My father belongs to a veterens club that has a train that they drive in parades. They have a 460 ford with a c6 tranny. My father says that they used to get so many MPH at a certain RPM on a level surface. Now, they have lost about 10 to 15 MPH under the same conditions. He had the tranny checked and they said there is no problem. The tranny has two coolers on it also. He had the engine serviced, but they still have the loss of MPH.

Does anyone have any ideas what could be the issue?

Thanks.

Helping Dad

 

i'd say chances are something has happened to the torque converter or transmission

 

go down to any prts store and pick up some marvel mystery oil and put a quart in the tranny fluid,should fix it