1963 shifting problem

[JimBurl]

I have a 1963 Thunderbird with a shifting problem. For the first mile or so it shifts OK. Then it shifts into second gear by itself and stays there for 3-4 miles and starts to shift OK for the rest of the trip. Any thoughts ???

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[Yadkin]

I have a 1963 Thunderbird with a shifting problem. For the first mile or so it shifts OK. Then it shifts into second gear by itself and stays there for 3-4 miles and starts to shift OK for the rest of the trip. Any thoughts ???

1. Check fluid level and quality. If not clear, will need to service, perhaps even rebuild.
2. Band adjustment (see the shop manual).

 

[hotrodbuilder]

I have a 1963 Thunderbird with a shifting problem. For the first mile or so it shifts OK. Then it shifts into second gear by itself and stays there for 3-4 miles and starts to shift OK for the rest of the trip. Any thoughts ???

Hi, It seems to me that the vacuum modulator at the rear of the transmission is bad or the hose attached to it is cracked and leaking vacuum. If OK, then there may be another vacuum hose leaking somewhere.