[65cayne]

Recent home rebuild, standard automatic valve body
In Drive - stuck in 1st. Will not shift to 2nd unless I pull down to L1 and back to L2
In L1 - drives fine
L1 to L2 - Will shift into 2nd and drive fine
L2 to D - Will not engage 3rd. Stays in 2nd
P and N fine
R drives fine

Air checks during assembly seemed fine. Clutch packs engaging.

Kick down solenoid checked prior to install (applied 12v and heard relay clicking... other possible failure mode here?). Currently not connected in the car (no wire connected).

Linkage adjustment fine

Fluid level fine. Full mark verified.

Going to check modulator, vacuum signal,, and then governor. Mind you this transmission would shift VERY early prior to rebuild and in D would hit 3rd before crossing an intersection. I have not calibrated the governor yet, just reinstalled as is.

If that yields nothing, I guess I will get a pressure gauge connected (do not have one at the moment), see what I have, and lastly pull the valve body if necessary.

Anything else I should be looking at?

 

[65cayne]

Modulator and governor check out okay. Disassembled the governor and cleaned it up. Test drive tomorrow.

 

[65cayne]

Update....

Took it up and down the street today and under light throttle in Drive (D) it is shifting into 2nd at about 4k and I think it may have hit 3rd but I was going too fast on my street. Need to get on the open road where I can go faster and put a load on it.

Anyway, this was repeatable so I am happy it is shifting. The 1-2 manual shift (L1-L2) and 1-2 auto shift (D) are crisp and very quick as I had hoped. Just need to figure out why its late.. Again, I have done nothing to change the shift points.

Here is what was done...

Modulator - was a little hard to get out. Seems to stick when fully seated but moves free otherwise. No sure if its a liquid suction or if its actually binding. Scotch brited the valve, cleaned, reinstalled. Modulator screw backed all the way out flush with vac fitting.

Governor - valve seemed sticky so I fully disassembled, scotch brighter, cleaned, assembled, and reinstalled.

Possibilities...
1 - detent is failed in an energized state (despite no 12v)
2 - modulator actually sticking or not enough vacuum (7 psi now, had 11 psi on dyno... needs more tuning)
3 - shift valves? Thinking it unlikely that the 1-2 and 2-3 valves are both stuck or would cause the symptoms I have.

 

[bop468]

This sounds like either lack of vacuum (leak) to the modulator or a the modulator itself issue. It's cheap to replace.

 

[dyno jonn]

If it's a TH350, sticking kickdown cable. If a TH400, a leak at the kickdown solenoid or a piece of trash keeping the valve from going fully closed.

 

[65cayne]

If it's a TH350, sticking kickdown cable. If a TH400, a leak at the kickdown solenoid or a piece of trash keeping the valve from going fully closed.

TH400 as noted in the title. When de-energized (no 12v connected), is the valve supposed to be open or closed? How can I determine what state it is in?

I dont really understand the solenoid operation other than its energized when you lay into the gas pedal. What does it physically do where it attaches to the case? The solenoid appears to have a diaphragm on the face that mates to the case but no passages or anything. The relay clicked and moved freely when I tested it prior to assembly.

This sounds like either lack of vacuum (leak) to the modulator or a the modulator itself issue. It's cheap to replace.

No vacuum leaks that I can find although the engine vacuum is a little low relative to what I had on the dyno (7 vs 11). Hard line from manifold to modulator with a short rubber line at each end.
Modulator is good, no leaks in diaphragm. However, as I stated above, the modulator valve (in the case) might be sticking when fully inserted into the case? I cant tell if it is sticking or if it is appearing to stick due to liquid suction when trying to pull it out (eg. like stepping into deep mud an losing your shoe when pulling your foot out... I don't know how else to explain it). It inserts easily, sticks when you remove it. I don't have another transmission to compare it to.

I should have it out on the road Monday for a little more testing after I get the front end back together.
-Kevin

 

[dyno jonn]

Kickdown on a 400 happens when the solenoid is energized and it is getting 12v. The valve in the center opens and fluid is dumped from the passage that is normally blocked, which tells the valve body it's time to shift to a lower gear. Normally the solenoid keeps the opening blocked.
Open = kickdown, closed = normal driving.

 

[Humberd]

Sounds like not enough vacuum 7# not much
Do you have the pin in the modulator ?

 

[shelteredv]

7 in. of vacuum is where I've had issues with a T400 shifting late. I got an adjustable mod valve from TCI, cured my issues. Just my .02

 

[65cayne]

...The valve in the center opens and fluid is dumped from the passage that is normally blocked, which tells the valve body it's time to shift to a lower gear. Normally the solenoid keeps the opening blocked.
Open = kickdown, closed = normal driving.

Thanks John. I will look at this unit more closely when/if I drop the pan.

Sounds like not enough vacuum 7# not much
Do you have the pin in the modulator ?

What pin are you referring to? The adjusting screw is in and back off all the way (not removed). I removed it once just seeing how far it would back out and simply screwed it back in.

7 in. of vacuum is where I've had issues with a T400 shifting late. I got an adjustable mod valve from TCI, cured my issues. Just my .02

Mine's just a generic adjustable replacement unit. However I just read today that there are "low vacuum" adjustable modulators which I will check into. Thanks for the input.

 

[65cayne]

Update...

Pressure readings at idle/1500 rpm using the port on the driver side of the case:

P 130/130
R 120/180
N 130/130
D. 125/130
L2. 180/180
L1. 180/185

I did install the new pump spring that came with the kit so all the numbers seem reasonable to me. Agree or disagree?

 

[lookback]

TCI chart on pressure and how to check. I use the Sonax line pressure valve. Books should have pressure info.

TCI Auto Transmission Line Pressure - TCI® Auto

The following charts provide the mainline pressure readings for all of the various TCI® transmission models. These readings can be obtained by attaching a 300 psi fluid pressure gauge to the appropriate pressure port on the transmission, and running the engine at 2000 rpm. These pressure...

www.tciauto.com

PRESSURE REGULATOR VALVE KIT, 400, 425 (SONNAX) | eBay

PRESSURE REG VALVE KIT, 400(SONNAX). This bore wear can be verified by testing line pressure and Wet Air Testing the pump. This hardened steel valve continuously oscillates within the cast-iron pump bore, resulting in wear.

www.ebay.com

When had the govern out did you flip up side down and can see exhaust ports? Govern Gear is not chipped or worn?
On modulator I leave out the small spring on valve, where mod goes.
Did you take the valve body apart in order and clean and assemble all of it?
The trans kits I use I never had a problem, and I am no expert, but very through, on cleaning and assembly.
I also did the pump mode to save the engine thrust bearing.

 

[65cayne]

TCI chart on pressure and how to check. I use the Sonax line pressure valve. Books should have pressure info.

TCI Auto Transmission Line Pressure - TCI® Auto

The following charts provide the mainline pressure readings for all of the various TCI® transmission models. These readings can be obtained by attaching a 300 psi fluid pressure gauge to the appropriate pressure port on the transmission, and running the engine at 2000 rpm. These pressure...

www.tciauto.com

http://[URL][URL]https://www.ebay.com/itm/PRESSURE-REGULATOR-VALVE-KIT-400-425-SONNAX/122034266992

[/URL]?[/URL]

When had the govern out did you flip up side down and can see exhaust ports? Govern Gear is not chipped or worn?
On modulator I leave out the small spring on valve, where mod goes.
Did you take the valve body apart in order and clean and assemble all of it?
The trans kits I use I never had a problem, and I am no expert, but very through, on cleaning and assembly.
I also did the pump mode to save the engine thrust bearing.

Thanks for your reply. Addressing your comments in order:

All my pressure readings are in line with the TCI chart except for L2/L1. Reading some other posts where people used Jake's Stage II kits, their L2/L1 was a little higher as well.
What governor exhaust port are you referring to?
Governor Gear is fine, no chips or wear.
My modulator did not have any springs. Just the modulator, and the valve in the case. Two parts.
Valve body was fully disassembled, one valve at a time, photographed and bagged, then everything fully cleaned and reassembled. Everything went together nice, no sticking or binding in the valves.
On the pump, I did the converter restriction feed mod, and installed the new spring from the kit. No other mods. My torque converter also has an anti-balloon plate.

I did not manage to get it out on the main road over the weekend. Hopefully in the next few days. Depending on the outcome, I may drop the pan and replace that kick down solenoid and/or the modulator (for a low vacuum version... red/black stripe?).

-Kevin

 

[lookback]

It's the piston inside govner that slides up and down.
Slits on govner are the exhaust ports.
One other thought the tubes leading out of VB to case did you use the small cone filter, some times they clog. It may well be also the kick down solenoid, mabey the gasket, some take it some dont. Modulator low vac one may help I have never used one.

 

[driveshaft-texas]

check the bolts on kickdown solenoid, and the gasket. If it has a rubber face on solenoid , no gasket (thin metal plate style) is needed. You may have a leak there
And I think the screw is out too far in the modulater. Center it and adjust as needed.... or just buy a new one and try it as it comes

 

[65cayne]

UPDATE
Just want to close this one out. The problem is gone.

My transmission is working fine in all positions (PRND21). Something definitely felt squirrelly when I initially got the car rolling on four wheels again. Whatever it was, actual or imagined, it's gone. I am pretty certain I was not imagining things though.
That said, the converter drastically changed the "feel" of the transmission such that when you are in (D) drive at light throttle well below the stall rating (in that "mushy" area), it really masks the 1-2 and 2-3 shifts. In fact you can barely feel them. Get into the RPM's a little and they are more pronounced. I've driven in D and "manually" shifting L1-L2-D and it works great all around. I think I just needed to get the car off my street and onto the open road where I can go more than 25 mph.

Maybe not a conclusive ending, but it's a happy one.