I recently rebuilt my 87 F-body 700R4. Everything seems to be working but when I shift into OD, the trans doesn't engage. But, it engages in every other gear with no problem and shifts all the way to 3rd. I haven't gotten on a long enough strait path to see if it will go into 4th by itself. Any suggestions?

 

if the tv cable is adjusted too tight it will not engage 4th even when manually shifting until the vehicle speed is reached where governor pressure is able to overcome tv or shift delay oil.if its too tight the car will usually shift all the gears late.also a sticky tv valve can cause the same symtoms.it is wise to install a pressure gage to verify source.if all is normal then suspect a stuck 2/3 shift valve or servo problem.www.ckperformance.com

 

Make sure you didn't cut the teflon seal, or knock it off the 4th piston in the servo. It's the piston that seals in the servo cover. If 2nd is good, I can't see it being a band problem. If 3rd is good, I can't see it being a 3-4 clutch problem.
As Chris said, this may be a TV cable adjustment. I've seen misadjusted cables cause a no 4th gear symptom. A stuck TV valve will most definitely cause a no 4th problem, also.

Did you "air check" the servo when you put the trans together?

Frank
CPT

 

Yes I air checked the clutch pack assembly and everything worked as it should. I haven't tried the tv cable yet (rainy weather) but as soon as the chance comes up, I will. Keep the ideas coming though. I really don't want pull the trans out if i don't have to.

could it possibly be a check ball problem?

 

The tv cable is fine. I still think there is either a valve body problem or a check ball problem. Any other help?