AP2 bumpsteer, differences between AP1 and AP2 rear geometry
08-24-2018, 09:02 AM
#21
Bumped up the front to 4 clicks from full stiff (using the reference of 1 being full stiff), and kept the rear at 3. Feels fantastic.
Conclusions are: I think the loosey-goosey feeling over 80mph+ large amplitude mid-corner bumps was from insufficient compression and rebound damping. Maybe from the way SBG revalved them with less compression damping? Apparently they can take up to 14K springs but even on 11K/11K I am nearing the end of adjustment before the car felt good in my hands.
On these settings even in low speed corners it feels dare-I-say more planted and definitely more direct than before. Ride quality is pretty much uncompromised despite going tighter on the dampers. DFV ftw. Will have to get it back on AMP for a final impression, but based on my test-loop it should be a whole lot better in all situations.
Conclusions are: I think the loosey-goosey feeling over 80mph+ large amplitude mid-corner bumps was from insufficient compression and rebound damping. Maybe from the way SBG revalved them with less compression damping? Apparently they can take up to 14K springs but even on 11K/11K I am nearing the end of adjustment before the car felt good in my hands.
On these settings even in low speed corners it feels dare-I-say more planted and definitely more direct than before. Ride quality is pretty much uncompromised despite going tighter on the dampers. DFV ftw. Will have to get it back on AMP for a final impression, but based on my test-loop it should be a whole lot better in all situations.
08-25-2018, 06:29 AM
#22
https://www.s2ki.com/forums/s2000-racing-competition-11/str-prep-suspension-alignment-904840/page7/
""2004 And Up/ AP2
• One of the "features" of the outgoing (AP1's) S2000's rear suspension was its tendency to exhibit bump steer at the limits. Honda's engineers have attacked this issue from several angles. Rear toe in (Alignment setting) was reduced from -0deg 19' to -0deg 10'. At a 50mm bump deflection, toe-in has been reduced from -0.19 (AP1) degrees to -0.05 degrees (AP2) Secondly, the rear roll center was lowered from 101mm to 92mm. Honda claims improved roadholding under full suspension compression or during severe body roll situations. ""
50mm is a little under two inches (1.968" to be exact). If nothing else, you can get a good, numerical idea of how dynamic the toe change is in the rear of the car. Simple math, -.05 / -.19 = 26%, or in other words a 74% reduction in maximum "toe gain" in the AP2 rear geometry vs. the AP1. For those that have driven both platforms, the difference in feel and stability is remarkable. There have also been evaluations done (a best motoring video comes to mind that analyzed differences between AP1 and AP2) that would "strongly suggest" the AP2 rear geometry equates to high cornering speeds because of the added stability, particular at corner entry when the rear of the car is most light. Not bashing the AP1 (much love for it) - just stating for reference.
The AP1 geometry seemed designed with a heavy bias to "trying to elminate understeer at turn in/corner entry." Crank in a lot of toe-in to combat this, and voila', the stock recomended alignment setting of 1/4" total toe in seems to make sense.
""2004 And Up/ AP2
• One of the "features" of the outgoing (AP1's) S2000's rear suspension was its tendency to exhibit bump steer at the limits. Honda's engineers have attacked this issue from several angles. Rear toe in (Alignment setting) was reduced from -0deg 19' to -0deg 10'. At a 50mm bump deflection, toe-in has been reduced from -0.19 (AP1) degrees to -0.05 degrees (AP2) Secondly, the rear roll center was lowered from 101mm to 92mm. Honda claims improved roadholding under full suspension compression or during severe body roll situations. ""
50mm is a little under two inches (1.968" to be exact). If nothing else, you can get a good, numerical idea of how dynamic the toe change is in the rear of the car. Simple math, -.05 / -.19 = 26%, or in other words a 74% reduction in maximum "toe gain" in the AP2 rear geometry vs. the AP1. For those that have driven both platforms, the difference in feel and stability is remarkable. There have also been evaluations done (a best motoring video comes to mind that analyzed differences between AP1 and AP2) that would "strongly suggest" the AP2 rear geometry equates to high cornering speeds because of the added stability, particular at corner entry when the rear of the car is most light. Not bashing the AP1 (much love for it) - just stating for reference.
The AP1 geometry seemed designed with a heavy bias to "trying to elminate understeer at turn in/corner entry." Crank in a lot of toe-in to combat this, and voila', the stock recomended alignment setting of 1/4" total toe in seems to make sense.
08-26-2018, 07:03 AM
#23
Former Moderator
I'm a firm believer in adding some type of rear bump steer correction to AP1 cars. I also raised the steering rack for front bump steer correction and noticed no difference in handling.
The S2000 can be difficult to drive at the limit but if you learn to do it you'll be a much better driver. The US Army uses a small, twitchy, very difficult to fly piston powered helicopter for primary training. It helps weed out weak pilots early in the program. The S2000 on a race track is kind of like that.
The S2000 can be difficult to drive at the limit but if you learn to do it you'll be a much better driver. The US Army uses a small, twitchy, very difficult to fly piston powered helicopter for primary training. It helps weed out weak pilots early in the program. The S2000 on a race track is kind of like that.
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dsgerbc (10-18-2018)
09-12-2019, 07:37 PM
#26
09-12-2019, 07:52 PM
#27
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Lol ok sorry didnt see the date. But adjusting only by damper settings or anything else in fact, thats just like putting a band aid to the problem. You will have much more potential by correcting what is actually wrong and then setting up from there. IMO
09-17-2019, 08:16 PM
#28
https://www.s2ki.com/forums/s2000-ra...-904840/page7/
""2004 And Up/ AP2
• One of the "features" of the outgoing (AP1's) S2000's rear suspension was its tendency to exhibit bump steer at the limits. Honda's engineers have attacked this issue from several angles. Rear toe in (Alignment setting) was reduced from -0deg 19' to -0deg 10'. At a 50mm bump deflection, toe-in has been reduced from -0.19 (AP1) degrees to -0.05 degrees (AP2) Secondly, the rear roll center was lowered from 101mm to 92mm. Honda claims improved roadholding under full suspension compression or during severe body roll situations. ""
50mm is a little under two inches (1.968" to be exact). If nothing else, you can get a good, numerical idea of how dynamic the toe change is in the rear of the car. Simple math, -.05 / -.19 = 26%, or in other words a 74% reduction in maximum "toe gain" in the AP2 rear geometry vs. the AP1. For those that have driven both platforms, the difference in feel and stability is remarkable. There have also been evaluations done (a best motoring video comes to mind that analyzed differences between AP1 and AP2) that would "strongly suggest" the AP2 rear geometry equates to high cornering speeds because of the added stability, particular at corner entry when the rear of the car is most light. Not bashing the AP1 (much love for it) - just stating for reference.
The AP1 geometry seemed designed with a heavy bias to "trying to elminate understeer at turn in/corner entry." Crank in a lot of toe-in to combat this, and voila', the stock recomended alignment setting of 1/4" total toe in seems to make sense.
""2004 And Up/ AP2
• One of the "features" of the outgoing (AP1's) S2000's rear suspension was its tendency to exhibit bump steer at the limits. Honda's engineers have attacked this issue from several angles. Rear toe in (Alignment setting) was reduced from -0deg 19' to -0deg 10'. At a 50mm bump deflection, toe-in has been reduced from -0.19 (AP1) degrees to -0.05 degrees (AP2) Secondly, the rear roll center was lowered from 101mm to 92mm. Honda claims improved roadholding under full suspension compression or during severe body roll situations. ""
50mm is a little under two inches (1.968" to be exact). If nothing else, you can get a good, numerical idea of how dynamic the toe change is in the rear of the car. Simple math, -.05 / -.19 = 26%, or in other words a 74% reduction in maximum "toe gain" in the AP2 rear geometry vs. the AP1. For those that have driven both platforms, the difference in feel and stability is remarkable. There have also been evaluations done (a best motoring video comes to mind that analyzed differences between AP1 and AP2) that would "strongly suggest" the AP2 rear geometry equates to high cornering speeds because of the added stability, particular at corner entry when the rear of the car is most light. Not bashing the AP1 (much love for it) - just stating for reference.
The AP1 geometry seemed designed with a heavy bias to "trying to elminate understeer at turn in/corner entry." Crank in a lot of toe-in to combat this, and voila', the stock recomended alignment setting of 1/4" total toe in seems to make sense.
This can be easily fixed by replacing the AP1 subframe with the Ap2 i suppose?
09-26-2019, 11:24 AM
#29
Registered User
i had major ap1 bumpsteer issues, tamed it with stiffer front sway, stiffer springs, rear wing, running less rear static toe setting, ap2 wheels with 255 in the back.
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