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2008 Exige S240
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Discussion Starter #1
I've driven with the BWR track arb for about 1.5 months.
It has reduced oversteer, which is s good thing. It is on the second
hole from the outside which is 60% stiffer than stock according to
BWR. I had it on the third hole from the outside for 2 weeks but it reduced the fun factor because power oversteer was difficult to induce even with nearly 200 ft/lbs of torque.
I tracked it at NJMP on Oct. 26-27 with great result on hole #2. All else same on the suspension, so i know it helped substantially with the pre-bwr arb excessive oversteer. My lap times were faster.
I want to be faster of course. Can anyone suggest suspension tweaks (psi, tires), more effective parts (dampers, bushings, etc). Do the ARB end link position affect the car much? I am primarily looking for inexpensive tweaks to what I already have installed.

-Robert



My current suspension is as follows:
-Nitron 525/650 single adjustable set at 7/9 from "full hard"(~4 years old)
- Bwr arb with end links
-s111 camber arms: maxed out at -2
-s111 Quikrack
-RTV toe kit
-s99 toe pins
-Seriously Lotus subframe stiffener (not installed yet)
-ride height: 110/120mm (approx.)
-rear toe is LSS spec
rear camber is LSS spec
-front toe is LSS spec
-R888 with RAC monolites
 

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IMO, your spring rates do not match the R888's you're running, and are overworking them. They're meant for Hoosier A6's or Yokohama slicks. Going further, running sticky tires is the easiest way to lower lap times.

ARB stiffness of course has a massive impact on cornering; give both positions a fair shake at the track. This means give yourself a few sessions each to acclimate how to drive the car with the ARB's posistion and how it impacts handling balance.

Installing that subframe brace may also make the car more consistent to drive if it's effective. Always a big battle of being quick is being consistent, so that's worth something.

That's my $0.02,
Ryan
 

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Discussion Starter #3
Great advice!

Since I don't use slicks, what are ideal spring rates for r888s?

-Robert
 

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I'd go with the "soft" springs, which are 450 lb/in front and 600 lb/in rear. That's what I run on my car, and honestly it's close to what V2 Motorsports sets up their race Exige's that run Hoosier A6's in SCCA T2. With the 450/600 setup, they're on the stiff side for R888's and on the soft side for Hoosier A6's, which for me make a great compromise for my mixed-use street/track setup.

This won't be a massive change, as the rates are only 17% and 8% change respectively. It will however not overwork the tires, making them run at more appropriate temperatures. IMO the R888's aren't all that great for track work, as they get greasy quickly, but that's just my opinion. That said, the 450/600 setup won't inherently understeer like the 525/650 springs, so you can likely run your front anti-roll bar at the stiffer setting, which will improve turn-in crispness and corner-exit traction.

You may want to consider going back to A048's, as they seem to be a better track-day tire than the R888.

Regarding alignment, -2 degrees front and back are good places to be. I don't recall what LSS toe specs are, 0mm toe in front and 2mm toe-in per side in back gives the car stable and predictable behavior while still being responsive, however with zero toe in front the car may tramline a tiny bit on uneven surfaces. I'd also ensure your front upper control arms are setup for maximum caster, as that will improve steering feel and high-speed stability.

I hope that helps,
Ryan
 

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I think if you're running nearly 200lb/ft of torque it's silly to be driving on anything but slicks. I suppose it doesn't teach you to be as good of a driver by learning how to deal with a fairly unstable rear end due to excess power, but if you have tires available that will keep you from spinning tires, it's pretty much a safety issue you oughta be "fixing"...

I was at the track a few weeks ago and drove on hoosier A6 for the first time and it was great. MUCH less stressful, and more fun. I suppose it was faster too.
 

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I think if you're running nearly 200lb/ft of torque it's silly to be driving on anything but slicks.
I just want to put this in context. The Mustang GT comes from the factory with 390 LbFt and 235/50-18 all-season tires with a 400 treadwear. That is a car that has a silly torque to tire function, IMO.
 

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What type of bushings are on the control arms? Is it something that can be upgraded to poly? It makes a huge impact on cornering and overall steering feel.
 

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... i suppose i should have qualifiied my statement on the silliness of not using slicks to be related to track duty.

The mustang also has the benefit of additional weight to increase traction and probably lots of stability control to cut power and stabilize the car if you're losing it... but regardless you're absolutely right, that mustang's power to tire combo is pretty odd.
 

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... but it reduced the fun factor because power oversteer was difficult to induce even with nearly 200 ft/lbs of torque.


...


I want to be faster of course. Can anyone suggest suspension tweaks ...


My current suspension is as follows:
-<stuff>-
+driver
fixed
 

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... i suppose i should have qualifiied my statement on the silliness of not using slicks to be related to track duty.

The mustang also has the benefit of additional weight to increase traction and probably lots of stability control to cut power and stabilize the car if you're losing it... but regardless you're absolutely right, that mustang's power to tire combo is pretty odd.
lol +1, my gf has one and you can barely give it half throttle from a launch with the all-seasons
 

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I don't know that the springs are too stiff, depends on your shocks setting and I don't know the Nitron valving. On our street car with Hankook RS-3s, we run 475F and 685R with mid-range shock on Penskes. I still think it rolls too much. Given your spring rates and assuming shocks are soft, you could use more negative camber given your roll-rates.

Remember on the Blackwatch ARB, the holes you attach each side do not have to match. It functions as 1 big spring, between the front wheels. Thus both at second from softest is softer than each side at 3rd from softest. One at second and one at third is halfway in between and is the same total rate to each side. Just be sure to adjust the endlinks so there is Zero preload when the car is on the ground with driver weight in the seat!

Have fun.
 

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Just my opinion... but there's nothing inherently wrong with roll if the suspension is designed for it (and the 111 suspension is). The biggest issue I have with soft springs is dive... so I'm looking to stiffen the springs and soften the bar...
YMMV
 
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