280z FP Build

[tube80z]

13 hours ago, Ironhead said:

My first response to the fuel cell next to the driver's seat is horror, but why not I guess?  Really no more dangerous than having it in the hatch area.  Maybe safer, in terms of less likely to take a major hit.

 

But don't the rules require a metal partition around it, and either braided steel lines or hard lines?

 

They do.  But I've seen this interpreted different from time to time.  My car has a separate metal box over the cell and the lines where they are in the cabin. I got busted at a hillclimb (GCR rules) that I didn't have metal over my fuel lines (braided hose didn't count) so I did what any normal person would in the middle of nowhere.  I built a cover using aluminum foil and riveted it to the floor here and there.  Technically it was a metal cover.  Rules were changed after that to be more specific.

 

[Ben280]

21 hours ago, calZ said:

I've long been planning on and working towards having traction control in my car. I've been doing some reading about the MK60 units. It's handy that it outputs the wheel speed and yaw data as raw values that ECUs can read as regular inputs. It avoids having to make the can systems communicate. The only downside is that the ABS unit requires the sensor ring on each wheel to have the same number of teeth. I haven't pulled my R200SN off the shelf to count, but I'm guessing it doesn't have the same number of teeth as the Subaru tone rings I have for the front. 

 

The MK60 does require the same tone rings on all 4 corners, but it's not super concerned what that number is or not. The 3dm Motorsport guys said really anything between 40-50 teeth ought to work. I'm using Q45 tone rings on the rear stub axles and they do match up with the 350z front hubs I'm using. Oh yeah, this is the front hub now!

 

 

15 hours ago, Ironhead said:

My first response to the fuel cell next to the driver's seat is horror, but why not I guess?  Really no more dangerous than having it in the hatch area.  Maybe safer, in terms of less likely to take a major hit.

 

But don't the rules require a metal partition around it, and either braided steel lines or hard lines?

 

Or am I all messed up and that's not a fuel cell?

 

Yes, almost all rule sets require a full bulkhead separating any aftermarket fuel modifications from the driver. This is just an in progress pic, and since I posted it, a bulkhead has been installed! I think it's arguably safer since it's fully inside the car's roll cage (and about 2" off the floor). It's also a fully SFI/FIA rated fuel cell. It's also much better for the weight distribution, which is why I've done it! 

[calZ]

23 minutes ago, Ben280 said:

 

The MK60 does require the same tone rings on all 4 corners, but it's not super concerned what that number is or not. The 3dm Motorsport guys said really anything between 40-50 teeth ought to work. I'm using Q45 tone rings on the rear stub axles and they do match up with the 350z front hubs I'm using. Oh yeah, this is the front hub now!

 

I suppose an alternative would be to just have the ECU(will be a Haltech in my case) output the wheel speed data to the MK60. I believe I could setup an output that scales one set of the VSS pulses to match the number of teeth on the other set. The MK60 wouldn't know the difference. 

[Ben280]

12 hours ago, calZ said:

 

I suppose an alternative would be to just have the ECU(will be a Haltech in my case) output the wheel speed data to the MK60. I believe I could setup an output that scales one set of the VSS pulses to match the number of teeth on the other set. The MK60 wouldn't know the difference. 

I'd be interested to see if there's a good way to interpolate that data and make it work. I don't think the MK60 would care at a theoretical level, but trying to bump a 35 tooth count up to a 46 tooth for example seems tricky at best, particularly with real time data. 

[Ben280]

Ok, finally have time to give y'all a long form update with some photos! Obligatory "go give my instagram a look if you want more frequent updates" since the semi-annual updates might not be enough for some folks here!

 

The big goal this year was to get the car to work well on 18” wheels. Running slicks that work for one session only is a frustrating way to spend the weekends, and since all the hot tires come in a 315/30r18 for modern cars, that seemed like the obvious choice. While it seems like an easy enough conversion, things quickly spiraled out of control! 18x12 medium offset wheels are pretty rare, and add 4 lug to that, and it’s impossible. It seemed like going 5 lug was inevitable, but that would mean a switch of all the brakes in addition to the hubs. Front hubs would take some thought, but the rear hubs seemed easy enough to use Techno Toy Tuning uprights with s14 5 lug hubs and z32 rear brakes.

 

New rear hubs. s14 + z32 + T3

 

A solid upgrade over what I’ve been running, but require a little bit less figuring. With the s14 hubs, I opted to pair these with a real Frankenstein axle setup. I knew I wanted to run an off the shelf axle, both for cost as well as ease of replacement. Enter Nissan’s unique Lego ability. For the final combo, we have s14 5 lug hubs, 350z axles, Weir Performance chromoly stub shafts. Weir Performance makes a lot of awesome parts for the drift crowd, among which is the 350z axle conversion. They make a 29 spline R200 stub shaft, cast with the 6 bolt pattern for the 350z axle. 

 

Weir Performance stub axles preparing for fun mods. 

 

The 350z axles caused a bit of an issue, since you may have guessed, a 350z is much wider than a 280z! Enter my buddies over at Apex Engineered. I scooped up their new rear sub frame for the R200, along with their lower control arms and had them extend the arms by 2” to cover the difference in axle length. The Apex subframe has the advantage of inboard heim joints over the standard poly, for a bit more rigidity, and roll center adjustment. Trying to keep a low ride height with the 18” wheels would require a lot of roll center adjustment. A quick modification to the bolt on uprights from T3 and the rear was buttoned up. 

 

Full rear setup installed in roller form

Mmmmm shiny!

Tone rings nice and lined up. Ready for a sensor!

 

The front end was a real trick. The fronts of these cars become a real adapter mess. Roll center adjusters, quick steer knuckles, brake adapters, weld on struts, and an old style wheel bearing to boot.  Too many things! I wanted to integrate all these adapters, an improved brake caliper solution, a modern bearing style 5 lug, a 2” drop knuckle, and since we’re going a little crazy, why not include provisions for ABS. The 350z again seemed like a good place to look. They use a bolt on bearing/hub, is reasonably available, and integrates ABS in a good way, via magnetic seals. I took a huge amount of measurements, modeled the hub, desired brake package and ended up with something that I could manufacture! As my machinist friend put it “Testing custom uprights on track is an expensive proposition” so I reached out to the guys at Zebulon MSC in Colorado to do some FEA on this part. I gave them a lot of info about the car, and he returned some analysis and suggestions for where we could lose some weight and still increase some strength. 

 

3d rapid prototypes through to final piece

 

With the parts piling up, it was finally time to bolt everything up. COVID delays meant assembly of the car didn’t really start in earnest until end on January. Luckily, things more or less went together easily, and a borrowed set of wheels got me to an alignment at the end of February. The alignment was easy, the Apex parts offer a lot of bulk and fine adjustment where you need it, so that was all good. It did turn up some issues. My planned strut housings for the front end, some stock style s13 housings, didn’t like the selected ride height. I ended up building some custom strut housings that included a pretty extreme drop and some shorter springs. Ride height is where I want it, but I have a good bit of travel. 

 

New "Max Low" strut housings. 

 

So suspension, and brakes done. Excellent! Off to the races. Or was it......

[Ben280]

A rules change meant that I needed to assess how I store fuel in the car. I’d built a custom fuel cell a few years ago which fit in the space under the cage, behind where the passenger seat normally goes. The SCCA decided to change the rules to require alternate fuel tanks to be SFI/FIA certified bladder in shell style with foam. 3/3 on things my existing fuel tank didn’t have. Luckily Radium Engineering makes some excellent small fuel tanks, that check all the boxes. I opted for one with their in tank surge tank setup installed, so I wouldn’t have to worry about running low on fuel. A likely thing when you’ve only got 6 gallons! Along with a fabrication project, adding more fuel pumps meant I needed more power to that area of the car. My electrical system is fairly old by this build’s standard, and been added on to for years now. I decided to update how power gets distributed, and integrate all the added on components into the fuse blocks! 

 

new fuse blocks installed and wired into the car

 

Scope creep was really a thing this year. ADD much?

 

Last on the list was getting the ABS installed. I had planned for this to be a mid season add on, but when I looked at what needed to happen as far as wiring, sensors and hard lines, it was “simpler” to get it done now. I opted to pair my 350z front hubs, rear tone rings and sensors with the BMW E46 M3 Teves MK60 ABS computer. There are a couple benefits here, it’s a 4 channel system, meaning each wheel is individually monitored and controlled by the computer. It’s also got dual inputs for my dual master cylinder setup, and maybe most importantly, it can be used in a stand alone mode without issue. More and more endurance race teams have been integrating these systems at a semi professional level for years now, so I felt pretty good about selecting this pump to do the job. It’s a fairly straight forward system, it needs a front and rear pressure sensor, and a Yaw/DCS sensor. Otherwise, it’s math! 3DM Motorsport provided the harness, built to an incredibly high standard. They also integrate the MIL light and an OBD-II port where you can plug in and access all the ABS diagnostics and bleed functions. The system went together nicely, about 60’ of hardline were needed so I got pretty good at bending it! 

 

ABS installed and plumbing started. Easier to put it here than try and get it in the engine bay. 

 

So! Where does this leave us. Basically a fresh car apart from the motor, transmission and diff. There are a couple things to wrap up, I need to finish installing the new sway bar, along with getting the fender flares modified and re-installed, but we’ve got a working vehicle that I can get out on track! Excited to get out to some events! 

 

After a successful first event!

Test fitting the fender flares! Front is good, rear is gonna be a bit tight

[clarkspeed]

Damn you Ben280, you made me go back and read this entire thread again!  How did you make the conversion to 18"?  #1 - What did you do for gearing? Change tranny ratio's or diff?   #2 - How did you deal with roll center, did the front and rear strut mods above get you there?  BTW this thing is a beast!  Really nice build.

[Ben280]

On 5/2/2021 at 8:39 PM, clarkspeed said:

Damn you Ben280, you made me go back and read this entire thread again!  How did you make the conversion to 18"?  #1 - What did you do for gearing? Change tranny ratio's or diff?   #2 - How did you deal with roll center, did the front and rear strut mods above get you there?  BTW this thing is a beast!  Really nice build.

 

Hey Clark! Sorry not sorry

 

Conversion to 18's was a major project. Gearing isn't fully sorted out yet, it was geared short for autox use, so it's not quite ideal for the track yet. Going to 18's gave me a 25.5" tall tire, from a 23.5" tire, so keeping everything the same has moved my top speed out a bit at the expense of low end grunt. I have a 3.90 rear end and a Jerico 4 speed, so I can get fully nutty with the ratios. I'm considering going back to the 3.54 rear end (need to find one) to get some more top speed, but right now being gear limited to 135mph feels just fine by me!

 

Roll center was hard. The Apex Engineered rear sub frame has movable inboard pickup points so that was fairly "easy" to bolt up. Just running as much adjustment back there so the control arms have a little angle. The front was "easy" as well, since when you start with a clean sheet you can sorta do whatever you want. The new front knuckle has a 2" correction built in, so imagine a second roll center adjuster added in on a normal Z strut! When I was running the 16" wheels, I drilled the front subframe to get additional roll stiffness. For the time being, I'm using the factory holes to mitigate bump steer, but am planning to space the rack up to try and get some of that back. Making the custom struts up front was needed to keep the low ride height I was after. I'd like to go a little lower even, but I'm at risk of hitting the tires into the upper frame rails. 

 

I went out to ORP on Monday, and thought I'd give you folks a quick ride along. Was practicing my shifting with the dogbox, so there's some gratuitous 4th gear grabs, (you can see where I checked to see if I snagged it once or not!). I need to work on running the motor out more before shifting, grabbing that 4th gear shift too early really kills the acceleration. 

 

 

[clarkspeed]

[Holly Shiiittte. I have dreamed of this many times and realize your difficulties. On gear ratio, I am facing a similar problem. I have a Jerico 4 speed in the car I am building which is always 1:1 in 4th for those in the know. I am looking at multiple tire diameters but limited to 16 or smaller on rim. Smaller the better for weight. But Daytona is one of the tracks I must build for, and that is max speed whatever your car will do. So unless I can move to a 3.3 or lower gear or I will need to increase tire diameter. So I am thinking about a 26-27 tall 15" tire (think Nascar) or swapping a Ford IRS rear. 

 

Of course money is always an influencer. I have 3.5 and 3.9 R200's loaded with Quafe's ready to roll. So gear ratio becomes an issue for just 1 track. I am trying to find a way to run from 50 mph to 160 mph with the same tranny.

 

That is really an accomplishment running 18" in competition. Looks like you adapted to the dog box very well in the video.

 

I can accommodate most any tire size with my current suspension  like you I may have some physical interference I need to watch for.  I am most impressed with you recent changes.  As I mentioned in a previous post, I am lucky to know some REALLY fast Z cars intamately. And your build is definitely pushing the envelope.

 

[JMortensen]

Those new ears on the strut tubes look BEEFY. Very nice.

Same problem here with gear ratios. I looked at Super T10s for weight and strength, but that 1:1 4th really kills top speed. F8.8 with 3.08s gets you to 165 with my 24.5" tire or 172 with Ben's 18s. A taller rear gear means a wider spread between gears too which isn't great. 170ish is about as fast as I ever want to go in mine, dunno about you guys. I won't be attempting that without some more aero though.

Nice thing about 18s is that there are a lot of race tires available as that's the common size for professional cars right now. Car looks great Ben. Congrats.

[Ben280]

Thanks guys! @clarkspeed Daytona sounds like a real trick with the speed differential. Can you opt for a main shaft that you can just barely get rolling off the line, but allows the top speed? I keep thinking about a Winters style quick change, so I don't have to rebuild a couple of rear ends around my diff. I think my ratios are good for my power, and I just need to modify top speed with final drive. 

 

Looking at west coast tracks, I think a top speed in the 150's is ideal. much faster you need tons more power, and a 5 or 6 speed to keep the ratios reasonable. 

 

2 hours ago, JMortensen said:

Those new ears on the strut tubes look BEEFY. Very nice.

 

I took your note and the Maximum Motorsport design to heart, so when I needed to build my own, I opted for .250" plate. It ended up being a problem, since I had to bend it with a torch and vice! Really needed a hydraulic press to go with the torch haha. 

 

Tire size was a big driver of this full conversion. All the new tires coming out share the 315/30r18 common size, and most race series include some form of a 12x25.5r18. The benefit of top speed gearing is an added bonus!

 

A quick link to the gear calculator I've been using: https://www.blocklayer.com/rpm-gear.aspx You can tie this together with a dyno plot of the car, and make sure that you maintain good powerband. It also lets you play with all the variables, so you can plan changes!

[clarkspeed]

The Winters style IRS is really trick, but not an inexpensive option. It is something I have considered. Too bad there are not a ton of used ones floating around like the 4 speed Jericho's.  Mine has a super close ratio so first gear is useable and tops out at like 70mph. Should be a lot of fun driving around the pits!  The cool thing about Daytona is all of the turns are around 50-55 mph min speed so if you have the right final drive, it works. I want to run the 24hr vintage race there to get that off my bucket list.

You really have your pick of slicks with the 18's. Everyone makes those and wheels are fairly plentiful also.  Do you know what your tire/wheel combination weighs?

[walkerbk]

What kind of flares are those on the rear? I looked through the 9 pages and didn't see a brand or name.

[Ben280]

11 hours ago, walkerbk said:

What kind of flares are those on the rear? I looked through the 9 pages and didn't see a brand or name.

 

Marugen Shokai http://home.att.ne.jp/sky/FairladyZ/ Can also get them from RHDJapan: https://www.rhdjapan.com/marugen-shoukai-works-over-fenders-standard-type-s30-s31.html

 

Designed for a front G nose car, so lots of modifications needed to make em fit a standard car with or without an airdam. 

[Ben280]

Another weekend, another day at the track!

 

 

[JMortensen]

Looking good! 

[AydinZ71]

Pretty awesome! Can't wait to take mine for a spin! What are the details on the event? Location, class, competitive or practice? 

 

Also, the G-force monitor is inverted in the accel-deccel plane.

[Ben280]

4 hours ago, AydinZ71 said:

Pretty awesome! Can't wait to take mine for a spin! What are the details on the event? Location, class, competitive or practice? 

 

Also, the G-force monitor is inverted in the accel-deccel plane.

 

Turn2 Lapping day at the Ridge Motorsport Park up in Shelton Washington. Practice day for the Global Time Attack event happening in late July, where I'll be losing in the Unlimited category haha! I'd like to get into the 1:50 flat territory, and maybe with some bravery and more aggressive shifting I can make it happen. Aero cars can go sub 1:50, but I need more power to get that quick. 

 

One day I'll remember to invert the Y axis on my datalogger, but for now, you'll just have to enjoy the backwards version!  

 

4 hours ago, JMortensen said:

Looking good! 

Thanks Jon!! Getting more confident. 

[Leon]

Love the build, any plans to make it down to any Norcal road courses?  

[Ben280]

23 hours ago, Leon said:

Love the build, any plans to make it down to any Norcal road courses?  

 

Would love to get down to Thunderhill! Didn't realize Sonoma was relatively close, any others worth visiting in the Bay area?