LSD

[GuidoK]

It says enough that when you sell your car, that selling the lsd will be far more easier.
You see that all the time on forums when someone is going to sell a tuned car.... nobody wants the car but everyone wants the BBK or KW clubsports or LSD or Supercharger kit or whatever goodies are on there.

Imho it's one of the best mods you can do to your car. At least if you use your car as a sportscar.
I also think its more useful for hooning around on canyon roads/mountain passes etc than on a track

[tintoverano]

how about accidental (not track, not pushing the limits) rear end step-outs on wet surfaces, driving conditions?

[GuidoK]

An LSD is less safe/predictable on rear end step outs on wet surfaces.
This might sound strange, but with an open diff, the chance that only the inner wheel is spinning (for instance when pulling away from a traffic light in the wet in a corner) is much greater than with an LSD (because thats what an LSD prevents).
Now, as long as your inner wheel is spinning, that means that there is no or less foreward torque (as it all gets wasted on that inner wheel), and the outer wheel always has grip. So no step out.

Of course WITH an LSD, you prevent that inner wheel spinning. Therefore you have more foreward traction in those conditions and you will be FASTER. But when you loose traction, it will step out, and you'll be going faster when that happens.

Therefore I always advise to leave traction control and esp on when driving in the wet/on potential slippery surfaces (that can also be dry with for example beach sand on the road), unless you are aware of this and actively want to play around a bit.

So imho an LSD is a performance option, not a safety option. Driving with an LSD requires more skill from the driver. Because you can go faster.
So an LSD is for drivers who are constanly annoyed by the traction control cutting in when driving over manhole covers, tight corners, traffic lights etc. So people with a certain driving style...

[Gabz]

I owned multiple BMWs with and without Quaife LSDs (330ci and Z4 35i). I have personally found the open diff a lot more unpredictable. The "ediff" comes in abruptly and aggressively (breaking one wheel) which is either enough to kick the end out violently for a split second or does absolutely nothing. The helical LSD that Quaife does never locks and distributes power continuously depending on grip levels, ensuring maximum traction. I have found it extremely predictable, with the rear end losing grip very gradually when applying too much power. If you are pushing a Stage 1+ map, you'll find it very difficult to put power down in 1st, 2nd and sometimes 3rd (wet) gear without an LSD.

I think the LSD is a must for any RWD cars pushing over 250bhp (provided you like to slingshot out of corners, junctions, roundabouts etc.). If you are a chilled out driver, it won't make any difference.. but then you might as well drive a Micra

One thing I'd say is that unless you have manual trans, forget "drifting" even with an LSD. The auto/DCT box is great but awful for low-speed fooling around.

[R60BBA]

It says enough that when you sell your car, that selling the lsd will be far more easier.
You see that all the time on forums when someone is going to sell a tuned car.... nobody wants the car but everyone wants the BBK or KW clubsports or LSD or Supercharger kit or whatever goodies are on there.

Imho it's one of the best mods you can do to your car. At least if you use your car as a sportscar.
I also think its more useful for hooning around on canyon roads/mountain passes etc than on a track

I don’t dispute that.

Selling the LSD shouldn’t be an issue.

My point was more referring to the labour costs of getting a mechanic to install and remove the LSD, outweighing the difference it would make on the road.

Changing the diff on a car requires mechanical knowledge, it’s not a DIY job and I highly doubt the average Z4 owner is a mechanic or knows how to competently to this job. *However if you are mechanically minded and can do this job then there’s no need to read further.*

Birds, Isleworth (who practically make a living out of this) quote 4 hours just to install a Quaife, and then another 4 hours to remove it. The average BMW independent charges £90 an hour. Thus, 8 hours of labour at £90 = £720. That is £720 which you won’t get back. Not to mention you will lose a couple hundred quid on the LSD itself come re-sale. All in you’ve already lost a grand, and for what? Just so that you can have more controllable skids at roundabouts? It’s not like these are 500+ bhp cars which struggle with putting the power down in a straight line either.

An LSD swap is 100% not worth it if the car’s power output is not going to be significantly increased or if it is not going to be put on track.

“If you want the LSD, just buy the M.”

[GuidoK]

Changing the diff on a car requires mechanical knowledge, it’s not a DIY job and I highly doubt the average Z4 owner is a mechanic or knows how to competently to this job. *However if you are mechanically minded and can do this job then there’s no need to read further.*

Birds, Isleworth (who practically make a living out of this) quote 4 hours just to install a Quaife, and then another 4 hours to remove it. The average BMW independent charges £90 an hour. Thus, 8 hours of labour at £90 = £720. That is £720 which you won’t get back. Not to mention you will lose a couple hundred quid on the LSD itself come re-sale. All in you’ve already lost a grand, and for what? Just so that you can have more controllable skids at roundabouts? It’s not like these are 500+ bhp cars which struggle with putting the power down in a straight line either.

An LSD swap is 100% not worth it if the car’s power output is not going to be significantly increased or if it is not going to be put on track.

“If you want the LSD, just buy the M.”

Where there's a will, there's a way.
knowledge is something you can master. The ability to learn skills is what makes us human. I speak from experience.
So looking around on the internet, asking around, going to a diy garage and rent a lift + gearboxjack for 10quid an hour or so... whats wrong with that? I bet the diy garage has a press and maybe you have to buy a hydraulic knifepuller for £80.
Then again I completely agree with that people who's rather not get their hands dirty should be charged insane rates by people who don't mind getting their hands dirty for others.

And if you're thàt worried about labour costs, buying an M sure is the way to go. With rodbearings that have to be changed every 50k miles, a Vanos that is far more complicated and that requires service on more aspects than the m54 vanos, and I can name another few points.

And people who think that LSD's are about controllable skids at roudabouts are people that have the driving style of a granny.
The straight line reference says enough I think. You couldn't be further from it
Imho an LSD mainly shines in slower awkward corners, you know, off camber corners and stuff like that.
If you're annoyed with situations like that when your car cant get the power down at those moments, then you need an LSD.
And it doesnt take a 500hp car to loose traction in those situations (especially if its also a bit damp or if its dirty or hot tarmac); with 150hp you can also struggle. It all depends on how sharp that turn is.

It was the first mod I did on the stock car (and imho probably the best one), but I guess it all depends on what kind of driver you really are.

[R60BBA]

Changing the diff on a car requires mechanical knowledge, it’s not a DIY job and I highly doubt the average Z4 owner is a mechanic or knows how to competently to this job. *However if you are mechanically minded and can do this job then there’s no need to read further.*

Birds, Isleworth (who practically make a living out of this) quote 4 hours just to install a Quaife, and then another 4 hours to remove it. The average BMW independent charges £90 an hour. Thus, 8 hours of labour at £90 = £720. That is £720 which you won’t get back. Not to mention you will lose a couple hundred quid on the LSD itself come re-sale. All in you’ve already lost a grand, and for what? Just so that you can have more controllable skids at roundabouts? It’s not like these are 500+ bhp cars which struggle with putting the power down in a straight line either.

An LSD swap is 100% not worth it if the car’s power output is not going to be significantly increased or if it is not going to be put on track.

“If you want the LSD, just buy the M.”

Where there's a will, there's a way.
knowledge is something you can master. The ability to learn skills is what makes us human. I speak from experience.
So looking around on the internet, asking around, going to a diy garage and rent a lift + gearboxjack for 10quid an hour or so... whats wrong with that? I bet the diy garage has a press and maybe you have to buy a hydraulic knifepuller for £80.
Then again I completely agree with that people who's rather not get their hands dirty should be charged insane rates by people who don't mind getting their hands dirty for others.

And if you're thàt worried about labour costs, buying an M sure is the way to go. With rodbearings that have to be changed every 50k miles, a Vanos that is far more complicated and that requires service on more aspects than the m54 vanos, and I can name another few points.

And people who think that LSD's are about controllable skids at roudabouts are people that have the driving style of a granny.
The straight line reference says enough I think. You couldn't be more from it

It was the first mod I did on the stock car (and imho probably the best one), but I guess it all depends on what kind of driver you really are.

Rod bearings (which can last up to 100k miles*) and vanos (lasts 120k miles) are preventative maintenance service items and maintain value come resale (ie. more people will be interested in a car which has had these done than one which hasn’t). Not to mention M cars in general hold their value much better than non-Ms.

You can have an awful lot of fun with a Z4 3.0si in stock form, it doesn’t need an LSD. I only realised my Z4 could do with an LSD when I took it to the Nurburgring and the inner wheel kept slipping. I respect public roads and never felt the car needed a Quaife before this.

This post is quite funny as initially I agreed with what you were saying (LSD is better than open diff). Of course it is. The point which I believe you’re still missing (due to your somewhat insecure ‘granny’ references) - is that it is expensive and not necessary.

One of the main reasons I bought an M car was due to the LSD mate.

[GuidoK]

It's not necessary if you drive like a granny.
But then you also don't 'need' a sportscar. A 60hp micra will also get you to your destination.
If you never felt the need for an LSD, you haven't used the potential of your car in situations where it matters.
Its very simple: an lsd makes the z4 a better car at the moment you need traction the most.
Some people have no problem to lift off the throttle in those situations (granny driving style), and some people get an lsd. Thats how I see it

And how can you say the car doesn't need an lsd, but you bought another car mainly because of the LSD?
Why do you contradict yourself?

And the matter of expensive is a matter of how tight you are. Fun things cost money. But then again you're also convinced that 100k miles on rodbearings shouldnt be a problem....
Show me 1 set of rodbearings with 70k mile or more without wear. Ok, 2 sets, I once have seen a set that was 'passable', but that is probably the exception on the 500+ examples you can find on the net... There is always 1 person that hasnt revved it over 4k all its life.

And then I'll show you 100k miles supercharged m54 rodbearings with virtually no wear (from an engine that produces way way more torque than the s54). Ok, only my cyl6 bearing had some uneven wear and thats probably due to the flexing of the crankshaft but thas to be expected if you raise the torque output with almost 60%

And I've seen vanos hubs broken on 30k miles cars. Those hubs have a design flaw that has no real relation to mileage or maybe even car use. On some cars they are just broken when you least expect it. So I have a feeling you don't know all the real problems at play in an s54 despite owning one.

[R60BBA]

It's not necessary if you drive like a granny.
But then you also don't need a sportscar.
If you never felt the need for an LSD, you haven used the potential of your car in situations where it matters.
Its very simple: an lsd makes the z4 a better car at the moment you need traction the most.
Some people have no problem to lift off the throttle in those situations (granny driving style), and some people get an lsd. Thats how I see it

And how can you say the car doesn't need an lsd, but you bought another car mainly because of the LSD?
Why do you contradict yourself?

And the matter of expensive is a matter of how tight you are. Fun things cost money. But then again you're also convinced that 100k miles on rodbearings shouldnt be a problem....
Show me 1 set of rodbearings with 70k mile or more without extensive wear.
And then I'll show you 100k miles supercharged m54 rodbearings with virtually no wear (from an engine that produces way way more torque than the s54). Because I get the feeling you havent got a clue what used rodbearings should look like when you say stuff like that.

First question:

My E86 Z4 had 261 bhp.

My E46 M3 has 338 bhp.

The cost of moving from Z4 to M3 was nil.

Yet I gained all of the M performance.

Second question:

My rod bearings came out clean despite having done 60,000 miles in 14 years. Easily could’ve lasted another 40,000 miles.

*by the way, the clue in the rod bearings is due to the S54 revving to 7,900rpm. I’ll let you work out the rest.

My question:

Didn’t know grannies drove Z4s?

[GuidoK]

I see wear on all your bearings.
Its obviously not the worst I've seen but they're certainly not 'clean' as you say.
But you do with your car what you want. If you're worried what the labour costs are for installing an lsd, I wont bore you what the labour costs are on a spun bearing.

Your vanos hub is also still in good nick? Check the vanos chain wheel bolts too while you're in there.
Maybe change the bolts on the left motor mount bracket? (the right one is always OK as thats the same part as on the m54; only the left S54 bracket has the bolt problem)
And of course no leakage at the diff input seal, also never happens on an m.

So yeah, buy an m if you dont want any labour costs....

Its very simple imho: if you want to play, you have to pay. Theres no way around it. Whether you buy an m3 or mod a z4.
And if you're willing to get your hands dirty, offering up a day in your weekend and do some research on forums speaking with people who have actual hands on experience then you can achieve huge savings on labour costs. Also if you go to a diy garage, there are probably also always guys around there that can give you some good assistance. Most people around there are car guys obviously.

And you may gained all the m performance, but you also gained 175kg
Thats 2 times me sitting in your rear seats
Try reducing that kind of weight and you'll really see what labour costs can add up to.

[R60BBA]

I see wear on all your bearings.
Its obviously not the worst I've seen but they're certainly not 'clean' as you say.
But you do with your car what you want. If you're worried what the labour costs are for installing an lsd, I wont bore you what the labour costs are on a spun bearing.

And you may gained all the m performance, but you also gained 175kg.
Thats 2 times me sitting in your rear seats

Show me a set of bearing shells that have done similar mileage to mine that are cleaner.

My bearing shells are proof that if the engine is looked after properly (ie waiting for the car to get up to temp before opening full throttle and conducting regular oil changes) - then the bearing shells will last.

A spun bearing can score the crank which could require a bottom end rebuild, starting from £4,000. Not something I have to worry about.

Don’t mind the rear seats either! Means my car is more practical and I can have all the lads back in it again when I want!

I think most of your posts on this thread illustrate the following points:

1. You find it difficult to accept that a stock Z4 does not need an LSD. (If it did then everyone on this bloody forum would have one).
2. You come across as a Mr Know It All. Now you may know all there is to know about supercharging a Z4 (I’m not gonna sit here and pretend I do because I don’t), however you clearly have a lack of knowledge and understanding of S54 variants.

See ya on the open road.

[GuidoK]

1. You find it difficult to accept that a stock Z4 does not need an LSD. (If it did then everyone on this bloody forum would have one).

Did your z4 have an LSD?
(I ask this because everyone here who has done this mod says it improves the car, and I wonder if you actually speak from hands on experience or that its just a prediction of yours)

however you clearly have a lack of knowledge and understanding of S54 variants.

What is the thread size of your conrod bearing cap bolts?

[GuidoK]

Show me a set of bearing shells that have done similar mileage to mine that are cleaner.

100k miles on my engine (see sig)

[Elmo85]

Well this is an interesting discussion about engine bearings
Back to Limited Slip Differentials...

This is actually my first post on the forum!

I've had my 3.0Si Coupe for only a month. Done less than 2000 miles in the car so far and I can tell you right now I will either be selling this car very soon or fitting an LSD shortly!

I cannot believe that some people on this forum think an LSD is not necessary. This is the only RWD car I have ever owned without an LSD and I cannot believe how much it ruins the car! I've been endlessly researching diffs since the first week I got the car. (I'm also surprised how little choice there is)

Due to an unfortunately very expensive year planned for me I have had to downgrade my cars recently and the 3.0 Z4 Coupe is what I have decided to give a try for a while.

As a very cheap daily run around I used to have a Mk2.5 MX5 Euphonic with 146bhp and even that low power figure benefited hugely from an LSD. I find it's more about driveability and control than pure grip. The 260bhp of the Z4 is absolutely enough power to require an LSD.

GuidoK I must thank you for your excellent detailed responses on this forum!

I genuinely think I have read every single one of your posts about your Quaife LSD and I'm quite sure it is the option I will end up going for. I rang birds this afternoon and they have parts in stock. I just need to make sure I like the car enough to spend this money on it. I am not totally sure so far by the electric steering but I plan to fit powerflex lower wishbone bushes next week to improve the snatching feeling.

GuidoK can you help me to understand 2 things please regarding your quaife LSD :-

1) How is the driveline noise over time Compared to the standard BMW unit? My car is on 88k miles and there is some small driveline whine nothing serious and my car is in very clean condition for the mileage. I just hope to reduce the noise when fitting a quaife.

2) Have you ever specifically used the quaife setup for drifting? Without ruining my car I hope to do some drift days this year and I think it could be a good option.

[GuidoK]

GuidoK can you help me to understand 2 things please regarding your quaife LSD :-

1) How is the driveline noise over time Compared to the standard BMW unit? My car is on 88k miles and there is some small driveline whine nothing serious and my car is in very clean condition for the mileage. I just hope to reduce the noise when fitting a quaife.

The Quaife diff itself works completely silent, also in tight turns.
However, if you already have driveline noise, chances are that that's already in your pinion/crownwheel or your input or outputshaft bearings.
The Quaife diff isn't going to change anything about that as you only buy the diff core from Quaife/birds (so you have to open your existing diff and transplate the Quaife, or buy a donor diff and put it into there.
Where your driveline noise is coming from is impossible to say. You have to put your car on a ramp, have it run in 3rd gear or so and start to listen with an engine stethoscope to try and find the source.

2) Have you ever specifically used the quaife setup for drifting? Without ruining my car I hope to do some drift days this year and I think it could be a good option.

I've done some driftdays with my Quaife and that goes fine. However if you're buying an LSD specifically for drifting, a plate style LSD might be a better choice.
The main difference between an Quaife LSD and a plate style LSD is that a Quaife LSD feels like an open diff, but with very sticky tyres. So the Quaife diff doesnt mess with the understeer/oversteer balance, but you just dont get that inner wheel spinning anymore.
A plate style LSD however gives more oversteer. A plate style LSD starts to lock up as soon as force is applied, so as soon as you're stepping on the throttle, it starts to lock. The more throttle (the more force on the wheels) the more the plate style diff locks up.
And in corners that gives oversteer. And for drifting you can use all the oversteer you can get (best trick for drifting is buying the cheapest crappiest rear tyres you can get to get as little grip as possible)
The Quaife diff balances torque and sends torque to the wheel that can handle the most torque, before any slippeage even occurs.