I'd like some LSD.

[C43AMG]

When i had the CL 55 and had it remapped, a slight acceleration would light up the rear's. After i had the Quaife the rears hardly ever lit up + of course the way the car felt planted Exactly the same with the 216, what a great addition. Highly recommended.

 

[Quackers]

I don't understand a couple of things in this thread.
How do you leave 2 black marks on a road without a locking diff?
Secondly how on earth can a non-locking diff (Quaife in this thread) make a difference to how the car feels on takeoff?
If it doesn't lock up then surely it's not doing any more than an open diff on takeoff?

There's a reason Quaife diffs are a fraction of the price of a locking LSD. It's because it's doing only half the job - if that.
There's also a reason some of the posters on this thread prefer the "feel" of a Quaife diff. That's because it's only doing the same job as an open diff.
A non-locking diff would seem to me to have no benefit whatsoever over an open diff.

 

[Steve84N]

You haven't got a scooby do what's what have you...

An open differential works fine most of the time but it's like lightning in that the power will be directed via the path of least resistance. Therefore, if a scenario arises where one wheel has little to no traction (inside wheel goes light when unloaded in a corner or ice/damp) then more power actually ends up going through that wheel and you get little to no drive on the wheel that still has traction. This is most often felt off the line or out of slow corners (which tend to be sharper so the inside wheel is more unloaded).

It's still possible to do 11s with an open differential when both tyres lose traction at the same time and/or partial application of the brakes provides a degree of 'false traction'. That is to say if the wheel is braked and you're applying power it's got to go somewhere. It stops one wheel spinning away with all the power and is basically how most traction control works. Hence, traction control can make you slower as it's braking the car whereas the more complex systems just cut power, usually via ignition cut.

Strictly speaking a Quaife is not a limited slip differential, it's a torque biasing differential hence the name Quaife TorSen (Torque Sensing). If there is literally no grip on one wheel then a TorSen is no better than an open. This only happens when a wheel is in the air or slick ice so in practice it's rare. More commonly one wheel will start to spin and suck away a lot of power but there's still some resistance to work with. A TorSen uses a system of gears to then multiply the small amount of traction available and send power to the wheel that has grip. It works on the principle of spur and worm gears, where a spur will drive a worm but you can't back drive a spur with a worm.

In practice something like a Quaife is very smooth and progressive in operation so is perfect for the road. It makes an obvious difference to a driver who is in tune with their car.

A true locking differential is usually based on a system of clutches that under slip conditions locks both axles together so that power is still applied to both wheels. This still covers one wheel being in the air. However, the progression from open to locked is more abrupt than a TorSen as it's pretty much on/off. Also, most of the time you want the wheels to be able to turn at different speeds when you corner as one has further to travel so the drag of a clutch can be felt during slow speed manoeuvring. Maintenance wise clutch differentials need more oil changes and the plates wear out a lot quicker than gears. Quite a lot of M or AMG cars with locking differentials are now driving around with a reduced locking effect as the clutches are worn.

An electronic differential uses a motor to apply the clutch intelligently based on various sensor feedback. Otherwise it's based on preload and springs.

Then you get the complexity of how much force is needed before locking occurs, whether it's 1 or 1.5 or 2 way (effective under acceleration or also under deceleration as well or in the middle).

Watch these videos, come back even further enlightened and perhaps ensure you know what you're talking about before you start making incorrect statements that are plain quackers and accusing people of not understanding how their car drives.

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[Quackers]

Yep, I know all that.
I think your explanation of doing "11's" sounds a bit thin though and even accepting it it would still seem impossible without traction control.
Of course a "Quaife is smooth and progressive" - it's not doing much. Or at least it seems to me. I suspect modern traction control functions have a lot more to do with how a Quaife diff "feels" to a driver than what the diff is actually doing.
Of course a clutch type diff will make a noise when the attached wheels are spinning at different speeds. It's to be expected - it's doing something.
An oil change every 30,000 miles or so doesn't seem too onerous a maintenance schedule tbh.

You also mention that a locking diff is more abrupt at locking than a torque biasing diff. Well yes, seeing as a torque biasing diff can't lock up at all!

And really why on earth would MB and BMW go to the trouble of buying and fitting clutch type LSD's to their cars rather than cheaper torque biasing units that would seem to please most of their customers?
Maybe they're better at the chosen application.

 

[st13phil]

Of course a "Quaife is smooth and progressive" - it's not doing much. Or at least it seems to me.

My guess from that statement is that you haven't driven a car with a TorSen-type diff? It does much more than you think it does.

And really why on earth would MB and BMW go to the trouble of buying and fitting clutch type LSD's to their cars rather than cheaper torque biasing units that would seem to please most of their customers?

I don't know the answer to that, any more than I know why people buy BMW M cars set up for track use and then only drive them on the road with all the pain and suffering that entails. Maybe it's just the bragging rights that it's x seconds quicker around the 'Ring than something else that's more suited to road driving? As I said earlier, if you're looking for ultimate performance off the line, or you're using the car on a track, then a locking LSD is probably a better bet; if you're driving on the road, a Quaife or other TorSen diff is likely more appropriate.

 

[moog999]

... when it spins the inside wheel under power on corner exit.

This is an easy way to tell.

Turn off TC.
Open drivers window.
Turn right out of a junction and give it some welly.
If the car does a graceful powerslide out it probably has an LSD....prior to this; check you are a driving god; dab of oppo and of you hurtle.
If you hear lots of tyre screech out your right window but no real over steer then it's likely an open diff.

On my lesser powered s212 you cannot induce a nice controlled oversteer type slide out of junctions. It just spins up the inside wheel, which you can both hear and feel. So, not worth wasting rubber on.

Back when I had a mazda MX5, with an LSD. In the wet you could get it to proper hang it's behind out on a rainy day excitable junction exit.

 

[Steve84N]

Quackers, if you 'knew all that' then you wouldn't still be asking these questions.

You don't actually need a differential to lock up under 99% of driving scenarios. If you have a too aggressive LSD it actually causes more understeer on corner entry and potentially more oversteer on the way out. It's why they created electronic LSDs as then you can leave it open most of the time where it's actually better and only lock it up when necessary. A mechanical LSD has more compromises.

A Quaife works and adds benefit both with and without traction control on, it actually means the TC kicks in a lot less. If you'd driven a car with one then you'd know...

Who says clutch is cheaper than geared differentials? I'd wager the manufacturing cost is higher for something like a Quaife. It's not just more oil changes as the clutch plates wear just like they do in a gearbox. Over time you lose some of the locking effect.

I don't care if you think the 11 explanation is a bit thin, the simple truth is it works (although not consistently like with some form of torque multiplying differential).

I will be fitting a Wavetrac soon which is like a Quaife but with some extra plates in the middle that apply pressure to still transfer torque when one wheel spins freely. This addresses the main weakness of the Quaife being effectively open if you're hanging the inside wheel in the air, like when pulling out of a T-junction on a heavily crested road.

 

[st13phil]

You don't actually need a differential to lock up under 99% of driving scenarios. If you have a too aggressive LSD it actually causes more understeer on corner entry and potentially more oversteer on the way out.

^ +1.

This is a very good explanation of why the Quaife or other torque-biasing diff’s are more pleasant to drive on the road, and why for the vast majority of circumstances are every bit as effective as a locking diff in terms of the additional traction provided.



Sent from my iPhone using Tapatalk

 

[tbourner]

My Supra didn't have one either, so I've never driven anything powerful with one - I'm not sure if I'm a good enough driver to notice or not, but all I can go on at the moment is that it drives pretty well. It may be a total revelation if I got one or I may not notice. Or if I do have one now I'm not sure how I'd tell the difference without driving one without, and then again I may not notice.

I can't afford one at the moment anyway. I don't think I asked MSL for a quote, only for exhaust work, but I can't remember as it was a while ago I filled in their contact form and haven't heard anything. Never mind, spend our money on the BM instead.

 

[Steve84N]

If you aren't missing it I wouldn't worry too much, just keep it in good tyres and that's half the battle won. I've just managed to get rid of the Yokohamas that were on when I bought it and the Michelin PS4S is in another league for traction.

 

[Quackers]

My guess from that statement is that you haven't driven a car with a TorSen-type diff?
That's correct. I've only driven cars with an open diff and a clutch type LSD (without traction control).

It does much more than you think it does.
I accept that this must be the case as people keep buying them and saying how good they are.

I don't know the answer to that, any more than I know why people buy BMW M cars set up for track use and then only drive them on the road with all the pain and suffering that entails.
Well, they're road cars.

 

[Quackers]

Steve84N, I concede above that people keep buying Quaife diffs so it might be that I'm just not getting things.
I've only driven with LSD's and no TC and other than reading about them I have no experience with using a Quaife diff, as you allude.

 

[Quackers]

You don't actually need a differential to lock up under 99% of driving scenarios. If you have a too aggressive LSD it actually causes more understeer on corner entry and potentially more oversteer on the way out.

That is true. A LSD can cause massive oversteer when the grip of both rear tyres is overcome.

 

[Steve84N]

I'm not saying clutch differentials aren't good, because they are. It's just that a torque biasing differential is also good.

 

[Steve84N]

I remember the massive understeer when both tyres span up in my old Honda Integra Type-R.

 

[PobodY]

This is an easy way to tell.

Turn off TC.
Open drivers window.
Turn right out of a junction and give it some welly.
If the car does a graceful powerslide out it probably has an LSD....prior to this; check you are a driving god; dab of oppo and of you hurtle.
If you hear lots of tyre screech out your right window but no real over steer then it's likely an open diff.

If I do this in the CLK it will certainly oversteer, but I haven't mastered the graceful powerslide... in fact if I stab the throttle it tends to violently swing the rear around; useful for hair-pin and U-turns, not so useful for taking off from the traffic lights.
I used to have the same thing in out R33 GTST, but that was much easier to control than the CLK and would perform a graceful poweslide; actually the bigger problem was getting it not to light the rear axle up. - Even my wife got quite practised at catching the slide and gracefully drifting the corner.

The little Nissan does have a limited slip differential, but that never spins the tyres because it immediately locks the viscous centre coupling and splits the torque. - It does an odd little "shimmy" as everything locks.

 

[PhilT]

All that info about the Quaife is correct thats why the Wavetrac one is better as it acts like a clutch type LSD. I have the wavetrac for mine just need to get round to fitting when I get some other things done.