Fitted a LSD to my e85 Z4 3.0

[Yorkie Z]

Job done......Works a treat soooooooo Happy

how did you change the final gear ratio ? i have a 2.5 and I would live to take some top end and swap it for acceleration

I brought a second had diff with a diffrent ratio. 3.07 stock and went to a 3.23

Have a look on here for an idea of the diff you could use..

http://www.bokchoys.com/differential/GearRatios.htm

 

[Tommy_hf]

Interesting, local shop in Holland cahrges 699 euros for the ATB and 889 euro's for the clutch type

 

[Yorkie Z]

Interesting, local shop in Holland cahrges 699 euros for the ATB and 889 euro's for the clutch type

Pretty much the same sort of price then really, think the clutch type is a bit better for the track rather than the road.

 

[ba3bas]

You say you got the final ratio off a sport, do you mean 3.0si and you have the 3.0i

 

[Yorkie Z]

You say you got the final ratio off a sport, do you mean 3.0si and you have the 3.0i

I used the complete diff from a 3.0si and fitted it to my 3.0i

 

[GuidoK]

I was going to go down the M3 diff swap route. But now i am not so sure this seems like a better option.

I wonder if the m3 diff swap is easy (so not a complete e46 m3 rear axle). Probably only an early e36 m3 diff will fit. The z4 has an 188k diff, and only the early e36m3's (3.0 s50) have the 188 diff. And what kind of ratio are you getting? And can you swap it for your own ring gear.
I mean: the diff housing doesn't fit (at least not the cover).
Also with an aftermarket diff you maybe can't fit all available ratio's. OS giken advertises that their lsd only fits the AT (gear ratio 3.46). I think that maybe the mounting flange position from the ring gear varies when using different ratio's (probably in 2 or 3 steps, so eg position 1 fits 2.90 to 3.25, postition 2 3.26-3.50 and so on (numbers are ficional).
But I don't know for sure.

 

[Yorkie Z]

I was going to go down the M3 diff swap route. But now i am not so sure this seems like a better option.

I wonder if the m3 diff swap is easy (so not a complete e46 m3 rear axle). Probably only an early e36 m3 diff will fit. The z4 has an 188k diff, and only the early e36m3's (3.0 s50) have the 188 diff. And what kind of ratio are you getting? And can you swap it for your own ring gear.
I mean: the diff housing doesn't fit (at least not the cover).
Also with an aftermarket diff you maybe can't fit all available ratio's. OS giken advertises that their lsd only fits the AT (gear ratio 3.46). I think that maybe the mounting flange position from the ring gear varies when using different ratio's (probably in 2 or 3 steps, so eg position 1 fits 2.90 to 3.25, postition 2 3.26-3.50 and so on (numbers are ficional).
But I don't know for sure.

Not sure about swapping internals from other diffs around.

Have fit a lsd unit into my casing now, go back a page or two

 

[McKoval]

I was going to go down the M3 diff swap route. But now i am not so sure this seems like a better option.

I wonder if the m3 diff swap is easy (so not a complete e46 m3 rear axle). Probably only an early e36 m3 diff will fit. The z4 has an 188k diff, and only the early e36m3's (3.0 s50) have the 188 diff. And what kind of ratio are you getting? And can you swap it for your own ring gear.
I mean: the diff housing doesn't fit (at least not the cover).
Also with an aftermarket diff you maybe can't fit all available ratio's. OS giken advertises that their lsd only fits the AT (gear ratio 3.46). I think that maybe the mounting flange position from the ring gear varies when using different ratio's (probably in 2 or 3 steps, so eg position 1 fits 2.90 to 3.25, postition 2 3.26-3.50 and so on (numbers are ficional).
But I don't know for sure.

I dont know the details, I only know that there's a garage in Poland which does it - as I was told by a guy who has that lsd in his 3.0i - its a diff shell and housing from a z4 and almost all the internals from e36 m3, set to $)% lock (1-way) , but I cant say what he meant by that. Makingh and fitting a hybrid like this costs around 400GBP but I'm a bit concerned bout two things:
- this is based on the used LSD so you cant be sure how long it will last (they claim to rebuild it but there is always a BUT )
- this is a clutch/plate type LSD so when I drive around 25k km a year it means I should service it at least once a year
- Clutch type LSD isnt worldwidely known for its delicate and subtle way of working in opposition to helical/torsen ones

So I am more than interested in MFactory option as its half price of quaife, and the same type (torsen).

 

[Yorkie Z]

Go MFactory it's spot on mate. Half the price and life time warranty

 

[ba3bas]

This isn't a party popper question at all, I just want to understand more….

What is the point?

I know what an LSD does but I want to understand why you would want to do this mod or have done this mod.
Cheers

 

[Machine monkey]

I was going to go down the M3 diff swap route. But now i am not so sure this seems like a better option.

I wonder if the m3 diff swap is easy (so not a complete e46 m3 rear axle). Probably only an early e36 m3 diff will fit. The z4 has an 188k diff, and only the early e36m3's (3.0 s50) have the 188 diff. And what kind of ratio are you getting? And can you swap it for your own ring gear.
I mean: the diff housing doesn't fit (at least not the cover).
Also with an aftermarket diff you maybe can't fit all available ratio's. OS giken advertises that their lsd only fits the AT (gear ratio 3.46). I think that maybe the mounting flange position from the ring gear varies when using different ratio's (probably in 2 or 3 steps, so eg position 1 fits 2.90 to 3.25, postition 2 3.26-3.50 and so on (numbers are ficional).
But I don't know for sure.

Not sure about swapping internals from other diffs around.

Have fit a lsd unit into my casing now, go back a page or two

I think you have to swap the hole rear axle to do the m3 swap and mod the prop shaft. Your option is looking better and better Plymouth

 

[sk93]

This isn't a party popper question at all, I just want to understand more….

What is the point?

I know what an LSD does but I want to understand why you would want to do this mod or have done this mod.
Cheers

First reason of all is traction. If one wheel is spinning, for example on split mu [different surface grip], an LSD can redistribute torque. If, for example, you have 1,000Nm available, you can have 100Nm on one side and 900Nm on the other side, instead of 500Nm on both sides.
Cornering is also improved. If you go through a bend at high speed the inner wheel becomes lighter and lighter until it begins to spin. An intelligent or passive torque-sensing differential can distribute torque to the outside to give an oversteering yaw moment to help you into the bend.

When you accelerate out of a bend you typically understeer because the front axle becomes light. If you add additional torque to the outside via an LSD (it doesn't matter whether it's on the front or the rear), that pulls the vehicle in and gives less understeer.

Another advantage is the opposite. Every LSD reduces throttle-off [lift-off] oversteer in a bend to a quite significant extent. Same goes for lane changing manoeuvres. If the vehicle becomes unstable the LSD more or less automatically reduces torque to stabilise and that's yaw damping.


Based on this, a tighter lsd, with a higher ratio, will give better acceleration and also better control through corners.
I drive my zed hard, and I really do miss a "proper" lsd.. you feel it a lot on twisty backroads up in the Yorkie dales 8)

 

[ba3bas]

Thanks SK

Best response to any question i've ever asked.

My next question, is doesn't this increase strain on the gearbox?

I heard it mentioned somewhere.
If you haven't noticed i am interested in the LSD.

It's cheap in comparison to most mods and seems to integrate perfectly with the car.

 

[Yorkie Z]

Wow SK93 nailed it

I'd say the strain on the gearbox would still be the same as you not adding power. Your only changing the way the car puts the power to the ground. In saying that I'd think with an LSD you put less strain on the diff as it's distributing the power more evenly.

Part of the reason I've put this Mfactory unit on my car is I really love to get the car sideways. When the roads are empty i love to switch off the driver aids Also if you ever do a U turn on a street you can spin the car round so easy. You'd have no chance doing this with the standard open diff. As you can tell I've fitted this for more of a hooligan reason. I only fitted it Saturday but after every trip I get out of the car buzzing
Driving the car normally thou you'd never know it was fitted so a perfect mod.!!!

£600 for the unit + two new oil seals + new oil and another oil change after 400 miles.!!!! Do it your love it I promise.!!!

 

[sk93]

Thanks SK

Best response to any question i've ever asked.

My next question, is doesn't this increase strain on the gearbox?

I heard it mentioned somewhere.
If you haven't noticed i am interested in the LSD.

It's cheap in comparison to most mods and seems to integrate perfectly with the car.

To answer the question regarding strain, I wouldn't say it increases the strain to anything more than normal driving.

Figuratively speaking the difference in strain between our open diff and a LS diff could be summed up as follows: if we have one wheel on ice, and one on tarmac, the gearbox would be "less strained" than if both wheels were on tarmac, as the torque required to spin the driveshaft will be less (as the open diff applies equal torque to both wheels.. and as one is on ice, thus requiring less torque to spin up to speed, the gearbox only needs to deliver enough torque to spin the iced wheel.). However, if you had an LSD fitted, then the gearbox would need to apply more torque to the propshaft to get it to turn,as the LSD will apply most of the torque to the tarmac'd wheel - which obviously requires more torque to turn than the one sat on the ice).

However, and this is the important point - the amount of torque (strain) required from the gearbox to rotate the driveshaft in this situation (one ice, one tarmac) is ALMOST the same as the torque required for a open diff (our standard diff) setup with both driven wheels on tarmac.
(I say almost, as the difference would be in the LSD scenario, only one wheel will be trying to push the car forward, whilst in the case of the open diff on tarmac, you've got two.).
It's not the case that as there's only one wheel "in play", you need to apply double the torque or anything like that amount.. we're probably talking a couple of percent difference.

So.. no. I don't believe you should be concerned with any additional strain on the gearbox, prop or engine caused by the LSD.
(However, if you start driving like a loon because you love the feel of driving sideways, well.. that's another story )

 

[GuidoK]

So.. no. I don't believe you should be concerned with any additional strain on the gearbox, prop or engine caused by the LSD.

There is indeed no extra strain on gearbox or propshaft. The maximum strain on those with lsd is exactly the same as without lsd but under good grippy conditions.
I mean: an lsd does nothing unless grip is not optimal :wink:
You can get extra strain on the driveshafts, because of lock (and the turning and vehicle mass can stress that), but that happens only with a clutch type and is obviously dependent on the amount of maximum achieveble lock versus the maximum strain the engine driveline can generate.
It can only happen to clutch types because a helical/torsen lsd technically has no lockup. It is a torque vectoring system. It also (always) already works before you lose grip (that's the point of the system. It is a balancing system between two wheels where the torque is devided between the two based on how much torque the wheel uses.
A variable clutch type lsd like an /m diff (uses a gerotor type lockup) or a centrifugal type can only engage after loss of grip is detected. That is a big difference between the two.

 

[ba3bas]

Cool,thanks guys


Very knowledgeable

As for fitting... Any special tools needed other than wrench, spanner maybe a hammer?

Also what fluid is recommended? You stated an oil change at 400miles. Do you mean 40k

 

[sk93]

also.. I've heard if you lick the LSD, you get to appreciate magic roundabouts more.. or something :roll:

 

[Yorkie Z]

Cool,thanks guys


Very knowledgeable

As for fitting... Any special tools needed other than wrench, spanner maybe a hammer?

Also what fluid is recommended? You stated an oil change at 400miles. Do you mean 40k

Torque wrench
big cerclip pliers
A decent set of bearing pullers

RECOMMENDED FLUID: When ordering your MFactory Helical LSD, we highly recommend that you order our Torco Manual Transmission Fluid (MTF).......From the website

Do I need to break-in your gears?
Our gears are fully finished and ready to run right out of the box. However, we do highly recommend that an initial fluid flush be performed after 3-400miles or 1 tank of gas, whichever comes first. The use of our Torco Transmission Fluid and Magnetic Drain Plugs is highly recommended....From the website

 

[GuidoK]

As for fitting... Any special tools needed other than wrench, spanner maybe a hammer?

Getting the diff out: E sockets (inverse torx)- for the drive shafts.
Carlift+transmission jack (the diff is heavy) or like here drive ramp+jack (but that's a nice challenge :lol: )

To get the drive flanges off: puller+ some inventive rig:

The drive flanges are hold in with a spring clip, but they can get stuck. Maybe you can get it popped loose with a well directed blow from a hammer, but you definately do not want to damage the dust shields connected to the drive flange! (this is also mentioned in TIS)

To get the diff out: Big ass C clip plier!


To get the bearings off: big ass hydraulic knive puller:

As I said earlier: this thing was not strong enough so I used a sharpened chisel and ferm hammerblow to get the inner bearing race going. You do not want to damage the bearing! They are not sold seperately by bmw! (you have to buy a whole diff!) (It is a FAG bearing, so maybe FAG can sell it seperately)

Magnetic holder and dial micrometer to measure backlash:

Do this check to verify the install is ok (or you will destroy your gears and the diff in the first few yards you drive the car)

For the diff cover you need some automotive silicone sealant. (The paper seal is not sold anymore)
And a torque wrench as the rear diff bolt has to be set at 170nm or so (quite high)

Also what fluid is recommended? You stated an oil change at 400miles. Do you mean 40k

Helical lsd's may use ordinary gear oil (only gears inside, so 75w90 or so). Clutch type lsd's use special lsd gear oil with clutch additives and different heat weight (80w140 or so).
And you need an oil injector syringe:

You could fill the diff off the car, but this is the proper procedure.

Imho you have to have some experience for this. I also wouldn't recommend an ordinary garage or dealer to do this install (getting it wrong with the bearings or gears will cause you a LOT of troubles), but look for a shop that is more performance minded. I mean: the bearings come off quite difficult. Getting them on is simple if you know the tricks (heating them in hot oil so they expand). And there are more little tricks to get this install right. For example it's handy to have some very large socket or so to tap in the new drive shaft oil seals (you need to replace them).
And TIS has no info about swapping the diff (as it is not a replacable item for bmw).
Have someone you can fall back on (and has a lot of tools) if you want to do it yourself and you're not experienced to do this kind of jobs.

As for flushing: I did my first diff oil change after more than 10k miles after the install. Oil was good and no iron residue on the magnetplug. But more frequent oil changes never hurt obviously, they can only do good.