Order and judgment (one paper), Supreme Court, New York County, entered January 21, 1977, dismissing and denying petition to stay arbitration, and granting cross petition to compel arbitration, is unanimously affirmed, without costs and without disbursements. We agree with Special Term that petitioner’s participation in the proceedings before the arbitrator is a bar to the present application for a stay of arbitration. But, in any event, the dispute is clearly one covered by the arbitration clause. And the question whether respondent union complied with the grievance procedure steps contemplated by the contract preliminary to arbitration is one for the arbitrators. "Questions of timeliness and compliance with step-by-step grievance procedures, prior to formal and final binding arbitration, are questions of 'procedural arbitrability’. Now it is clear that such questions must be left to the arbitrator.” (Matter of Long Is. *525Lbr. Co. [Martin], 15 NY2d 380, 386.) (See, also, Wiley & Sons v Livingston, 376 US 543, 557; Matter of Triborough Bridge & Tunnel Auth., 55 AD2d 871.) Concur—Kupferman, J. P., Lupiano, Silverman and Markewich, JJ.