Suspension mods- FD2R
here. Suspension Part II here. Part III here. Basics
The original FD2R set-up feels like something right out from a race car but in truth if one examines the actual spring rates (f: 4.8 kg/mm, r :6.5 kg/mm) they are nowhere close to a race set up which are around 21-25 kg/mm. So why is it so stiff and unyielding? The answer lies in the damping, more precisely the compression damping.
Its like what they have done with the S2000 CR the initial damping rate starts with a moderate degree of damping force right from zero velocity. Most dampers gradually ramp up the forces or even have a quick rise but start from zero forces. Honda's own figures for their damping forces are particularly vague and only make reference to the standard Civic's dampers. The FD2R's front dampers are 153-264% greater which I surmise is in reference to the compression-rebound rates of the standard Civic. The rears are even more severe with a 309-277% increase over the standard items.
The front springs are between 66-164% stiffer indicating some progressive rates and the rears are a huge 110-220% stiffer. So its clear that the rears have been firmed up considerably and the damper rates operate with a huge increase (309%) in compression damping which is odd as it would probably gives it reverse characteristics compared to the fronts.
It is also apparent from driving the standard FD2R that the fronts manage to soak up a bump but the rears kick up hard and this causes a jiggle as one passes the hump which indicates over damping.
In the first few months of the FD2R ownership there were no aftermarket suspension kits. Mugen offered one but its specifications differ little from the standard with a 5.3 kg/mm spring in front and 6.9 kg/mm in front and lowers by 10mm.
Koni Sport Dampers
Koni offered the Sport Yellow (f: 8641 1497 Sport, r: 8041 1360 Sport) adjustable dampers (not a kit with springs and not specifically for FD2R but fits any FD2) below $1000 a set were a genuine steal. The rears were a simple direct swap-out of the dampers without even altering the geometry as the springs are mounted separately. The fronts however were not so straightforward as it is a strut insert which means one needs to cut open an old damper unit, remove the insides and bolt-in this new Koni front insert. Fortunately some discarded standard Civic struts were around so we could perform the surgery. Note- Only the dampers were changed using original springs.
The resultant ride was a tad too cushy! The sharp alert feel at the helm was gone, replaced with a very european feel with typically higher rebound rates than compression. Even cranking up the rates did not reproduce the alert feel of the standard dampers. Examination of the damping rates of the standard dampers will lead one to the conclusion that the rear dampers (and not the springs) with the 309-277% increase that are likely to be the culprits of the poor ride.
The Combination- OE Honda front suspension plus Koni rear damper
The original 1995 Integra Type R (DC2) was the oversteer champ of the FWD brigade. It would oversteer in tandem with power application in corners and seemed to enhance cornering speeds. What actually happens was not power oversteer as we know it in a RWD car but when we apply power we increase speed and as we gain speed through a corner, the rears step out more as they pass the limit of adhesion especially with the heavy rear sway bar.
However if one backed off, the tail would snap around. Not for the faint hearted and Honda backed off. The next ITR (DC5) was not as tail happy but it had a snappy oversteer after understeering. While it feels safer to drive with mild to moderate understeer, it is kinda boring around a track. many tuners strive for some looseness in the rear to have more neutrality or even oversteer in corners to work the rear tyres equally instead of working only the fronts when understeering.
To get the FD2R to rotate or oversteer more, the front was given more negative camber to improve the grip from the front tyres. Camber of the rear was also reduced a degree to lower its on-limit grip.
Update: 07-2010. The increased front negative camber (-ve 2 deg) increases both front end grip and turn-in response. It gives the FD2R a better balance in corners with less understeer. However the trade off is tyre wear and overly responsive steering at high speeds. It is hard to keep the steering still enough to travel in a straight line at speeds over 140 km/h. Small steering movements make the car move too much in the lane. Full concentration is a must. Cannot imagine those who have opted for 3 deg negatiive. If one does not do much track time, it might be prudent to keep the negative camber to a minimum or stock.
Cusco rear sway bar
Even with 1 deg less negative camber the rears still were holding on too much and so the rear roll stiffness was increased by a stiffer 23mm Cusco rear anti-roll bar(OE=21mm). We were looking for a 25mm rear bar but the search has been in vain.
With the Cusco rear bar the steady state cornering did not feel too different but if one backed off in mid corner, the FD2R would rotate more but sadly nowhere as playful as the DC2. Newly installed the bar made a groaning sound but was traced to an untorqued bolt. No futher noise was reported and greasing the bushing carefully before assembling is important. The ride if it was effected didn't amount to much.
To adjust camber in the front one needs a pair of camber bolts which is a cheap and cheerful way of achieving the static camber. The rear camber was more difficult and needed a control arm to be swapped to one with an eccentric bushing which might add $450 to the bill.
By increasing front camber and reducing rear camber the FD2R was less prone to understeer but the tail happiness of the first ITR(DC2) was hard to replicate. The rear multi-link suspension is just to well developed to relinquish grip easily.
The Tein MonoFlex suspension
While the OE suspension seems mostly fine after the small Koni mod there is a nagging concern that it is too soft for the track (not that bad tho!) and it sits a little high although it clears every sort of road obstacle on our streets. Plus there is no facility to alter damping rates but is a moot point if the OE items are spot on. But how do we know if it is if we don't compare it with something else?
So off with the OE items and on with a set of Tein MonoFlex coilovers. The ride height is dropped about 10mm in front and 15mm in the rear. Of course the MonoFlex can adjust for ride height and spring seat preload apart from camber and damping.
However this is not to say that it does not transmit noise, it does of course raise road roar a bit but is nowhere as bad as one would imagine for such a direct connection. The damper noise has been fixed completely it would seem.
Mono-tube dampers have the reputation for better, more consistent and accurate damping characteristics thanks to its simpler and larger size but also supposedly has a slightly harsher ride. With the Micro-Speed-Valve technology Tein has filtered out the harsh high frequency movements and this allows the mono-tube design to be used on the street comfortably.
In fact the MonoFlex at its lowest damping settings are far more comfortable than the OE set up even with the increase in spring rate from 4.8 to 7.0 kg/mm. But at their highest setting, the Teins cannot be used on our roads for long as they are far too over damped and jiggle like crazy. Perhaps they will suit the track but that will be another report.
FINAL TEIN SETTINGS
After much fussing back and forth, the final settings are much closer to max settings than earlier reported. Thanks to the micro-valve technology, the comfort remained acceptable until 4-clicks away from max for the front dampers and 6-clicks for the rears. Some may opt for more but it can become tiresome on bumpy stretches. This setting mind you is still far better than stock settings.
What one gains is better damping and also ride comfort but not much loss in the way of steering sharpness. The OE suspension has a fairly long suspension travel and the Teins typically have much less. On our roads this has not been a problem but at least in theory longer travel has more consistent contact with the road in extreme conditions.
If one is cornering (in a car without LSD) at or near the limit and applies power, the lightly loaded inside front wheel will start to have wheelspin. If one has shortened the suspension travel so much that the inside wheel lifts earlier then wheelspin, theoretically speaking will be a problem when trying to power out of a corner. But thanks to the Torsen LSD already fitted to the FD2R, 50% of the torque is still applied to the grippier, outside wheel.
While noise has always been a worry with pillow mount type suspensions, the Tein MonoFlex at least I can vouch for that it only mildly increases noise and that is nit-picking.
Will update on how it behaves on the track, watch this space.
Original bar 21mm = 3.4kg
Front Struts+Springs = 7.8-kg
Rear Struts+Springs = 4.4-kg
Front Spring+strut = 6.6kg (all)