Still not shifting properly

Well i got some great tips from the archives and from my last post.

RECAP: 1986 2.8l 2bbl Roch carb. Former manual now auto (th-400 changed by P/O) Delayed Shifting

Well i dropped the tranny and the fluid looked and smelled perfect. No trash in the pan but i did replace the filter and fluid just in case. I correctly adjusted the aftermarket B&M shifter. All of this seemed to help. Now the 1-2 shift seems near perfect but the 2-3 shift seems delayed. I thouht perhaps it was the TPS. But I doubt that because this tranny doesn't have any connections that I can find going in to it, other than the shifter cable.
I was told by an old hand at the local parts-hut that those th-400 had no external modulator. Darn, there goes that theory.

So how exactly would this tranny tell what the engine is doing? There is about 2 cm of slack in the kickdown cable. I would shorten it but I can't find any adjustment. Heck i'm not sure where the cable came from. It is unlike the ones shown in the haynes manual. And my parts-hut doesn't have one I could replace the current one with for a th-400.

HELP!
Any assistance would be greatly appreciated.
Zel

hbtmcg said:

So how exactly would this tranny tell what the engine is doing?
Zel

Click to expand...

That's what the TV cable does. If you leave it too loose, you will burn up the tranny. I am assuming that you configuration is modern enough that it doesn't use a vacuum modulator. On older hydraulic trannys, it used engine vacuum to sense engine load.

I don´t have a TH 400 in the garage to go look at, but I remember a vacuum modulator being on the TH 400, black tin can looking thing. The second item on my TH400 troubleshooting list for late 2-3 shift, is faulty modulator or vacumm line.
A faulty governor will also cause late shifts, I´ve seen a govenor with a broken spring. There is a selection of color coded governor gears, for various applications. A performance governor is gonna shift late. A truck governor earlier.
Trash in the valve body, can mess with shifts. Pretty common with the TH700, imagine it can cause problems with the 400 also. You have, to have the tranny cooler line hooked up (not plugged) or a loop between the two lines, or things aren´t gonna work right.
The way I adjust the kick down or the TV on a tranny conversion, is to measure from the pivot on the throttle cam, to the TV cable attachment point (pivot pin) and measure from the end of the cable jacket to the TV pivot pin, on a motor with a OEM TH400 (or most any tranny). And match the distances, drill a hole in the throttle cam, for a new TV pivot pin location. If the geometry of the TV rod or cable is the same, it should be pretty close enough. I fab a bracket for the TV or kickdown rod, at the proper distance from the TV pivot pin on the throttle cam.
Three kinds of TV cable that come to mind are, the push button type, need to push a pin up with a small screwdriver under the plastic block on the end of the cable jacket and push the pin/button down when the TV is adjusted. Another type is a pivoting tab, the last I can bring to mind is the newer thumb push tab type (large thumb shaped tab/button on top).
There are various kinds (lengths) of pivot cam for the TV valve itself (in the pan). For different applications.
I´d get some better books and/or manuals, even if you have to order one from Summit or somebody. Summit may have a TH400 TV mounting kit, TH400 is a fairly common tranny conversion.
Sorry I couldn´t be more help, but have rarley had a TH400 screw up on me, so my knowledge is limited.

Something doesn't sound quite right! A TH400 has a vacuum modulator, but no kickdown/TV/detent cable. Kickdown is with an electric solenoid on the valve body. There should be a one wire pass-thru electric connection on the tranny case, and some kind of wide-open-throttle switch somewhere between the gas pedal and the carb. Also, 2.8's don't share the Chevy V-8 bellhousing pattern, and I can't think of a stock 2.8/TH400 application so there must be some kind of adapter needed to make it work.

If you don't have a Chrysler tranny which was mentioned in your previous post, the tranny you describe sound like the TH200. No vacuum modulator, and has a throttle valve cable to time the shifting. That would make sense, because the PO could have taken the engine/tranny combo out of a Chevy S-10 2wd. A TH200 has a one piece case (no bolt on rear extension housing), and the pan is rectangular shaped with the right rear corner cut off, plus the word "metric" stamped in it.

hbtmcg said:

Well i got some great tips from the archives and from my last post.

RECAP: 1986 2.8l 2bbl Roch carb. Former manual now auto (th-400 changed by P/O) Delayed Shifting

Well i dropped the tranny and the fluid looked and smelled perfect. No trash in the pan but i did replace the filter and fluid just in case. I correctly adjusted the aftermarket B&M shifter. All of this seemed to help. Now the 1-2 shift seems near perfect but the 2-3 shift seems delayed. I thouht perhaps it was the TPS. But I doubt that because this tranny doesn't have any connections that I can find going in to it, other than the shifter cable.
I was told by an old hand at the local parts-hut that those th-400 had no external modulator. Darn, there goes that theory.

So how exactly would this tranny tell what the engine is doing? There is about 2 cm of slack in the kickdown cable. I would shorten it but I can't find any adjustment. Heck i'm not sure where the cable came from. It is unlike the ones shown in the haynes manual. And my parts-hut doesn't have one I could replace the current one with for a th-400.

HELP!
Any assistance would be greatly appreciated.
Zel

Click to expand...

ok. There is no way a TH400 bolted up to a 2.8 WITHOUT an adapter. And, a TH400 will suck about 1/2 of the power that motor makes.

does the trans pan look like Illinois? Or Texas? If Illinois, it's a TH350, OR more than not a TH200.

The TV/Kickdown cable is adjusted at the Carb end...Lift up the little black tab on the bracket that holds the cable, Mash the gas, and while holding the gas down, push in the black tab.

Vacuum Modulator SHOULD be on the side of the transmission, about 1/2 way down. That requires Throttle Vac(Below Throttle plate). It CAN be adjusted by inserting a small straight screwdriver into the vac. hole, and turning. Clockwise increases shift pressure, counter decreases.

EDIT: Vac. canister is the big can-looking thing on the Pass. side.
Pic is a TH400

Tomorrow I am going to crawl under the and look at the tranny closer to figure out what kind it is.

I heard that TH-400 were put in older jeeps could they have taken an older tranny and placed it behind the 2.8l?

Zel

hbtmcg said:

Tomorrow I am going to crawl under the and look at the tranny closer to figure out what kind it is.

I heard that TH-400 were put in older jeeps could they have taken an older tranny and placed it behind the 2.8l?

Zel

Click to expand...

Very unlikely. You would still have the bell housing bolt pattern issues at the very least.

A bunch of extra (empty) bolt holes on the bell housing, can be an indication of which tranny you have.

UPdate: Well I still haven't figured out my tranny, mostly 'cause of the rain here in Florida. But I did adjust the TV cable.. I figured out how to. My TV cable is the kind that is adjusted by screwing the cable mount in our out.

THANKS 8MUD!

I haven't had a chance to drive the car to test it but at some point today I will. I hope this fixes it.

By the way how much slack should there be in the TV cable?

hbtmcg