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Absolute power does what?
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Discussion Starter #1
Because I certainly do:

lean.jpg

My current setup is stock '06 Exige (suspension, power) with Pagid Blacks (RS14), RBF 600, Sector UltraDiscs and BOE Ti brake shims (brakes never fade). Running -3.1 front camber and -2.1 rear (and need more in the left rear). Tire wore very evenly (running 20/23 pressures). I'm running Yoko A005 S01 slicks and according to Traqmate I'm getting 1.7 lateral G (in this corner I'm at about 1.55). Here I'm in 3rd gear, flat at about 75mph in the picture. For aero I have the APR GTC-200 wing, APR canards, Sector RaceSills and BOE under-aero and diffuser.

My question is - can I just upgrade the springs or should I go with a whole new setup (Nitron doubles)? Would I get less lean or more grip? Pretty thrilled with the grip I have now but when I saw these pictures I couldn't believe how much the car is leaning over.

Thoughts?? For those of you with Traqmates how much lateral are you getting??

-Ross
 

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Consider adding a BWR sway bar, and adjust it for mag G's of grip, rather than minimum lean. 1.7 G's is pretty phenominal; a certain amount of sway is actually good (provided you have matching camber), max G's is NOT at maximally flat.
 

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Consider adding a BWR sway bar, and adjust it for mag G's of grip, rather than minimum lean. 1.7 G's is pretty phenominal; a certain amount of sway is actually good (provided you have matching camber), max G's is NOT at maximally flat.
How can one complain with that level of G force?
Is the lean bad other than for how it looks in photos?
 

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The only reasons that body roll is a bad thing are if the roll is causing a kinematic situation that is putting the tires into a non-optimum position- excessive positive camber on the laden wheel for example, or if the elastic load transfer is to a point that it is overloading the tire's load capacity and saturating the amount of lateral force it is capable of producing given a load - this is know as operating in the nonlinear range of the tire.

You can be pretty certain that you are not near the nonlinear range of the tire given such a light car on radial slicks. This is usually only a concern with very very high downforce cars (formula cars) and bias-ply slicks.

Judging by your pictures, your outside tire doesn't seem to have positive camber. This is good.

Stiffening the springs will reduce roll, but will also increase ride and pitch frequencies.
Stiffer antiroll bars would be the first step to changing the roll gradient of the car.

If you are happy with the current balance of the car (understeer/oversteer gradient) then look into increasing the antiroll bar stiffness an equal percentage front and rear. (equal at whatever the rate is at the wheel- I am not sure of the motion ratio of the ARBs front and rear and if there are large differences or not)
 

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A sway bar wont do much in this case, you are bottoming the suspension at this point which means you don't have suspension. I ran into this problem with tires a lot less sticky than yours, mostly during braking and turning in as the suspension takes time to "recover" from being bottomed when turning in so it always had a sloppy initial turn in, and as I loaded it more and more I would lose grip again due to the suspension bottoming out again.
You need stiffer springs, a lot stiffer, and your stock shocks, whichever they are, will not be able to deal with it. Get the Nitrons or Quantums or whatever, you'll be a lot happier, plus you can lower the car enough to make all your fancy aero parts work ;)
 

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I think that you can't evaluate the behavior of a shock/ARB setup through a photo. In addition, Lotus doesn't use rear ARB and expect to improve simply hardening the front ARB is a misconception.

Your 1.7G are many, thanks to S01 and to an extremely negative camber. The roll is very pronounced due to the fact that you probably have the stock Biltstein, but if you feel comfortable to drive and if you are satisfied with your setup, I wouldn't change. That's IMHO.

In this photo you see how behaves mine Exige at "only" 1.1g with ToyoR888 tyres.



P. S. : I recently installed a set of Nitron Fast Road (425/550lbs), these are certainly more appropriate for a "sporty" use, but they require attention and time to their configuration, before getting a satisfactory result.
 

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If I was getting 1.7G (which I doubt is really happening, and what is average value?)...
(Starts over)

If I was getting 1.7G the last thing I would do is start changing it to make it better.
 

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I don't understand why people on this forum repeatedly try to convince themselves and others that this type of roll is normal. I was not evaluating based on the photo, although enough can be seen on it to do so.
Most people running aftermarket suspensions gain avg. 3 seconds per lap depending on the track and driver of course. 1.7G lateral acceleration is respectable but I am pretty sure it's not continuous. My average is 1.1 through corners but I do get spikes up to 1.6 on r-compound tires, not that it really matters...
 

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Absolute power does what?
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Discussion Starter #11
Thanks for all the great conversation guys - to be clear I am very happy with the way the car handles and with the lap times I'm getting. I haven't wanted to change anything as the car feels great - but when I saw this picture I thought holy hell that's a lot of lean.

And obviously I'm not getting 1.7 sustained G, that's just my max spike. There are a few points on the track I'm above 1.5 (in this corner I'm at about 1.55) - again this is all data from my Traqmate not the seat of my pants.

I think for this season I'm going to leave things as they are then look at my upgrade options in the off-season. I'm guessing a set of Nitron doubles are on the list for me...
 

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IMO- Don't waste your time/money with doubles. If you want great value, go with singles. If you want to mess with valving more (read, a LOT more), go with triples. Doubles are this weird in-between model that require a *lot* more work to dial in than singles and won't perform any better than a tuned single, yet the doubles leave you longing for more adjustment like that of a triple if you like to tinker with valving... I think people buy the doubles because they think they're a *good* compromise on price and complexity... really, they're *just* a compromise... I've talked with Niton about this and they would tell you the same thing, FWIW...

-PV
 

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I don't understand why people on this forum repeatedly try to convince themselves and others that this type of roll is normal.
...
It is normal for a Lotus. They all do that and they are designed that way.
I agree that it is NOT normal for most other cars.

But you are correct that stiffer springs do minimise a lot of the roll, and also result in better times; but usually with some other factors like tires.

Or that the main point is that solely minimising roll may not result in better times.
It is more along the lines of stiffer springs helping in other ways, which also has the effect of minimising the roll.
If it was solely minimising the roll that helped, then we would all have weak springs and massive sway bars... Which no one has made work.
 

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Ross,

IMHO, you need to consider upgrading your suspension setup to one better suited for slicks ... both spring rate and shock valving optimized for slicks will significantly improve handling. If you want to go the easy route, try to find a used set of Cup car 2-way Ohlins .... according to the factory, the valving and spring rates selected by Lotus were optimized for Yoko slicks and they provided some recommended bump/rebound settings to make the adjustment process a bit easier. Alternatively, a number of Lotus Cup guys have found the Nitron singles (46 mm) worked well.
 

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Ross,

IMHO, you need to consider upgrading your suspension setup to one better suited for slicks ... both spring rate and shock valving optimized for slicks will significantly improve handling. If you want to go the easy route, try to find a used set of Cup car 2-way Ohlins .... according to the factory, the valving and spring rates selected by Lotus were optimized for Yoko slicks and they provided some recommended bump/rebound settings to make the adjustment process a bit easier. Alternatively, a number of Lotus Cup guys have found the Nitron singles (46 mm) worked well.
Well said Jack.

The Quantums are also well received and available through Elise Parts.
(But I got a used set of Ohlins, because I was cheap).
 

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Absolute power does what?
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Discussion Starter #17
Ross,

IMHO, you need to consider upgrading your suspension setup to one better suited for slicks ... both spring rate and shock valving optimized for slicks will significantly improve handling. If you want to go the easy route, try to find a used set of Cup car 2-way Ohlins .... according to the factory, the valving and spring rates selected by Lotus were optimized for Yoko slicks and they provided some recommended bump/rebound settings to make the adjustment process a bit easier. Alternatively, a number of Lotus Cup guys have found the Nitron singles (46 mm) worked well.
Thanks Jack - I obviously agree, just not sure if I'll do it now or in the off season. Right now it's new suspension or 3 days at Road Atlanta. I'm leaning toward the latter.

I suppose my question is this - am I risking anything here? Tires are wearing very well (save for rear, which I plan to address soon) and I'm getting great grip, lap times and the car handles extremely well.

While I have you Jack - have any new slicks available, I'm guessing I'll need another set this season.
 

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A sway bar wont do much in this case, you are bottoming the suspension at this point which means you don't have suspension.
And a sway bar may indeed prevent this bottoming. A sway bar adds the inside spring's power to the outside. thus increasing the outside wheel spring rate, resulting in a higher ride height.
 

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And a sway bar may indeed prevent this bottoming. A sway bar adds the inside spring's power to the outside. thus increasing the outside wheel spring rate, resulting in a higher ride height.
Ride height is only changed for the outside wheel, the inside wheel ride height is lower, as the total vertical force is the same regardless of lateral G-force.
The roll bar only increases the stiffness about the roll axis.

With everything else being equal, then lowering the car gives less roll as the CoG is closer to the roll axis. But that also get you closer to the stops.

When the handling is good it is hard to improve upon it.
 

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Dampers do nothing for steady state roll stiffness. They are dampers. Not springs. They dictate transient response, not steady state response.

Those suggesting an upgraded damper to change the roll angle of the car need to understand this.

A stiffer damper will increase transient response to a point and therefore reduce the amount a car rolls, say, through a slalom. But in a steady state corner the only things that dictate body roll are tire stiffness, ride spring rate, and roll bar rates.

Now if you upgrade the damper and at the same time change out the springs.. then yes, that will change things.

Changing the ride height will change roll center height and roll moment and thus can also change roll stiffness.
 
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