My question: Taking personal ride preference out of it, what are the best settings on my AGXs for the Mach V springs. More details: Last Friday, I installed my KYB AGXs w/ Mach V springs and haven't really driven it much since it hasn't been aligned yet. That's besides the point though; what I'm looking for is some advice on the ideal settings for the struts. I have an '07 WRX so both the fronts and rears are adjustable 4 ways. I'll try to provide as much info as possible to hopefully bring about the most helpful responses. Here is a post I found on Nasioc by our one and only Back Road Runner: The AGX products have the following approximate damping force values. When adjusted, both rebound and compression damping forces change. Setting#: Relative Value 1 - Same as Factory 100 2 - Same as our GR2 products (10~15% firmer than Factory) 115 3 - 50% firmer than #2 172 4 - 30% firmer than #3 223 That being said, the Mach Vs have the following spring rate: 175 lb/in front, 116-156 (progressive) rear I installed them with front and rear set at 2 thinking middle of the road would be a good place to start. However, I'd like to know a little bit more in regards to under-dampening/over-dampening. Would setting 3 over-dampen do you think? Thanks in advance!
I'll take a stab at answering this (I'm sure Shane and others will chim in as well): Engineers and technical folks will say that there is truly only one "proper" rebound and compression value for a given spring rate, car weight etc. Adjustable struts/dampers allow you to match that perfect compression/rebound value with the springs that you've chosen. However, adjustable dampers can also be used to customize the ride and handling characteristics for your own preferences. In general: Softer dampening will allow for a smoother ride, better handling on low grip surfaces (wet, snow, gravel, etc), more load is transferred to the suspension (vs the tire), etc. A suspension that is far under dampened (or just crappy dampers) will provide a "bouncy" ride (ie think blown struts; cheap coilovers). Firmer dampening will allow for better handling on dry surfaces. Body roll is reduced, turn-in "feel" is increased, more load is transferred to the tires, etc. A suspension that is far over dampened will provide a harsher ride. That is not always a bad thing for aggressive driving, but you can get some pretty interesting wheel hop and body pitches if you're over dampened on a rough surface. So what should you do? Experiment. Try messing with the settings from soft to hard and then set them at a level that suites your driving style and conditions. For a DD, somewhere right in the middle on AGX's will be ideal for most. If you want some crisper handling for a canyon jaunt on dry pavement, firm up the settings. If you want a cushy ride for city streets or want to play on some snowy back roads, soften them up. That's the beauty of having an adjustable suspension.
Oh and FYI for the Mach V's, they are just a little higher spring rate than stock (I don't have the exact numbers in front of me). I would venture to guess that if you wanted the "exact" dampening level, according to your chart of dampening percentages, level 2 would probably suffice for the front. All the AGX's that I've worked on have 9 settings for the rear, so pick one towards the bottom of the scale (I believe a lower number is softer in the rear).
Thanks for the detailed answer. I know there will always be some personal preference behind it, but the underdamped vs. overdamped explanation is pretty much was I was expecting. Besides ride quality, are there any ill effects on the springs or struts by under/overdamping the vehicle? Lastly, just a point of clarification...from what I understand the GC/GM specific AGX struts had rears that adjusted 1-8. The '02-'03 WRX specific AGXs only adjusted 1-4 in the rear.
Ah that very well could be. Actually I think the only AGX's I've worked on are for the GC chassis. As far as ill effects - literally none on the springs...they are springs. However if you put too high of a spring rate on an under dampened strut, you will accelerate the wear of the strut. Since yours are adjustable, that should not be a problem. As far as running your struts - some struts have issues/accelerated wear when run at the extremes of their dampening ranges. However the ranges of the AGX's are well defined. Might want to do some quick research on their longevity and potential issues. For example, with Tokico D-specs, there is no defined bottom end (softest setting), so running them on a super soft setting is not advisable. With Koni yellows, I just learn that even though they have defined setting ranges, running them at full soft can cause issues with the adjuster sticking. I haven't heard of issues with AGX's, but you may want to research more.
