I am new to the Vette world & learning every time I post a new thread. I am about ready to drive my 70 Coupe 350... 4 speed manual... the forward gears work fine... but I cannot get her into reverse. The tranny was rebuilt and installed when I bought it, so I haven't taken a good look at it. The shifter has a lockout. The lockout works fine, spring loaded. Where do I begin looking now? Thanks!

 

Have you started the engine/shifted the transmission into each forward gear and let the clutch out enough to see if each forward gear engages fully so that the car will try to pull forward? Other than making sure the lock-out is completely disengaging to allow the transmission to go into reverse. I'm guessing you need to put the car on jackstands or a lift to see if the Reverse linkage needs adjusting.
(My rookie guess)

 

Our cars had a reverse lockout cable as a theft deterrent. Basically you have to put the transmission in reverse to move the key out of the run position and take the key out. If that cable is frozen or not working right it could cause your issue. Are you able to get the ignition tumbler out of the run position and take the key out when not in reverse? If so then your interlock cable is not connected and not your problem. Just be sure to check to see if the lever at the steering column is secured in some way where it will not move. I would be a bad day if that lever decided to move and lock your steering wheel at 50mph.
Another thing it could be is the linkage may need adjustment.
See the cable running from the reverse linkage above the clutch fork. That cable runs up the the steering column on the firewall and move a lever that allow the key to be removed and locks the steering wheel when shifted into reverse.


As suggested put your trans in neutral then start it up. Run through all the gears with the clutch pushed in then try to put in in reverse. Sometimes I have to do that with my trans but not very often.
I suspect you need to adjust your linkage or rebuild your shifter as they do wear out over the years

 

Thanks for the info and the great picture. I have been an old Ford guy and can adjust their linkages in my sleep. Now, dumb question: which rod is the reverse linkage rod in the picture above? I am assuming the smaller rod near the tranny, with the longer rods being for forward gears? Yes, I know I can look at my AIM... but the book don't say it all.

 

the short one

 

It could also be the shifter bracket is a little loose. If it's loose it could bind up. The stock shifter is not bolted to transmission as shown in the picture. You can also see where the cable I was talking about attaches to the reverse lever of the trans and yes the short rod is reverse.