TH 350 Torque Converter

[BigAl285]

Im just putting my truck back together after swapping the frame. Took my truck for a little test drive to say I did and it wont go into gear with out stalling. I checked all vacuum lines, module on the trans all check out good. I replaced the vacuum line going from motor to trans. I switched vacuum from intake to the carb and it made no difference. It acts like the Torque Converter is locked up. It doesn't have any wires for the torque converter its an older trans. I only have maybe 1000 miles on it. I replaced the trans and converter last summer. I still have to check the brake booster. My truck is a 75 k-25. 383 stroker 500 lift cam 11.5 to 1 pistons, edlebrock air gap intake, holley 750 carb. motor was dyno tuned so I know that's good. It was working fine before I switched frames. Any help is good. I wanna drive it.

 

[bucket]

So can you not get it to move at all? Have you tried giving it a little throttle while putting it into gear to get it rolling?

 

[crazy4offroad]

What's missing in the story? Is this a different torque converter? Different trans? Did you take the converter out and not get the lugs aligned with the pump right? Was there a problem with the trans before? Or the torque converter? Modulator valve should be on full manifold vacuum.

 

[BigAl285]

If I two foot it can get it to move but its not right. It will just die or tires will squeal a little when Im giving it gas an holding the brake to get it in gear and moving. I know the torque converter is slid all the way in and splined up properly. The trans had issues when I pulled it out to switch frames and do my motor work. The trans rebuilder guy I went through didn't tighten up the nut on inside of the trans and the shift linkage fell off. I could go forward in every gear. He put a new nut on and lock tighted it. The toque converter was never messed with. Just pulled off and covered up. When I put it back in I topped it off with oil and installed it. Just confused since it all worked before I pulled the trans to get it fixed and new frame swapped out. I am on intake vacuum too.

 

[crazy4offroad]

Might be a sticking valve in the valve body from the trans sitting for a while. I have some videos that might help, see if you can access them here...
https://drive.google.com/folderview?id=0B8AYAo0y4rOPNTIzNEI1WTNuNHc&usp=sharing

You'll want to see the one "TH350 Part 2 - Valve Body.m4v".

 

[foamypirate]

Was it behind the same engine?

 

[HotRodPC]

And this is a Non Lock Up Trans right? Sounds like a strange issue I"ve not heard of before. You mention you could go forward in all gears, THEN he put on a new bolt on the shift linkage? And now you have this problem? Makes me wonder if he didn't tweak the manual valve linkage at the rooster tail and with the manual valve linkage not right according to the detents in the rooster tail, then you might be opening up passages into more than one gear at a time and causing a trans binding problem. How about all the way down in manual low 1? How does it act there?

 

[BigAl285]

This is a non lock up trans. I was able to go forward in all gears the rebuilder said the nut on inside of the trans fell off and everything was laying in the trans pan. I wish I never had this trans rebuilt by him! He has "30" years of experience too lol. I will try it in manual low today when I go to the shop. Ive just tried it going from park to reverse, park to drive and neutral to reverse and neutral to drive.

Same motor just have had a lot of motor work done to it. Im at 475 hp now.

 

[BigAl285]

I tried it in low gear and the same thing. Truck dies. I checked to make sure I had the shift linkage going from column down to the trans and that moves freely. I took it off the trans and manually shifted it without it running you can hear it click into gear and feel when it clicks in. I tried to move it from park slowly with the shift linkage from the column connected and with out applying much pressure and it will go past reverse to neutral or drive. Shouldn't it at least stop at reverse? Or is that just how they normally are? I didn't have much time today and I just was messing and trying easy things.

 

[crazy4offroad]

First thing I would consider is the converter, unless the linkage coming loose inside could have damaged something.

 

[HotRodPC]

I tried it in low gear and the same thing. Truck dies. I checked to make sure I had the shift linkage going from column down to the trans and that moves freely. I took it off the trans and manually shifted it without it running you can hear it click into gear and feel when it clicks in. I tried to move it from park slowly with the shift linkage from the column connected and with out applying much pressure and it will go past reverse to neutral or drive. Shouldn't it at least stop at reverse? Or is that just how they normally are? I didn't have much time today and I just was messing and trying easy things.

Yes, it should make a noticable STOP in each gear position. That part that has all the detent stops in it is what I'm referring to as the nickname of Rooster Tail, hence, cuz it looks like a Rooster Tail. There is a detent flat spring with a roller that should engage into each position of the Rooster Tail. If that is missing or broke then you won't feel clicks or stops between gear changes.

Even if you are feeling the stops, if the arm on the Rooster tail is bent, or the S clip from the arm to the manual valve is bent, then your valve body is not getting full flow into its respective ports and passages. Also, it can be setting the manual valve half in one gear and half in another causing the planetaries to be trying to be 2 gears at once.

What has me puzzled though, is even at idle and if in 2 gears at once it should still idle since the converter should stall and keep and gears from engaging. What I"m wondering is if you don't have the wrong converter. You say it's a non lock up trans, but it is a non lock up converter too? I want to say NO, that is not possible. IIRC, the NON Lock up conveter will go on a Lock Up trans, but the Lock Up converter will NOT go on the NON Lock up trans cuz the input shaft is much bigger around.

I'll see if can't dig you up some pics and help you identify the different input shafts and converters. I guess it's possible too if this wing nut that built the trans didn't know WTH he's doing, he many have even put a Lock Up input shaft in a NON lock up trans. Hopefully the guy is smarter than that.

 

[HotRodPC]

Rooster Tail w/ detent locking roller.

Rooster Tail wo detent roller and spring. See the S clip that connects the manual valve to the rooster tail assembly. If the S clips is bent, or the arm off the rooster tail is bent, is throws the location of manual valve in the valve body off.

 

[HotRodPC]

The difference in input shafts,

NON Lock Up

Lock Up aka Th350C

 

[HotRodPC]

I"m still looking for some Converter pics so you can identify a NON Lock up converter from a Lock Up converter. In short, the NON Lock Up unit is round like a dounut. The lock up unit is round in the back toward the trans, but it's flat up front toward the flywheel. In this flat part, that is where the converter clutch that locks up is housed, so to make space for the clutch, it's more flatened. If your converter is flat up front against the flywheel, you have the wrong conveter.

 

[BigAl285]

I looked at the pictures and I have the correct converter for my input shaft. Input shaft is a non lock up and the converter is rounded not really flat except for where it bolts up to the flex plate. I'll check part numbers tonight. Looks like I'll be pulling the pan off and see what I can find too. This sucks