Competition Clutch VQ35HR/VQ37HR Stage 4 - 6 Pad Ceramic Clutch Kit

The Competition Clutch 6073-1620 is the Stage 4 Strip Series kit for the later VQ cars: the VQ35HR 350Z and G35 and the VQ37VHR 370Z and G37 with a manual gearbox. It is aimed at the high end of the power range, such as a twin-turbo or big-boost supercharged car, a drag build, or a car on its second or third upgrade clutch. If a lower-stage clutch is already slipping or fading behind your build, this is the step where the disc stops being the weak link.

What the Stage 4 kit does in a 370Z or G37

The VQ drives a single dry clutch and the six-speed manual through a hydraulic release system. Competition Clutch builds the 6073-1620 around its performance pressure plate and a six-puck ceramic disc on a sprung hub. The maker notes that the -0620 version of this kit uses a solid hub, so the -1620 is the one that keeps the damper springs. Those springs matter on a street-driven car because they take some of the shock out of hard engagements before it reaches the gearbox and rear driveline.

Competition Clutch rates the Stage 4 Strip Series at up to a 250 percent increase in torque capacity over stock, the biggest jump in its single-disc range for this platform. Six ceramic buttons give a smaller friction area that bites quickly and survives heat that would glaze an organic or brass disc. Expect the engagement to feel close to on or off, with chatter when you creep in traffic. That is normal for this kind of disc and is the price of the holding power.

Symptoms that point to a Stage 4

• Slip at peak boost in third or fourth gear, even with a Stage 2 or Stage 3 clutch
• A disc that glazes or loses bite after a few drag passes or launch-control starts
• Burnt smell and a fading engagement point after repeated hard pulls
• Heat checks or blue spots on the flywheel face at the last clutch job

How to confirm before you buy

Make sure the problem is really slip. Check the clutch fluid and bleed the system so the release side is not holding the clutch partly open, which will overheat any disc. Then make a full-throttle pull in fourth from low rpm and watch whether the tach runs ahead of road speed. Our slipping diagnosis guide explains the test, and shift flare vs. slip helps separate a flare on the shift from true clutch slip. If the trouble is grinding or a pedal that stays down, start with our clutch won't disengage guide instead.

Is Stage 4 too much clutch?

For many builds, yes. A naturally aspirated or lightly boosted car is usually happier on the 6073-2600 Stage 3, which uses a segmented ceramic disc and smoother take-up. Pick the 1620 when power or launch abuse has outrun Stage 3, and accept a harsher clutch in daily traffic.

Fitment

Competition Clutch lists 6073-1620 for the 2007-2011 Nissan 350Z and 370Z and the 2007-2013 Infiniti G35 and G37. That means the VQ35HR and VQ37VHR manual cars. The earlier VQ35DE 350Z and G35 use Competition Clutch's 6072 series and will not take this kit. If you own a later 370Z, an engine swap or an aftermarket flywheel, check your old clutch or send us your year and VIN and we will confirm before it ships. More clutch parts are in our rebuild kits collection.

Install notes

• Competition Clutch's spec table lists the pressure plate, one disc and an alignment tool. It shows no flywheel, throwout bearing or pilot bushing, so inspect or buy those separately.
• A six-puck disc needs a flat, fresh friction face. The 17.5 lb steel flywheel is made for these cars, and the ACT XACT Streetlite 600590 is another option.
• Use only a light film of grease on the input splines. Competition Clutch warns that too much grease can damage the disc and void the warranty.
• Torque the pressure plate bolts in a star pattern to factory spec and bleed the hydraulics with the fluid named on the reservoir cap.
• The maker's break-in advice is to shift as often as possible for the first 500 miles so the disc material beds into the pressure plate and flywheel.

Does the 6073-1620 fit my 2005 350Z?

No. The 6073 series is for the 2007-2011 350Z/370Z and 2007-2013 G35/G37 with the VQ35HR or VQ37VHR. The 2003-2006 VQ35DE 350Z uses Competition Clutch's 6072 kits.

What comes in the box?

Competition Clutch's spec table lists the performance pressure plate, one sprung six-puck ceramic disc and an alignment tool. No flywheel, throwout bearing or pilot bushing is listed, so plan for those separately.

How much power will a Stage 4 hold?

Competition Clutch rates its Stage 4 Strip Series at up to a 250 percent increase in torque capacity over stock. It does not publish a single horsepower figure for this kit.

What is the difference between 6073-1620 and 6073-0620?

Both are Stage 4 six-puck ceramic kits. The maker states the -0620 versions use a solid hub disc, while the -1620 uses a sprung hub that damps driveline shock and suits a car that still sees street miles.

Will it chatter?

Some chatter on takeoff and in slow traffic is normal for a six-puck ceramic disc. If the car is mostly a daily driver, the Stage 3 6073-2600 is the smoother choice.

How do I break it in?

Competition Clutch recommends shifting as often as possible for the first 500 miles so the friction material beds into the flywheel and pressure plate before hard launches.

• How to Diagnose Transmission Slipping
• Shift Flare vs. Slip: How to Tell Them Apart
• Automatic vs. Manual Transmission Repair Cost