LSD service life?

[N3_Gabe]

Hey guys I was just browsing turner motor sports dreaming of my perfect track M3 and I came across this when looking at Diffs. In the paragraph it says that the service life for the LSD is 80k miles. Can anyone elaborate a little more for me? It seems straight forward(unless I'm reading it wrong) but is this really saying I would need to replace my Diff around 80k miles?? Any help would be great as I am now at 86k on my own M3.

[N3_Gabe]

Here is the paragraph I am referring to

[italyix]

I read that too a while back and I can honestly say YES. My diff was making all kinds of noises and wasn't working right. I replaced it with Florian's custom diff (m3racing dot de) and the car now turns much better.

Btw my swap happened at 84k

[N3_Gabe]

Ok great. Did you stick with the original gearing ratio as well or did you choose a different ratio?

[N3_Gabe]

And what kind of noises should I be listening for?

[dparm]

LOL WUT

80k service life? That's absurd. Unless you are perpetually on the track, or are introducing insane levels of drivetrain shock (think supercharging or constant use of launch control), it should last much longer.

I don't know how many people here are over 80k, but there's tons of them and I don't remember hearing about people just replacing the LSD "because it wore out".

While I appreciate Turner's candor and expertise, remember that they are still a business so selling LSD rebuilds is in their best interest.

[N3_Gabe]

Originally Posted by dparm

LOL WUT

80k service life? That's absurd. Unless you are perpetually on the track, or are introducing insane levels of drivetrain shock (think supercharging or constant use of launch control), it should last much longer.

I don't know how many people here are over 80k, but there's tons of them and I don't remember hearing about people just replacing the LSD "because it wore out".

I don't track mine and is like to think I don't put it under the levels of stress you mean. I don't hear any noises and the car turns just fine. I just had a question about that paragraph I read because it looks pretty straight forward on what they're saying. I just wanted to see if anyone else had experience on this or knowledge about the LSD

[Richbot]

Service life at optimal performance is probably accurate. I have noticed some loss of sensitivity of the diff over time now that the car has 81000 miles on it, to the point where it will spin the inside rear a little longer before locking up hard under certain circumstances like light throttle in the rain.

But for hard driving I have noticed no diff-erence

[drwankel]

80K seems a little soon, but the fact of the matter is LSDs will wear out due to the simple fact that the clutches inside are a wear item. Most cars I see above 100K with a LSD, the LSD is not working so hot past that point.

I'd imagine that some m3's LSD gets beat up significantly worse than others, so the 80K figure could be low.

If you intend on keeping the car for an extended amount of time (200k), you will most certainly be rebuilding the LSD at some point.

[italyix]

I replaced the diff out of necessity cause it waster locking up quick anymore and I was spinning only one tire. Every time I shifted I would hear a clunk in the back (I have all solid bushings and spherical suspension in the rear, zero slop). Even a shop thy services my car once said they could hear he diff make noises and had no idea what my plans were.

Now lock in almost instant, solid and makes for some serious drift fun. In the twisted I can corner much better and the car does not let go. Corners are much easier to handle now.

For everyday driving I would not bother touching the diff at all

I am on stock gearing

[TomHudson]

Originally Posted by dparm

LOL WUT

80k service life? That's absurd. Unless you are perpetually on the track, or are introducing insane levels of drivetrain shock (think supercharging or constant use of launch control), it should last much longer.

I don't know how many people here are over 80k, but there's tons of them and I don't remember hearing about people just replacing the LSD "because it wore out".

While I appreciate Turner's candor and expertise, remember that they are still a business so selling LSD rebuilds is in their best interest.

I'm at 86 km (55 miles) just having the LSD replaced under warranty...no track time at all. Next to the throttle actuators, it's the most common problem under warranty.

[dparm]

Originally Posted by TomHudson

I'm at 86 km (55 miles) just having the LSD replaced under warranty...no track time at all. Next to the throttle actuators, it's the most common problem under warranty.

According to who?

You guys sure are paranoid. I have no plans to replace the LSD at 80k. If it fails at 80k, so be it...I got my money's worth. I expect it to last far longer.


Anyway, back to OP's question: some guys running higher power levels and/or those who track the car have opted to change out the LSD, but for a daily driver or one that occasionally gets on the track/autocross I see no reason to use something other than OEM.

[doogee]

My differential was replaced at 37K, I find even this replacement one after 48K is pretty clunky.

[bigjae1976]

I would think you'd start to see some wear in the clutches at 80k miles but service life will really depend on what level you'd consider the LSD as no good.

Originally Posted by Richbot

But for hard driving I have noticed no diff-erence

Nice!

[admranger]

If you can put two black stripes down when you dump the clutch (or whatever you non-skilled DCT owners do...), then the locking function is working. Is it working at optimum? Probably not.

FWIW, the E46M3 has the same diff for all intents and purposes. I have no complaints on mine and it has ~90k miles with a substantial number of those being track miles (on 10th set of tires, fwiw).

Groaning is a fluid/lsd additive issue. Clunking can be loose bolts, bad bushings or something internally wrong with the diff.

[italyix]

Mine so so badly worn that the bearings had seized on the housing and had to be hammered out. Needless to say it was in bad shape.

[TomHudson]

Originally Posted by dparm

According to who?

You guys sure are paranoid. I have no plans to replace the LSD at 80k. If it fails at 80k, so be it...I got my money's worth. I expect it to last far longer.


Anyway, back to OP's question: some guys running higher power levels and/or those who track the car have opted to change out the LSD, but for a daily driver or one that occasionally gets on the track/autocross I see no reason to use something other than OEM.

According to BMW

[admranger]

Originally Posted by italyix

Mine so so badly worn that the bearings had seized on the housing and had to be hammered out. Needless to say it was in bad shape.

miles?

[italyix]

Originally Posted by admranger

miles?

84k

[bigjae1976]

I haven't seen many BMW diffs actually fail. I've heard that the E39 M5 LSD unit had a short service life. I know the shaft seals tend to leak after 100k miles. Other than that, haven't heard too much.

My experience...

On my 111k mile E46 M3, the diff is a little slow to lock up compared to my E90 M3. More noticeable is how the E46 unit operates somewhat abruptly which results in some interesting tank slappers. The rear axle can be somewhat unpredictable at times.

I just think back to me 2004 330ci which had a Metric Mechanic 3 clutch LSD 30/90 ramps. That car on street tires with a supercharger was hard to get sideways. Then it was much easier to get the car straight again after getting sideways. I knew what the car was going to do. Not so much in my E46 M3.

So I think the 80k mile service life is the LSD unit in the diff. Not so much the bearings or internal parts of the diff. Not surprising since the LSD unit has friction surfaces which would be classified as a wear item.

Most of the wear probably comes from all of the tight turning in parking lots and lifetime fluid fills.

[N3_Gabe]

Originally Posted by bigjae1976

I haven't seen many BMW diffs actually fail. I've heard that the E39 M5 LSD unit had a short service life. I know the shaft seals tend to leak after 100k miles. Other than that, haven't heard too much.

My experience...

On my 111k mile E46 M3, the diff is a little slow to lock up compared to my E90 M3. More noticeable is how the E46 unit operates somewhat abruptly which results in some interesting tank slappers. The rear axle can be somewhat unpredictable at times.

I just think back to me 2004 330ci which had a Metric Mechanic 3 clutch LSD 30/90 ramps. That car on street tires with a supercharger was hard to get sideways. Then it was much easier to get the car straight again after getting sideways. I knew what the car was going to do. Not so much in my E46 M3.

So I think the 80k mile service life is the LSD unit in the diff. Not so much the bearings or internal parts of the diff. Not surprising since the LSD unit has friction surfaces which would be classified as a wear item.

Most of the wear probably comes from all of the tight turning in parking lots and lifetime fluid fills.

Thanks for the good info!

[dparm]

Originally Posted by TomHudson

According to BMW

[citation needed]

Please show me, in writing, where BMW makes this claim. And no, one SA (read: service center salesperson) telling you that is not evidence. I am tired of anecdotal bullshit being peddled on here as fact in an attempt to scare people into ridiculous unnecessary maintenance and laughable babying of their cars.

But then again, if you guys love sinking money into stuff that is literally not even broken, nor close to it, go for it -- your car and your money. Just stop scaring others with unverifiable claims.