Technical Another TH400 question

My -32 has a '67 TH400 that "Slams" into gear from either neutral or park. I assume it has some sort of shift kit in it, but I don't know for sure. (it was in the car when I bought it) It does have a deep pan and a small converter of unknown origin. It shifts really nice and firm through the gears, and has no electric kick-down. Idle speed is roughly 800 to 1,000 rpm. I have changed the modulator twice and adjusted it both ways. Good clean vacuum source. I am wondering if anyone has any ideas? TIA

 

Check the line pressure, maybe it has a really stiff regulator spring in it?

 

What kind of vacuum does your engine produce at idle? It needs to be in the 14 in range so that the transmission operating pressure is in the "normal" range. Also getting the idle speed down between 700 -800 rpm will also help. I'd put a pressure gauge on the transmission and see what the pressure is at idle. It should be 50 - 60 psi in neutral or drive (pressure will be over 100 psi in reverse which is normal). I would also put a mighty vac (hand held vacuum pump) on the modulator and see if you can put a good vacuum on it and get it to 50 - 60 psi. If the operating pressure doesn't respond to vacuum, you may have to live with what you have (? shift kit).

You say you have no electric kick-down. Do you mean there is no provision for it or that it isn't hooked up? If there is no electrical connection on the left side of the transmission, are you sure you have a 400? If it is a 400, the vacuum modulator will be on the right side of the transmission rather than on the rear.

 

Could be internal mods. Cushion springs removed from clutch packs , clearance issues or could be a heavy spring in pressure regulator.