722.3 Transmission Issues
 

SO this is the car that I've done the engine swap in. The car has a rebuilt 722.3 automatic transmission. Two days ago I replaced the shift modulator with a brand new "upgraded" unit. Now, it shifts very well through the forward gears. It goes into Drive and Reverse with authority and without hesitation. The problem is when going over hills... (this issue is kind of hard to explain). When you crest a hill going around 25MPH and you're not hitting the throttle, the transmission will shift either up or down depending. Now, here's where the issue lies. Whenever you resume acceleration, the engine will rev up before catching and/or dropping back into gear. It's almost like the transmission sits between 3 and 4 in neutral and when you hit the throttle it shifts one way or the other back into a forward gear. The transmission has the proper amount of fluid (Valvoline max life) and when I put the car back together, I changed out the filter as well. ANY IDEAS??

When it finally shifts into fourth gear is that a hard shift?
I have a similar problem going into fourth if at a neutral throttle.
Smooth if throttle is applied.

Mine is really strange. It's when you're coasting and (in theory) it downshifts to 3rd gear. well, once the throttle is re-applied, it slams into 3rd like it's coming from neutral. Shifting between all other gears is fine on normal acceleration.

Do you mean the transmission was recently rebuilt or rebuilt like thousands of miles ago?

I can't answer your specific qutestion but the modulator can be adjusted and the same with the bodwen cable.

There is also 2 places to check the the pressure (during the modulator adjustment?).

Also you have an Vacuum Valve adjustment on the Fuel Injection Pump.

Is the fluid Dexron II?

These transmissions don't like other stuff

My apologies for not specifying BUT the transmission was rebuilt about 3,000 miles ago, so not long at all. And of course, I replaced the modulator and I'm sure it's terribly out of adjustment. My vacuum system has a few issues but I wasn't sure if the modulator could cause this particular issue or not. I think I have the modulator cranked to compensate for a weak vac system... I'm going to get the transmission modulator vac and hydraulic test gauges (from m-source) and set it according to his specs and see where that gets me.

The Maxlife ATF is a full synthetic "general purpose." It came highly recommended from a buddy who works on these cars quite often and even drives one every day. Honestly, it helped a LOT with going into gear from neutral. Before, I was running standard Dex III (I believe) and it shifted really hard into reverse and now it's considerably smoother. However, even with the old fluid, it had the same issue I came here about initially. The old modulator was also cranked up to compensate (for what I imagine is an out of adjustment vac system).