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Tranny shifting screwy

J

JOEDEZZY

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TUCSON, AZ
Ok heres the problem, I have a 350t, When I accelarate quickly the tranny shifts great all the way through the gears, but if I accelerate to 25 mph and try to hold it there, the tranny feels like its shifting back and forth between 2nd and 3rd. It does this until I get around 28 or 29 mph and stops, I havent had any other problems. I did a search and found this http://coloradok5.com/forums/showthread.php?t=170322&highlight=tranny+slipping but i dont think it really applys to me because its a 700 and I'm running a 350. So far i have changed my fluid, filter, and vacum modulator. I'm dont know much about trannys so I'm lost here. Any ideas guys?
 
From the sounds of it Either your cable needs to be adjusted or the governer is malfunctining... ID try the cable first and see what its doing..one way i have tested them when having shifting problems is to completely unhook it, if its still doing the same thing you can just about rule that out and go to the governer... Try that first and let me know what happened.. Nate
 
BTW, is this a Lockup 350 or a nonlockup, If you dont know how to tell a 350Lockup it should have a wire going to the side of the case with a connector.. If thats the case and its going into and out of lockup check your brake switch (theres two on a factory lockup truck, one for brakes and the other is for the cruise and lockup..).. Nate
 
Its a non-lockup type. By the cable your mean the kickdown cable on the carb or is there some other cable I dont know about?
 
He's talking about the kickdown cable but you do not need to have that hooked up on a TH350 trans, that is only for passing gear and not like a 700R4 where it is a must or you kill a tranny.

The first thing i would do is double check fluid level. Sounds exactly like what happens when you're low on fluid. Do you have the correct dipstick in it? If you have a deep pan but used the sotck dipstick over again the fluid level will be low and possibly be your troubles.
 
4X4HIGH said:
Do you have the correct dipstick in it? If you have a deep pan but used the sotck dipstick over again the fluid level will be low and possibly be your troubles.
Click to expand...

Actually 4x4, You do not need to change the dipstick when you go to a deep pan, The hughes pan i have on my 700 is a full 4 quarts more than stock and I did not half to go to a deeper dipstick, but had to put a spacer underneeth the filter so it would lower it into the pan more... Nate
 
Well, that does make sense but i know there are different dipsticks out there so tell me why?
 
I have the stock pan and I just went and bought a new dipstick and dipstick tube(?) so I know thats right, the fluid levels are right.

Ok so, I dont need to worry about the kickdown cable so is it the governor or does that not apply here either? How do I adjust the governor? I've been looking around and I've seen that there are various kits to adjust the shift points but I havent seen anything about adjustment while its on the vehicle.
 
4X4, depending on your year, make and model the dipsticks will be shorter or longer.. A RV i worked on today with a 400 in it had a really long dipstick so it could reach the front of the cab, where as my 69 Nova with a 400 had a dipstick that was about 2 feet long... it all depends on where the factory wanted to route it.. When you put a deep pan on a transmission it does not affect where the fluid level needs to be, it still needs to be up in the full crossmarks like the instructions tell you to do.. The reason behind the deep pan is to get more fluid (which is why its deeper) in the tranny to help it stay cooler for a longer period of time, the finned ones are even supposed to help with the cooling.. If your fluid level is here

----------------- (fluid level at full)
-----------------your filter needs to be here- (top of filter)



-----------------Bottom of pan here


You see, i can change how deep the pan is without affecting the dipstick at all, just like on a engine, you put a moroso 8 quart offroading pan on ur Small block, you dont hafta change the dipstick.... Do you get it now?? Not trying to be a a-hole, just trying to explain it, hehe... nate
 
Joe- On the side of your Th350 is a cover plate, pop it off (pull the Spring retainer off and gently tap on the cover on the back side of it with a screwdriver and hammer evenly to pop it off.. Inside you should see a Square looking metal thing with two springs, weights, a valve and a plastic gear on it after you get it out... Pull it out and hold it by the gear in the air.. Look for a few things, does the valve inside of the shaft move up and down when you press the two weights in??? Is the Gear missing any teeth, wearing incorrectly or damaged at all??.. The next part is pretty complicating on the adjustment of the valve inside of the shaft, if its not adjusted properly it will act weird when it shifts if it shifts at all.. Answer a few of those questions if you can and keep things clean (take some brake cleaner and clean the governer as best you can, and the housing it rides in..).. If you get bound up do not be affraid to give me a call at 480-209-2949.. im a tranmission specialist and can help you through it.. :wink1: Nate
 
I completely understand what you're saying but there are different dipsticks that are longer to the inside of the tranny pan not just the outside portion making them sit in different places under the hood. I know the vans use a long stick and tube so that it comes all the way out to the hood but this isn't what i'm talking about.
 
OHHHH ok, i see what your asking, there was two differnent types of dipstcks for 350's some had a rubber O-ring that went over the tube and sealed it, and one had a rubber boot that went over it.. the one with theboot is just a tad longer to accomidate the length of the boot and thats where people mess up.. you can do either or, but you cant use the boot with the o-ring type tube.. Nate
 
Unfortunately that isn't what i'm talking about either, i know the difference between those 2 as well. Guess we may never know, oh well. In any case my suspicions are that the longer tube and stick were used with the deeper pans so that you could actually tell when the fluid level was low not just that it's full.
If you have a deep pan but use the factory tube and stick then once the fluid becomes low to a certain point you can no longer tell how low it really is so this is probably were the longer tubes and sticks i've seen are used. There were 2 different depth of tranny pans from the factory as well.
 
HEHE,, I get ya now, ive never personally seen one but im sure there out there... Even being a certified tech i still learn new things every day.. nate
 
You said you changed your vacuum modulator. Have you tried adjusting it? Did it do the exact same thing before and after you changed the modulator?
 
joe, also make sure your vacuum going to the modulator is MANIFOLD and not venturi vacuum.. If its venturi it will cause problems like your describing sometimes.. Dont know why i didnt think of this earlier.. Nate:D
 
ak bandit said:
You said you changed your vacuum modulator. Have you tried adjusting it? Did it do the exact same thing before and after you changed the modulator?
Click to expand...

It did the same thing before I changed it, thats why I changed in the first place actually, it shifts a little more agressivly now but its not bad.

NateInChandler said:
joe, also make sure your vacuum going to the modulator is MANIFOLD and not venturi vacuum.. If its venturi it will cause problems like your describing sometimes.. Dont know why i didnt think of this earlier.. Nate:D
Click to expand...

Whats venturi vacuum? I have it hooked into the side of my carb next to the choke, should I put a nipple in the manifold between the carb and the distributor? I have a plug there right now.
 
You have it in the wrong spot, venturi vacuum is the vacuum that works off of your throttle opening and closing, you need FULL vacuum to the modulator which is manifold vacuum.. thats most likely your problem.. Nate
 
Ok I'll put it back on the manifold, I had it there before. This problem is actually why I moved it to the carb, I was thinking that maybe it should be on the carb instead of the manifold, maybe thats why I'm having the problem, but when I changed it and it was still shifting funny I thought that it didnt really matter.
 
Ok I havent had the chance to pull the governor apart and check it out, but I've had a leak on the tranny for a while now, I thought it was from the dipstick so I didnt pay it much attention but I replaced the dip stick and found that the leak was actually coming from the kickdown cable, I have no idea on how this actually works (gonna do some research here in a second) but could the kickdown cable actually be causing the problems??
 
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