Working with Founders after Sale of Control to PE/VC Firm

I was wondering if anyone had any advice/experiences they could share about challenges they encountered if they were brought on as CFO to a PE/VC Portfolio Company and the founders remained in the business as part of the executive team (including the CEO position).

We have a great triad of entrepreneurs who built a great business over the last 5-6 years. They have done a fantastic job building the company but last year the founders sold 96% of the shares to a PE firm to gain access to substantial capital to invest in the firm. I was than subsequently hired after the Board decided it was time to add a CFO to help build out the Finance/HR/IT/Procurement functions as we prepare the company for anticipated rapid growth. We have a great management team, but there has been some tension as the founders and I grapple with changes to the Delegation of Authority in the company. There is particular reluctance by the CEO to even allow me in the capacity as CFO to sign low dollar checks that are disbursed or even approve payroll runs with-out his approval. I really want to free-up his time so he can spend most of it on strategy & business development, but I sense he is hesitant to relinquish these types of responsibilities he has managed since he started building the business. I also sense a bit of tension having to come to a CFO for spending approvals from the other 2 Founders who are still in the business as VP's.  I assume that this sort of tension with founders still in a company is not all that unusual, and is somewhat understandeable, so I am certainly trying to be patient. I think as the business grows the CEO will be forced to withdraw from some of these tasks a CFO would normally oversee. I was just curious as to whether anyone else at PE/VC backed companies has gone through similiar challenges and how they managed them.