Okay, I thought that I'd start by stirring things up a bit with a U class car because it brings to light a little something I call Variable Spring Rate.
This is a misnomer, of course but, that is the overall effect of this type of combination of ARBs, Springs and Dampers. The idea is to match firm bars with a combination of soft springs and firm dampers. The result is that when initiating changes in direction, the firm dampers effectively cause a momentary increase in the spring rate but, as the corner is held and the damper starts to allow the body to roll over onto the soft springs, you eventually end up at your 'actual' spring rate.
This can be a very useful technique with high performance cars ( typically S class and above ) where the vehicle may be called on to corner at both 160MPH and 60MPH within just a few seconds. While a soft setup is better for a pure slow, twisty track and a firm setup better for high speed, the VSR setup gives you a bit of both, which makes it a good fit for a majority of tracks.
This is the setup that I ran a week or so ago at the Nurburgring so you might find that dropping the spring% or the rebounds by a percent or two might be better for tracks without so many high speed corners. I would encourage you to play around with the spring percentages and damper settings after you've gotten used to the feel of it. Ultimately, you may need to tailor the car to your individual driving style. You'll note that I typically leave the bumps alone and at fairly low settings to make sure that I don't slow down the car's ability to change direction too much and instead, make damper adjustments with the rebounds almost exclusively.The Mercedes CLK-GTR has a very wide power band so, I've geared it accordingly as a 5spd. That also makes it a no-brainer to setup the gearbox to be a 4 speed on tracks without similar top speed demands...
The Build : It's U Class so, that means every upgrade available for this one. I chose the Goodyear race rubber and the rims are 30R19 Fiske Mach Vs front and rear. They could be upgraded one more diameter to 295/25R20 fronts and 345/30R20 rears but I chose the lighter 19" rims and the extra sidewall flex that goes along with it.
The Setup:
Tire Pressure:
Front:29
Rear:28
Gearing:
Final Drive: 3.20
(1): 2.89
(2): 1.63
(3): 1.21
(4): 0.99
(5): 0.86
(6): 0.82 ( not used )
Alignment:
Camber Front:-0.8
Camber Rear:-0.6
Toe Front:+0.3
Toe Rear:0.0
Caster:5.5
Anti-Roll Bars:
Front: 25.00
Rear: 32.30
Springs:
Front: 315.2
Rear: 364.7
Dampers:
Rebound Front: 13.0
Rebound Rear: 10.0
Bump Front: 3.8
Bump Rear: 4.2
Aero Adjustment:
Front: 331 (max)
Rear: 661 (max)
Brake Bias:
Bias: 45%
Pressure: 98%
Differential:
Acceleration: 30%
Deceleration: 20%
For those of you who like to play along with a spreadsheet or a calculator, with a curb weight of 2464lbs that gives us a weight bias of 46.4% and a spring percentage of 55.2%. Or as I would notate it in my setup savename: U NUBRING B464 S552 A2532
Have fun, drive fast and let me know if you have any questions or comments.
J
