well... its not the valve body... the frustration is setting in . guess ill be pulling the tranny again
Ok, you got me puzzled on this one and I have been building these a Looong time. When you say "pull" do you mean slip? Engine revs and car does not move? If so, that is the foward clutch slipping. The forward clutch is applied in ALL forward speeds, low 2nd and 3rd. The forward clutch locks the hub in it to the mainshaft that turns the planetary gears. It rotates the sun gear/spline shaft couter clockwise turning the direct drum. The sprag/rolller on it is locked and the intermediate clutches rotate in that direction as well. When the trans shifts to 2nd, the intermediate clutch locks, holding the sprag and the direct drum is stationary. The forward clutch then moves the planetaries around the sun gear and the trans is in 2nd. Again, the forward clutch is still applied. In 3rd, the direct clutch locks the sun gear shaft, the sprag/roller is held by the intermediate clutch while the direct drum now rotates clockwise (sprag/roller free wheels) and the whole planetaries rotate at the same speed as the forward and direct drum as a unit which is 1 to 1. Once more, forward clutch not locked means slippage???????????? Now, for reference, the low band and intermediate band are only applied in L1 and L2 ranges. They are NOT used in Drive and thereby only are there for engine braking. In Reverse, the forward clutch is not on, the direct drum locks the sun gear shaft and, with the low band applied, rotates the planetaries counter clockwise thereby making reverse. No slippage there means all is fine. So, to my way of thinking, the problem is related to the forward clutch. Why there is no problem when 2nd/3rd are applied is a brain twister!!!! As I said earlier, very hard to diagnose when I can't hear and see what is going on. Is it "slippage" locking or binding? Partly in 1st and 2nd at the same time? All I can suggest at this point is to start at step one and follow the assembly manual to go through it again. Question anything that does not go back together "by the book". Make sure all the seals and gaskets are correct. I can try to get pics of the correct valve body gaskets compared to the "incorrect" ones. Just can't right now. Forward clutch center seals are slightly different than direct clutch ones and need to be installed correctly. The TH400 is a great transmission and should NOT be giving you these problems. Will try to help when I can. Good Luck!
when its in low it will go until you hit the gas and it slips really bad. once it goes into 2nd all is fine, pulls good and hard, shifts into 3rd fine and pulls fine in 3rd. when i had the trans apart all the clutches still looked new. im thinking about pulling the forward clutch and the 'one way clutch' and having a tranny shop redo the lip seals and set up the clutches. then if it dont work... ill dump it off a cliff.
Ok, you got me thinking. The forward clutch MUST be applied or you would NOT have 2nd or 3rd. So, the issue has to be 2nd. Sounds like when it is supposed to be shifted into 2nd it is not grabbing. That will appear to be slippage, but actually is 2nd not grabbing and the trans stays in low (1st). Some thing is delaying the application of the intermediate clutch. Bad seals in the center support, leakage between the support and the case or the 1-2 accumulator valve in the valve body is not installed properly. There are a couple of designs of accumulator valves. In both, the inner most spring MUST be installed or a piece of tubing can be installed to make sure the inner valve is extended. The outer spring can be left out. There are 2 piece valves and 1 piece valves. In both cases, the inner spring MUST be strong. This opens the valve and applies oil to the servo piston under the low servo to firm up the 2nd gear apply. If you left out the inner spring, it "tells' the servo to soften the shift and can delay the 2nd apply. This will cause what appear to be slippage, but is really just a late apply of 2nd. Once 2nd does apply, the trans will function normally. So, look at what you have modified in the valve body. You may have left out the wrong spring! If all else fail, use a piece of copper tubing in the valve body. You need to size it right so that it is just long enough to hold the valve open so that you can just put in the round aluminum end and install the pin. This will make sure that full pressure goes to the inner servo piston and makes a very firm 2nd shift. There are 3 types of springs that go under the low servo. Blue - soft, Black - firm and yellow - very firm. The blue will work if you modify the 1-2 accumulator valve in the valve body. Black is good and yellow is best (my opinion). All in all, it sounds like you got some mixed parts in the trans somewhere. All must in line or you can have problems. Look at what you have and I can guide you through some of this. Let me know. Will be on and off the site here over the next few days. Keep plugging! Good Luck!
The spring I left out was on the accumulator in the valve body I had to use the vice to press the piston down to remov the clip on it. I removed the spring then. But.. I just replaced the valve body with a good known one and left te spring in didn't drill anything but I did only put 3 check balls back in. But as far as that goes valve body is unmodified and I have good engine braking in low and 2nd so I assume both servos are doing what they're supposed to do. Should I mess with the modulator it's adjustable
Tried to attach a pic. The "mod" hole needs to be the size shown. Same size as other holes. The spring you removed is the direct accumulator and is correct. Seems like you need to modify the 2nd (intermediate) apply circuit.
Here is a pic of a valve body. The highlighted green spring should be removed. The #20 spring needs to be left in or replace with a firmer spring or a piece of copper tubing to make sure the valve is held open. This increases the pressure to the 2nd gear apply and firms the 2nd shift. This along with the larger "mod" hole in the previous pic makes a nice 2nd gear shift. The 2nd apply hole in the valve body plate should be at least 1/8" (.125") drilled. That is the "green" 2nd cl feed in the previous pic. You can (not always recommended) leave the check ball out there too. Though, that makes a very hard 2nd shift. Check your mods and let me know.
Different yellow spring. The one you removed from the valve body is correct as it softens the 2-3 shift. Leave that one out. The one I referred to is the one under the low band servo (under the steel cover with 6 bolts) which is the 1-2 accumulator spring. The stronger that spring, the firmer the 2nd shift becomes. There are only 3 springs for that. Blue, black and yellow.
so, what i should do is remove the green spring in the picture and drill out the highlighted passage to 1/8 and see what happens?
I put my spare tran in that wa out of a big Pontiac and once I got it in, the trans mount is offset and the wires to the kickdown solenoid has 2 pins on it one goes to the valve body accumulator and the other goes to the kickdown. Trans works fine though.
