<SUBMISSION>
<ACCESSION-NUMBER>0000868780-09-000003
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090915
<FILING-DATE>20090916
<DATE-OF-FILING-DATE-CHANGE>20090916
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>BERMAN STEVEN L
<CIK>0001205405
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-18914
<FILM-NUMBER>091071183
</FILING-VALUES>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>Dorman Products, Inc.
<CIK>0000868780
<ASSIGNED-SIC>3714
<IRS-NUMBER>232078856
<STATE-OF-INCORPORATION>PA
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>3400 E WALNUT ST
<CITY>COLMAR
<STATE>PA
<ZIP>18915
<PHONE>2159971800
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3400 E WALNUT ST
<CITY>COLMAR
<STATE>PA
<ZIP>18915
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>R & B INC
<DATE-CHANGED>19930328
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-09-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000868780</issuerCik>
        <issuerName>Dorman Products, Inc.</issuerName>
        <issuerTradingSymbol>DORM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001205405</rptOwnerCik>
            <rptOwnerName>BERMAN STEVEN L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O DORMAN PRODUCTS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3400 E. WALNUT STREET</rptOwnerStreet2>
            <rptOwnerCity>COLMAR</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>18915</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President &amp; COO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-09-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7600</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.15</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1496640</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 25, 2009.</footnote>
        <footnote id="F2">This transaction was executed in multiple trades at prices ranging from $15.05 to $15.43.  The price reported above reflects the weighted average sales price.  The reporting person will provide to the SEC staff, the issuer, or security holder of the issuer, upon written request, full information regarding the number of shares and prices at which the transaction was effected.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Steven Berman</signatureName>
        <signatureDate>2009-09-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
