There are a lot of options out there when the time comes to replace your Nissan clutch. A lot of people see the myriad of available options, then realize they don’t know anything about clutches… So they panic, and just choose the cheapest thing they can find – or worse yet, they pay the dealership service department WAY too much to install an OEM clutch.
Don’t let this happen to you. You don’t need to be an expert, but a little reading will go a long way towards making sure you choose a clutch for your Nissan that’s not going to disappoint you. Let’s listen in as David Norton from SPEC Clutches and Flywheels takes a question from one of our members…
I have a question about high-performance clutches for my 2003 350Z. The car is currently pushing about 300 horsepower at the rear wheels, but my goal is to hit around 375 rwhp. My present clutch is not holding up at this power level, so I definitely need to get another one. I need something I can use both on the street and on the strip. What do you recommend? Also, I need a recommendation for an S14 SR20DET at the same power level.
There are many gains to be realized by upgrading the clutch in your Nissans. However, a clutch change on that application involves more than the clutch itself, and you will want to do everything right the first time because it is labor intensive. These guidelines should be used when choosing a clutch for any high performance Nissan.
There are several considerations we address when making a recommendation, and the end-user should rank or prioritize these before choosing a high performance clutch.
The first consideration is torque capacity, or how much power you need it to hold. That is most often the first priority, as you have stated that your current unit is not holding and you have plans for 375rwhp. The proper formula by which to rate a clutch is ft-lbs torque, not horsepower. Based on the nature of your modifications, you should be able to determine your torque level and most of the time it will be within 15% above or below your horsepower. As an example, we will assume you will have a stroker motor or power adder than will produce at least 375 ft lbs torque. It is recommended that a 10-15% capacity buffer be added to your goal to be safe and allow for underrated modifications and/or owner’s greed for more power. That buffer can also help maximize clutch life. So a clutch with a 413-432 ft lb capacity would be a good choice. Based on our ratings, any stage from 2 past 5, as well as our street/strip twin disc, will support your power. Our ratings take into consideration that sticky tires may be used, as well.
The second consideration is drivability, or how you want the clutch to feel at engagement and pedal requirement. Pedal requirement is not a concern on the Nissan, as the hydraulic system lends to ease of use and we are able to produce a lot of clamp load with the lowest possible actuation requirement (a popular feature of SPEC clutches). The feel at engagement would be important since you drive the car on the street and likely incur stop-and-go situations. You would probably want a fairly smooth engagement. The choices for a streetable engagement would narrow the field to a sprung hub (dampened) disc and a material configuration that is somewhat forgiving. Based on the characteristics of our stages, the field would be narrowed to the 2+, 3, 3+ and Twin Disc. The stage 2+ feels very much like stock, the 3+ is very street-friendly and the stage 3, though very streetable for a puck clutch, has a noticeably more aggressive engagement.
The third consideration is life expectancy. It is very hard for a clutch manufacturer to rate or guarantee life expectancy simply because there are many after-sale factors that determine the wear cycle. Clutch life will be maximized as long as you stay within the clutch capacity (choose with the buffer as explained above) and follow special instructions that accompany a high performance clutch, as well as industry standard installation practices like replacing old bolts, refreshing worn hydraulics, surfacing or replacing the flywheel, etc. Given instructions are properly followed during and after installation, a high performance clutch not only will last a lot longer than an original equipment clutch in a modified car, but also outlive a an original equipment clutch in an unmodified car. The SPEC stage 2+, 3+ and Twin Disc offer excellent life cycles, and stage 3 would offer a good cycle.
The fourth consideration is weight. Some street and track driven cars can benefit from a clutch that is lighter in weight. The benefits can be in throttle response and horsepower/torque. The lightweight clutches will not produce benefits or changes in drivability as drastic as a lightweight flywheel, neither are they as costly. A lighter clutch alone will not produce any substantial downside and is a great way to complement your round modifications with part that can produce gains without adding stress to any other part of the car. SPEC offers s lightweight clutch option for the VQ, KA and SR engines.
The last consideration is price. Value will be based on how you prioritize the above considerations. Basically, a clutch is like taxes. Spend sufficiently now or your will be penalized in the near future with additional parts and labor costs!
Now that we have narrowed the clutch choices, there is an application specific issue to address. The factory flywheel in the 350Z, which is the component that most contributes to the performance, life and drivability of a clutch, is a 2-piece unit deemed ‘not serviceable’ by the manufacturer. In other words, you must change it with every new clutch. The 370Z, G35, G37, 02+ Maxima, 02+ Altima, Sentra SPECV and S15 each have the 2pc flywheel from the factory. The original dual mass casting is very porous, and an attempt to resurface an original dual mass casting can result in pitting on the surface, imbalance, and a compromise in structural integrity. The top rotates over the bottom via a bearing shaft, which can develop play and, therefore, oscillation. Sometimes they can go another round, but it is not worth the risk on a high hp car (note the safety connotation in the last phrase) and we will always recommend a new flywheel. You can purchase a performance flywheel for less than a dual mass factory replacement. SPEC offers two billet flywheel options (steel and aluminum). Both are serviceable, manufactured to an industry-best .001 machine tolerance and can enhance the performance of your 350Z. I can make a recommendation on which would be best for your car based on the nature of your modifications, where you drive or race, and tire compound choices. Normally we recommend steel for naturally aspirated cars that drag on slicks and large-turbo cars, with which keeping boost up in between gears is important. We recommend aluminum for all other combinations.
So, to finally answer the question, I would only be able to give a range of recommendations based on the information given. The choices would be stage 2+, 3, or 3+ clutch kit, billet steel or billet aluminum flywheel, all of which would be shipped as a precision balanced assembly from SPEC with all necessary hardware for installation included (bolts, release bearing, guide tool). I look forward to talking to you about your priorities to finalize which clutch stage and flywheel material will complete the best possible clutch solution for your VQ and SR!
David Norton – SPEC Clutches and Flywheels
Like this article? Have a clutch question of your own? Here’s the spot: Choosing a Clutch for your Nissan