posted on March 29, 2011 22:00
An Early Look at Dai Yoshihara's 2011 Formula D Ride
By Mike Kojima
Team Falken's Dai Yoshihara will once again be driving his Chevy LS powered Nissan S13 in the 2011 Formula D season. The car has been undergoing a complete rebuild at SPD Metalworks, a rebuild so intensive that it is basically going to be an all new car. A lot of the rebuild was needed to bring the car up to 2011 Formula D specs.
| A lot of cool hardware lurks at SPD Metalworks!
|Starting at the front of the chassis, the core support was removed and this tubular structure fabricated to mount the bodywork and heat exchangers to. This structure is easier to repair than the stock unibody in an accident. It is also stiffer in torsion. It is designed to bend in an accident and absorb impact sparing the main structure and suspension pick up points from damage. A push bar bolts to the forward frame rails.
In an effort to align Formula D competition cars with their roots as highly modified street cars and to hold down the costs on new builds for privateers, the new rules do not allow for the removal of as much of the car's unibody chassis as they did previously. The structural parts of the unibody must remain intact from the farthest suspension pick up points backwards in the front and forwards in the rear.
|Details of the front of the frame rails, the rails are boxed in and provide mounting for the front push bar. The forward cage extension terminates here. The box section up front is much stronger than the stock core support.
|These tubes are an extension of the cage. Formula D rules do not allow the cage tubes to go through the firewall so they bolt through the firewall. This aids repairability though. The bars stiffen the chassis and aid handling. They also add strength. Areas of the unibody were bent inward for more tire clearance at full lock, important because drift cars are modified for increased steering angle.
Wednesday, March 09, 2011 10:32 PM
I say add some a-arms of front, some 5x5 trailing arms in the rear and Dai could have the first S13 sand car down at Glamis! Speaking of sand toys, wasn't Rhys trying to start up extreme drifting with his prerunner a few years ago?
Wednesday, March 09, 2011 11:04 PM
Damn Mike, i wanna see this thing run time attack. Its so nice, gonna hate to see it take some taps.
Thursday, March 10, 2011 12:36 AM
Will the car go to RHD or stay LHD? Either way is cool, seems like Dai is quite comfortable either way, lol.
Thursday, March 10, 2011 4:45 AM
On page 3 there's an interior shot where you can clearly see that the car retained LHD steering.
Thursday, March 10, 2011 5:44 AM
Wow I'm amazed you guys were able to use the stock front fender wells. All serious drift S13s I've seen cut them out and replace them with mini tubs. I guess that has to do with the rules? I prefer it I'm sure it's less work than cutting out fenders and replacing them. Certainly looks great, Dai should have a killer car for the new year. Good luck to the team!
Thursday, March 10, 2011 7:00 AM
i thought i saw somewhere that theres a new rule that the car and engine had to be from the same maker, but i guess thats not the case becaus eof the ls.
Thursday, March 10, 2011 8:09 AM
Some of those welds are nasty. Obvious porosity on some of them. If I had turned in some of those welds in welding and metals fabrication school I would have failed. Specifically the second and fourth pictures on page two.
Thursday, March 10, 2011 8:13 AM
It's hard to weld chassis seams perfectly, seam sealer inside the folds and oil residue bubbles out of the seam while you try to weld. I can assure you that you probably don't weld better than Scott. You probably have never seam welded a unibody chassis either.
Thursday, March 10, 2011 8:21 AM
Thursday, March 10, 2011 8:26 AM
That is beautiful work. Thanks for the detailed look.
What is that canister in the trunk right under the fuel cell breather?
I had a similar fuel system with fuel cell output at the top and pump mounted right below the cell (Bosch 044, not A1000), and it vapor locked a couple of times. I think you'll always have issues with an external pump and drawing fuel from the top of a fuel cell. I switched to an internal pump mounted inside a trap-door surge tank inside the cell and haven't had any issues since. Why not add an external surge tank with low pressure pump drawing out fuel? You guys are looking to add some weight anyway.
Thursday, March 10, 2011 9:07 AM
Hey mike can we get a writeup when they wire the car?
I'd like to see that.
Great work as always!
Thursday, March 10, 2011 9:25 AM
I am not sure which canister you are talking about? The breather is for the transmission and differential. I see the fuel pump and filter?
A surge tank with submersible pumps would be better but we also try to make the car as simple as possible. Drift cars are brutal on electrical systems and having 3 pumps to draw down the battery might be trouble. At least with the pump low, it won't have as much of vacuum to prime. THe pump used to be mounted on top of the cell so this should be better.
When the battery is 140 plus degrees in the vegas heat or Atlanta humidity, all of the fans, pumps and cool suit are going full blast and and the car heat soaks and idles a lot due to how the show goes, battery voltage gets iffy.
Thursday, March 10, 2011 9:56 AM
top notch as usual. great write up and i look forward to seeing the car on the track. i might be at the nj event. hope to see you there.
Thursday, March 10, 2011 10:33 AM
Are there any modification to the strut mounts up front? I remember in SCC's final S13, they modified the tops to improve camber adjustment. I was curious to see if SPD did something similar to this car.
I saw another drift S13 under construction yesterday and they too did a skip-seam welding on the chassis. I wondered why they did that (as opposed to doing full seam welding), but on a drift car I suppose quick and easy repairs are pretty important.
Totally off subject, pk386 do you actually own a Morgan? My dad has a 1953 +4. Always like talking to a fellow Mog fan. PM if you want to chat about cars built out of wood.
Tuesday, March 29, 2011 10:20 PM
HAHAHA its back! Good to see, time to start sharing link.
Tuesday, March 29, 2011 10:22 PM
I was wondering where this article disappeared to? I figured maybe we had seen too much and were lucky men in suits weren't knocking on the door!
Tuesday, March 29, 2011 10:28 PM
It is not legal to mod the strut tops so they are complexly stock.
Tuesday, March 29, 2011 11:10 PM
Do you guys use a heater core in your car?
Tuesday, March 29, 2011 11:16 PM
Wednesday, March 30, 2011 12:38 AM
what size front tire are you running?
Wednesday, March 30, 2011 12:40 AM
245/35-18 for drift, 275/35-18 for gymkhana
Wednesday, March 30, 2011 8:10 AM
@8695Beaters My real name is Morgan T.
I don't own a Morgan. the pic is from a local who has a Morgan +8 with an LS3 under the hood 0_0. But I do have respect for the wood framed cars.
Ironically my brother is named Austin. Some one asked my mom once why she named us after English cars. (My parents didn't intentionally do it they just liked the names ^_^)
Wednesday, March 30, 2011 9:27 AM
FD says: lighter cars, less tire
Kojima says: simplify and add.... heaviness?
i think youre onto something Mike, might not be Colin Chapman levels of profoundness, but youre definitely onto something.
totally looking forward to FD this year.
Wednesday, March 30, 2011 10:58 AM
We are just adding a little weight so we can run our present size tires. The car is gonna corner balance better and we are getting a stiffer more resonisve chassis.
Thus I think our performance won't change too much.
Wednesday, March 30, 2011 12:07 PM
Mike, I don't know about the fuel cell location.
Let me explain:
I would have relocate the fuel cell EXACTLY in the center, and use the entire space of that area available (where the Optima battery is). Having the same size fuel cell with a bigger area available= the fuel cell can actually sit MUCH lower into the chassis = better handling. Not only that, but if you had the fuel cell closer to the shock tower it would be even further away from the rear bumper, making it a bit safer (basically have those welded steel arms that support the fuel cell closer to the shock tower so that you diminish the polar inertia even more.
THEN relocate the Optima Battery exactly in the center inside the cabin behind the sheet metal that separates the trunk space and the cabin.
Another thing. There are two sets of rear kickers. How about an X brace from the main loop onto the rear shock tower?
As far as adding extra weight. How about using ballads on the passenger seat area?
Just my .02
Wednesday, March 30, 2011 1:26 PM
I don't agree with you, it's all about packaging and the rules about cutting sheet metal out. You gonna have the driveshaft go through the center of the fuel cell? Or have the the Diff in the center of the fuel cell?
What about weight distribution? Are you willing to have 2 percent more front weight bias? What about servicing? Try working and filling the fuel system in the middle of a bunch of tubes? We moved the fuel cell forward a few inches from last year.
The two sets of kickers are not by choice, we would have done an X but FD forced us to add them last year. They made Ross Petty do the same thing.
Wednesday, March 30, 2011 2:10 PM
What is skip welding?
Wednesday, March 30, 2011 3:48 PM
Great writeup as usual!! I agree with pk386 a writeup on the electrical system would be great. It is great to see an in depth analysis of how a professional drift car is built.
Wednesday, March 30, 2011 11:35 PM
No, the fuel cell would be closer to the rear diff. Close enough so that you guys can still swap the diff if need it.
The driveshaft wouldn't be an issue. It seems from the pictures you posted that there is some space left between the fuel cell and the sheet metal that separate the cabin from the trunk. I'm just saying. A bigger area to play with (by relocating the battery) would allow u to drop the fuel cell lower, and instead of having the gas cap on the cell, weld a duct to the C-Pillar so you guys don't have to open the trunk to fill in. Again, you don't have to agree really. Just my .02
Good car nonetheless. Wish you a successful season !
Wednesday, March 30, 2011 11:35 PM
without a heater core what do you guys do to defog the windshield during cold/wet events?
Wednesday, March 30, 2011 11:37 PM
It doesnt fog up, its plastic.
Thursday, March 31, 2011 8:01 PM
Thanks much for posting this up. I read every little bit I can about Dia's car.
Thursday, March 31, 2011 8:17 PM
@Dusty- skip welding is just any weld that isn't a full length weld, usually denoted by example "2 on 6" or "1 on 3" meaning 2" long welds on 6" centers or 1" long welds on 3" centers, etc.
Thursday, April 07, 2011 2:36 AM
"Drift cars won't see high speed side impacts like a road racing car might but safety comes first."
One thing that has bothered me for a long time is the low amount of side impact protection on pro drift cars. the past ASD cars with their flimsy FRP doors and sparse door bars seem lacking to me.
While it is true the top speeds are lower than road racing and usual speed differential between cars is low there are always outliers.
The best example is Tommy Suells T-Bone incident at Long Beach (I think it was in '08). In practice he spun and with the smoke and next driver missing the flagger he was T-Boned full speed caving in the passenger side enough to have made contact with the driver had it taken the hit on the drivers side.
Another good example is Dai's Seattle Lexus crash. What if he had spun and rotated a few more degrees and caught the wall on the door instead of the front corner at 70mph?
Personally, I think that SCCA Pro rules for drivers door bars are a smart way to go for drifting.
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