Nov 19, 2020 update to the Nissan 350Z project car

Project LSZ: Big Brakes and Adjustable Suspension Parts for Our LS-Powered Nissan 350Z

We’ll start with an apology: We spent our last update cutting and grinding our Z-car’s interior, removing as much weight as possible while prepping it for a fresh coat of paint. That’s what this article was going to be about, since finishing the interior is the logical next step in our LS1-swapped 350Z’s transition from street car to race car. 

Then the UPS guy showed up, and that adjusted our priorities a bit. Suddenly there were boxes and boxes of shiny new StopTech parts in the shop, and we just couldn’t look away. We’ll pick up the paint gun next time. Today we’re installing brakes.

Hold It Right There

Why drop everything and put brakes on the car? Two reasons: First, StopTech’s big-brake kit is so big that it took up valuable storage space in the garage. And second, we were terrified that we’d be tempted to track our 350Z without first upgrading the brakes. We’ve seen “A few shakedown laps can’t hurt” turn into “Wow, tire walls are harder than they look!” We simply wanted to spare ourselves from going down that path. 

What’s so bad about our 350Z’s brakes? It was still sporting the factory equipment, meaning 296x24mm front rotors and 292x16mm rears. If this was a Miata, we wouldn’t be knocking a rotor that’s more than 11.6 inches in diameter, but this isn’t: It’s well known in 350Z circles that the stock brakes are inadequate for any real track work, and that’s for cars that aren’t powered by V8 swaps. 

What about the optional Brembos? We asked a few Z-car experts, but the answer didn’t really change: Although the Brembos feature slightly larger rotors and fancy red calipers, they’re still inadequate for the real track duty that we have in mind. 

With the factory options scratched off the list, we set out to find a big-brake kit that could handle the heat of back-to-back, V8-powered laps on track. Our goal was simple: Find something that featured a real track-focused caliper, application-specific development, support and advice from the manufacturer, and easily sourced consumables. Or, put simply, we wanted to buy once and cry once, then never have to worry about brakes on track as we develop this car into a faster and faster machine.

A few paddock conversations convinced us to skip the homebrewed kits featuring OEM rotors and calipers from other Nissan products. We also nixed a few budget-focused aftermarket kits that fit a 350Z but weren’t extensively developed on the platform. Call us picky, but as soon as a racer mentioned issues like pad knockback or needing to shim the caliper for proper alignment, we crossed the option off our list. Again, buy once, cry once, then move on to making the car faster. 

Finally, after lots of research and a bunch of conversations, we found StopTech in the middle of an extensive instrumented test done by Zeckhausen Racing. StopTech was one of the first to develop a brake kit for our Z33 chassis when it was introduced nearly 20 years ago. The company’s pitch was simple: an exceptionally balanced system that works well even without a proportioning valve. 

Fortunately, we’re not the first people out to improve the 350Z’s brakes and suspension. We used off-the-shelf parts from StopTech, SPC and DIFtech to create a track-ready package. We also replaced all of the car’s wear items to prevent any unexpected failures.

Just like that, we had $7800 worth of big brakes on their way to our door–the going rate for a full StopTech setup. In the boxes was a four-wheel, big-brake kit featuring the STR-60 calipers up front and the STR-22 calipers in the rear. These are fully forged calipers with bolt-in front caliper bridges, meaning they’re lighter and stiffer than other options.

StopTech recommended its largest available rotors up front–measuring 355mm in diameter and 32mm thick–and sent 328x28mm rear rotors. All four feature a two-piece design with Inconel hardware. Why use two-piece rotors? They’re lighter than all-steel pieces.

This kit would deliver more than enough thermal capacity for whatever we could throw at our 350Z–even when we graduate to slicks and aero in the future. Oh, and bonus points to StopTech for using common pad shapes, allowing us to choose from a few dozen different companies when it comes time for fresh pads. For now, we went with StopTech’s recommendation, using the SR34 race pad in the front and the SR33 race pad in the rear. 

One More Stop

While we had the brakes off the car, we took the opportunity to cross a few more items off our to-do list. First up: alignment, or a lack thereof. We were in a hurry to get to Holley LS Fest when we originally installed our MCS coil-overs and ended up leaving the job half finished. We couldn’t run the car at our desired ride height without ruining the alignment, which was fine for one event but not the path to a winning time trials effort. 

To fix our alignment woes, we turned to SPC Performance. The company makes alignment bits for almost every car, our 350Z included. We ordered a pair of SPC’s adjustable upper control arms for the front, matching them with a pair of the brand’s camber arms for the rear. 

Before we talk about the huge range of adjustability we’d gain (more than 4 degrees of camber and caster up front; 3 degrees of camber and 2 degrees of toe out back) and the high-quality xAxis bushings that promise to “handle like a monoball and last like an OE ball joint,” we’d like to take this opportunity to cast some shade on the OEM parts: From the factory, only toe can be adjusted on the front of a 350Z, while the rear allows toe and camber adjustments through alignment cams, but only slightly. 

Aftermarket parts like these are a necessity for any Z-car that sees time on track, and you should budget about $1000 for the ability to properly align your 350Z with these high-end SPC parts. Or, if you’re willing to sacrifice some adjustability and trade those fancy bushings for traditional rubber pieces, you can save a few hundred bucks with SPC’s simpler options. 

Could we have saved some more money here? Absolutely. There are a few other brands that more or less copy one another selling similar parts to SPC’s, but we’ll explain our reasoning this way: We really, really don’t want to be worrying about whether or not our control arm is going to break while going through Turn 12 at Road Atlanta. We might buy off-brand wiring connectors and zip ties, but we draw the line at suspension components.

Okay, time to face our second to-do list item: spring and shock mounts. Also thanks to that last-minute thrash to make it to Holley LS Fest (and, if we’re honest, a mixup when we ordered our MCS shocks), our 350Z was still riding on its factory upper shock mounts. And in the rear we’d left the factory springs in place, hoping the softer suspension would help our drag racing launch. 

What’s wrong with the factory parts? If you’re driving down the highway, nothing: They use big chunks of rubber to locate the shock while still allowing it to move around, isolate vibration and noise, and (in the front) serve as the upper spring perch.

But if you’re racing? Everything. “Big chunks of rubber” basically means “nonlinear undamped springs” on track, and NVH isn’t even a consideration while racing. Even worse: Thanks to our earlier shortcuts to make LS Fest, the entire front coil-over was essentially mounted to the 350Z’s OEM bumpstop. That’s not good.

Fortunately, we’re not the first ones to face this problem, so we called DIFtech. This California-based speed shop specializes in really, really nicely machined suspension parts, and it has off-the-shelf solutions to address our 350Z’s suspension shortcomings.

For the front, we ordered DIFtech’s 350Z front shock hats along with the necessary hardware to bolt them up to our MCS shocks. For $365, this kit replaces all of the factory rubber with a giant spherical bearing and also serves as the new upper spring perch. The benefits are huge: No more undamped rubber compliance, reduced shock bind thanks to the coaxial design, and a full inch of additional compression stroke that should help us stay off the bumpstops on track. 

With the front solved, it was time to address the rear suspension’s rubber top hats and factory springs. Here we faced a choice: Replace the OEM lower control arm/spring bucket with one featuring an adjustable perch sized for common 2.5-inch race springs, or delete the factory spring locations entirely and switch to a true coil-over spring in the rear. 

Both options have their pluses and minuses. Moving the spring to the shock saves weight and simplifies things, but it puts the entire weight of the car on an upper and lower shock mount that was never designed to carry it. Putting a race spring in the factory location is the heavier option and requires buying new control arms, but it frees up rear wheel and tire clearance and reduces the chance of shock bind. It also makes changing springs much easier than a coil-over. 

We’d left the factory top hats and rear spring perches in place when we first installed our MCS shocks. To eliminate the OEM rubber from the system, we chose DIFtech top hats fitted with spherical bushings and a DIFtech conversion kit to install 2.5-inch race springs. 

We weighed these options, then decided to go in a third direction: Use a DIFtech kit to modify our stock spring buckets into adjustable 65mm lower spring perches that would accept commonly available 2.5-inch race springs. For the $500 price of the kit, we’d solve our rear spring problem and actually improve the car’s geometry: DIFtech’s perch kit includes spherical bearings top and bottom, meaning the spring isn’t unevenly loaded like it would be in the stock configuration. That will keep spring rates more linear as the suspension moves, making tuning easier. Custom perch sizes are available, too.

Since we were keeping the springs in the stock location, our choice was simple for rear shock mounts. We placed one final order to DIFtech for its rear top hats. Like the parts we ordered for the front, this $315 kit replaces rubber with a spherical bushing and adds an inch of compression stroke to the rear suspension. 

Stop at the Shop

Plan made and parts in hand, we threw the car up on the lift and went to work installing our new equipment. Almost instantly, we were hit with the reality of using top-shelf parts with real-racer price tags: It was almost too easy. 

StopTech sent everything required for installation–down to little bottles of thread lock and new braided brake lines–and told us how to do it with more than 50 pages of instructions, with photos of each step. And the same was true for the SPC parts, albeit on a smaller scale. We didn’t have a single question during the entire installation, and every single part fit without so much as a single burr in a bolt hole or lock washer missing from the package. It was perfect. 

Of course, just because we had instructions doesn’t mean we followed them. StopTech says to trim the factory dust shields to accommodate the larger brake rotors, but race cars don’t need dust shields. Instead, we unbolted our hubs and threw the shields in the spares pile, shaving more than 4 pounds of unsprung weight in the process. We also completely removed the car’s parking brake system, which was good for more than 8 pounds of weight savings. The StopTech kit allows the factory e-brake to be retained, but we didn’t see any use for it on a race car. 

While we had everything apart, we cleaned as much as possible. Besides looking better, clean parts are easier to inspect for damage between trips to the track. 

Speaking of race car, there’s no better feeling than throwing away rubber parts and replacing them with spherical bearings. Our DIFtech top hats were far better quality than we expected and installed without issue. Thanks to all that fancy machining, they’re even lighter than the stock parts by a few pounds.

We did add a little bit of weight by switching from 2.25-inch to 2.5-inch springs in the front. Why make this change? Simple economics: We already have a shelf full of extra 2.5-inch race springs, and the more cars we have that use the same parts, the easier and cheaper it will be to adjust spring rates as we develop the car further. 

We also added fresh bumpstops to each shock, choosing hard circle-track bumpstops from Summit Racing and leaving them full-length for now. We’re not sure if these are absolutely necessary yet, but we’d rather remove bumpstop material than have to add it back in and risk bottoming our MCS shocks in the process.

Next up: Install the rear spring perches, which wasn’t quite a bolt-on affair. Nine new holes need to be drilled in each OEM lower control arm, but the proper holesaw was included in the box along with a handy template. After 10 minutes of work with the drill press, we’d turned our spring buckets into fully adjustable articulating lower mounts. The upper spring mount installed in place of the 350Z’s factory rubber spring pad with a few hex head screws (no drilling required).

We also took this opportunity to clean and inspect the car’s uprights for cracks and defects while installing four new wheel bearings plus fresh ball joints and tie-rod ends. Was this necessary? Probably not, but for about $200 per corner, we know we won’t lose a race weekend (or worse) thanks to a failed 200,000-mile part. 

There was one last bit of while-we’re-in-there work: swapping out the last few degraded OEM rubber bushings in the rear for urethane pieces from Prothane. We’ll again credit that last-minute LS Fest thrash for causing us to skip this step originally.

Once everything was installed, we stepped back and admired our handiwork. It might not have an interior yet, but our 350Z is looking more and more like a serious track car every day. We guess that means we finally have to finish the interior–which we’ll cover in the next installment. Promise.

The Weight Game

Top-shelf big-brake kits don’t just perform better: They also do a great job at managing weight, as we found by obsessively weighing parts as they came on and off the car. And remember, these are the smallest factory brakes that you could get on a 350Z:

The results, put simply, are amazing. The StopTech kit drastically increases the size of the front rotors and calipers but weighs exactly the same as the factory parts. It does add 10 pounds of weight to the rear, all due to the heavier StopTech rotors. They may be lightweight two-piece designs, but they’re still heavier than the non-vented OEM rear rotors. Ten pounds for drastically better brakes is a tradeoff we’ll happily make, especially since that weight’s added to our 350Z’s light rear end. 

Of course, we couldn’t leave well enough alone. Because we deleted the dust shields and parking brake, we actually had a net weight loss of about 2 pounds overall thanks to our work on the brakes. Take that, physics.

But it’s not all good news. The factory front upper control arms are cast aluminum and have no adjustability, which makes them much lighter than the adjustable forged-steel SPC pieces we replaced them with. This modification cost our car a net gain of 7.4 pounds. 

In the rear, we added 3 pounds by switching to those adjustable SPC camber links. We also dropped a pound during our conversion from factory springs to the articulating perches. That’s a net gain of 2 pounds.

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Comments
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350z247
350z247 New Reader
11/19/20 2:14 p.m.

Why go with SPC over Z1 Motorsports? SPC is great stuff, but SO expensive. I definitely wouldn't consider Z1 an "off brand"

Tom Suddard
Tom Suddard Director of Marketing & Digital Assets
11/19/20 3:46 p.m.

I'll admit, I made the decision based on spec sheets rather than a head-to-head test. But it was clear that the SPC front upper arms are way beefier than the Z1 parts, and also allow a much broader range of caster and camber adjustment. SPC parts allow more adjustment than the Z1 parts in the rear, too, and they're only slightly more expensive by the time you add the eccentric bolt kits and the race heim joint upgrade to the Z1 stuff.

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