LSD noise when cold - normal?

[smbstyle]

I've noticed this noise for about as long as I can remember, bought the car with 5 miles on it. It's only the first one or two very low speed 90 degree turns, when I'm starting from a dead stop or very slow speed, I hear kind of a dragging/growling sound coming from the driver's side rear wheel area. After the first two turns, no noise whatsoever. Only does this after cold start-up.

Anyone else have this, and is normal? I figured a high performance LSD is gonna make a little racket.

[TheseColorsDontRun]

This is my second rwd LSD (LS2 GTO). They both have done it.

[smbstyle]

Originally Posted by TheseColorsDontRun

This is my second rwd LSD (LS2 GTO). They both have done it.

Good to hear! Now I can sleep easy tonight. lol. thanks.

[SloS14]

I like the noise. Reminds me I have an LSD. I don't think it matters if it's cold or not.

[Suberman]

Originally Posted by smbstyle

I've noticed this noise for about as long as I can remember, bought the car with 5 miles on it. It's only the first one or two very low speed 90 degree turns, when I'm starting from a dead stop or very slow speed, I hear kind of a dragging/growling sound coming from the driver's side rear wheel area. After the first two turns, no noise whatsoever. Only does this after cold start-up.

Anyone else have this, and is normal? I figured a high performance LSD is gonna make a little racket.

The Torsen in this car is a 4:1 bias which is REALLY tight. The noise you hear is the tires in tight low speed turns. This same bias kicks the tail out if you really floor it in the same turns.

[Suberman]

Originally Posted by SloS14

I like the noise. Reminds me I have an LSD. I don't think it matters if it's cold or not.

Not an LSD. Torsen is a torque sensing diff. An LSD locks up after a certain wheelspeed differential occurs. A Torsen biases torque to the slower spinning wheel. If you are on ice or have one drive wheel off the ground you will surely notice the difference.

[FRSBRZGT86FAN]

I do believe it is normal when cold on cars is rear differentials to make a small chirp or noise when cold, they need to be warmed up first by the friction of the gears and the heat spreading through the fluid.

[garfull]

so thats what that gear noise is. i only hear it when i first move the car after a cold start.

[Mikem53]

Sounds like the clutch packs in the diff.. Just need to heat up..
I know the Torsen diffs are different.. But on a normal LSD they sometimes add a friction modifier to ease the noise you get with tight turns.. It allows the clutch packs to slip a bit more so it doesn't make noise..

[BRZnut]

On tight low speed turns I get the rear sound too. Sounds like rear tires are "skipping" over the pavement, if that makes any sense. I especially notice it each morning as I turn out of my development.

[CSG Mike]

Totally normal

[Suberman]

Originally Posted by Mikem53

Sounds like the clutch packs in the diff.. Just need to heat up..
I know the Torsen diffs are different.. But on a normal LSD they sometimes add a friction modifier to ease the noise you get with tight turns.. It allows the clutch packs to slip a bit more so it doesn't make noise..

No clutch packs in a Torsen. The diff spider gears are helical one way gears (think of worm gears, non reversible) that develop their torque transfer effects by binding inside the carrier. Because they move axially slightly in one direction under load and in the other direction on overrun they can be made to slip more easily on overrun but tighten up under load, which creates the bias ratio.

Not a true LSD because they transfer torque by accelerating the slower spinning axle rather than braking the faster spinning axle. If you have no grip at one wheel you'll get no drive at the other wheel because zero torque remains zero no matter what the transfer ratio might be. This is the Achilles heel of Audi's vaunted Quattro drive. It relies on at least two wheels having grip, one at each end of the car. There has to be a wheel with grip to allow torque to transfer to another wheel. Quattro drive is also useless in reverse as you will find our Torsen diff to be if you get stuck going forwards. Torsen don't limit slip in reverse very well.

I found this helpful:

Be patient, it looks goofy and geeky but the explanation is first rate.

[cevin45x]

The exact noise the OP stated just started to happen to me this morning. Got me really worried. Sounded like a scrapping noise at low speed, left and right turns. And yes it got colder today (63 degrees)
But in my head it sounded like it was coming from the front right of the car. No sounds on the freeway or going on a ramp tho. Idk whats happening, debating if I should have it checked out.

Had the car since July 30th 2012. Been through one winter and no noises until today.

[rice_classic]

Originally Posted by Suberman

Not a true LSD because...

Everything else you said is right but that because it's opinion. As long as the inside tire is connected to the ground and has traction the Torsen Diff will bias torque. That is the definition of limiting slip and quite succinctly so. It seems to me that your definition is that of a "locker" or a "locking differential". I know I'm being pedantic but I just want to clarify the semantics. (and now I'm rhyming...)

The Torsen Diff does meet the definition of a slip-limiting device.

There are even torsen diff's (like the WaveTrac) that utilize an internal arc ramp so that the diff functions even when the inside wheel becomes unloaded, which is something would have been nice on this car.