusco type MZ diff that will whine from about 45-60mph.
It goes away but then makes a louder whining sound around 80mph.

I put some shims around the diff bushings to make them nice and tight... but I dont think that alone will create a whine.

The guy that had the diff before me claims he never had any problems with whining from the diff at all...

I have dropped this diff 3 different times now and tried bolting it on different everytime with no change.

I also have stock suspension besides a ST sway bar and subfame collars.

Any help is appreciated.

Thanks

[Dousan_PG]

no sir
quiet as can be!
your ring gear might be going...

[az_240]

I inspected everything inside the diff housing... everything including the ring gear looked fine

[20 til 3]

what fluids are you putting back in it?

[az_240]

redline.... whatever is recommended.... i think its 75w90 or something.... with the ford friction modifier.
At first it had a thicker oil... redline 75w140 iirc

[20 til 3]

so you went from a thicker oil to a thinner? imo i think you might want to run the thicker stuff again, i'm no expert but process of elimination would come into play before spending a bunch on a new diff

[az_240]

it made no difference what oil I used.... still made the same whine

[Dousan_PG]

pinion bearing or output bearings could lead to whine

[drift freaq]

if you don't fix it, it will get worse and go boom. At which point you will wind up with a possible jacked ring and pinion and chunks of metal floating in your diff case. Which is not good for the clutch pack.

[az_240]

^exactly why I want to figure out what it is.... the whining itself I can take i just dont want to ruin my $800 diff.

Im gona have a chat with the mechanics at my work tomorrow and see what they say

Thanks for the replys

[scottie]

I had the same thing happen to mine. The tooth gap was not correct. There is supposed to be a specific amount of "play" the diff is suppose to have. You should be able to turn the input shaft (driveshaft) and the output shafts (axles) and there will be or should be some play before the teeth catch. It its off by even the smallest of margins, your diff will whine. I would check that if i were you.


Scott

[Dousan_PG]

get another open diff and swap the lsd
see if that fixes it.
cost is nothing
time is maybe a few hours.

[az_240]

I was gona do what Dousan suggested but I talked to some mechanics today and they said more than likely it is because of what Scottie is describing.... the diff is not configured correctly inside the housing and the teeth are slightly off....
Im gona drop the diff again and put some dye on the teeth to see how the mating pattern looks....
Then Im going to try calling some off road shops to see if they can help me since the transmission guy at my work will be busy for a while.

Thanks again for the help!

[!Zar!]

So, you bought a diff, tossed it in, and didn't check your backlash?

Uuuggghhh

Scottie is right. Since Scottie is right, Dousan is starting to be right being as how you are in the process of destroying your gear. You need a dial indicator and the dye to get your diff the way it needs to be. To adjust the backlash, you'll need shims. To either raise or lower the pinion untill it's where it needs to be. Being as how you are hearing a whining, it's more than likely too tight. So you might not need to buy any shims.

Either way, drive the car only to the shop.

[az_240]

mechanic said it wont do anything bad to the diff... just an annoying sound.

[Dousan_PG]

hahaha
great mechanic!

[Sir]

LOL.
That backlash issue will kill the diff.
All you need is right sized shims and someone who understands diffs.