Exige - the Diff debate

[CRM82]

5 hours ago, GFWilliams said:

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

Thanks for the great explaination! I never drifted a car, and I am considering to attend a day-course to learn before doing anything "stupid"!

Regarding race mode: I read that it learn the grip from the track. However it is not clear how much time it takes to learn: a few turns, or should I get a strong oversteer on a turn first? How do I know that it learned - do you feel a difference? If I turn off the car it resets?

[GFWilliams]

2 minutes ago, Cristiano said:

Thanks for the great explaination! I never drifted a car, and I am considering to attend a day-course to learn before doing anything "stupid"!

Regarding race mode: I read that it learn the grip from the track. However it is not clear how much time it takes to learn: a few turns, or should I get a strong oversteer on a turn first? How do I know that it learned - do you feel a difference? If I turn off the car it resets?

If you haven't, have a proper read of this: https://www.thelotusforums.com/latest-news/lotus-cars-news/tlf-on-dpm/

If you're pushing hard enough you'll feel race mode working. You can occasionally get a bit of a moment as it learns but it's pretty good on the whole.

[Martrack]

May be one the reasons why Cup 430 does not have a LSD :
https://twitter.com/Ad_Kelsall/status/1075669664481591296
Lotus have hinted that the Exige has been borderline needing an lsd for a while with the V6 Exige. JMG their ex boss mentioned that to fit one to the 430 Cup would have required much more stability control calibration and chassis set up so they didn’t bother.

Fitting a LSD may then not be the only thing needed to do the job properly...

[CRM82]

Wow - this topic is still alive. I posted that message in January 2018.. more than two years later I have tried the car in race mode (actually I use mostly this mode now) and even without ESP (just once!). I can confirm that the car is very stable in RACE mode, and (in my opinion) the mechanical LSD is really not needed.

I know that people who added LSD say it improves the drives, but (again in my opinion) this is very questionable, particularly if your engine is stock. Lotus has done a very good job on my CUP 380 and I do not feel the need of that. Clearly, if you start to add engine tuning (more power/more torque), different tyre size, etc... then the factory ESP might not work well anymore and then an LSD might help. So I would consider that only for that case.

The only actual issue I have with my CUP 380 is trail braking. The car does not like brake hard and turning at the same time....

 

[NANO]

22 minutes ago, CRM82 said:

The only actual issue I have with my CUP 380 is trail braking. The car does not like brake hard and turning at the same time....

 

what do you mean ? did you have any problem ?
cheers / ciao

[Martrack]

51 minutes ago, CRM82 said:

The only actual issue I have with my CUP 380 is trail braking. The car does not like brake hard and turning at the same time....

Interested to know more about this, as I saw other comments, at least from a Cup 430 owner, telling that you can't brake and turn at the same time. Don't know at which point though.

Your instructor (as per your Youtube videos) also seems to confirm this at both SPA & Nordschleife...

Curious to know what would prevent to trail brake with such cars, especially as that's the proper way to brake...

[CRM82]

3 hours ago, Martrack said:

Interested to know more about this, as I saw other comments, at least from a Cup 430 owner, telling that you can't brake and turn at the same time. Don't know at which point though.

Your instructor (as per your Youtube videos) also seems to confirm this at both SPA & Nordschleife...

Curious to know what would prevent to trail brake with such cars, especially as that's the proper way to brake...

Indeed, this has been confirmed by Daniel Schwerfeld, who is a great coach and amazing driver (really!!!). I am not 100% sure, but in my opinion it is about the lightness of the car (particularly on the front) combined with the too small tires at the front (standard 215, now I have 225). In practice, the width of the tire is appropriate for the weight distribution, however when you brake hard you have too much pressure on them and they can't turn anymore. You can see this very well in the Nordschleife video when Daniel brake hard and turn at Hocheichen - the car understeer like crazy and he has to open and release the brake to turn.

At Imola this issue was very evident, in practice you need to brake a bit earlier, enter in the turn with small/none brake, or in some cases even with already some gas. It takes some time to get used to it.

[BatMobile]

Have you had your geo done to change the car's characteristics from understeer to oversteer? I had most of the shims taken out to give the right amount of negative camber which aids turn in - lotus set them up to oversteer as they feel its easier for the novice.

My 430 has no issues trail braking and at my last day at snetterton it was perfect. 

[CRM82]

Shims were all out, camber was maxed both on the front and the rear. I think it was -1.6 degree front, -2.1 degrees rear. Now my garage have milled the front and I have -2.4 there, but I have not tested the car since the modification. 

Regarding sway bars, I have it on soft at the front and on medium at the rear. What do you use?

[Martrack]

Rear toe setting is important too.
On road cars, we generally (always ?) see toe-in, so that rear is as stable as possible, for security purpose.
On race cars, we generally see toe-out, so that rear helps rotate the car when it enters the corner.

Of course, on its road cars, Lotus recommends a toe-in value.
I don't know how others do, but IMO, you should at least verify you're not above it 👍

Of course interested to have your feedback whether or not you'll find better settings / better car behaviour

Edited September 2, 2020 by Martrack

[CRM82]

Regarding toe, I have now 2.0 mm out (total) on the front, and 4.0 mm in (total) on the rear. This is similar to what Komotec also reccomend, as far as I know. 

[Mattmahope]

I have a Quaife LSD fitted in my Exige and find it only has positive effects with no negatives, especially given the power I am running now. Easy to adjust handling to suit with geo changes and adjustable dampers. Certainly do not think it is essential though.

I also have ECU Master Black so not running factory stability control etc, so don’t have any issues with that either.

[Seriouslylotus]

3Eleven has a Quaife LSD as standard, with essentially the same traction control etc as the 430 Cup Exige, 

So the factory have already done it on  a platform that is essentially a V6 Exige (Front suspension arms are a little longer, steering arms slightly different, but thats about it)

[alias23]

On 02/09/2020 at 14:51, Martrack said:

On race cars, we generally see toe-out, so that rear helps rotate the car when it enters the corner.

I've found 1mm toe out at the front to be have a great effect on turn in on track. At the rear im pretty much neutral on toe, would be interested to hear what you've seen running well on the rear if you mind sharing?

[Martrack]

Unfortunately I've no experience with Exige yet, I hope next year though.
But with Clio Cup race cars, where at the front we set 0 or a very very slight amount of negative toe.
And at the rear, we set toe out. The more toe out you set at the rear, the more easily the car will rotate entering the corner, the less steering-wheel angle you will have to use for the same corner (which also helps saving your front tyres).
While the rear inside wheel will be almost unloaded, the outside one, due to its angle, will pull the back of the car out of the corner.
This is rather "surprising" when you experience it, entering the corner while braking, with front axle weight-loaded, you really feel the rear end swigging out around the car's center.
If you've set enough rear toe out, the car can even be still turning with steering-wheel back straight-aligned, until rear inside wheel is loaded again.
Note that a slight difference in toe setting should allow you to feel the difference.
On a Clio Cup, running -0°10 vs -0°20 (at each rear wheel) makes the car totally different.

On a street car though, I would tend to be careful with rear toe out, as it could lead to a less stable car in emergency situations...

[Seriouslylotus]

The dynamics of a rear wheel car and especially a Lotus are TOTALLY different to a Front wheel drive car. We raced C1 Citroen's in endurance racing the rear was set to 1.25 overall degree toe out. 

An Exige V6 with rear toe out would be terrifying IMHO

[Martrack]

Thank you Dave for your feedback.

Mmmh yes you're right regarding RWD cars.
We should then keep some amount of rear toe-in, IMO possibly reducing it until the rear is not too much / anymore constrained entering the corners, without becoming scary exiting the corners and under hard / heavy situations. Experiencing is certainly the best to find the right balance, but of course it takes time.

Additional interesting reading : https://www.turnology.com/tech-stories/baseline-alignment-specs-for-fwd-rwd-and-awd-to-make-you-faster/

[Jack]

I think rear toe-out would be great..... IF ...... I wanted to turn my CupR into a drift car and even then, it could still be a terrifying ride, as Dave opined.   

[Exx]

Is the EDL still ON with DPM set to OFF ?

[Bravo73]

Yes

Edited to add: No!

Edited November 17, 2020 by Bravo73

[Arun_D]

Is there some literature that backs that up? I don't believe that was the case. 

Back when I had a standard diff, the car would spin its inside wheel at will with everything off and general behave as if there was no intervention. Brake wear backs that up too.

[Bravo73]

On 11/11/2020 at 23:57, Exx said:

Is the EDL still ON with DPM set to OFF ?

I’ve just checked back though the Service Notes for the Evora (same DPM system) and Arun is correct. 
 

The EDL is a DPM feature so when the DPM is off, so is the EDL. 

[Bibs]

I believe the only thing left with it all off is the ABS which cannot be turned off at all. 

[Exx]

Yep ABS always ON

So if EDL is OFF with DPM OFF that would explain why laptime are better in Race mode, that s not because of the helps that s because there is no diff

[Bibs]

https://www.thelotusforums.com/latest-news/lotus-cars-news/tlf-on-dpm/