400 kickdown

[53burb]

I temporarily hooked up my remote starter switch on my kickdown switch. This is what I found out when I push the button: it will kickdown at any speed below 2000rpm, and will stay in 2nd until about 2800rpm, then it will shift into 3rd. So it will not engage above 2000rpm. Is this correct???

[ac102nv]

Depending on how the trans is setup ie modulator, govenor, and valve body....this could be correct. However, to tell a little more info is needed. When you tested this, trans was in Drive and you went to WOT...right?

[53burb]

Trans was in Drive. I didn't go into WOT. I simply pushed the button on the switch. I have it hooked up to test the kickdown. I don't have a normal switch on the gas pedal or carb.

[53burb]

What do you guys think????

[ac102nv]

Originally Posted by 53burb

Trans was in Drive. I didn't go into WOT. I simply pushed the button on the switch. I have it hooked up to test the kickdown. I don't have a normal switch on the gas pedal or carb.

This sounds like normal behavior to me. When you activate the kickdown, the trans looks at a number of input signals: vac from engine, driveshaft speed, and internal pressure to figure out how to react. At part throttle cruise what you observed is probably normal. If you try it again but with more pedal the RPMs should climb higher before upshifting back to 3rd. The more throttle, the more RPMs before upshift (to a point).

Hope that helps.

[53burb]

It helps. I just wanted to make sure it was normal. Is this adjustable at all??

[ac102nv]

Sure, you can adjust this within reason. But this is normally based on the upshift at WOT at a specified RPM. Once you get that set you can them slightly modify when it downshifts. Most people don't worry about part throttle upshift as this is the "passing gear" settings, not cruise. Hopefully that makes sense, if not or you have more ?? please post.

[76bonanza]

You need to try it at WOT then push your button the vaccum at WOT is very diferent than at part throttle and the tranny will react very different. So to test what you want, go to WOT then push you button and see what how the tranny reacts.

[Green Machine]

Assuming that is a momentary contact starter switch, to emulate normal operation, you need to hold the switch in during the duration of the WOT, and ONLY during WOT, cause thats what is is, it's designed to tell the tranny when you go to WOT, to activate it at any other time during part throttle is not what it was designed for.

[53burb]

I am holding it down for quite a few seconds, basically until I am satisfied that it is not going to engage. I have done this at WOT and partial throttle.

[Green Machine]

Try this - from a dead stop in drive, do not push switch, floor it and tell us at what rpms it shifts to 2nd and what rpm it hits 3rd. Then do same thing from a dead stop, hold the switch down the whole time now until it hits 3rd, floor it and tell us what rpms it shifts at then, that will help tell the rest of the story....

[ac102nv]

Greenmachine is right...I failed to mention, you should be holding the switch down, not releasing it. This will tell the whole story. Once you know that the kit I used to modify the trans was a B&M - 20248. You can search on Summit's website for BMM-20248, runs just under $30. Nice part is it comes with decent instructions to get what you want.

[76bonanza]

Do you have to drain the tranny to install and after install can you adjust it with out draining tranny again?

[ac102nv]

Originally Posted by 76bonanza

Do you have to drain the tranny to install and after install can you adjust it with out draining tranny again?

You actually remove the gov from the trans and modify it with this kit. And each time you make changes you have to remove. But there's no need to drain the trans. The gov is behind a little cover plate on the passenger side of trans just before the tailshaft, held on by 4 bolts on the TH400. If I remember correctly I jacked up the pass side of truck a little so-that no/very little fluid was lost during changes.

[53burb]

Sorry it's been awhile, but anyways, in normal driving, the trans shifts from 1st-2nd from 1500-1600RPM & 2nd-3rd from 1700-1900RPM. At WOT it shifts into 2nd at about 3400-3500RPM & into 3rd at about 3500-3600RPM, this is W/O the switch being pushed at all. So, do want me to try this same test with the switch being pushed the whole time from a dead stop at WOT???

[ac102nv]

Originally Posted by 53burb

... So, do want me to try this same test with the switch being pushed the whole time from a dead stop at WOT???

Yes exactly. The RPM's should raise, how much I'm not possitive. So far though it sounds like everything is working normally.

[stueber68]

I hace the factory kickdown switch that goes on the firewall if you need it. You can have it, just pay the postage. The trick will be getting the bolt on the pedal. Let me know. I can even get you pics if you need them.

[53burb]

When I stomp on it at WOT from a dead stop with the button pushed it shifts from 1st-2nd @4300-4500RPM & 2nd-3rd @3700-3900RPM. If this is normal, do you think that governor kit you bought will enable the kickdown to be actuated at 2000+RPM??

Stueber68, please send me pics of the switch. Right now, I have a rod-type mechanical linkage, but I will be switching to a cable-operated one shortly.

[ac102nv]

Those numbers sound like everything is working as it should. The kit I have is primarily used to adjust the upshift point at WOT. However, when you raise the upshift point typically the max rpm that it will kickdown at raises also. Not sure if I worded that right, but the higher the upshift the higher the RPM which it will still kickdown. Becasue of this I have mine set to upshift at approx 5k which gets me the kickdown rpm I want. When I want to run up to my max rpm of 6200 I shift manually.
To answer your question about the kit getting you the numbers you want is very tough. I would say most likely you'll be fine.

[53burb]

If I understand you correctly, if I use the kit, 2nd gear will kick in at a later RPM. The kickdown will also be enabled at a later RPM. So, right now, my kickdown is inop at over 2000RPM in normal cruising. The kit should let me increase this RPM range. This will have to wait until I change my rearend. I will talk to Summitt or B&M when I am ready. Thanks for the help. Just reread your post, it only changes at WOT?? Not at cruising in 3rd gear, then going to WOT, because you are already in 3rd, right?? But if you are in 2nd, it will hold 2nd longer before it shifts into 3rd. Any suggestions on getting it to downshift at 2000RPM + w/o doing it manually??

[crazy longhorn]

The gov recurve kit will raise & spread the WOT shift points. From what I have seen, it also raises the part throttle shift points somewhat. I dont run the elect kickdown on my longhorn, as I didnt want the 3 to 1 kickdown (lots of revs & squirrely!) the trans will downshift from 3 to 2 without the switch, & the shift out point is not affected (as much) from 2 to 3, as from 1 to 2. The shift kit in my trans lets me shift up/down @ any speed, or hold a gear to any speed manually.You might find that with the 3.08 gears, the recurve is not needed....your kick down & shift out points will be @ the same RPM relative to the driveshaft speed, but the truck will be moving faster with the taller gears. with the switch hooked up, & you shift out @ 4300 & 3700/3800, thats about right for a stock or mild combo. L

[ac102nv]

Originally Posted by 53burb

If I understand you correctly, if I use the kit, 2nd gear will kick in at a later RPM. The kickdown will also be enabled at a later RPM. So, right now, my kickdown is inop at over 2000RPM in normal cruising. The kit should let me increase this RPM range. This will have to wait until I change my rearend. I will talk to Summitt or B&M when I am ready. Thanks for the help. Just reread your post, it only changes at WOT?? Not at cruising in 3rd gear, then going to WOT, because you are already in 3rd, right?? But if you are in 2nd, it will hold 2nd longer before it shifts into 3rd. Any suggestions on getting it to downshift at 2000RPM + w/o doing it manually??

The purpose of the kickdown is only WOT. No changes to cruising shifts. By using the kit to modify the govenor you are changing the WOT shifts and to a certain extent the cruise shift points.
It's starting to sound like you want to modify part throttle shifts, I would recommed getting a good transmission book. When you start changing this stuff you need to know how the different "systems" work together, or it can be a real mess. I have one intitled "How To Work With & Modify the Turbo Hydramatic 400 Transmission"...Summit has as number MBK-0879382678, about $22. There's other sources I'm sure....

[Green Machine]

Gotta jump back in here, it is totally pointless to try to guess what rpm/speed the tranny will kick down at without a properly hooked up and working kickdown switch. Thats what is for. Once you have a switch hooked up to the carb or gas pedal that activates at WOT, then you can play with the governor weights and springs and the vacumn modulator to fine tune things. Shift kit may be an option also. The 400 does not have a cable like a th350, so it has does not have a direct way of knowing the throttle position, it relies on the vacumn modulator and the WOT switch for proper automatic operation. If you want to run without the WOT switch, you need to manually downshift unless you set the upshift points very high.

[crazy longhorn]

Originally Posted by Green Machine

Gotta jump back in here, it is totally pointless to try to guess what rpm/speed the tranny will kick down at without a properly hooked up and working kickdown switch. Thats what is for. Once you have a switch hooked up to the carb or gas pedal that activates at WOT, then you can play with the governor weights and springs and the vacumn modulator to fine tune things. Shift kit may be an option also. The 400 does not have a cable like a th350, so it has does not have a direct way of knowing the throttle position, it relies on the vacumn modulator and the WOT switch for proper automatic operation. If you want to run without the WOT switch, you need to manually downshift unless you set the upshift points very high.

Yes, you will probably make yourself "nuts" trying to modify the gov to change the pass gear shift points, without the switch hooked up. You WILL have a 3-2 kickdown without the switch......but probably not above say 45mph. If I am running 65 mph & need pass gear, I have to shift manually. If it were mine, I would hook up the switch, swap the gears,.....& see what happens L

[53burb]

Thanks for all the help guys. I guess it is working correctly. I guess if I want to use the passing gear at 65mph, then I will have to do it manually like you do. Happy Thanksgiving!!!!!