MFactory Mechanical Clutch Plate Diff soon available for E89 DCT

[stuartinzg]

The MFactory Mechanical Clutch Plate Diff is available soon for our E89's, apparently 3 months or so.

http://www.teammfactory.com/

While researching the right diff for my car, plus speaking to a few friends who are racing/drifting - I've decided not to go for the Quaife diff but instead opt for a mechanical clutch based system, same as on the M3 etc.

The prime candidate was a Drexler but they are very expensive ($3000+). MFactory has been making diffs for a while now, with a solid proven history and getting great reviews. Their mechanical diff will be circa ~$1500 for the E89, plus installation, I expect $2000 all in (~£1500).

There is a great comparison of the different diffs here: http://www.n54tech.com/forums/showthread.php?t=29755

Their other clutch based systems have the following specs:

MFactory® Metal Plate LSD™:
Availability - since 2008
Country of R&D - USA
Country of Manufacture – Taiwan (In-house)
Quality Control – ISO Regulated
Metallurgy – Housings are open-die forged from SAE4320 steel. Internals are cold-forged from SAE9310 steel
Origin of Barstock - Japan
Heat-Treatment – Double Tempered, Super Sub-Zero (Deep Cryogenic), Micro-Peened Surface
Lock Capacity: 20 clutch-disc setup, allowing an adjustable 20/40/60/80/100% Lock Capacity
Pre-Load: Spring type. Adjustable between 0-100% Pre-Load (~85lbfts)
Aggressiveness: Variable Cam with adjustable ramp angles
Warranty: Lifetime, Globally Transferable (excluding wear parts)

I think I'll be one of the first with this LSD for this car :driving:

 

[stuartinzg]

Also considering some of the suspension upgrades this chap has done here

http://e89.zpost.com/forums/showthread.php?t=879624

- Stock struts/shocks (with adaptive suspension) (got this already)
- Eibach or H&R lowering springs (done this)
- Front M3 tension struts (planned)
- Front adjustable sway bar end links (planned)
- Rear adjustable camber arms (planned)

 

[GuidoK]

for a mechanical clutch based system, same as on the M3 etc.

You're not going to get anything "same as on the M3", because the M3 has a speed actuated (gerotor or piston) LSD, and you'll probably get a torque actuated LSD (like OS Giken, Drexler, Kaaz). Those two have different mechanical workings.

With the M3 diff the clutch is actuated by the speed difference between the left and right wheel (so going in a straight line, the diff is not locked), and the m factory diff is actuated by the amount of torque on the wheels (so by how deep you press the gas pedal), so it's locked when accelerating, also in a straight line (and/or braking, depending if its 1.0, 1.5 or 2.0way).
If it has a clutch or not is of no importance, it's on what basis locking takes place that makes how a diff reacts.

Are you getting a diff with a welded gear or with a bolted gear?
I think the stock one was welded? (or was that only the case for the 335i/135i?)

 

[techathy]

I think the stock one was welded? (or was that only the case for the 335i/135i?)

It's welded. All applications take the OE diff an machine the gear so it can be bolted to the LSD. This is why I've not gone for some kind of LSD on my Z4 yet. Every avenue will be explored without going down that route before getting one.

 

[GuidoK]

Yes I've seen them (on video) grinding down the weld and drilling/tapping holes in the crown wheel from a 335i diff (I think at VAC motorsports).

The other solution is buying an aftermarket diff and an aftermarket crown gear. Obviously the crowngear will also cost money..
The welding of the gears wasnt bmw's best side in trying to save money imho. (the cost of a few bolts..)
Putting in a LSD was the first mod I did to my car (over 5 years ago already....)

When getting the diff out it's also a good time to beadblast the rear cover (they corrode like hell) and give the rest of the diff a lick op paint so everything looks new again (or is that just me :roll: )

 

[techathy]

Never managed to find an aftermarket item with the correct ratio for the 35iS. All were lower ratio for racing use. The last thing I want is a lower ratio on my final drive.

 

[GuidoK]

But you're sure it's welded? I mean information about the e89 is really dodgy on that front. Or have you opened it up?
It's a different diff from the 335i (the housing at least, ratio too I believe)

 

[techathy]

2 specialists said they'd need my car for a week as there aren't enough people doing LSDs on Z4s to have in stock crown gears. thus they'd have to machine mine & also I couldn't pay extra to not do an 'exchange' on my OE diff

 

[GuidoK]

did you spoke with birds?
Because they indeed speak of "E89 Exchange Quaife BMW Final Drive Z4 35is Dual Clutch" (for £1700), but they dont have a ready made swap lying on the shelf?
Thats rather amateuristic...

 

[stuartinzg]

for a mechanical clutch based system, same as on the M3 etc.

You're not going to get anything "same as on the M3", because the M3 has a speed actuated (gerotor or piston) LSD, and you'll probably get a torque actuated LSD (like OS Giken, Drexler, Kaaz). Those two have different mechanical workings.

With the M3 diff the clutch is actuated by the speed difference between the left and right wheel (so going in a straight line, the diff is not locked), and the m factory diff is actuated by the amount of torque on the wheels (so by how deep you press the gas pedal), so it's locked when accelerating, also in a straight line (and/or braking, depending if its 1.0, 1.5 or 2.0way).
If it has a clutch or not is of no importance, it's on what basis locking takes place that makes how a diff reacts.

Are you getting a diff with a welded gear or with a bolted gear?
I think the stock one was welded? (or was that only the case for the 335i/135i?)

Ah ok, I was under the impression that the E46 M3 ran a clutch plated LSD which was very similar (or supplied by?) Drexler. Don't know about the E9x. I'm still reading into all the various options, settings, - lot of different potential avenues and setups, but I've been told 1.5 way is the best balance between performance and street use.

I believe only the clutch based ones maintain traction with 1 wheel off the ground/no grip ? Friend of mine here was into competitive drifting and he was explaining the various types . Being crowned the Croatian Drift King he knows a few things about the various diff types, so I'll just take his word for it as I don't have any practical experience he is of the opinion that a clutch based LSD provides the best balance and maintains composure when the road surface changes mid-corner.

Yes, the E89 needs the grinding work done.

in his element

 

[stuartinzg]

Never managed to find an aftermarket item with the correct ratio for the 35iS. All were lower ratio for racing use. The last thing I want is a lower ratio on my final drive.

This Mfactory diff maintains the same OEM ratios.

 

[GuidoK]

I believe only the clutch based ones maintain traction with 1 wheel off the ground/no grip ?

No that's also not true (at least not entirely). Both quaife and wavetrack have an internal system that gives a little bit of preloading.
The preload prevents traction loss with 1 wheel off the ground, both on torsen diffs and on clutch type LSD's (except for the Mdiff).
Without preload a normal clutch type lsd also has no torque transfer, so no lockup!

Every type of LSD has advantages and disadvantages.
Obvioulsy for drifting or dragracing you want something with a lot of lockup. So probably a torque actuated clutch type with 2.0 ramp and lots of preload. For those type of applicatons the last thing you want is an agile car. (drifting is trying to loose traction, not to gain it )
But for agility in corners it might be completely different. For example in high powered fwd hot hatches (megane RS and such) not one of them uses a clutch type (as that would induce huge amounts of understeer!). Its all torsen (except the leon cupra r/290whatever, that uses a computer controlled torque vectoring type). The torsen diff wont have as much straight line stability (as there is no lockup when both wheels have traction), but agility is the opposite of straight line stability.
So every LSD has it's specific pro's and cons.
Even for racing, the new Radical RXC Turbo 500 (that McLaren P1/porsche 918 beater) has a quaife ATB LSD and that car as said easily outperforms the mclaren or P918 (equipped with advanced computer controlled torque vectoring LSDs). (if wanted you can also get that radical with a clutch type LSD, Quaife makes everything bespoke if you pay them)

In practice when driving and one wheel looses ground contact, the energy needed to accelerate that wheel will provide enough torque to lock up both diffs and provide traction to the other wheel.
ONly when for example off roading when standing stationary and one wheel hangs in the air and carefully apply the throttle it may spin. but in that situation the need for a LSD is long gone. You want 100% lockup (like an air locker or so) in that situation like true offroaders have.
(or maybe you're doing things with your Z we can't imagine :rofl: )

 

[35i-Nut]

Also considering some of the suspension upgrades this chap has done here

http://e89.zpost.com/forums/showthread.php?t=879624

- Stock struts/shocks (with adaptive suspension) (got this already)
- Eibach or H&R lowering springs (done this)
- Front M3 tension struts (planned)
- Front adjustable sway bar end links (planned)
- Rear adjustable camber arms (planned)

thanks for posting , some excellent info here !

 

[stuartinzg]

Stuff

Did you try a Z with a clutch diff? Just curious.

I believe it also helps when using the car in bad weather conditions - it's unusable for around 4 months a year here - and I'm on a hill with snow. Even the slightest ice strands me. Would a Quaife help me in this case?

At the end of the day I haven't tried all the types to comment, but I'm told by pretty knowledgeable people that if I'm going to pick a diff, pick one which will do more, in more situations, for the little extra it costs. I'm tending to agree with that principle.

 

[GuidoK]

Stuff

Did you try a Z with a clutch diff? Just curious.

No I didnt buy 2 LSD's, but I have driven my quaife in snow etc and have never had the problem with one wheel spinning and no traction (like with an open diff)
But in the snow a Z is pretty much useless anyways with the wide rear tyres, rwd/front engine etc.
If you're buying a clutch lsd because you cant get up an iced hill in the winter, you're buying it for the wrong reason imho.
An LSD is less safe anyways in winter/snow/ice/rain, because when you loose traction it's on both wheels and the car is out of control. With an open diff there still is one wheel with traction so it can at least move along the direction the steering wheel is in. With the lsd the rear will spin in that scenario. So it doesnt make it a better car for daily driving in snow conditions, unless you're racing. Faster, not safer.

 

[stuartinzg]

Did you try a Z with a clutch diff? Just curious.

No I didnt buy 2 LSD's, but I have driven my quaife in snow etc and have never had the problem with one wheel spinning and no traction (like with an open diff)
But in the snow a Z is pretty much useless anyways with the wide rear tyres, rwd/front engine etc.
If you're buying a clutch lsd because you cant get up an iced hill in the winter, you're buying it for the wrong reason imho.
An LSD is less safe anyways in winter/snow/ice/rain, because when you loose traction it's on both wheels and the car is out of control. With an open diff there still is one wheel with traction so it can at least move along the direction the steering wheel is in. With the lsd the rear will spin in that scenario. So it doesnt make it a better car for daily driving in snow conditions, unless you're racing. Faster, not safer.

No, not buying it for that reason alone - but the added control benefit. Just wondering if you had driven a Z with both clutch based and quaife so you could do a back to back comparison.

 

[techathy]

Having drive both FWD & RWD cars on snow/ice with a locking 1.5 way (FWD)/2 way (RWD) & helical LSDs (FWD without internal pre-load). No LSD is a magic bullet, it just increases the margins you have, a very small amount on snow & ice. The reality is you need to drive very carefully at low speeds maintain control of the vehicle regardless of what’s going on.

If you’re gently feeling in the power rather than trying to drift then there’s not enough force being delivered to the diff to significantly increase the torque applied to the wheel with traction, this applies to plated or helical LSD. Which means there’s a low likelihood of the locking LSD spinning the high-traction whee. However, with a helical LSD there’s nothing to actually quell the wheel spin so you can end up with a low-torque wheel spin. With an locking low-torque spin is less likely or the slip speed is reduced as the act of locking gives resistance to spin. Another interesting point is that when BOTH wheels break traction then a locking LSD will tend to be more controllable than a helical LSD or an open diff as the spinning wheels will tend to spin at the same rate rather than being effected by small differences in surface friction.

Under braking a 1.5 or 2 way LSD gives better stability on the drive axel, where as a helical is just sitting there being a lemon. On a FWD car the locking LSD behaviour is a problem on low-grip surfaces, as it means the front wheels are less likely to lock than the rear wheels & it’s spinning top time. On a RWD car this same behaviour means when the front wheels lock, which is the more likely scenario, the car will tend to travel in a straight line as the rear of the car is trying to slow down faster than the front.

 

[stuartinzg]

Thanks techathy, this mirrors what my friend was saying - although he recommends avoiding 2 way for the road entirely. He uses the characteristics of the 2 way under braking and corner entry to induce drift, which obviously I don't want ... :rofl:

 

[techathy]

Thanks techathy, this mirrors what my friend was saying - although he recommends avoiding 2 way for the road entirely. He uses the characteristics of the 2 way under braking and corner entry to induce drift, which obviously I don't want ... :rofl:

Yeah. 2 way LSDs are interesting to drive on, even on track.

 

[GuidoK]

Another interesting point is that when BOTH wheels break traction then a locking LSD will tend to be more controllable than a helical LSD or an open diff as the spinning wheels will tend to spin at the same rate rather than being effected by small differences in surface friction.

This also means that a helical lsd finds traction faster when one wheel comes on a decent piece of road.
I think that's one of the reasons Audi used torsen and also why a clutch type lsd doesnt work in a FWD car. A clutch type lsd just blocks by the amount of power applied and thus induces a force that makes the rear wheels turn the same rpm. A helical LSD is a force balance and sends the torque to wheel that can handle the most power regarding the rpm the wheels make. That's why it performs so good in corners (and why a fwd car would have massive understeer with a clutch lsd)

Under braking a 1.5 or 2 way LSD gives better stability on the drive axel, where as a helical is just sitting there being a lemon.

This is a common misconception. A helical LSD also has a bias under braking.
Look at it this way (very simple representation of the inner workings of a helical LSD): basically a helical LSD is a bunch of wormgears. If you have a wormgear driving a spur, you can drive the spur by turning the wormgear. But you cant drive the wormgear by turning the spur. That goes for driving the spur clockwise (driving) and anticlockwise (braking).
The same goes for the helical LSD albeit that the braking bias is in practice always less than drive bias. (something like 4:1 or so)
(this is set by the relative angle of teeth both gears have and on what curve they are grinded, which makes it very complicated to calculate)

On a FWD car the locking LSD behaviour is a problem on low-grip surfaces, as it means the front wheels are less likely to lock than the rear wheels & it’s spinning top time.

On a fwd car the characteristic of a locking LSD means that the front wheels are more likely to lock than the helical lsd, not less likely.
That induces understeer (as steering requires a different rpm on left and right front wheel ). A clutch locking diff would lock here (with power applied) regardless of the road conditions whereas the helical LSD regulates the torque by what the requirements (dictated by tyre road surface) really are. That's why only a smart (computer controlled) torque vectoring LSD can compete with a helical lsd in terms of functioning.

On a RWD car its just the other way around: more likely to lock on the rear (where the diff is) induces now oversteer.
That's why bmw develloped the M diff. that only locks when there is loss of grip from one wheel. If your diff always locks on power, you always have a problem in corners as one wheel wants to turn faster than the other one (both on fwd and rwd). (more oversteer when you passed the apex)