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TH350 not shifting to third

T

trmn8r

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Amarillo, TX
Getting my '78 blazer running again after it sat for about 12 years.

Everything is working pretty good with the exception of the transmission.

Basics of what I got. 383, TH350, NP205. TH350 has a B&M shift kit installed in it a long time ago, by myself.

When I parked it long ago it was shifting fine. Shifts hard between first and second... harder than I remember it shifting even after putting the B&M kit in, but maybe I just don't remember right. Checked fluid before ever trying to move it after getting the motor running again, it was low, has a leak somewhere. Think I topped it off with Chrysler tranny fluid, it was all I had setting around. (maybe that's the entire issue? doubt it.) Shifter is going into drive not second, one click above where I'm running it is neutral, so confident my shifter isn't causing it by going straight to second. Checked vacuum line running down to shift solenoid, it's hooked up (have had it come loose years ago when I used this as a daily driver and as I remember that kept it from going into second... seems like it made the first to second shift either slip or very hard, can't really remember).

Basically that's it, any ideas what my next check ought to be? what to look for?
 
If the vac line is hooked up at both the modulator and the manifold (direct vacuum, not ported) and you are getting a good 15 inches or more of vacuum at the modulator that should be all it requires. Sitting for a while, the line could have a crack in the rubber connections or the modulator diaphram could have a hole in it. Pull the line at the modulator when you check for vacuum and be sure no fluid runs out of the line or modulator nipple. If all is well in that system, move to the kickdown cable. Check to be sure the cable is not too tight or is not bound up and is adjusted so that it is only fully extended at wide open throttle. When you pull it , the cable should snap back to position. If not, the internal kickdown valve could be hung or the spring broken. Third, you can remove the round governor cover from the rear of the trans by carefully tapping around the edge with a blunt chisel or screwdriver. Remove the governor and check to be sure the valve that runs through the center of it is moving frelly when you compress the governor weights. Also check the condition of the gear for damage.
 
ok, modulator had no fluid running out, went ahead and pulled it out, seems to hold a vacuum on both sides of it, guess it's supposed to. kickdown cable is not tight, it will kick it into first at about 15 or 20 in second, floor it, it kicks down to first. Next is to pull the governor, cleaned around it (my tranny is covered in crud) cant figure out how to get it out. Thought there was a inside snap ring, you pushed in on the governor a bit, popped snap ring out then tapped around on governor to get it to pop out... but cant find an end of what I thought was an inside snap ring...soooo maybe I'm all wrong about that... off to look for instructions somewhere.
 
read somewhere there was a snap type latch similar to master cylinder cover... if thats what you mean by snap off cover ring then mine's different.

and I'll be dang if I can find ends of an internal snap ring like I thought was there.

I'll have to try tomorrow when I can have better light than I had this evening.
 
brother in law came over and logged on to his alldata account from his work has diagrams yada yada, now I'm not so sure I wasn't trying to take off the wrong cover COMPLETELY... I was on the passenger side, should have been on the driver side... I was trying to get into second gear servo or something.... frustrated, couldn't find my chiltons when I was over working on it... it'll go better tomorrow I'm sure.
 
pulled governor, looks fine to me nothing sticky etc... nylon gear engaging and looks good. put it back in, dropped valve body.. ugghh been a long time since I put the B&M shift kit in, forgot what a pain that was gonna be... messy... only have one ball I can locate on plate above valve body. thought there were 2 or 3... off to B&M's web sight to try and find out for sure.
 
couldn't find anyone open on a saturday that has valve body gaskets... guess it's gonna have to wait for monday. buttoned the bottom of the tranny up with a couple of bolts in the pan to keep the 50 MPH wind from blowing dust into the tranny till then.
 
You only need one check ball, it will go in the transmission side just above the modulator valve line-up. Hope it works out for you.
 
yea read the install instructions on B&M web sight, figured out I only was using the one ball setup for street/strip/offroad... now my question I havent answered yet is whether it uses a special gasket after the B&M shift improver kit install or if still uses the stock valve body gasket... guess tranny shop will know tomorrow, cant find a valve body gasket at any parts stores.
 
This depends on the kit model. The plate to valve body and plate to case are the same as factory but some kits used another seperate gasket for the thick steel plate at the top end of the valve body. If your kit did not use an additional gasket on this oil transfer plate then stock gaskets will be fine.
 
must be fine then... just got around to getting it all back together... shifting fine now, now sure what it was, but if shifts to third now. maybe it was simply the dried out (though I dont think leaking) vacuum line I replaced to the modulator, maybe it was taking out the governor and playing with it (didn't seem to be stuck at all it all seemed free and as it should be to me) maybe it was pulling the valve body and cleaning it, working all the valves in it manually (nothing seemed sticky there either coated with a bit of worn band material but not excessive I didn't think)

I guess all that matters is I got three speeds again, whatever it was.
 
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