ACT HD Rigid Race Clutch Kits for 1989-1991 Civic/CRX

ACT HD Rigid Race Clutch Kits: HC4-HDR4 and HC4-HDR6

If you're putting a race clutch in your D-series Civic or CRX, these are ACT's four-pad and six-pad rigid-disc kits with the H023 Heavy Duty plate. Both are 212 mm and rated at 300 lb-ft at the crank. You'll use them for the 1990-1991 manual-transmission application; on a 1989 car, you'll need the flywheel change below as well. Neither kit is for a 4WD application.

Choose the disc for the way you'll use the car

ACT recommends both kits for race use only. You'll have the aggressive engagement and increased gear rattle that ACT lists with its rigid race discs. The light-to-moderate pedal effort doesn't change that takeup. If you're after something you can bring in gently on a road car, you'll want to compare ACT's street-disc kits before choosing one of these.

You're choosing ceramic friction pads here for heat tolerance. ACT makes the hub from heat-treated chrome-moly, and there's no spring pack in the center. You'll give up the damping of a spring-centered disc with that rigid construction. ACT rates friction life as moderate and notes that spline wear may increase. Those are part of the choice, along with how you'd like the clutch to engage.

You'll get H023 with either disc. ACT uses a stamped cover for rigidity and puts the diaphragm through four stages of heat treatment. Its diaphragm design increases clamp load and reduces deflection. So when you switch the option from four pads to six, you're choosing another disc layout with the same pressure plate.

With the rigid hub, you may hear more gear rattle. ACT describes a light knock or growl while you're idling in neutral, particularly after a long drive. A spring-centered disc dampens the engine's torsional pulses; you're giving up that damping here, so more of the gear-tooth impacts can be heard. If the car shudders as you engage the clutch, that's chatter rather than the noise ACT is describing. An unfamiliar sound still needs checking on the car.

Available options

HC4-HDR4 gives you disc 4212004; HC4-HDR6 gives you 6212004. ACT describes its four-pad design as suited to smaller discs and engines, and its six-pad design as suited to larger clutch sizes where heat absorption is useful. On your Civic/CRX, though, you'll have the same 212 mm diameter and 300 lb-ft rating either way. Don't buy six pads expecting a larger clutch or a higher listed torque capacity.

Specifications and kit contents

You'll get one pressure plate, your selected disc, the release bearing, pilot bearing and alignment tool. You'll supply the flywheel separately. ACT's torque figure is measured at the engine, so compare it with engine torque, not a horsepower figure.

Fitment and the 1989 conversion

If your 1989 CRX still has its original 200 mm flywheel, you'll need to change it to use this 212 mm kit. ACT specifies a 1990-2001 Civic SOHC flywheel or the appropriate ACT flywheel for that upgrade. The same applies to a 1989 Civic. If you've bought a car with a swap or a previous clutch conversion, check the transmission and flywheel that's in it before ordering by chassis year.

If you've also got HC5 on your shortlist, check the release bearing before treating it as the same kit. You'll find RB427 in HC4 and RB820 in HC5. The plate and disc numbers can match across those families, but the bearing needs to suit your release system.

Before fitting the new clutch

You've got access to the cable, fork, pivots, guide tube and seals with the gearbox out. Check them before you put the new clutch in. If you've found a leak, fix it first: oil on the friction faces can cause slip or judder. ACT calls for replacing a cracked flywheel. If you're having yours resurfaced, use a professional shop and make sure it keeps the correct step height.

Try the disc on the input shaft to check its fit and movement. Use the light coat of spline grease ACT specifies, then wipe off the excess. You're keeping that grease away from the friction faces. Have Honda's procedure and ACT's instructions to hand for assembly and the release adjustment.

You'll need ACT's race-disc break-in guidance for these discs. ACT describes a few hard slips to lap the surfaces, without overheating them. Its 300-500-mile recommendation is for organic street discs, so don't carry that mileage advice over to this kit.

Warranty

You'll have ACT's listed 12-month limited warranty for material and workmanship defects. Keep the receipt from your authorized dealer with the kit's paperwork. You'll need it for a claim, and you'll want to check the current terms before returning parts. ACT excludes labor charges.