Th400 not going into third

[Big70]

So I had a thread on here talking about not being able to shift into third with my th400. Some one said it could be my modulator. One thing I do know is I only have a vacuum hose connected all the way up to my intake mana fold. no hard line. My question is can I just make a hard line out of brake line and vacuum line at both ends? Also some one asked if I over filled it and I think it might be a half quart to a hole quart over. This tranny sat for almost ten years but ran fine when we pulled every thing. please help. Thanks in advance!

[LockDoc]

Originally Posted by Big70

So I had a thread on here talking about not being able to shift into third with my th400. Some one said it could be my modulator. One thing I do know is I only have a vacuum hose connected all the way up to my intake mana fold. no hard line. My question is can I just make a hard line out of brake line and vacuum line at both ends? Also some one asked if I over filled it and I think it might be a half quart to a hole quart over. This tranny sat for almost ten years but ran fine when we pulled every thing. please help. Thanks in advance!

You can use any kind of hard line. Steel brake line, copper, copper/nickel, or stainless.

Shifting problem could also be that the linkage has moved and is out of adjustment. Block the wheels, loosen the clamp bolt on the shift rod under the hood, manually put the transmission in park, have someone hold the shift lever in the park position and re-tighten the clamp bolt. See if that changes anything.

LockDoc

[MAC71Cheyenne]

What Leon stated.
Replaced my modulator, took 12 bucks and about 15 minutes. Adjusted the rod properly and spot on.
A adjustable modulator can help with shift points. Having the rod set proper is the big thing.
PO had it all out of wack and set to shift at way too high rpm and at 3 g's.

[Big70]

Originally Posted by MAC71Cheyenne

What Leon stated.
Replaced my modulator, took 12 bucks and about 15 minutes. Adjusted the rod properly and spot on.
A adjustable modulator can help with shift points. Having the rod set proper is the big thing.
PO had it all out of wack and set to shift at way too high rpm and at 3 g's.

Well I tried to put it in neutral and back in drive and it still did not shift and I thought the modulator just changed the shift points... I hat it just above 4g's and it still would not shift... I don't get it... I'm going to drain a half quart out and see if it will shift then

[MAC71Cheyenne]

If the modulator is wonky it sometimes won't shift up to 3rd until its really way past reasonable or not at all.
I may have missed it but have you dropped the pan and changed the fluid n filter?. By no means a tranny expert but a valve in the body could also be gummed up and syuck

[Big70]

Originally Posted by MAC71Cheyenne

If the modulator is wonky it sometimes won't shift up to 3rd until its really way past reasonable or not at all.
I may have missed it but have you dropped the pan and changed the fluid n filter?. By no means a tranny expert but a valve in the body could also be gummed up and syuck

It has fresh fluid in it. I know it's a little overfilled. Now that you guys have been talking about the modulator thinking back it does shift a little late in to second. Also I have a soft vacuum line from the modulator all the way up to the carburetor. I have some quarter inch copper line on its way to bend up a new modulator line.

[LockDoc]

Originally Posted by Big70

It has fresh fluid in it. I know it's a little overfilled. Now that you guys have been talking about the modulator thinking back it does shift a little late in to second. Also I have a soft vacuum line from the modulator all the way up to the carburetor. I have some quarter inch copper line on its way to bend up a new modulator line.

That will be a good start. Hope that cures it. I had a leak in the vacuum line on my TH350 and when it was cold and you put it in reverse it would kill the engine. once it got warmed up it worked fine. Sometimes you run into some strange stuff with them.

LockDoc

[Big70]

Where do you guys plug your modulator vacuum line on the other end? in the carburetor or the intake?

[dmjlambert]

On the intake, on a vacuum tree, behind the carburetor. In 1969 there were only 3 ports on the Quadrajet carburetor and they were occupied by the heat stove valve, the distributor, and the choke pull off. The TH400 and air conditioner vacuum ball get their vacuum from the intake vacuum tree. That's my 2¢.