TH-400 Question
 

Got a TH-400 it has a mild converter around 2500 stall and it shifts fine in Drive for normal driving. But at full throttle it shifts at around 3,500-4,000 RPM. I do have the governor kit with weights and springs. I'm wondering if it's worth it to try to mess with the governor to get it to shift at a higher RPM in Drive or will that mess up the normal driving shift points. The kick down works when I floor it but it still shifts at too low of an RPM at full throttle.

It is odd that it shifts so low!
I thought that they where programmed to shift between 4600 and 4800.

Try your kit, I mean you got nothing to loose.

I have a kit as well. I didnt use it though i found an article that mentioned grinding some weight of each weight and then going for a drive. mine was just like yours and now after 3 trys it shifts into 3rd at 5k when its at wot. didnt take alot off i ll look for my notes later. i used a kitchen scale and took a little off each weight. same springs.

It's been over 25 yers since I did one, but it seems there is 2 sets of weights on the govenor that control the shift. Only one needs to be trimmed for what you want?


The instructions that came with the kit explained all of it.


:confused:

Suffice to say Shorter inner weights and softer inner springs will raise the WOT upshift. One of the 2 mods will raise rpm upshift, the other will spread the shifts; 1-2, 2-3.

Big outer weights are for off-idle creep shift points.

Something you might try is on my truck started short-shift at full throttle if the downshift energizer wire came off the plug. It was a bad plug connection and I would have to jump under the truck and re-attach the plug. I got around to fixing it not sure if I got a new plug and wired it up or replaced the energizer in the pan. but its something cheap to try.

All good suggestions above. Additionally, I would verify your detent solenoid is working.....they DO go bad occasionally and the test is easy. Put 12V to the spade connector on the trans and listen for the click.

The worst thing about changing governor weights or removing them to grind on them, is the tiny e-clips you have to use if you use the pins in the kit....especially if you're an old fart like me....you just can't hardly see them. Also, with the governor out, inspect the gear closely and they will wear and break or crack. Replacement gears are available and cheap.

That's always a fun project Tim.......not lol :)

Sounds like you have a later model governor in there that shifts at 4000. My 79 454 pickup was the same way.

It's a long exercise to play with those things and get them exactly perfect. No additional advice that hasn't already been given other than have patients and enjoy taking that governor in and out a dozen times and hot fluid running down your arm pits. :)

Something I’ve noticed when adjusting governor shift points is that the shift point will be different with the kick down working vs disconnected. Going by memory I think it’s a couple hundred rpms higher with it connected.

I've done a LOT of governor tuning with TH350s and 400s. What you do is, get the shift points close with the weights and then select springs to set shift spacing and fine tune the shift points. Only change one weight or spring at a time and take careful notes. Drive the car at least 2X with each change, at part throttle and full throttle to judge the impact of the change.

If you're happy with the spacing between shifts but the WOT RPM shift point is too low, you'll need to reduce weight from the inner weights. Take the governor weights out, noting which spring went with each weight. Get a scale that measures in grams and weigh the weights. Shave 2 grams off the heaviest weight, or change to the next lightest weight in the kit, reassemble and re-test.

You'll need to do this several times to sneak up on the settings. Once you get it shifting at part throttle and WOT close to where you want it, then play with the springs. Lighter springs raise shift point RPM, heavier springs reduce shift points. Springs close in tension will stack shifts together, but a combo of heavy/light springs will move the shift points apart. That's why you have to take careful notes, as its easier to get lost in what change did what.

Keep in mind that both weights and springs affect all shifts, not just WOT. If you get the WOT shifts close to where you want them with weights, but part throttle shifts are early, you'll need lighter springs. That will move your part throttle AND WOT shift points up in RPM. So watch the trend in the behavior. If the WOT shifts are not quite what you want, but part throttle is too low, then start tuning with springs, because the lighter springs will move everything up.

Any valvebody/plate mods, torque converter efficiency, modulator setting, line pressure, governor, kickdown all affects shift points, so you've got to take them all into account when setting up a transmission. Work your way to the governor and then make changes there.

The above post makes sense, #9.

I pulled out my info and in terms of any 400 cid TB400 from a A or F body car with a 4 bbl they had 3 different shift point they could have been programmed for.

1). 4400

2). 4800

And for the RAII , III or IV motors 5200.

Here's an example: When I bought my red car, it had 2.56 gears. It was set up to hold first gear out a little longer, and then stay in second until about 50 MPH at light throttle. The car felt like it had 3.73s until about 55MPH when it would shift out into 3rd. Reviewing the governor found stock weights, but one very light spring and one very heavy spring. Modulator set to shift at light load, loose converter and very high line pressure. It's been a real challenge to tame once I changed the rear end to 3.25 gears. I've had to go to much heavier weights and closer spring spacing to keep the 1-2 shift but lower the 2-3 shift. With the loose converter, it'll still redline at WOT before it auto shifts.