Defendant appellant’s only assignment of error is the denial of his motion to be allowed to amend his answer to plead the prior judgment as res judicata on his cross action against the additional defendant for contribution. The motion to amend was made on 6 August 1968, more than two years after the original answer was filed and long after the time for filing answer had expired. “After the time for answering a petition or complaint has expired, the respondent or defendant may not as a matter of right, file an amended answer. The right to amend after the time for answering has expired, *579is addressed to the discretion of the court, and the decision thereon is not subject to review, except in case of manifest abuse.” Hardy v. Mayo, 224 N.C. 558, 31 S.E. 2d 748. This well-established rule has been repeatedly announced and followed by our Supreme Court. Vending Co. v. Turner, 267 N.C. 576, 148 S.E. 2d 531, and cases cited therein.
Appellant contends nevertheless that he has been denied a right to which he was entitled as a matter of law, citing Sisk v. Perkins, 264 N.C. 43, 140 S.E. 2d 753. In that case, however, the defendant had been allowed to amend his cross action so as to plead the judgment in the parallel action as res judicata on the issue of the additional defendant’s negligence, and the decision furnishes no support for appellant’s contention in the case now before us that he is entitled to amend as a matter of right or that denial of his motion to amend was in this case an abuse of discretion.
[1-3] While the record does not disclose what factors were considered by the trial judge in exercising his discretion in the present case, we note that in Sisk the prior' judgment pleaded as res judicata was based upon a jury verdict, while in the present case the prior judgment was a judgment of nonsuit. Therefore, even had the motion to amend been granted it would still be necessary to defer a ruling on the plea in bar until after all evidence is presented upon the trial, as only then could it be determined whether the evidence at the second trial was substantially the same as at the first. Batson v. Laundry, 206 N.C. 371, 174 S.E. 90. Furthermore, in the case before us, unlike the Sisk case, the defendant has pleaded, in his first and second further answers, that the additional defendant was acting as agent of the plaintiff, thereby seeking to hold plaintiff responsible for any negligence on the part of the additional defendant. Even if defendant’s motion to amend had been granted and he should ultimately establish his defense of res judicata on the issue of the additional defendant’s negligence, the plea of res judicata would be valid only in connection with his cross action for contribution against the additional defendant and could not be effective as against the plaintiff, since a prior judgment establishing negligence on the part of an agent is not conclusive in a subsequent action against the principal. Coach Co. v. Burrell, 241 N.C. 432, 85 S.E. 2d 688; 46 Am. Jur. 2d, Judgments, § 569, p. 729. Therefore, allowance of the amendment in the present casé would have been at most of only limited value to the defendant. In any event the- record fails to *580disclose any abuse of discretion on the part of the court in refusing to allow the motion to amend. The order appealed from is therefore
MallaRd, C.J. and Britt, J., concur.