Electronically Controlled Limited Slip Differential

[iDiaz]

Again, nothing new:

http://forums.bimmerforums.com/forum...php?p=10485717

[atr_hugo]

Powerman - we have seen that - In fact someone made a fairly big fuss recently that that's exactly what we're getting. (And that someone wasn't me - honest! ; -)

[bradford]

See this thread for much discussion...

http://www.1addicts.com/forums/showthread.php?t=1118

[aesthetect]

i guess the long and the short is that its a cheap upgrade from a purely open differential, theoretically inhibiting you from completely slipping away on one wheel. whatever load/brake-torque will reflect the amount of torque transferred to the other wheel (up to half of what is produced).

but its no replacement for a true LSD and just keep your fingers crossed that it acts predictably once the ass-end gets a little loose.. thats when im the most skeptical about its operation. although isnt it what is equipped on the euro 1er hatches? not a lot of complaints from over there..

i still just dont like it fundamentally. seems half-assed and wasteful, although that is a bit of an exaggeration.

[iDiaz]

Originally Posted by aesthetect

i guess the long and the short is that its a cheap upgrade from a purely open differential, theoretically inhibiting you from completely slipping away on one wheel. whatever load/brake-torque will reflect the amount of torque transferred to the other wheel (up to half of what is produced).

Yeah... as I said earlier, it would definitely serve to spare your tires from unnecessary wear if you're used to stomping the throttle without modulating for wheelspin.

Originally Posted by aesthetect

but its no replacement for a true LSD and just keep your fingers crossed that it acts predictably once the ass-end gets a little loose.. thats when im the most skeptical about its operation. although isnt it what is equipped on the euro 1er hatches? not a lot of complaints from over there..

Not a lot of complaints, but depending on how it can be disabled, chances are most spirited drivers disable it, much like they do with DSC.

Originally Posted by aesthetect

i still just dont like it fundamentally. seems half-assed and wasteful, although that is a bit of an exaggeration.

Well, regarding it being wasteful, it's likely part of the ABS controller supplied by Bosch, and more a function of software than anything else, so I doubt it costs BMW much more money to use it. The ABS controller already handles tons of different stuff, including dynamic stability control (taking feeds from wheel speed sensors, yaw sensors, steering wheel position sensors, and throttle position sensors), corner brake control (controlling brake distribution when braking mid-corner to ensure stability), electronic brakeforce distribution (distributing brakeforce fore/aft based on loads), and BMW's excellent ABS system itself, so it's just a matter of using the same hardware in a different way through software to accomplish this traction control "E-LSD".

[321]

i think he meant wasteful as in all the power doesn't get to the wheels, but rather goes to the brakes. :iono:

[atr_hugo]

Actually - it's only when the inside rear needs to be stopped that the energy is transformed into heat. Basically the way the E-LSD should work is when the inside rear starts to spin at a rate detected by the ABS sensors/software - braking force is applied to that wheel - since it's still an open diff, power will be routed to the path of least resistance - in this case the outside rear. The kicker will be is how seamlessly and smooth that tranistion will be and the brake release will be.

[bradford]

Originally Posted by zba857

i think he meant wasteful as in all the power doesn't get to the wheels, but rather goes to the brakes. :iono:

The funniest part is that we're talking about throttle here. "Wasteful" can be controlled with judicious application of the right pedal.

When lateral traction differential gets in the way, EDL will help you out, just like a mechanical diff.

Remember your buy-in point for this car, and stop bitching about the lack of a mechanical performance LSD.

[iDiaz]

Originally Posted by bradford

Remember your buy-in point for this car, and stop bitching about the lack of a mechanical performance LSD.

*flamesuit on*

The only way you can consider this car to be a great value is to compare it to other BMW models. I love BMW, and I'm definitely going to pick one of these up, but one only needs to look across the other pond to wonder why BMW is not installing a mechanical LSD.

The Evo MR (a direct competitor to the 135i) has not one, but THREE limited-slip differentials. A cockpit-controllable viscous center, front helical, and rear clutch-type. Admittedly, the engine isn't a BMW, but it's also nothing to scoff at, and the price of an all-wheel-drive system likely balances out to the price difference between the Evo MR turbo-I4 vs the 135i turbo-I6.

I'm not really a fan of Mitsubishi, but when you stack both cars up next to each other, though it's an incredibly sexy high-performance coupe, the 135i is not a good value, in my opinion. Regardless, where do I sign? :biggrin:

PS: Looking to another thread on this forum, there's the Mazdaspeed Miata, which had a mechanical limited-slip in its previous generation, and will likely have one in this upcoming generation. For $10,000 less.

[gotgemini2000]

Originally Posted by bradford

Remember your buy-in point for this car, and stop bitching about the lack of a mechanical performance LSD.

I completely disagree. A LSD is a 500 dollar option on the Mini Cooper S, a car which starts out below 25,000 dollars. The 1992 BMW 325i that my brother traded in on a new BMW 335i had a LSD as a 510 dollar option, the lack of a mechanical lSD is a huge rip-off if you look at almost any other competitor. The only reason that BMW will not be putting a LSD in the 135i is because it is not an M-car. In other words, the lack of a LSD is all marketing and has very little to do with the cost. All this being said, I will be purchasing a 135i regardless of what type of differential it has simply because I can't find another car that I want.

[bradford]

I've driven an Evo and my last car was a Mini Cooper S with the LSD. Both cars have incredibly low-rent interiors - no better than a Hyundai, and perhaps even worse. You get what you pay for.

[gotgemini2000]

The Mini Cooper S interior is terrific as far as I'm concerned. Yes, it's quite goofy, you kind of feel like you are driving inside of a cartoon, but that's the whole point of the thing. As for the Evo I'd have to agree with you. However, you still haven't addressed all BMWs made before 1995, all of which either had LSDs standard or as an option. Aren't we kind of going backwards by not having LSDs in the new BMWs?

[bradford]

Have you owned one or physically manipulated the working parts in one? It's cheap crap. Cheap hard plastic, crappy headliner. Everything is just junk.

I'm not referring to how it looks - I'm referring to material and assembly quality.

[iDiaz]

Originally Posted by bradford

Have you owned one or physically manipulated the working parts in one? It's cheap crap. Cheap hard plastic, crappy headliner. Everything is just junk.

I'm not referring to how it looks - I'm referring to material and assembly quality.

Yeah, the Evo interiors are crap, but the MINI is pretty much on-par with say, the base model 3-series. All base-model BMWs are made of a bunch of cheap plastic inside. The only differences in materials are the headliner being made of a different material, and a little bit of extra padding in the padded plastics (like the MINI dash and doors). Regardless, even if you were to use leather to upholster the interior, it still wouldn't amount to that dramatic of a cost difference (I used to work in the automotive leather industry). Certainly not enough to force them to not install an LSD for the sake of affecting their profitability.

Besides, this is supposed to be a return to their roots; to a lightweight, powerful, small, agile BMW. The 2002 that they trace the 1-series' lineage to was a pure sports car, so why would I expect anything less from its spiritual successor, the 135i? Spare me the extra padding and fancy headliner cloth and give me a proper mechanical LSD, dammit! :wink:

[gotgemini2000]

Originally Posted by bradford

Have you owned one or physically manipulated the working parts in one? It's cheap crap. Cheap hard plastic, crappy headliner. Everything is just junk.

I'm not referring to how it looks - I'm referring to material and assembly quality.

The tactile feel of the switches is great, the seats feel terrific, the doors shut with a great sound and feel extremely well put together, the engine is terrific, the shifts are perfectly placed, the quality of the interior of my family's 2007 Mini Cooper S is absolutely on par with my family's 2007 BMW 335i, 2002 BMW 540i, and 1996 328i, the only difference being that the cheaper Mini Cooper was offered with a LSD for only 500 dollars.

[larryn]

The e9X series has a decent interior (not stellar, but good), and other than the leather used, is identical in materials to the e60.

I've had Audis, LandRovers, many BMWs... the modern BMWs all have decent materials, but they are less driver-centric, compared to the e36 and e30 cars. Speaking of e36s, I still own one, and that's a cheap interior, but is much more driver-centric than the e46s and even more so when compared to the e9x.

Btw, Pre-1995 BMW offered LSDs because they did not have ASC or any sort of traction control. Remember, BMW tries to portay themself as a "forward thinking" company, pushing technological edges. Brining out new electronic doo-dads are their "thing". Some work and some don't. Let's hope this new eLSD works.

[bradford]

Originally Posted by gotgemini2000

The tactile feel of the switches is great, the seats feel terrific, the doors shut with a great sound and feel extremely well put together, the engine is terrific, the shifts are perfectly placed, the quality of the interior of my family's 2007 Mini Cooper S is absolutely on par with my family's 2007 BMW 335i, 2002 BMW 540i, and 1996 328i, the only difference being that the cheaper Mini Cooper was offered with a LSD for only 500 dollars.

They must have vastly improved quality. My 2005 interior was utter junk.

Great car otherwise though.

[grant]

Originally Posted by larryn

Btw, Pre-1995 BMW offered LSDs because they did not have ASC or any sort of traction control. Remember, BMW tries to portay themself as a "forward thinking" company, pushing technological edges. Brining out new electronic doo-dads are their "thing". Some work and some don't. Let's hope this new eLSD works.

Don't be too naive. If that system worked so well, why did they put a real LSD on the M cars back then? There is no substitute for a mechanical LSD...

[larryn]

Originally Posted by grant

Don't be too naive. If that system worked so well, why did they put a real LSD on the M cars back then? There is no substitute for a mechanical LSD...

LOL! Who's being naive? I'm explaining BMW's reasoning, as they've said. Please don't misread that post as my opinion. I only stated why BMW did what they did, as they themselves have said.

You may not want to be too naive yourself. Until this car is driven, that ELSD might suit 99% of the drivers that buy it. Personally, I'm skeptical, but hopeful that this gizmo works well.

Btw, I just installed a locking diff in one of my bimmers a couple months ago, because I know that the electronic nannies are no match to really putting the power down.

[ducati]

As mentioned above, Land Rover has been using a similar system in their vehicles for years. I've had off-road experience with Discovery 2's, 3's, and the Freelander 1. The technology is getting better, to the point in the Disco 3 that it works quite well, but it is still not as good as a mechanical limited slip (or if you're talking offroad, fully locked). Land Rover knows this, and started offering locking diffs again: on the LR3/Disco 3, you get a locking centre standard, and a locking rear option.

The big problem with traction control "diffs" was discussed at length above: you are using the brakes to slow the spinning wheel and let the natural diff action transfer power to the side with more traction. This has multiple negatives, but the two biggest are 1) your diffs wear faster and can even be "hammered" to death, and 2) wasting acceleration through braking/heat is not the best way to make further forward progress.

This can easily be seen in 4ETC-equipped Land Rovers that will actually grind themselves to a halt in some offroad conditions. The 135i obviously won't do that, but the analogy should not be lost: you will never be as "fast" with e-diffs as mechanical diffs.

The more I think about the lack of LSD in the 135i the more it annoys me. As mentioned above, a Mini buyer can have LSD for $500. BMW only saving LSD's for the ///M cars is a very weak exercise to keep the M's on top.

Re: Mini, EVO, and (I'll add) STI interiors: EVO < STI < Mini, IMO. The Mini is a little overstyled, but I thought fairly equal quality to a 3er. The EVO is super low rent. The STI's are a little better, but not up to the German's standards.

I personally don't buy a car for the interior, though, I find it hard to feel the soft-touch materials when I'm hammering down the road with a huge grin on my face

[grant]

Originally Posted by larryn

LOL! Who's being naive? I'm explaining BMW's reasoning, as they've said. Please don't misread that post as my opinion. I only stated why BMW did what they did, as they themselves have said.

You may not want to be too naive yourself. Until this car is driven, that ELSD might suit 99% of the drivers that buy it. Personally, I'm skeptical, but hopeful that this gizmo works well.

Sorry, I didn't mean to sound that judgmental (bad choice of words on my part).

However, I've owned a Porsche 996 which has enormous grip in the rear (from the 60%+ rear weight bias and 10" wide rear wheels) and it only had an electronic LSD. The results sucked and were very frustrating and I would expect the situation to be worse with less weight on the drive wheels, skinnier tires and more torque...