TH350 problems

[Buster]

Hi everyone,
I have a problem with 3 shifting in and out on tranny. Fluid level is OK and leakage is right, detint cable is hooked up and adjusted properly. What happens is it shifts fine in 1 and 2 and if I hold throttle down it will shift into 3 at about 70mph, then will down shift to 2 at about 50 mph. I'm getting vaccum to modulator valve and line is secure. Question will the modulator cause this problem and how is this thing adjusted. I know there is a screw inside modulator/ and was bought for a 1972 and tranny is 1967. I have not made any adjustments on it (yet) suppose to be factory set. Any ideas or solutions to this problem?

 

[railroad]

Well, it would not hurt to start there. Make sure you are using manifold vacuum, high vacuum at idle. Make sure the rubber vacuum line is stiff wall like fuel line. It sounds like you need to loosen the modulator adjustment. Use 1/4 or 1/2 turn adjustments and see how it does. If you put the valve in, was there a rod in the end on the trans side? I am a Ford fan, but think chebbie has the rod also.

 

[Buster]

I'm not hooked into manifpld vaccum except at carb maybe not getting enough. Yes rod to modulator is in proper place made sure of this when it was installed.

 

[railroad]

You can get manifold vacuum at the carb, but again make sure you have high vacuum at idle on the port you are hooking up on.

 

[Buster]

will check vaccum at maifold with gauge and see what I have. thanks will let you know if that is it.

 

[Buster]

I have 17inhg at manifold and at modulator when engine idleing. I turmed set screw counter clockwise 1/2 turn in modulator and it made no differnce. Then talked to friend of mine who owns a tranny shop he said that the governor may not have enough weight on it because car is so light and does not take a lot to move it. And it may need more weight on governor. (?) Anyway I'll take car to him on monday and let them repair it.

 

[2old2fast]

I'm not 100% positive but I think the governor only responds to driveline speed.

dave

 

[Screaming Metal]

Was it working good, the this happened all of a sudden? Or have you just started it up and this has happened? Sounds like 'passing gear' is actuated and is stuck. If this is the case, you might have to pull the pan and free up the linkage, wither rod or cable....

 

[Screaming Metal]

I'm not 100% positive but I think the governor only responds to driveline speed.

dave

I'm with you, the trans should not care if its a turbo 350 sitting in a Nova behind a smallblock, or in a 1200 pound econo altered. Shifting will be done a certain rpms unless your missing vacuum, your mech. kickdown lever has been moved or slipped. Have you tried to readjust your kickdown, or is it the cable with the slotted end that goes over the nub on your carbs linkage?
Weight on the governor? Does he mean the flyweights? Well, I could be wrong, but, a governor governs rpm, thats what I thought. Maybe he meant the weights could be sticking------
Maybe someones been fiddlin' with my coffee....

 

[Screaming Metal]

Let me also say that in 67', there where kickdown rods that were connected to a bellcrank for some reason, on some cars with the TH-350. That bellcrank, didn't have a 1:1 ratio, which would affect your kickdown, if it were bypassed. Also make sure that your linkage inside the trans. is adjusted correctly.

 

[Screaming Metal]

Inside your trans is a shaft mechanism with a ball detent device. Theres a linkage there at activates a shifting valve. Make sure all is cool there. Then make sure your shift lever coincides with the shift arm out side the trans. If all is ok, try disconnecting your kickdown linkage, an see what you got.
You should not need it, if you need to downshift to get around a car for whatever, you are seriously underpowered, and having a kickdown linkage is the least of your worries.
If all else checks out, you could have a problem in your valvebody, governor, or possibly band problem.

 

[Screaming Metal]

I know there is a screw inside modulator/ and was bought for a 1972 and tranny is 1967.

Do you know this modulator will work with that trans? If you aren't familiar with troubleshooting these areas, go to a trans shop.

 

[Screaming Metal]

Forget What I said about the kickdown...one of the guys here in the shop is picking my brain for trans info too, but he has another problem....trying to multitask is not for me.....

 

[Buster]

Cable is not stuck,you can feel it pull back when cable is all the way pulled out, I also disconnected it compleatly from carb made no difference according to freind in trans shop, either govenor or front pump?

 

[Buster]

fixed tranny in tbucket, bought a brand new one 50m warrienty.

 

[Buster]

wow, what a differnce it made with new tranny. Bucket will giddyup now.