ACT 2007 BMW 135/335/535/435/Z4 HD/Perf Street Rigid Clutch Kit
The ACT BM14-HDSD is the clutch tuned N54 and N55 owners reach for when the factory unit starts slipping after a downpipe or a stage 1 or 2 map. It covers the 6-speed manual 135i, 335i and 335is, 435i, 535i and Z4 sDrive35i, and it is designed to bolt up to the original dual-mass flywheel, so the job stays a clutch swap rather than a full flywheel conversion.
A turbo inline-six makes its torque low and keeps it flat, which is hard on a stock clutch sized for factory boost. The BM14-HDSD answers with ACT's Heavy Duty B015 pressure plate, which uses a stiffer heat-treated diaphragm to raise clamp load, and a 240 mm (9.4 in) rigid-hub organic disc. ACT rates the kit at 465 ft-lb at the crank, 52 percent above OE.
The rigid hub is the key difference from the sprung BM14-HDSS. It has no damper springs, which makes it the lightest street disc ACT offers for this car and helps quicker shifts. On these BMWs the factory dual-mass flywheel stays in place and does the torsional damping, which is why ACT can specify a rigid disc here. ACT is upfront that the trade-off is more gear rattle at idle and possible extra spline wear.
Rule out the hydraulics first: check the clutch fluid, look for slave cylinder leaks and make sure the pedal returns fully. Then load-test in a high gear at low RPM; if the tach rises faster than speed, the clutch is slipping. Our guide to diagnosing slipping explains the process. Also check the dual-mass flywheel when the transmission is out: excessive free play, knocking or grease leaking from the flywheel mean it should be replaced, because this kit relies on it.
The listing names 2007, but ACT's chart for the BM14-HDSD runs much wider on manual-transmission cars:
ACT splits the N54 cars at January and February 2009 production on its chart, so check your build month on the door jamb. If you are unsure, send us the year and VIN before ordering. More BMW options, including the sprung-hub BM14-HDSS and the higher-clamp BM14-XTSS, are in our rebuild kits and clutch section.
Inspect the OE dual-mass flywheel and replace it if it shows play or damage; a worn one will cause chatter no matter what clutch is on it. ACT also lists the 601030 XACT flywheel as an available option for this kit. Use the supplied bolts, center the disc with the alignment tools, and draw the pressure plate down evenly in a star pattern to spec. Bleed the clutch hydraulics with fresh brake fluid of the grade marked on the reservoir cap. ACT quotes 15 to 40 percent more pedal effort for Heavy Duty plates, and recommends 300 to 500 miles of easy driving to bed in the organic disc.
| Brand | ACT |
| Part number | BM14-HDSD |
| Fits | ACT 2007 BMW 135/335/535/435/Z4 HD/Perf Street Rigid Clutch Kit |
| Vehicle fitment | BMW 135/335/535/435/Z4 Hd/Perf (2007) |
| Type | Clutch Kits - Single |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. ACT designs this kit for the OE dual-mass flywheel and includes the M8-1.25 x 20 mm pressure plate bolts. Replace the flywheel only if it has excessive play or damage.
Same Heavy Duty pressure plate; the HDSD uses a rigid-hub disc and the HDSS a sprung-hub disc. The rigid disc is lighter for faster shifts but ACT notes increased gear rattle and possible spline wear.
ACT rates the kit at 465 ft-lb at the crank, 52 percent over OE. Compare that with your tune's crank torque; higher-output builds should look at the Xtreme BM14-XTSS.
Yes, with the manual transmission: F30 335i 2012-2015 and F32 435i 2014-2016 are on ACT's chart, along with E9x, E8x, E60, F10 and E89 Z4 35i cars.
Somewhat. ACT describes light to moderate effort and quotes 15 to 40 percent more pedal effort for its Heavy Duty plates, depending on the application.
