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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 KWPbbFRBSPrCT3rQw/ne603FpjtSxWosuLtN9LEhfIhS9Z/KMx7O8m6lS3m0QMsO
 2ozCY1bmOTC3MxFc2GQ9lg==

<SEC-DOCUMENT>0000908255-05-000104.txt : 20050913
<SEC-HEADER>0000908255-05-000104.hdr.sgml : 20050913
<ACCEPTANCE-DATETIME>20050913111459
ACCESSION NUMBER:		0000908255-05-000104
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050912
FILED AS OF DATE:		20050913
DATE AS OF CHANGE:		20050913

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BORGWARNER INC
		CENTRAL INDEX KEY:			0000908255
		STANDARD INDUSTRIAL CLASSIFICATION:	MOTOR VEHICLE PARTS & ACCESSORIES [3714]
		IRS NUMBER:				133404508
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3850 HAMLIN RD.
		CITY:			AUBURN HILLS
		STATE:			MI
		ZIP:			48326
		BUSINESS PHONE:		2487549200

	MAIL ADDRESS:	
		STREET 1:		3850 HAMLIN RD.
		CITY:			AUBURN HILLS
		STATE:			MI
		ZIP:			48326

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BORG WARNER AUTOMOTIVE INC
		DATE OF NAME CHANGE:	19930628

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ADAMS ROBIN J
		CENTRAL INDEX KEY:			0001044213
		STANDARD INDUSTRIAL CLASSIFICATION:	MOTOR VEHICLE PARTS & ACCESSORIES [3714]
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12162
		FILM NUMBER:		051081416

	BUSINESS ADDRESS:	
		STREET 1:		C/O BORGWARNER INC.
		STREET 2:		200 S. MICHIGAN AVE.
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60604
		BUSINESS PHONE:		3123228500

	MAIL ADDRESS:	
		STREET 1:		200 S. MICHIGAN AVE.
		STREET 2:		19TH FLOOR
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60604
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-09-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000908255</issuerCik>
        <issuerName>BORGWARNER INC</issuerName>
        <issuerTradingSymbol>bwa</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001044213</rptOwnerCik>
            <rptOwnerName>ADAMS ROBIN J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, CFO, CAO &amp; Director</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-09-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1121.303</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>57.7602</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>18163.268</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>common stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8490.0604</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">By Retirement Savings Account</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Laurene H. Horiszny as attorney-in-fact for Robin J. Adams</signatureName>
        <signatureDate>2005-09-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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