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Project G37S: Suspension Upgrade with KW Variant 3's and Eibach Swaybars

by Aaron LaBeau

 

When we completed our wheel and tire install, it was hard not to feel like the work was only half done. Not being able to lower the car to achieve the aggressive ride height to match the extra wheel width and rubber under the car was a bit of a disappointment. I also wasn’t happy with the tire shop alignment that was done on the car. More time was spent hanging the laser alignment mirrors on the wheels than actual time spent turning wrenches to fine tune the suspension geometry. The 4x4 look of the stock suspension with the lower profile rubber was tolerable only because the ride was still comfortable, but I was left with the desire to see if the KW Suspension hype all my colleagues write about was real. I had to know if comfort, flatter transitions in the corners and the desired height drop could all be achieved while still being able to haul the family around. After all, it's one thing to live with a racecar-like suspension on the street with a hardcore car, like an Evo or STI, but we’ve also used KW variant 3’s on our Lexus ISF and BMW M5 projects, and it’s at this point we start our suspension transformation.

 

KW has gone through a lot of effort to make sure the variant 3 suspension will perform well in all kinds of environments. The v3's are a part of the inox-line, which use stainless steel bodies for corrosion resistance.
 
The suspension is adjustable both in the compression with 12 damping settings, and the rebound can separately adjusted with 16 damping settings.

Our particular car has gone 78k miles, and since KW reuses some of the stock components with the Variant 3's, we thought it would be a good time to freshen up those factory pieces. We went to InfinitiPartsDeal.com, which seems to offer some of the lowest prices we’ve seen for factory parts. We ordered new upper spring seats for the front and rear that both have rubber bushings sandwiched in the housing, new gaskets for the spring seats up in the strut towers, new lower rubber spring seats for the rear and new nuts to bolt the whole assembly up. In total, it was about $500 worth of parts, but reusing the old items would have been a mistake.

 

The adjustable spring seats are made of aluminum and anodized for corrosion resistance. The collar is designed with a polymid composite super plastic to function when exposed to harsh brake dust and other fine particles.
 

We didn't want to add any noise to our car, which typically happens when switching over to a coilover setup. The variant 3's rear damper will use the stock rubber upper isolator we're sourcing from Infinitipartsdeal.com, so our improved suspension will still ride nice and quiet.
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Comments
CTK
CTKlink
Sunday, October 08, 2017 6:13 AM
Nice work! Although the stance looks a little boaty (low in back, high up front). Part of that might be the camber settings.... isn't it customary to run more negative camber up front? I had a Z with a decent amount of camber out back stock and it absolutely chewed through the rear tires.

I'm still loving my Tein Basis Zs, though I do wish I had sprung for the stiffer and adjustable Flex Zs.
Sootfoot
Sootfootlink
Monday, October 09, 2017 8:42 AM
@CTK - Boaty, ha it was dumped in the back. Howard and I did our best guessing front to back height as the adjustment range on the KW's is different front to back. We got it dialed back in at WestEnd which is the image on page 8. Much less boaty there.

Yes, it is customary to run more negative camber in the front but as I wrote in the article there's a toe issue with the G37 that only allows so much camber to be dialed back after lowering. If that work was done, West End said I could dial the camber back to as little as about 1.3 degrees negative from the 1.7 it's set at now. Since we can't rotate the tires front to rear there's no reason to have the fronts match the rear setting.

The difference front to back is so minor I doubt anyone but a pro could tell and it's a far cry from the negative 3 degrees or more of camber guys run to stuff overly wide wheel tire combos.
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