[spectre]

I have read way to many threads on this subject and people upgrading
but I really got to experience it more this past weekend. I had mine
lowered – corner balanced and really was amazed how much this thing
leans after being optimized.

I have two pictures below that show the same turn from different angles.
They are big so you can see.

Also, a link to an in car video. Ironically you don't see lean in the video
but you will hear some tire squealing as it was chilly and they never
really got up to temp, plus a new track for me so I was not balls to the
walls yet. It's long so if you get bored just stop.

midohio

 

[xtn]

And? The roll bothers you?

xtn

 

[spectre]

I think it's a few things and will say I'm still fairly new to the track game. The amount of lean at times in certain spots felt unsettling although I never had any issues in corners or in transition, etc. upsetting the car. But I am curious on how a setup like the Nitrons would be or if the limits would even increase to be that noticable.

 

[chrisp993]

At that spot it's also body roll combined with some pretty extreme compression from the uphill start of T8 "Madness" maybe also combined with braking - although no braking in the one picture I noticed

 

[fitfan]

roll does not allways = bad... depends, roll aids in a progressive feel. and of course the compromise for compliance.

what settings do you have the dampers for the track vs street?

if the car "feels" good in transitions, and into loading, and track out - i think thats the most important thing for fun runs...

 

[spectre]

Yeah, I wasn't saying it was bad as you need some roll. On some corners that fall off like the keyhole (I think that's it before the back straigh) at mid ohio, it felt a bit unsettling but that maybe my line...I was more curious about how a change to something like nitrons may help or not.

I do 8f 7r for track and usually 4f 3r or 5f 4r for street.

 

[spectre]

At that spot it's also body roll combined with some pretty extreme compression from the uphill start of T8 "Madness" maybe also combined with braking - although no braking in the one picture I noticed

Yep, back on the throttle :evil:

 

[chrisp993]

:up:

 

[xtn]

spectre -

I switched from the Track Pack to the Nitron SA units with a bit higher spring rates. This has reduced the roll a bit. They are now offered with even higher spring rates than the ones I got.

My personal experience is that less roll - by itself anyway - won't ultimately make the car any faster. But I felt that it made ME a bit faster as a driver, just because leaning over so much made me a bit nervous and the higher spring rates helped me up my confidence level a bit.

Other than that psychological factor, which may or may not be an important one for you, the car will be faster running the softest springs that will prevent the suspension moving beyond it's ideal range of camber curve. The stickier the tires, the more spring you need to prevent excess travel or hitting bump stops (or tire/fender interaction).

xtn

 

[spectre]

Cool, this is the info I was looking for.
Thank you!

 

[robains]

That much roll seriously deminishes the effectiveness of the front splitter and rear wing. You don't see race cars with that much body roll.

Nice track

I'm in the same boat. Does anyone know the Track Pack (Blistein) spring rates?

 

[apk919]

...Does anyone know the Track Pack (Blistein) spring rates?

They are dual rate springs: Front: 180/271 lb/in, Rear: 266/371 lb/in

 

[robains]

Ahh, progressive rate -- that makes sense based on the coil layout. But thank you for the specific rates.

 

[apk919]

Ahh, progressive rate -- that makes sense based on the coil layout. But thank you for the specific rates.

Yeah, the Lotus spec says "dual rate", but they're probably more accurately described as "progressive rate"

 

[Uncle Sam]

You should have an adjustable front anti-roll bar with the track pack. Making it stiffer should decrease your front roll angle, but it may/will increase your understeer. I use "may" because that picture looks like alot of roll and you might be out of optimum camber range and stiffening the front bar might give you a flatter contact patch and thereby increase front grip a bit. Did you do the front shim mod? Soft springs are good for the street and roll gives you a good read in the rain; everything is a trade-off. BTW, I am not an engineer so ignore possible inexpert advice.

 

[spectre]

I have -1.5 on each side in the front with machined arms.
All camber should be pretty well spot on...

 

[xtn]

That much roll seriously deminishes the effectiveness of the front splitter and rear wing. You don't see race cars with that much body roll.

Any hard data to back that up?

I would guess that the effectiveness of the front splitter, compared to a purpose built race car, is more seriously diminished just by it's small size and extreme height above the road surface more than it would be diminished by a bit of body roll. I mean during body roll one side is moving up and the other side is moving down. Effectively I would guess the same amount of total air is getting under it.

And as far as the rear wing goes, I don't imagine it give much of a hoot if it's tilted a couple degrees to one side or another. If it's giving 50lbs of downforce at 100mph, and then you tilt it a couple degrees, perhaps it's only giving 49lbs of true perpendicular downforce then? Not what I would consider a significant difference.

I admit the above is purely speculation, but it makes sense to me and I would appreciate data if you know better.

xtn

 

[robains]

I don't have data on how much downforce is lost per offset increment in splitter and/or rear wing -- don't have access to a wind tunnel I know I can feel my splitter (Reverie one) working above 60 mph -- steering actually feels heavier (no speed sensitive steering in the Lotus).

I'll not be at the track til next Tuesday (May 5th) to test out the full effects of my splitter, but under remote roads I've tested on, I can feel the transition of downforce when the roll angle gets too steep.

I agree that it's not as significant as F1 aero where a millimeter of roll can have a big impact on traction/downforce. But it does have a noticeable affect.

You'll surprised just how low the front splitter is at speed -- I've got some pics of my older stock style splitter almost dragging along the ground under braking -- I'm a little worried I'll be scraping my new Reverie because of the soft Track Pack spring rates.

The stock front splitter produces 128 lbs @ 100 mph, stock rear wing 221 lbs @ 100 mph. The Reverie front splitter produces 306 lbs @ 100 mph and the Reverie 1650mm wing produces 617 lbs. I don't have the equation to determine loss in downforce per mm horizontal motion -- but as you can see in the pic, there is huge change in horizontal angle. Pending how close the driver is at, on, or above the edge of traction, it really doesn't take much change in aero downforce to go too far beyond the edge of traction.

My 2 cents, but I have no data to back that up -- I might next time out using G data but that's not necessarily a proof of theory.

Rob

 

[spectre]

I don't know how accurate the chasecam pdr is but it's about 1g at this point in time in the photo. A few seconds later it's about 1.15 as I creast the turn...to me this seems like an excessive amount of lean.

 

[shay2nak]

You're quoting much higher downforce numbers for the stock parts. Where did you get those from?