Limited Slip diff (LSD) in the 2.0 with DCT?

lostpilot28 · Oct 28, 2022

Coming from a Cayman 718 2.0L, I really, really want to know if Lotus is going to offer LSD for the Dual Clutch version of the Emira. There is no factory or aftermarket option to add Limited Slip in the Cayman 718, and it SUCKS not having it. Otherwise, amazing performance.

Does anyone know if Lotus will have LSD in anything besides the manual?

Eagle7 · Oct 28, 2022

It's only listed with the manual V6, and welcome to the forum!

lostpilot28 · Oct 28, 2022

Thanks! I really hope there's an option for LSD with the 2.0L. It was a serious miss on Porsche's part with the Cayman...I hope Lotus doesn't follow suit.

VulcanGrey · Oct 28, 2022

I've seen a LSD available for the AMG M139 with the same transmission (I believe). So it might be possible.

lion shf · Oct 28, 2022

I just assumed the 4 had it. Not great if they don’t. It would come in handy in the winter.

VL3X · Oct 28, 2022

The AMG A45 S has a LSD.

lion shf · Oct 28, 2022

VL3X said:
The AMG A45 S has a LSD.

Option or standard?

VulcanGrey · Oct 28, 2022

VL3X said:
The AMG A45 S has a LSD.

in the rear...

I actually can't find the reference, that I thought I found, to the LSD in the 8G-DCT transmission for the front wheels.

VulcanGrey · Oct 28, 2022

the 8G-DCT has an open diff, but it looks like a LSD could fit there, if one exists.

VL3X · Oct 28, 2022

VulcanGrey said:
the 8G-DCT has an open diff, but it looks like a LSD could fit there, if one exists. View attachment 10201

Pretty sure it'll have an e-diff with the Emira setup.

VulcanGrey · Oct 28, 2022

VL3X said:
Pretty sure it'll have an e-diff with the Emira setup.

Correct for stock Emira. It'll most likely have an open diff with an E-diff function.

lostpilot28 · Oct 29, 2022

VulcanGrey said:
Correct for stock Emira. It'll most likely have an open diff with an E-diff function.

Isn't an e-diff a limited slip differential with electronic actuated clutch packs that make it more or less aggressive depending on traction? Technically, it's not an open diff at all. Right?

VulcanGrey · Oct 29, 2022

lostpilot28 said:
Isn't an e-diff a limited slip differential with electronic actuated clutch packs that make it more or less aggressive depending on traction? Technically, it's not an open diff at all. Right?

No, an E-diff is the ECU actuating the brakes to help prevent traction loss..

kitkat · Oct 29, 2022

lostpilot28 said:
Isn't an e-diff a limited slip differential with electronic actuated clutch packs that make it more or less aggressive depending on traction? Technically, it's not an open diff at all. Right?

No, the industry jumbles nomenclature for the purposes of marketing. eLSD, e-diff etc etc.

The Emira 2.0L M139 comes with an open differential that uses the rear brakes to limit wheel slip. It’ll work fine for the majority of people and it will annoy the minority of track goers.

Replacing it with a mechanical LSD and disabling the functionality will likely require reprogramming, replacing or bypassing a lot of control units that make the whole package work in the first place. I highly doubt this will be easily done with no other side effects. Modern engines and stability control systems are tightly integrated these days.

lostpilot28 · Oct 29, 2022

Gotcha. The Porsche has that but they call it PTV (Porsche torque vectoring)... basically brakes applied to the spinning wheel to get torque to the outside wheel. But they also give you a torsen mechanical LSD with that option.

kitkat · Oct 29, 2022

lostpilot28 said:
Gotcha. The Porsche has that but they call it PTV (Porsche torque vectoring)... basically brakes applied to the spinning wheel to get torque to the outside wheel. But they also give you a torsen mechanical LSD with that option.

Interesting they do that and a torsen. Torsens are decent and robust LSDs so long as both wheels are on the ground. I’m guessing they’re using the additional brake torque to fine tune the slip characteristics dynamically and to handle any wheels in the air conditions. Pretty smart of them!

lostpilot28 · Oct 29, 2022

kitkat said:
Interesting they do that and a torsen. Torsens are decent and robust LSDs so long as both wheels are on the ground. I’m guessing they’re using the additional brake torque to fine tune the slip characteristics dynamically and to handle any wheels in the air conditions. Pretty smart of them!

Yep... That's why I think adding a mechanical LSD to the Emira probably wouldn't upset the electronics too much.

Tokion · Apr 19, 2023

I have an order in for the Emira I4 with AMG M139 engine and DCT transmission. I have made another thread here at Emiraforum regarding the I4 possibly including the limited slip differential tech (for the rear drive wheels only) that is present on the A45 S. This is NOT an “e-diff” and it is not a “brake-based” system, but an active torque distributor. Unfortunately there is no response to me thread, and it seems that Lotus’ complete silence on everything concerning the I4 (FE), and also a general lack of knowledge on this matter in this community leaves us without any answers.

Here is an article published about the Mercedes AMG A45 S Limited Slip Differential and torque distribution system. It is important to be aware that the A45 S is a front-engined 4WD car. If any part of this AMG system will be used in the Emira I4, it can only be the rear axel Limited Slip Differential (which the article spells out is not a brake-based e-diff system, but supposedly a mechanical limited slip differential.)

<<With a clever twin-clutch rear limited-slip differential (paired with a system called AMG Torque Control) in the new AMG A45 S, the super hot hatch is able to split torque more cleverly than its predecessor.

While the first A45 could split torque between the front and rear axles, the new ‘S’ can take the torque that’s being delivered to the rear axle and split that however is necessary between each of the rear wheels.

This means the A45 S has proper torque vectoring (rather than just electronically-controlled ‘brake vectoring’), and can more easily maintain traction on the road when drifting isn’t the goal.>>

Are there any members here with knowledge regarding how the rear axel differential of the Emira I4 is designed? Does it include any AMG-tech, or does it contain any other system to distribute torque (including non-brake activated limited slip differential)?

kitkat · Apr 19, 2023

Tokion said:
I have an order in for the Emira I4 with AMG M139 engine and DCT transmission. I have made another thread here at Emiraforum regarding the I4 possibly including the limited slip differential tech (for the rear drive wheels only) that is present on the A45 S. This is NOT an “e-diff” and it is not a “brake-based” system, but an active torque distributor. Unfortunately there is no response to me thread, and it seems that Lotus’ complete silence on everything concerning the I4 (FE), and also a general lack of knowledge on this matter in this community leaves us without any answers.

Here is an article published about the Mercedes AMG A45 S Limited Slip Differential and torque distribution system. It is important to be aware that the A45 S is a front-engined 4WD car. If any part of this AMG system will be used in the Emira I4, it can only be the rear axel Limited Slip Differential (which the article spells out is not a brake-based e-diff system, but supposedly a mechanical limited slip differential.)

<<With a clever twin-clutch rear limited-slip differential (paired with a system called AMG Torque Control) in the new AMG A45 S, the super hot hatch is able to split torque more cleverly than its predecessor.

While the first A45 could split torque between the front and rear axles, the new ‘S’ can take the torque that’s being delivered to the rear axle and split that however is necessary between each of the rear wheels.

This means the A45 S has proper torque vectoring (rather than just electronically-controlled ‘brake vectoring’), and can more easily maintain traction on the road when drifting isn’t the goal.>>

Are there any members here with knowledge regarding how the rear axel differential of the Emira I4 is designed? Does it include any AMG-tech, or does it contain any other system to distribute torque (including non-brake activated limited slip differential)?

So the A45S has the 4th generation system called 4MATIC+

- The DCT gearbox up front mated to the engine's output shaft has three outputs: front left axle, front right axle, rear driveshaft.
- The front left and right axle do not have a mechanical differential electronic or otherwise, it is a purely open differential.
- The gearbox has the ability to send up to 100% of the power to the rear driveshaft.
- The rear differential has an electronically controlled hydroelectric clutch that allows torque distribution to either left or right rear wheel.

What you're reading and interpreting is correct about the A45S, it has a real differential moving power to the front and rear of the car and a real differential moving power left and right in the rear of the car.

What you're not understanding about the Emira is that Emira only has half of this system. The half that powers the front wheels in the A45S. The half with the open diff. The emira doesn't have the output shaft to the rear differential, it doesn't have the rear differential, it doesn't have the hydroelectrically actuated clutch controlling left and right power.

All the Emira has is brake based vectoring using the open differential.

kitkat · Apr 19, 2023

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