Exhibit 3.21

State of Delaware

Secretary of State

Division of Corporations

Delivered 01:29 PM 07/02/2004

FILED 01:26 PM 07/02/2004

SRV 040491108 - 3142046 FILE

CERTIFICATE OF FORMATION
OF
WARNER ELECTRIC TECHNOLOGY LLC

THIS Certificate of Formation of WARNER ELECTRIC TECHNOLOGY LLC (the “Company”), dated as of July 2, 2004, is being duly executed and filed by Thomas M. O’Brien, as an authorized person, to form a limited liability company under the Delaware Limited Liability Company Act (6 Del.C. § 18-101, et seq.).

1.Name. The name of the limited liability company is WARNER ELECTRIC TECHNOLOGY LLC.

2.Registered Office. The address of the registered office of the Company in the State of Delaware is c/o Corporation Service Company, 2711 Centerville Road, Suite 400, Wilmington, New Castle County, Delaware 19808.

3.Registered Agent. The name and address of the registered agent for service of process on the Company in the State of Delaware are Corporation Service Company, 2711 Centerville Road, Suite 400, Wilmington, New Castle County, Delaware 19808.

4.The effective time of the conversion shall be at 11:59 p.m. on July 2, 2004.

IN WITNESS WHEREOF, the undersigned has executed this Certificate of Formation as of the date first-above written.

/s/ Thomas M. O’Brien

Thomas M. O’Brien

Authorized Person