th400 kickdown?

I kind of have 2 questions here.

So I've been driving my truck around lately (since I replaced the tranny pan gasket and inspected some things there). It drives well most of the time but every now and then it wants to shift sporadically between first and second. I'm still leaking fluid from what seems to be the gasket. I can't find anywhere else it seems to be leaking from. I used a rubber gasket with no silicone or anything and first tightened to 10 ft. lbs. and bumped it up to 11 ft. lbs after it was still leaking at 10. Any suggestions?

question 2 is... Right now I don't have a kickdown switch hooked up. It seems like my father in law said I don't really need it since it has the governor and the vacuum modulator (Governor controls down shifts vacuum controls up shifts... correct?). I've seen kits for about $75 for an electric kickdown kit for a th400. Could this help improve the shifts in my tranny? It just seems to not have consistent hard shifts. When I inspected the governor it was in good shape. I never did check or replace the vacuum modulator. It seems to have more troubles up shifting than down. This tranny sat for a couple of years. Should I replace the vacuum modulator anyways (I know they're cheap)?... install a shift improver kit?

I guess I need to look at my carb to see what type of kickdown I need if I use one.

Just new to transmissions and trying to learn. Thanks in advance.

I no you won't hurt it running without the kickdown, I run mine that way. I am pretty sure theonly thing the KD does is downshifting when you floor it at speed, ie. passing gear. I would replace the modulator. Someone smarter will chime in I am sure.

More than likely it's the front seal leaking, I agree with 42 Chevy on the modulator...also make sure the vacuum line isn't pinched.

Can the vacuum line be too big? I used a piece of steel line from my old fuel pump with a short rubber piece on each end. I found the original steel line the other day and it seems to be one size skinnier. The short rubber hoses are the same size as the old ones though.

I'm going to replace the modulator first and see if that helps. I need to do one thing at a time so I know what the fix is.

The metal line should be fine just make the the hoses aren't so soft that they suck shut.

Th400

The th400 I got from the caddy did not use a kickdown, it had no cable or rod to the transmission or carb. just a vac. line to the modulator, I drove the car and it all worked good before I pulled it all out. do some th400 use a kickdown and others dont ????? I am not a tranny guy or was the car missing something ?????

TiredIronGRB said:

The metal line should be fine just make the the hoses aren't so soft that they suck shut.

Click to expand...

Yeah, I recently had problem with that and upgraded to thicker rubber. I think this should be okay. I'm going to replace the modulator tomorrow. I'm also doing a little work to the front suspension so when I get it back on the ground I'll test it out with a new modulator and see what that does.

It sounds like the kickdown shouldn't be the issue.