Exige - the Diff debate

[Maxi_z]

Ok after a lot of talking with pb racing and different advice from different racers or owners of race lotus I choosed to fit the quaife differential

I got maybe more people that would choose the plate lsd but off course in a trackday lotus with the differential not being easy to access or remove to change settings etc maybe the quaife will be a better average that should work almost in any conditions if not all and as I already used a torsen on the exige cup 260 and drove the elise cup racing car with slick with it and did not found anything I didn t like I think it s the less racing choice but still a very good upgrade but will see after the next trackday.

They will also change the oem gearbox oil for something that should be better suited to the track.

I ordered the innovative mounts in 75A but will fit them later when they are delivered.

 

[Arun_D]

Great, let us know how you get on with it, as I will more than likely follow suit next year.

[Jack]

11 hours ago, Maxi_z said:

Ok after a lot of talking with pb racing and different advice from different racers or owners of race lotus I choosed to fit the quaife differential

I got maybe more people that would choose the plate lsd but off course in a trackday lotus with the differential not being easy to access or remove to change settings etc maybe the quaife will be a better average that should work almost in any conditions if not all and as I already used a torsen on the exige cup 260 and drove the elise cup racing car with slick with it and did not found anything I didn t like I think it s the less racing choice but still a very good upgrade but will see after the next trackday.

They will also change the oem gearbox oil for something that should be better suited to the track.

I ordered the innovative mounts in 75A but will fit them later when they are delivered.

 

A torque-sensing LSD will be an improvement when running with no traction control/handling nannies on.

Good luck!

[Maxi_z]

Just did some track laps today with the quaife lsd

The differential work really well as expected and nothing at all to complain about it

The inner wheel do not spin anymore and the lap time improved of around 1.5 seconds on same track.

The car behaviour is about the same as before without any noticeable increase in understeer or any noise etc just good traction no slipping of one wheel and if drifting a little it feels more natural and predictable.

My car also had the hubs shimmed for more camber at the front set around -2.4 degrees each wheel so that helped too but the diff itself make a really noticeable difference.... well in fact you do not notice much.... it s the lack of limited slip differential that you notice a lot....

I did not drive a lotus with a plate type differential and maybe I would like it even more but I think that there could be also a few thinks to like less if it s not setup near your preferences and maybe it s better for a car really well setup for the track

and with tyres that are more sticky while the quaife is always really neutral and makes the right work most of the time.

BTW if you track the car especially on a track with thight curves in second gear any type of limited slip differential would be a really good upgrade and even on the street even if less noticeable is much better.

 

[alias23]

8 hours ago, Maxi_z said:

The inner wheel do not spin anymore and the lap time improved of around 1.5 seconds on same track.

My car also had the hubs shimmed for more camber at the front set around -2.4 degrees each wheel so that helped too but the diff itself make a really noticeable difference.... well in fact you do not notice much.... it s the lack of limited slip differential that you notice a lot....

The 1.5 seconds is a substantial improvement was that properly timed or more a feeling of what the improvement has been?

-2.4 on the front? I know most folks struggle to get -1.5 on the front by removing all shims. Have you milled back your hubs?

It would be really helpful to understand the differences mechanically, and in character for road and track usage of the Quaife vs Dexler diff. 

[Arun_D]

Great feedback, Maxi. It's good to start getting more people's real-world feedback on the LSDs. I never ever bought the 'this guy with a Lotus salary doesn't like them, therefore the cars definitely don't need them' argument. For a rounded proposition suiting the majority of customers, then fine, the Bosch DPM system is adequate enough.

As above, some more details on your camber setup would be appreciated. We were targeting -2.1deg when my car had its TTX dampers fitted last week, but of course we culd only get to just under 1.5deg without more major mods being made.

[Maxi_z]

4 hours ago, alias23 said:

The 1.5 seconds is a substantial improvement was that properly timed or more a feeling of what the improvement has been?

-2.4 on the front? I know most folks struggle to get -1.5 on the front by removing all shims. Have you milled back your hubs?

It would be really helpful to understand the differences mechanically, and in character for road and track usage of the Quaife vs Dexler diff. 

It was timed with aim solo lap timer

I could only get around -1.2 each wheel front by removing the shims and not lowering the car

They milled the hubs so it should be able to go up to around -3.0

It s true that the car wants to go left or right a little more easely with more camber and that you feel slightly less braking grip but it s much better on the track and you can alway play with toe.

 

[Maxi_z]

2 hours ago, Arun_D said:

Great feedback, Maxi. It's good to start getting more people's real-world feedback on the LSDs. I never ever bought the 'this guy with a Lotus salary doesn't like them, therefore the cars definitely don't need them' argument. For a rounded proposition suiting the majority of customers, then fine, the Bosch DPM system is adequate enough.

As above, some more details on your camber setup would be appreciated. We were targeting -2.1deg when my car had its TTX dampers fitted last week, but of course we culd only get to just under 1.5deg without more major mods being made.

I think that many of the Lotus choices are just marketing on those things look as how they were saying that they did not fit the watercooled supercharger as it s heavier to then make of course the exige 430 cup or used small brakes for years and now full sized ap racing calipers etc....

Lotus have a base platform withthe elise and exige that is excellent for the feeling and for the track and they improved it with success in many many things lately but if you really want to use the cars you still have to loose time and money not just to improve them but to modify things that are not well made and not up to the rest of the car.

Another example my older cup 260.... I bought it used and at the first track use I had the problem of the fuel pick up and was told that standard the fuel tank is made in a way that at half empty it wont pick up the fuel on track...

I mean how can you let any car out of a factoly that way.... but especially how can you let a cup car out of a factory that way....

Or it s engine mounts where so soft and so much movement of the engine that even on a backroad it was really not easy to downshift as gears wold not want to go in.... after switching to innovative mounts it was almost perfect...

I did not actually measure the new camber setting after they milled the hubs but they told me it s around 2.4

Elise parts have some nice suspension arms for the v6 but unlike their older models they do not change camber so I did not find any part to buy that would allow for more camber and could only make the hubs modification.

 

[Jack]

 

4 hours ago, Maxi_z said:

Lotus have a base platform withthe elise and exige that is excellent for the feeling and for the track and they improved it with success in many many things lately but if you really want to use the cars you still have to loose time and money not just to improve them but to modify things that are not well made and not up to the rest of the car.

Another example my older cup 260.... I bought it used and at the first track use I had the problem of the fuel pick up and was told that standard the fuel tank is made in a way that at half empty it wont pick up the fuel on track...

I mean how can you let any car out of a factoly that way.... but especially how can you let a cup car out of a factory that way....

Or it s engine mounts where so soft and so much movement of the engine that even on a backroad it was really not easy to downshift as gears wold not want to go in.... after switching to innovative mounts it was almost perfect...

 

@Maxi_z --- So true in so many areas of all Lotus cars that will see significant time on track.  Had to do several "mods" to all my Lotus track-only cars, including the Cup240, Cup255, 2-Eleven and even the V6CupR.  As you would expect, the CupR came stock with "more of the right stuff already done" and was the best built car that I had received to date from Lotus Motorsport compared to the others I listed above.   But, even with the CupR,  we had to mill the front hubs to be able to get the optimum negative camber up front for track use.  Granted, from the factory, 2 degrees of negative was possible, but it wasn't enough. Same for the rear, the eccentric cam plates had to be repositioned in order to get additional negative camber. Milling the front hubs and modifying the rear eccentric cam plates are, IMHO, essential if you plan on doing significant track duty.  We also had to make some improvements to the water, oil and transmission cooling systems,  abs system,  instrumentation, etc.  Some of the changes may have not have been absolutely mandatory, but certainly made the car better.  For me, it's an enjoyable part of the Lotus journey; besides, I'm just a "modaholic" anyway.

My new Lotus Motto …… "simplify, add lightness and then modify"   

 

[MartynB]

For clarity, do you guys mean milling the hubs for camber (if so I assume for clearance) or just a typo for uprights?

[alias23]

On 17/11/2017 at 17:39, MartynB said:

For clarity, do you guys mean milling the hubs for camber (if so I assume for clearance) or just a typo for uprights?

Milling hubs to get better camber on front

[MartynB]

Sorry Imran. That still doesn't make sense to me. Time for a diagram...

I've been assuming that to get more negative front camber, people would be milling away the shimable surface at the top of (part 1) the Upright. Are you saying that there is a mod done to (part 2) the Hub Unit? That would seem very strange. Surely the uprights?

[alias23]

Sorry forgive me! Terminology... you are completely correct it’s the top of the uprights.

[chumaxa]

I know it is not the purpose, but have you had the chance to test with the lotus dpm system on ? Everybody think the lsd and the dpm system won't work together, and you are the only one here able to actually tell us the truth, would you mind testing please  

[Bravo73]

3 hours ago, chumaxa said:

Everybody think the lsd and the dpm system won't work together

No, they don’t. That was just a recent bit of JMG bs. 

There are plenty of V6 cars around with LSDs. None of them seem to be having any issues with the DPM. 

[chumaxa]

That's exactly why I ask, I think like most people, I have done it yet because I want the dpm to be fully operational if I resale the car.

Edited December 2, 2017 by chumaxa

[NW76]

Yep ... lets find out ... I cant really think of a reason why the DPM should not work anymore with an LSD fitted ... but would also really appreciate if someone who went down that route writes a brief feedback.

There were also rumors that the DPM would not work anymore after a significant power increase (EX460) ... I can definitely say that it still works fine after the EX460 ? ... 

[Swiss380Cup]

@NW76 Don't think KT would propose LSD knowing that DPM doesn't work anymore. DPM-TC whatever basically is an electronic brain analyzing wheel spins, etc. so it should be able to adjust to any condition including a mechanical LSD.... don't you think ???

[NW76]

also my rational ... @GFWilliams already wrote that RACE mode still seems to work ... 

[GFWilliams]

I now have a LSD fitted. Only driven it on the road in very slippery conditions.  So far I can't conclude if it helps with traction at all, but I can conclude that it's made the car a LOT LOT more fun!! 

[Maxi_z]

The only times I use the car on the road in sport or touring mode I wasn t in situations where the traction control would work but if I accelerate in a roundabout in first gear as if I wanted to drift in touring the traction control cut off power and the car do not go sideways much if that is what you wanted to know then the traction control and dpm are working.

If you want to know if in extreme situations there is a change in how the traction control reacts when there is also the quaife fitted I don t know I would have to do a few laps on track in touring or sport but I really don t think that there should be any noticeable difference apart that it will react as any car with a limited slip differential before the traction control is on.

Komotec and many others fit quaife or other lsd and no one complain about electronic problems of the tc.

 

[CRM82]

On 4/10/2017 at 19:48, GFWilliams said:

This photo sums up why I want an LSD.

This is a very interesting picture. Can you clarify me a couple of things please? Without LSD it looks like you can still drift the car and powerslide it. Do you do it in the same way youbwoild do with an LSD? I read you (or someone else) says it is harder to do and control.. why?

Another point: on my cup 380, between race and off, there are also a few "almost off" settings that allows between 1% and 12% of slip. What should happen if to drift we use one of those settings, e.g. the 12%? In theory, your interior wheel should still slip (as above) but less, and maybe you get more close to an LSD case. Am I wrong?

 

[GFWilliams]

10 hours ago, Cristiano said:

This is a very interesting picture. Can you clarify me a couple of things please? Without LSD it looks like you can still drift the car and powerslide it. Do you do it in the same way youbwoild do with an LSD? I read you (or someone else) says it is harder to do and control.. why?

Another point: on my cup 380, between race and off, there are also a few "almost off" settings that allows between 1% and 12% of slip. What should happen if to drift we use one of those settings, e.g. the 12%? In theory, your interior wheel should still slip (as above) but less, and maybe you get more close to an LSD case. Am I wrong?

Any car is possible to drift if you're committed enough, it's simply a case of how you approach the corner. This corner I approached at the top of third gear on the inside of the corner (it's a right hander), dab on the brakes as I then then turn hard left to unsettle the car, then turn back to the right and the car will be sliding. It's all about weight transfer and causing the rotation. Once it's sideways, in high speed corners it's pretty easy to keep it sideways as there's enough power so even with an open diff you can keep both wheels spinning.   I'll add that with an Exige, when you start to add some rake and front camber to the setup, you can go into a corner nice and fast and just lift the throttle causing lift off oversteer to start a drift.  When the car was standard I had to overcome the oversteer and make sure the weight is really on the front wheels.

The problem with an open diff and drifting is both in the initiation phase and the finishing the drift or transitioning to a drift the other way, phases.  When you have an open diff the inside wheel will just spin if you try and initiate the drift under power alone, which is why I had to commit with big entry speed etc as above.  When ending a drift or transitioning to the other way an open diff is quite problematic. Because your inside wheel is spinning quite a lot faster than the outside wheel, as you come back to a straight angle the inside wheel suddenly becomes the outside wheel. This gives you a sudden kick which makes drifts hard to smoothly finish. If you're trying to transition it can cause you to end up more sideways in the other direction than you'd like.  Now, it's not impossible to transition or end a drift smoothly, but it requires very precise throttle control and you have to basically get the wheel speed right back down to avoid the kick.

The modes in the 380 CUP are very interesting. I've driven the 430 CUP at Hethel where I had a bit of an experiment with the modes.   So starting in Race mode, this is of course the same as older Exiges, it learns the track surface and is pretty effective but IMO a little on the safe side. The good thing about race mode is that it can work the brakes so can be beneficial on track in the braking phase in keeping you braking in a straight line. It does similar with the brakes to effectively make an "e diff". It's of course not possible to drift in race mode though as the focus is on as much traction as possible. Going from Race mode to traction control off, but allowing % slip you lose the braking help and I believe it's just working the engine to control the slip.  We tried all the different % slips and they pretty much do what they say on the tin. I was being a bit overly aggressive to cause the car to slide a little and 1 or 3% just cut the power and waited for traction. as you got to 12% slip the car let you have a good amount of power even when the car was sliding. This allows you to power through a slide to a degree, but it still wasn't drifting IMO!  You need everything off to properly drift, when the car is sideways, you don't want the car applying brakes or cutting power at all!

Since adding the LSD I haven't driven the car much, and not on track yet. All I can say from my limited driving is that it wants to go sideways a lot more easily when under power and that transitioning slides is very very easy. It's gone from being a bit terrifying when sliding to being like my old Caterham (but with 4x the power)!

[chumaxa]

Would you say it is also more progressive, or communicative ? 

[GFWilliams]

49 minutes ago, chumaxa said:

Would you say it is also more progressive, or communicative ? 

More progressive yes, communication is about the same to be honest.