ACT 1998 Chevrolet Camaro HD/Perf Street Sprung Clutch Kit

ACT GM9-HDSS is the street clutch for an LS1 Camaro that has started to slip after bolt-ons, a cam or a tune. Our listing is titled for the 1998 Camaro, and ACT builds it for the 1998-2002 Z28 and Z28 SS with the 5.7L LS1 and the six-speed manual. It pairs a Heavy Duty pressure plate with a full-face organic disc, so it holds noticeably more torque than a stock clutch while still driving like a normal car in traffic.

What this clutch kit does in an LS1 Camaro

When you release the pedal, the diaphragm spring in the pressure plate squeezes the disc between the plate and the flywheel, and the disc hub turns the T56 input shaft. A stock clutch that has worn thin or has lost clamp load lets the disc slide under full throttle. ACT rates GM9-HDSS at 709 ft-lb at the crank, 42% more than the factory clutch, using its GM015 Heavy Duty plate.

The disc is ACT's Performance Street sprung disc, part 3000909: 11 in (280 mm), organic facing with high copper content, a steel-backed lining and a 1.125 in input spline. The springs in the hub soak up driveline shock, and ACT describes the feel as light to moderate pedal effort with smooth, positive engagement and OE to mild gear rattle. That makes it the right pick for a car that is driven on the street most of the time. If the car makes big power or sees launches every weekend, the GM9-HDG6 6-pad race kit uses the same plate with a ceramic disc rated at 908 ft-lb. For a near-stock car, the GM9-SPSS Sport kit is the milder option.

Symptoms of a worn LS1 clutch

• Tach climbs but the car does not pull harder in third, fourth or fifth at wide open throttle
• Engagement point moving toward the top of the pedal travel
• Hot, burnt smell after a hard launch or a long uphill drive
• Shudder pulling away from a stop, often from glazing or a hot-spotted flywheel
• Gears that grind or a pedal that feels different, which can point at the hydraulic slave rather than the clutch itself

How to confirm the clutch is the problem

Do a road test first: in fourth gear near 2,500 rpm, floor it and watch whether engine speed rises faster than road speed. Then check the release side. The LS1 F-body uses a hydraulic slave inside the bellhousing, and a slave that leaks or a system with air in it can cause slip or drag that looks like a bad clutch. Our clutch slipping causes and fixes page walks through the tests, and chatter on takeoff covers shudder. If you are pricing the whole job, see clutch replacement cost.

Fitment

Our listing says 1998 Chevrolet Camaro. ACT's application list for GM9-HDSS covers the 1998-2002 Camaro Z28 and Z28 SS 5.7L LS1, 1998-2002 Firebird Formula and Trans Am LS1, 1997-2004 C5 Corvette including the LS6 Z06, 2005-2013 C6 Corvette with the LS2 or LS3, and the 2004-2006 GTO. It is not for V6 Camaros or the 1993-1997 LT1 cars. ACT notes it must be used with a flat flywheel, or ACT's 600585 Prolite flywheel on LS2, LS3 and LS7 engines. If your car has an engine swap, a stepped aftermarket flywheel or a different transmission, send us the year and VIN before you order. More F-body parts are on our Camaro parts page.

Install notes

• The kit is three parts: GM015 pressure plate, 3000909 disc and ATGM026 alignment tool. There is no release bearing because it is built into the LS1 hydraulic slave; replace the slave if it is weeping or has high miles.
• Have the flywheel surfaced flat or replace it. Our resurface vs. replace guide explains when each makes sense.
• Install a new pilot bearing; a pilot bearing puller pulls the old one without damaging the crank bore.
• Center the disc with the tool, snug the plate bolts evenly in a crossing pattern to factory torque, then bleed the hydraulic clutch.
• ACT recommends 300-500 miles of easy, mild engagement on an organic disc before any hard launches. See how to break in a new clutch.
• Expect pedal effort to go up; ACT says its Heavy Duty plates typically add 15-40% depending on the car.

Will GM9-HDSS fit my 2000 Camaro SS?

ACT lists it for every 1998-2002 Camaro Z28 and Z28 SS with the 5.7L LS1 and manual transmission. Our listing is titled 1998, so send us your VIN if you want us to double check a later car.

How much power can it handle?

ACT rates it at 709 ft-lb of torque capacity measured at the crank, 42% more than the factory clutch.

Is a throwout bearing included?

No. The kit is the GM015 pressure plate, 3000909 organic disc and ATGM026 alignment tool. The LS1 F-body release bearing is part of the hydraulic slave cylinder, which is sold separately.

What is the difference between GM9-HDSS and GM9-HDG6?

Both use the GM015 Heavy Duty pressure plate. HDSS has a full-face organic street disc for smooth engagement; HDG6 has a 6-pad ceramic race disc rated higher, at 908 ft-lb, with much more aggressive engagement.

Do I need a new flywheel?

ACT requires a flat flywheel. A stock LS1 flywheel without cracks or heavy hot spots can be resurfaced; on LS2, LS3 and LS7 engines ACT also lists its 600585 Prolite flywheel.

How do I break it in?

ACT recommends 300-500 miles of mild engagement, such as normal city driving, before racing or spirited driving, and warns not to overheat the clutch during that time.

• Transmission Slipping Diagnosis Guide
• Shift Flare vs. Slip: How to Tell the Difference
• Automatic vs. Manual Transmission Repair Cost