Team America World Time Attack – ARK Design’s BNR32 Skyline GT-R Intro Part 2

 

Team America World Time Attack – ARK Design's BNR32 Skyline GT-R Intro Part 2

By Eric Hsu,  Important Stuff By Mike Kojima

Mike was driving my G35 home from the Scion FR-S Media Preview Party in Little Tokyo a couple weeks ago. It was a great party where I caught up with a lot of people I haven’t seen in a while, but I drank way more than I should have due to Scion’s very generous open bar. Here’s how the conversation went in the car (Mike is completely sober):
Me: “Dude, who were those last two chicks I was talking to?”
Mike: “Uh I don’t know. I thought you knew them.”
Me: “Hahah…damn it must be fun to be single these days. The tall one schooled me on the Android Swype keyboard. That shit is the bomb – you gotta use it. Hot chicks that use Android are DOPE! Chicks that use iphones are played out dude. Hey man, what’s the last CD you bought?”
Mike: “Uhhh….it was a long time ago man. Maybe Pearl Jam. The cover was red.”
Me: “Whoa….dude, isn’t that from 1991? You talkin about the one with Jeremy on it?”
Mike: “Yeah that was it. Music is lame these days mostly so it’s not even worth paying for music. I just rock the Sirius all the time. But hey seriously, when are you going to write part 2 on the ARK Design GT-R build? People keep asking me when the hell Part 2 of Team America is coming!”
Me: “Fuck I know man. People be blowin me up on FB too. There’s no time! Between the Greddy FR-S, ARK GT-R, work, and family, my life is completely consumed. I have like four stories that are half written for BTD, but I don’t have time to finish a single one. Hey I have an idea [actually a drunken revelation], why don’t you do a guest BTD post? Part 2 is mostly about the front suspension anyway. You can get all crazy with that suspension terminology that you bust out on and confuse the shit out of everyone.”
Mike: “Man….I miss my G35. These cars drive so good. No dude, I’m going to write the entire Part 2. If I wait for you, you’re going to take forever! I think I took more pictures than you did down at Gary’s anyway.”
Me: “You took better ones for sure. Ok, cool, you write part 2 then. I’ll send you some of my pics too.” 
Read it and weep keyboard tuners and JDM fanbois. Contrary to popular belief and legends of awesomeness, the R32 GT-R has really shitty front suspension geometry.  Very short, highly angular links result in a stupidly poor camber curve, bad roll center location, seriously bad lateral instant center location, a lot of scrub and too much anti dive.  The result is serious understeer and torque steer with big tires. (Just ask Takumi in Initial D) and worst of all, jacking.  A lot of the problem is the upper link location as shown in this photo I borrowed from Geoff Raicer of Full Race.  The upper link is super short, angled forward and canted upward.  This photo is at full droop, imagine how bad the upper link angularity is at ride height.  I think some Jr. Nissan engineer was trying to design a suspension with more negative camber gain when the wheels were turned and he either didn't know or care about other things.  I want to kick this guy in the nuts. Besides having a retardedly ungood amount of negative camber gain, the upper link angularity means that the lateral instant center is very close to the wheel centerline and the roll center is very low.  When an attempt is made to correct the roll center by moving the pivot for the lower arm, the lateral instant center gets even closer.  This means that the front suspension wants to jack with a lifting moment that also causes wheel tuck.  Yikes this is bad!  We have photos of this happening to the car and other R32's on the track. What was leading edge technology in the early 90's sucks now. 
Some clever folks ditched the Multilink on this R32 , converting the front suspension to McPherson strut.  Belive it or not, a well designed Mac Strut is probably better than the R32's Multilink.  Interestingly, the Z32 was designed a few years after the R32 and has almost identical front suspension except the upper link's angularity is reduced.  Z32's have less understeer than R32's and don't jack.  For us, struts were not going to cut it.  We wanted to package giant front tires and they would get in the way.  Plus we wanted the freedom in controlling the camber curve, scrub radius, anti dive, king pin inclination, roll center height and side scrub that good old unequal length A arms would produce.  We also wanted to get rid of the R32's really heavy front crossmemeber.  Time to get fabbing!
Meeting of the minds.  Eric Hsu, Tyler Hara, Mike Kojima, Chris Marion, Katsu Hibio and Gary Castillo ponder how to package a lot of the suspension that was not clear enough in CAD. Cosworth, KW Suspension and MotoIQ representing!  Many times there is no substitute for eyeballing the actual parts vs trying to do the whole thing on the tube. 

 

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