I have a 72 mustang with an FMX transmission. The car runs great most of the time and when I start it to use it for the day it jumps into reverse like its a brand new car. But after a few hours of driving itI cannot get it to go into reverse. It does shift into reverse but it does not do much. It acts like its slipping but as I said it works great when I start the car up in the morning. I suspect a vacuum leak but I am not sure. What do you guys think?

 

Check your fluid. It may just be low.

 

I did and its not. I plan on flushing it here once I have time and installing a new filter and adjusting the bands. YOu do not think its a vacuum problem?

 

It sounds like a viscosity related issue (changes with heat). My next step would be like you said, give it a flush and new filter. Does your fluid smell burnt and whats the color? These could be indications as to the condition of the tranny. Itseasier and less costly to fix the simpler things first. I wouldcheck the vacuum also. Gauges are not that expensive.

 

That is what I am going to do. First I am going to give it a good scrubbing so that I can check all of the outside then I am going to check all of the vacuum lines and make sure the diapragm is not leaking then I am going to change the fluid and the filter then I am going to flush it and change the filter again.