If you file for bankruptcy and reaffirm on the car loan, as long as you continue to make timely payments to the creditor your co-signer will not be affected in any way by your bankruptcy. A reaffirmation agreement in a Chapter 7 bankruptcy reaffirms the debtor's personal liability and has the same legal effect as if there was no bankruptcy regarding that debt. Your co-signer is at risk if the debt is not paid, therefore it really doesn't matter if it is reaffirmed or not, as long as it is paid it should not affect your co-signers credit. But if payments aren't made. Then there will be a problem. And may fall on your co-signers shoulders to pay since they didnt file BK.