Hi all, So 2 years ago I blew up the 350 engine in my 34 truck. I finally got it up and going with a engine rebuild, but now the th350 will not shift into 2nd gear. It only has about 2500 miles on it since I rebuilt it about 8 years ago and installed a shift kit. It use to shift well 2 years ago. So, first it would not shift out of 1st gear. I found a big hole in the vacuum line by the modulator and fixed that. There was also no oil or anything in the modulator so I figured it was good. I also pulled the govenor and it is in good shape. I cleaned it with brake clean and an air gun while I had it out. Now I can get it to shift from 1st to 3rd by manually shifting it if I'm going above about 25 mph. It will not manually shift into 2nd at all. The oil looks good and there are no funny smells. The only thing I changed was going from a Holley to Edelbrock carb. The kick down cable is set to be tight at WOT. Does anyone have any ideas on where I should look next?
It was replaced about 2,500 miles ago during the rebuild. I think it has good pressure, when I manually shift from 1st to 3rd at 25-30 mph it chirps the tires even if I ease off the gas. So if I move the shifter from 1st to 2nd, it stays in 1st even at speed. If I move the shifter from 2nd to 3rd at speed, it will shift from 1st gear directly to 3rd.
Could be a stuck valve in the valve body, or broken sprag or roller clutch, or the 2nd gear clutch pack. That is if your sure the modulator and detent cable are correct. Sent from my SM-G900V using The H.A.M.B. mobile app
I'll take Stuck Valve for $100, Alex. Anything else,..you'd get a "neutral " or flare up on the shift. 1-2 shift valve is where I'd look first. Not sure of the flow on the 2-3 . I don't have my books with me right now. Pull the pan. No metal or black stuff? ..Pull the valve body.
I guess I'll have to pull the pan and take a look. If it is a stuck valve, how would I go about freeing it? Soaking it in ATF didn't work lol. Pull it out and hit it with fine sandpaper maybe?
Yes. You have to pull the v/b and start at the 1-2 shift valve. Pull the spring and then see if you can move the valve easily with a seal pick. Take it all the way out then. Shoot some carb cleaner in there. Then spin the valve in a battery drill. Run some 400 wet on it..then maybe 600 to shine it up and break any sharp edges. Might as well do them all, one at a time. There is some teflon valve spray available from transmission suppliers..Wouldn't hurt. Don't take the separator plate off unless you have the trans upside down. You don't know what check balls the builder put in there, plus you'll probably need new gaskets that you'll have to match perfectly.
I was told a seal pick or anything steel could damage the valve surfaces while easing them out, I use a piece of 1/8'' bronze welding wire sharpened / shaped to a pick..
2nd pulling the valve body something is stuck would be my guess. I’ve done it with winter beaters that have funny shifting transmissions but I don’t really recommend it with something you care about. But just idle down the street at 1-2 mph then stuck it in park!!! I’ve ...... ahem..... “ fixed” a few transmission issues doing this. Lol Again on stuff I only needed to run a few months or so !
Hmm, maybe I'll try dropping from 3rd to 2nd and see if that pops something loose. I don't think I'm brave enough to try park. I have a filter kit on order so I'll drop the pan if that does not work.
If it hasn't fixed itself by now, stuffing it in park while moving is just stupid! Can brake parking pawl or the case . Drop the valve body and fix the problem you have, don't cause more, sheesh.... Sent from my SM-G900V using The H.A.M.B. mobile app
Only is they're good and stuck. Gotta get it out some way. Then smooth then off. Should just about fall back in. I'd worry more about the aluminum casting.
I pulled the govenor, everything looked good, valve and weights moved under gravity. The plastic gear was solid and the springs had smooth resistance on the inside plates. Unless I missed something? I was going to try to pull the valve behind the vacuum modulator and check it out before i drop the pan sometime this week.
Well, I dropped the pan. Topped off an 8 quart drain pan. I noticed the transmission filter had a bit of stuff in it. Nothing to alarming in my opinion. I did notice that the seal between the filter and valve body looked like it slipped during installation and had a wrinkle in it. The atf fluid looked like new. There was no debris on the magnetic drain plug. All of the valves in the body move freely. Maybe replace the governor and see if that fixes it? I tested the vacuum modulator for proper movement and it looks good. The valve behind it also is moving freely. Any ideas on what to look for before I have to pull the transmission? I'm not an expert so it could be something simple.
8 quarts? Does it have a deep pan? What about the seal on the filter,,,,it should be perfectly flat to seal,,,,not wrinkled. Could that cause it to lose pressure maybe? Tommy
That seal must have been working, you had oil pressure to work everything else. Did you take the valve body out? How about the separator plate and check the check balls? They can be held in place with vasoline to put it back together. Sent from my SM-G900V using The H.A.M.B. mobile app
Well I polished all the valves in the body with 600 grit just because I had it apart and decided to put everything back together and see if that fixed the issue. While putting the separator plate back together I noticed that something did not look right. The upper and lower gaskets were reversed... so it turns out I should not rebuild transmissions. I put everything back together and it works great. I don't know how it worked for many years with it installed like this but I always thought the shifts were too firm, which I attributed to the shift kit. Now it shifts much earlier and softer. Thanks everyone for all the ideas and help! It was definitely a learning experience.
Glad to hear that you got it resolved! Now drive the hell out of it! Sent from my SM-G892A using The H.A.M.B. mobile app
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