posted on April 30, 2012 00:00
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.
Posted in: Magazine
, Beyond the Dyno
, Race Cars
, XS Engineering BNR32 GT-R
, KW Suspensions
, Borg Warner
, Vibrant Performance
, Time Attack
, Skyline GT-R
, 2012 WTAC
, Project Nissan BNR32 Time Attack Skyline GT-R
, ARK Design BNR32
Monday, April 30, 2012 4:22 AM
The level of fab work here initially seemed a bit baffling. Then I saw the fourth photo down on the second page...
... O_O !!!
Wow. That... That's a lot of meat you guys are cramming under those fenders. 295s on the FRONT of an R32!? That is fucking OUTRAGEOUS! I... I think I'm in love...
Hellafunctional For The Motherfucking Win! Go team America, rah, rah rah!!!
Monday, April 30, 2012 5:52 AM
Holy crap, this is serious! Reminds me of this car...
Note the double wishbone suspension on both axles and the RB26 mounted so far back. It's an incredible project. Shame that it never turned a wheel in anger, I'm sure that by now it would've been right up there with the Cyber Evos and the like.
Monday, April 30, 2012 6:28 AM
This car looks great! Can't wait to see how the drivetrain and cage turn out. The fab work is top notch and very interesting.
Though Mike should continue updating the Ultimate Guide to Suspension & Handling to help explain some of the terms being thrown around in this article.
Monday, April 30, 2012 9:24 AM
Suspension looks awesome! One question though the shock towers are made from several layers on metal am i right? are you going to stitch weld them together or leave them as they are? Just wondering as ive seen it be done before for strength.
Monday, April 30, 2012 9:39 AM
1. How does the roll center migration look?
2. I'm surprised you guys aren't shimming at the upright for camber...Custom uprights out of the budget? =)
3. The intake manifold looks amazing...is that the piece that will actually be on the car? I only ask because all the rapid prototyped parts I've seen are very brittle plastic and have no business being bolted to a racecar.
Monday, April 30, 2012 9:41 AM
Haha, the FSAE in me was whining about double shear on those inner mounts so thanks for that caption. Despite that, I'm REALLY impressed with the adjustability you were able to package there!
If you don't mind, I'd love to pick your brain on suspension desgin some... I'm guessing for the kinematics stuff you used OptimimG Kinematics or similar?
How do you predict how small changes to caster/KPI and anti-geometry will change the handling of the car? I feel pretty familiar with camber and roll center effects but don't have hardly any theoretical knowledge or experience about the aforementioned.
Monday, April 30, 2012 9:49 AM
How cool would it be to fly around Tyler's Solidworks models!
Monday, April 30, 2012 9:52 AM
What considerations have to be made in mating a tubular subframe to a unibody car? To the uninformed it would seem the stresses and strains would tear the old metal inboard of the strut tower.
This is so far of the normal scale of normal tuner articles I am giddy with excitment.
Now if only I knew how to weld I would do the same to a third gen Camaro... Or mate an ITR front end to an FA5... The possiblities are endless!
Monday, April 30, 2012 10:16 AM
That's a HUGE caster increase. Nice.
Monday, April 30, 2012 10:25 AM
I see on the front boxed upper control arm mount, that you could have easily run a longer bolt and kept double sheer, though...ignoring a little extra work in shimming.
I'm curious if that simply wasn't thought of or if you guys had a reason for keeping the bolt in single sheer and now having a bending moment. Just thinking about fatigue issues like many extended ball joint kits have.
Still looking good!
Monday, April 30, 2012 11:17 AM
Love this. Obviously there's a lot of analysis that goes into making everything work right with geometry; familiar with that myself to at least some degree. I've just always wondered why more people don't do things like that; leaving aside the people who don't have the ability to do the analysis (or at least get it closeish) or the people who don't have the fab ability to be confident in stuff lasting... there's still far fewer people doing that sort of thing than I'd expect.
To people asking, I'd suspect the rapid prototyped manifold is there for fitment, because it's lighter than the real one, and possibly because it was sitting around at Cosworth.
Off topic of this specific car, but I wonder how some of the WTAC rules would be interpreted for non-unibody cars. I can't but look at the Garage Revolution '7, and things like a C6 Corvette (or other things with a composite body over a frame) and wonder what you could legally replace.
Monday, April 30, 2012 11:18 AM
Great picture of Mike with his credit card and great work on the car! I can't believe how much you knock the suspension....and I like that you do!
Monday, April 30, 2012 12:54 PM
LeathanE: Yes, the factory shock towers are actually double layered sheet metal with three layers in some spots. They were already been stitch welded in the original build
NBruno: Yes, custom uprights are out of the budget. The rapid prototype manifold is just there for placement. We actually used the plastic pieces for testing during the manifold's development, but I wouldn't use one on a race car.
Jasonrg77: The shock tower is being supported by the addition of tubes (not all visible in the pictures within this story). We considered plating over the factory shock towers, but we deemed that unnecessary after discovering the factory shock tower is double and triple layered in some places. We had to keep the shock towers in place because that is part of the Pro Class WTAC rules.
Micah: Yes, we can convert to double shear with the addition of spacers.
Kenku: WTAC Pro class rules basically say factory shock towers and firewall must be present and in their stock locations. Other than that and CAMS (the Aussie FIA) safety considerations, it's pretty much open.
Monday, April 30, 2012 12:59 PM
Huh; that's what I figured, and actually kind of a scary answer, though maybe I've been looking at old IMSA GTP / FIA Gr.C cars too much lately. Given that sort of bodywork freedom, it's not hard for me at least to see a clear path from, say, a Lotus Esprit to a GTP car, tunnels and monocoque and all... probably for the best I don't have the resources to build it.
Monday, April 30, 2012 1:09 PM
But...but...I thought the unmatched GT-R was master of the uphill?!
Monday, April 30, 2012 1:48 PM
I'm suprised you guys didn't come up with a "weld-in kit" for the JDM homeboys to buy and start fixing the front ends on all those BNR32s over the pond.
I find the level of thought and engineering going into this nothing short of a masterpiece!
Who came up with the MR-S realization? Any design color ARK is leaning toward?
I've been following this car since the first build, what 7 years ago? Lovin every minute of it...:-)
Props to everyone!
Monday, April 30, 2012 2:10 PM
speaking of uphill, any the car would be ready to run at Pike's Peak on July 8th
Monday, April 30, 2012 2:27 PM
Nbruno-the roll center migration is way better than it was, which was like just as bad as the wheel travel. We didn't fab new uprights due to budget considerations although that would have been better as we could get a decent bearing system in there and had a little easier time with the geometry. Once we measured the bits up we saw that we could get pretty close with the stock parts so we saved the money and time.
Bigbcraig- on sedans small changes don't affect things much. Messing around trying to control them doesn't usually equal faster lap times.
Jasonrg77- yes we consider the subframe mounting careful and it is much stronger and stiffer than stock.
Micah- We would not have done single shear if it was the lower control arm or if the dampers were mounted to the upper arm. Overall this area is still much stronger than stock.
Der Bruce- I have already had several heated arguments of R32 fans that are in love with the RB and the stock suspension. Facts have no impact on these kinds of people.
Monday, April 30, 2012 2:54 PM
You guys have done an amazing job on fabbing a better front suspension. That setup must have taken tons of measuring and prep, but it is going to produce the best handling R32 in history no doubt.
I'm definitely keeping that outboard damper mounting and a few other tricks from this article in my back pocket from now on!
It's also awesome how you found such great engine placement. The front/mid setup coupled with your new suspension design should allow you to truly use all the power you plan to pump through this bad boy!
Plus the dry sump motor mounts are (to me at least) slightly reminiscent of the F1 way of tying the motor and trans into the suspension/chassis - cool!
Monday, April 30, 2012 4:58 PM
This is so sexy. I wish I would have known some of this stuff years ago. Times like when we were racing an R34 GT-R. The R34 is a little different in the front, but not great.
I know a good amount about cars, and racing, but a lot in here is over my head. Going to have to read it twice, and get my wife to explain most of it to me.
Monday, April 30, 2012 5:45 PM
Nice! Awesome post, way over my head for most of it, which is fine as long as there is some form of ending statement for us mortals to understand (E.G. this mean good, this mean bad)... which there were! Thanks for such a good post.
Good to get part2 finally, I have been on the edge of my little chair for it. With this much knowledge/effort into the suspension alone, I have no doubt this car will bring the pain in 2012. The front tires, and the engine placement have my jaw dropping; waaaaay down and back! I can't wait to see/read more details on the engine (or any portion of it really)
Monday, April 30, 2012 6:06 PM
Sean, the R34 has not great but way better front end geometry than the R32. Each generation of the GT-R gets progressively better. The R35 has a large amount of anti dive but is reasonably straightforward.
I wonder if you would have been able to get to the SCCA to allow you to do something like this back in the day when you were racing?
Monday, April 30, 2012 7:42 PM
Question on the damper mounting on the lower wishbone. Does'nt having the damper mounted so far from the outer pivot point, lead to a bending moment introduced into the wishbone? Wouldnt this lead to a structural weakness and possible breakage?
Can this also lead to a 2nd (unintended and undamped)spring into the system? I'm pretty sure the reason for designing it that way is for clearance of the driveshafts. Is this just an engineering compromise?
Monday, April 30, 2012 8:10 PM
SCCA will allow about anything until you get competitive. The rules are pretty flexible. Did you see what they did to the front of the CRP R35? Convert to rwd, move the upper, give it a tubular upper arm.
Monday, April 30, 2012 8:43 PM
Mike, what is the advantage of having a low roll center? I always thought you want to minimize your roll moment, which is the distance from the roll center to the CG? If that's true, shouldn't you try to get the roll center as close to the CG as possible, not low?
Monday, April 30, 2012 8:49 PM
Please post images of the SW20 MR2 system.
I have the pump in my garage and I want to see how you guys will hook it up to the VSS, if any hookup at all.
Monday, April 30, 2012 9:24 PM
High roll centers induce chassis jacking and other weird things, in short.
Tuesday, May 01, 2012 2:13 AM
NBruno, what Kenku said. Markc, the lower mounting point is actualy close to the end of the LCA which leads a smaller bending moment and a lower motion ratio which is why we designed it that way.
Tuesday, May 01, 2012 7:33 AM
Eric youve got your work cut out for you this was posted on the World Time Attack Website.
Tuesday, May 01, 2012 8:55 AM
It wouldn't be any fun if the Cyber EVO wasn't there.
Tuesday, May 01, 2012 11:09 AM
Ever think of switching the hubs around, making the calipers trailing? Did I ever send you guys the Group A FIA documents? Some interesting stuff in there.
Tuesday, May 01, 2012 2:16 PM
Sean, If they did swapped the hubs they would have to move the steering rack. A bit complicated at this point.
Mike, I see you are running springs with helpers. The lower mounts are fixed. Are you planning on making a ride height adjustment at the upper hat? This will allow spring preload adjustments separate from ride height.
Tuesday, May 01, 2012 4:15 PM
Any plans to replace the rod end in bending on the upper a-arm on the front? At least there's no spring and sway bar loading through through it, but it could still be bad on a car that's obviously going to have some crazy aero and sticky tires on it.
Tuesday, May 01, 2012 8:21 PM
Why not convert to a mechanical steering rack over an electric PS (MR2) setup? There is not much weight savings to be had, but every little bit helps up front. I have heard of a couple people doing this & have been happy with the results.
Tuesday, May 01, 2012 11:24 PM
I would imagine unassisted steering and 295 width front tires would not be a very good match.
Tuesday, May 01, 2012 11:28 PM
Um, this talk of CyberEvo has me wondering; What's the target weight of the Team America BNR32? Is someone gonna be keeping an eye on those CyberEvo tires that everyone can buy? ;-)
Wednesday, May 02, 2012 12:00 AM
There are two decreasing radius hairpins at Eastern Creek. Manual steering isn't going to happen in a car with three differentials, 295s, and a shifter.
Bruce: Target weight = 2500 lbs. How is anybody going to keep an eye on Yokohama? It's Yokohama's event! I nominate you to come and raise hell if they pull that super softy stuff again (and then hang out at the pub after and drink Carlton Draught with us).
All those other questions up there are for Mike...
Wednesday, May 02, 2012 1:28 AM
Sean- I don't like front steer, it tends to understeer more. Induetime- there is no way this is going to go with no power assist. Have you ever tried to drive a race car with no power assist? No fun. Def- Don't worry, the hardware we chose is many time stronger than the anticipated load.
Wednesday, May 02, 2012 11:03 AM
I just like the idea of having a trailing caliper so that you can get some air into the rotor of an all wheel drive car a little easier. In this situation when everything is fabricated, it seemed like it might have been an option.
I still think that MRS rack might light on fire and die trying to steer some 295's and a lump hanging above it. Its going to need a MSD box to keep it going.
Wednesday, May 02, 2012 2:49 PM
Just make sure that the MRS rack uses the factory toyota fluid, it'll take a crap really quick if you use regular PS fluid.
Kinda like the supra getrag MT fluid
Wednesday, May 02, 2012 7:53 PM
Arghhhh.. Already the talk of the Yokohama Super-Special-Secret-Sauce tires... the TA world has been "dealing" with them for quite some time. :-/
How bout Paul Jho and Hankook pull some strings and get the C91 compound poured into the Ventus TD mold for you guys for WTAC...? ;-)
That should level the playing field just a tad, eh? :-)
Wednesday, May 02, 2012 9:37 PM
Sean, the calipers in the rear also give a stabilizing moment to the steering.
Thursday, May 03, 2012 1:26 PM
I'm absolutely speechless on this build.
Wonderful work here and wish you guys much success.
No technical questions here or conversation but just my way of saying that I truly enjoy every one of these articles and gives me hope to the future of Time Attack and automotive excellence at it's best.
I look forward for more on this build. Awesome work guys. :)
Friday, May 04, 2012 8:39 AM
Wow! I can't wait to see the start up and shakedown videos! Have you guys found a driver yet?
Friday, May 11, 2012 12:56 PM
Eric - I would make an excellent designated driver and could impress the locals with talk of their national treasures such as Eric Bana (see the Beast people), Hugh Jackman and Anna Torv! I did peak at my schedule for that weekend and as it stands now, I'd have to reschedule somewhere between 100-130 people and close down our office. But If you guys were doing something stateside this year and gave me a heads up/ invite a few months out, I could probably make something happen and be there to help/learn/entertain!
Friday, May 11, 2012 7:11 PM
Great collaboration of minds! What a power house.
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