I have a Olds 442 with 455 CI and Th400 Trans. When I’m driving at highway speeds and give it gas shouldn’t the kick down engage to drop trans into the next gear down for the acceleration? There’s substantial torque to accelerate but I thought the trans should kick down. Am I missing something?
From what I remember growing up the trans should kick down a gear.

 

Only if you floor it.

 

Ok thanks Eric. That proved my point. This 442 doesn’t do that. The reason I asked is I have a leak and the shop called and asked me a couple of questions and it seems the trans wasn’t rebuilt correctly.

Thanks for the reply.

 

The T400 uses an electrical switch to go into passing gear.

 

The turbo 400(& the 2 spd jetaway) use an electric down-shift switch mounted inside the car, above the gas pedal. The first thing I'd do is make sure it's there & the wires are hooked up. Did it ever work for you? Was it an original TH400 car?? A factory 4 spd car won't have the mounting bracket for the switch. It's a slide type switch that can go out of adjustment,especially if new carpet was installed. The piece that slides can be reset by gently pushing it towards the firewall 'til you feel it click, it will be locked all the way forward until you floor it for the first time. That should reset it. From there a wire goes down to a spade terminal on the drivers side of the TH400, it should be a single green wire on a '68, it can fall or break off. The switch under the dash can be easily checked with a test light. Turn the ignition on so the switch is hot. It's been a long time but I think the hot wire at the switch is pink, ground your test light,find the hot wire & then put your test light on the other one & move the switch slide forward, if it lights up you're at least ok inside the car. If everything looks ok on the outside of the trans you may have to replace the down shift solenoid inside the trans(I've seen the wire inside fall off too). Both switches,the mounting brkt & the plastic terminal hsg that goes through the trans case are easily obtainable. I posted a pic from Fusick's that shows the switch & solenoid

 

You said highway speeds? It's probably as simple as the TH400 not allowing passing gear (next lowest gear as it works in 2nd gear also) to engage above a certain speed?

 

That was my thought as well. Try mashing the pedal at 40 MPH and see if it downshifts.