Is it normal to have a slightly audible diff noise?

[Vash]

As stated, a MSM Torsen now occupies the place of the stock 1.6 diff. However it's been slightly noisy ever since the swap was done. The noise level is light and only audible when no AC or radio is on.

Various experts, including miata specific techs and a diff guru have told me that it's normal for a slightly worn torsen to be a little noisy and it's completely ok, but I am just slightly worried. I do not have any proof behind my fear except for my daily driver, a current Gen civic Si, and a Gen Coupe owned by my brother both are equipped with a Torsen, and both are fairly quiet during operation.

I guess I just don't want to lose this rather hard to source part prematurely( In fact, I persisted in search of a MSM unit as it was said to be the strongest available) Your opinions are appreciated in advance.

[SM16RMSM]

I am interested. I have a MSM. I would think a noisy diff means your running a bit low on diff fluid. It could also mean something else since the noise could be that the gears are rubbing to close.

[jux]

Do you still have the carpet and insulation in the back of the car?
I pulled these items at the same time as installing the Carbing lower triangle brace, and there's a very definite whine...primarily on hard acceleration above 3k rpm.

[Vash]

SM16R: I'd certainly hope so. It's currently filled with a quart of Redline 75W90, perhaps I should try a different brand of juice? I also got this diff already installed in the carrier/pumpkin as a unit, and only have to seal it up against the housing prior to installation. therefore if the backlash was set wrong it would be a defect from back when the donor car was built.

jux:
The rear deck carpet's still there, however I pulled out most of the insulation underneath since they hold water like nothing else and corroded the fuel pump cover horribly( the rain rail has since been replaced and a hard top put on). And now come to think of it, the 1.6 diff did get slightly louder after the insulation pull, however the MSM unit simply makes a even louder noise.

To clarify, it's a low pitched whirring type of noise,kinda similar to a old hub bearing except for that both rear hubs have no play. And the noise is always present anytime the car is in motion, volume relative to rear end speed.

Sorry Yellowyata, I was dozing off while typing the above post, thanks for cleaning it up!

[SM16RMSM]

Do you know any history on the donor car?

[Vash]

My apologies, however, none was provided at the time of purchase except for that it's never been messed with since removal, I was simply promised a mechanically sound MSM diff and it indeed functioned fine except for the increased noise level.

[concealer404]

The diff in my MSM is rather noisy as well. I wouldn't worry about it. I notice it mostly on decel, though.

I would try Amsoil. I put all Redline fluids in mine this summer, and i'm not terribly impressed. Miataturbo seems to like the Amsoil products, proclaiming it to be "magic unicorn jizz." I'll be switching to Amsoil in Spring.

[Vash]

Thanks concealer! Yeah It's the most audible during decel/coasting in my case as well. although you can somewhat hear it in other occasions.

I will give amsoil a shot. I've already put the motorcraft Chuck Norris cum in the tranny and noticed a subtle improvement over redline MT90. amsoil might just work better in the rearend.

Now which one would you recommand? Severe gear or 75w-90 long life?

[The Driver]

How many miles in your car? It could be the rear hubs...

[concealer404]

Thanks concealer! Yeah It's the most audible during decel/coasting in my case as well. although you can somewhat hear it in other occasions.

I will give amsoil a shot. I've already put the motorcraft Chuck Norris cum in the tranny and noticed a subtle improvement over redline MT90. amsoil might just work better in the rearend.

Now which one would you recommand? Severe gear or 75w-90 long life?

I don't know which i'd try... probably the long life for a street car.

How many miles in your car? It could be the rear hubs...

Dunno about him, but mine has done it since i picked it up @ 65k miles.