the car is shaking when on reverse holding the brake

[festifrank]

Hi everybody i have a 1992 automatic festiva and when i put the shifter on "R" position by holding the brake to make the car doesn't move, the car is shaking. I feel and see the dash shaking. The same thing did not happens on "D" position. When i release the brake and push the gas to go backwards the car stop shaking and shake again when i stop it with the brake on "R" position. The transmission fluid is red clean and smell nothing and the transmission runs good and never knock. Wat could i try ? I wish i don't need a new transmission.

help would be awesome

thanks a lot

[GenevaDirt]

what is the idel like when you put it in reverse....is it real low?
or maybe a motor/trans mount going bad