i am installing a TH400 in my cherokee with a chevy 350, i have a manual in it now and i need to know the small things i need for the install, i am installing a TH400 with a herst star shifter, its going to hook up to a box 4 rocks then in to a D300. do i need a vacume kick down or can it be a manual down shift or if i need a vacume kick down where should i hook it to, will i need a neutral safety switch and if i do need those things, why?
the rig is off road only and driven only by myself, i am a good mech but i have never done this conversion and just need some experenced tranny techs advise.

thanks and see you on the trails

this is what i have, on the shelf is the cooler and shifter in the box's and i know i need the dip stick too

http://i6.photobucket.com/albums/y241/steagall9301/100_0192.jpg

http://i6.photobucket.com/albums/y241/steagall9301/100_0191.jpg

TH400's use an electric signal for the "kickdown" feature.

It's not part of the throttle linkage like a TH350

The shift linkage is manual, so if you feel like wiring in a safety switch then go for it.

That'll be a kickass combo in your Cherokee

you will still need manifold vacuum if you want 2nd gear. or 3rd

Put a full manual valve body in it, then you can put it which gear you want it in anytime. Drawback is you will have to drive it like a stick. Shift through gears, but on the trail gives you better options. While you have it upside down put a shift kit in it also. Good luck, Jason.

the full manual valve body IS a shift kit. it modifies the valve body, which is the same thing a shift kit does.

it just does it more effectively.

so, if you put a shift kit in a full manual valve body, you might be going backwards.

just follow the APPROPRIATE instructions for either.

I Did the manual valve body in my truck and I love it. It shifts hard and firm and you can run it to the moon in first gear and it will not shift, and you can also downshift at any time.

TH400's use an electric signal for the "kickdown" feature.

The shift linkage is manual, so if you feel like wiring in a safety switch then go for it.

That'll be a kickass combo in your Cherokee i dont want the safety switch, thats 1 good thing.

where would i be getting the electrical signal for the kick down from and do i need it? cant i just down shift manually?

why do i need the vac for 2dn and 3rd gears, if i dont put the vacume line and shift it mechanicaly will i still have those gears or do i need it for them? i know it is simple to hook up the vacume line any ways.

thanks for the help so far, i will keep every one posted on the progress ( by the way, where would i get the full manual valve body from?? )

just buy a transgo shift kit for it. Not sure if they offer more than 1 for the 400 but if so get the manual shift kit and it will shift manually. My buddy put one in his tranny and it made it full manual. Even installed in with the tranny in the truck.

If you want it to drive like an automatic you will need to hook everything up ie you put it in drive and it will go through the gears and downshift when it is needed. You go to a manual valve body set up all you need is a shifter hooked to your trans. you shift to the gear you want. you put it in third you start in third so on and so on. you want to downshift you downshift. It no longer has any auto functions. the best i can describe it is like the old three wheelers and four wheelers with a gear shift and no clutch. Same principle. Get a ratchet shifter and down the road you go.

i dont want the safety switch, thats 1 good thing.

where would i be getting the electrical signal for the kick down from and do i need it? cant i just down shift manually?

why do i need the vac for 2dn and 3rd gears, if i dont put the vacume line and shift it mechanicaly will i still have those gears or do i need it for them? i know it is simple to hook up the vacume line any ways.

thanks for the help so far, i will keep every one posted on the progress ( by the way, where would i get the full manual valve body from?? )

From the factory, there is either a switch on the carb throttle linkage, or they used a switch that was on the gas pedal (in the cab), so when you mashed the gas to pass, it would make the switch, and downshift the tranny to pass.

I been drivin my truck w/TH400 w/out the kick down solenoid disconnected since I put it in. When I need to pass, I manually shift it down to 2nd.

There's several places you can get a kit to install a switch on the throttle linkage. Run a hot wire to one side of the switch, the other side of the switch goes to the solenoid on the tranny. When you mash the gas, make the switch, and wha'la... the tranny will downshift. Of course if you're inclined, you could easily make one yourself.

You do need the vacuum line to go to the modulator valve so that the transmission will shift. This vacuum line is usually connected to manifold vacuum just behind the carb on a SBC, or BBC. Unless you go manual valve body, you must have a vacuum line installed. Otherwise, it will not shift correctly.

From the factory, there is either a switch on the carb throttle linkage, or they used a switch that was on the gas pedal (in the cab), so when you mashed the gas to pass, it would make the switch, and downshift the tranny to pass.

I been drivin my truck w/TH400 w/out the kick down solenoid disconnected since I put it in. When I need to pass, I manually shift it down to 2nd.

There's several places you can get a kit to install a switch on the throttle linkage. Run a hot wire to one side of the switch, the other side of the switch goes to the solenoid on the tranny. When you mash the gas, make the switch, and wha'la... the tranny will downshift. Of course if you're inclined, you could easily make one yourself.

You do need the vacuum line to go to the modulator valve so that the transmission will shift. This vacuum line is usually connected to manifold vacuum just behind the carb on a SBC, or BBC. Unless you go manual valve body, you must have a vacuum line installed. Otherwise, it will not shift correctly.very cool, thats what i will do, no kick down switch, manual kick down. vacume line, easy to do and no loss of performance!! win win.

Rookie question if you can help. Just got a 77 Cheif with the TH400 and doesnt seem to kick down. Should I just be looking for the vacume issue?

Rick

You bumped a three year old thread to ask a newbie question? I don't know a ton about ALL TH400's but mine has a single wire kickdown. If you search "TH400 kickdown" and other key words, you will find alot of info on them here......

Rookie question if you can help. Just got a 77 Cheif with the TH400 and doesnt seem to kick down. Should I just be looking for the vacume issue?

Rick

:shaking:

No, the vacuum line on a th400 is for the vacuum modulater, it has nothing to do with downshifting! You couldn't read all that was just stated up there ^^?

If you want it to automatically kick down then u need the electric kickdown switch. Google it, there is tons of info about it heck just open a summit catalog and you will find one.

On the dirver side of my th400 transmission there is a post for a spade style connector. What is that for?

Your question was actually answered in the post above yours. it should have been asked in the newbie section.......

I didnt know thats where it hooks on.

If I use this with a hurst ratchet shifter will this work? If it shifts down and my shifter is in the 3rd gear positon will it bump down? Or will my transmission shift from 2nd back into 3rd once i let off?