Mexicans pleased with fixed peso rate, less sure about other reforms

After a week of chaotic uncertainty, Mexico's newly nationalized banks quietly reopened Monday against a backdrop of wide-ranging monetary reforms aimed at taking some of the chaos out of the nation's economic system.

The reforms, which include stabilization of the peso and elimination of foreign currency investments in banks, amount to a major reorganization of the system. But many details of their implementation have yet to be worked out.

And it is uncertain whether Mexico's fiercely independent business and financial leaders will accept some of the measures.

Most everyone seems pleased, however, with peso stabilization. The government of President Jose Lopez Portillo has set up a two-tier fixed exchange rate - with a basic, ordinary rate of 70 pesos to $1. A ''preferential rate'' of 50 pesos to the dollar for indispensable imports was also set up. (Last week, black market speculation carried the peso to nearly 200 per United States dollar.)

Whether the government-imposed fixed rate, crackdowns on black marketeering, and other measures will keep the peso at 70 remains to be seen. But economists generally agree that the peso's real value is somewhere between 70 and 75 to the dollar.

The problem, of course, is that Mexico and Mexicans are dollar short. Peso stabilization does not change that.

In fact, none of the measures taken within the past week solve the basic dilemmas facing the Mexican economy. Those problems stem from vast overspending by the government and by individuals.

Mexicans were simply living beyond their means. President Lopez Portillo indicated that banks and bankers were considerably to blame for the situation. But the Mexican Bankers Association over the weekend strongly rejected as ''unjust and unfounded'' the President's accusation that banks had encouraged the flight of capital that brought Mexico's weakened economic situation to light.

One leading Mexican economist said the President's rhetoric cannot mask the government's own ''profligate ways. The basic problem is the lack of confidence in the economy - a lack of confidence that rests at Lopez Portillo's doorstep.''

But the seriousness of the situation, with banks about to collapse because they could not pay their dollar loans, has begun to dawn on Mexicans. Criticism of the Lopez Portillo government has been tempered this past week. Even in the northern industrial city of Monterrey, where sharp criticisms of the government are often heard, there were murmurs of support for the President.

''He has almost no other choice,'' an official of Grupo Alfa, a huge financial and industrial complex, privately admitted to the Monitor on the subject of bank nationalization. Alfa and its arch rival, the Grupo Visa, dominate the economic and industrial scene in Monterrey. At the same time, Visa executives are bitter over the President's action. Visa controlled one of the nationalized banks.

Details of the bank nationalization, the exchange controls, and other economic measures came to light over the weekend. They include two measures expected to win public approval - a reduction of almost 25 percentage points in the cost of mortgages and a four-fold increase in savings account interest from the previous 5 percent.

These measures came out of a week of frantic scrambling by officials working overtime to put order into the banking system following the President's nationalization announcement. Additional measures are expected in the next week or so.