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#323: 05-13-2009, 01:12 PM
 
 Underdog
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Title: Wrench for Hire
Location: Ayer, MA
Car: GRP '06 LGT/5MT; DBM '09 OBXT/5MT
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Some more impressions:

So I drove the car for ~2 weeks with the adjusted ride height, but still no alignment. I definitely noticed a difference in comfort from the Konis/Swifts to the Tarmacs. By the way, I am still riding on 16 clicks in the front, 14 in the rear (# clicks from full firm, as per RCE recommendations). My current drop is -1.22"/-.34" which is inside the recommended range.

Before I get going, I want people to know the ride is still firm. If you are looking for the ultimate isolation from the road, look somewhere else (like a buick or something )... To me, a firm ride means that the body of the car follows the contour of the road. By contrast, a "soft" ride would be where the body floats along the road while the suspension does all the work. Obviously the ideal would the control of a firm ride, but the comfort of a soft ride, however that is not practical in this case.

So, the ride is established as firm... When a particular corner of the car reacts to a bump or just follows the curvature of the road, I feel it in the driver seat. I still cannot drive over potholes, speed bumps, frost heaves, and cold-patch with impunity like I could with the stock suspension. This isn't to say that the suspension can't take it, rather, I can't take the idea of shaking my car to pieces (OCD).

The thing that separates the Tarmacs from my last setup is the how the suspension deals with the firmness. This brings me to "harshness". To me, harshness is when the suspension can't cope with the road conditions, for whatever reason. Examples of this would be when I hit the aforementioned imperfections, the car would shake violently and the suspension would jump around and emit loud slamming sounds. Now if I hit the same imperfections I can still feel it, but the car maintains it's heading without any fuss. Also, the suspension never feels like it's bottoming out or "jacking down". I don't cringe when I hit the same bumps that used to make me crap my pants with the old setup.

Consider the following examples:

Konis/Swifts

1. Car is traveling at normal speed, say 35-40mph, approaching a medium sized pothole.

2. As the car "hits" the pothole, the suspension cannot rebound quickly enough for the wheel to follow the road, so the whole corner drops, hence the "whoa" feeling. I've heard this referred to as "jacking down".

3. The body of the car is still accelerating downward from "falling" into the hole by the time the wheel has started climbing out. Since the car had almost zero bump travel anyways, this elicits a loud bang as the suspension bottoms out and the force of the wheel climbing is transferred to the body of the car.

Tarmacs

1. Same as above.

2. Appropriate spring-rate/damping allow the wheel to descend into the hole at a controlled rate, better isolating the car from the drop.

3. With more bump travel, and better matched spring rate/damping the wheel can climb out of the hole without smacking the bump stops. This takes all the harshness out of the pothole, even though you can still feel the road surface.

There are other scenarios where the improved rate/damping combo makes the car more comfortable. There is a hill that I crest on my way home from work every day... typically I am driving ~45mph. On the other side of the crest is a divot where freshly laid pavement meets the older portion of the road. With the old suspension setup I had to slow down before the crest or it would feel almost like I was getting air. (I had to keep the rebound damping jacked up or bumps were very harsh.) I probably wasn't really losing contact with the road, but the suspension certainly wasn't at full available droop either. Anyways, when I "landed" I would get a thud with a light *clang* from the underside of the car. (I've checked many times for bottoming-out damage, but found nothing.)

Now when I crest the same hill, I no longer need to slow down. The car no longer feels like it's loosing contact with the road and the landing is soft and cushioned. No more thud, no more *clang*... very nice.

Before I got the alignment the car felt very darty... Turns out my front and rear toe was pretty far off which certainly contributed to it. Also, my camber was off, but not by too much (actually it was closer to what I wanted before the alignment, but that's another story ). With my current alignment I have zero toe all around, zero camber up front, -.8 in the rear... I had asked for -1.5 front camber but they could only get -1.1 so they set it to zero.

Anyways, with the alignment the comfort and performance of the new setup feels even better. Where it was a little more concerning going through potholes and stuff before because the car would dart a bit, now it just runs it's course, straight and true. I'm actually not that concerned about the front camber becuase I wasn't having understeer problems anyways and my tire wear has always been completely normal. I may try doing my own alignment next time because I'm sick of putting my car in someone elses hands.

Anyways, sorry for rambling. Hopefully this info helps some people... I'm sure there will be more to add in the future.
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