What you are mentioning is two different things. If I get the acronym right, CCA stands for City Compensatory Allowance that can be disbursed through Special Allowance or can be a header in your Salary items. Such an allowance would make sense for an organization having offices and functions demarked clearly between rural and urban centers.
Conveyance allowance is non-taxable up to Rs 9,600 per annum or Rs 800 per month. Typically, if your Basic is Rs 9,850 per month or Rs 118,200 per annum, which should be 35-40% of your gross.
I assume your CTC is around Rs 340,000 (35%) and Rs 300,000 (40%), and hence your CCA could be up to Rs 3,000 - 5,000 depending on your CTC. Also, keep your reimbursements high to save tax.