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I took the tranny out and had it rebuilt. After installation and finding out that the neutral safety switch was bad I replaced the switch aligned it and it starts as it should now. But, it is not shifting. When I put it in Drive it starts in 2nd and won’t shift to 3rd. I double checked the modulator vacuum line to make sure it was connected properly, also pulled the vacuum line off of the modulator to ensure no fluid came out. The modulator was replaced by the transmission shop.

Another note is that the accelerator linkage was bent, carb linkage was cut and JBWelded back together to make it shorter and due to these problems whoever I bought the car from tied the kick down cable in a knot to make it function. I ordered all new linkage and kick down cable which arrives tonight. I did not put the old one back on. Would the lack of the kick down cable being connected prevent the tranny from shifting?
 

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No kick down cable is just for when you go to full throttle and kicks down from 3rd to 2nd for passing. I had mine for years not working because it not being connected right internally. But it doesn't prevent it shifting from 1-2-3, etc..
 

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No kick down cable is just for when you go to full throttle and kicks down from 3rd to 2nd for passing. I had mine for years not working because it not being connected right internally. But it doesn't prevent it shifting from 1-2-3, etc..
That’s what I thought. Might have to go back to the shop and have them check it out...
 

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How do you know it’s starting in 2nd and not 1st?
Does reverse work?
Try driving it with the shifter in 1st. Then manually shift to 2nd and then D.

Might be a bad governor
 

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First thought: Do you have the early C4 shifting pattern with the big and little dots or the newer PRND21 pattern?

If your transmission is set up for the dots I think putting it in the dot that you'd think was D actually designed to only start in 2nd. This thread seems relevant:

along with this from the internet:


Or it could just need adjusting. The process is in the shop manual in the transmission section.
 

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Well I used to put it in the normal Drive position under N and it would always shift normally until I had the transmission rebuilt. I took it in to the Transmission shop that rebuilt it and am letting them figure it out.
 

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Here is my limited background with automatic trans. We had hundreds of them in the fleet. We serviced them and replace parts like governors that could be accessed from the outside of the transmission, like on the Allsisons. I replaced shift solenoids like the Ford AOD trans have inside. We did not rebuild them in-house because of the time it took. We pulled them and swapped them out with factory rebuilds. In order to get my ASE Masters Certification I had to pass a test on automatic transmission operation and repair. I can read a book and pass a test but I wanted to rebuild a couple before taking the test. We had two guys in another yard that were drag racers and were both real good at rebuilding them. I went to their yard one night and we rebuilt one 727 Dodge trans together. Then I came back and rebuilt two more on my own after I bought the tool to compress the clutch discs. They both worked and ran for year's until they went off to auction. I'm not an expert but I know how they work.

If your were looking for transmission problems the first thing yo do is look in the pan. There is usually a little grey film on the bottom of the pan and tiny bit of metal on the magnet if it has magnet. Its always a good idea to stick one in there. That is normal. If the pan is full of material from the clutch disc or the bands or if there is a mountain of metal filings on the magnet. No amount of fluid and filter flushing is going to fix that trans. Its rebuild time.

If the pan is clean the friction material is probably good. Then you could have a shift linkage adjustment problem. on some transmissions a kick down linkage adjustment problem, a fluid pressure problem or a broken hard part like a planetary gear. If your linkage is adjusted properly and there not a pile of gear teeth or clutch material in the pan then you need to check fluid pressure. Most transmissions have test ports and there will be specificaitons to what pressure should by at each pot what in what gear.

In your case you need to know which clutch packs and which bands are being applied or not applied to create third gear. Your looking to see if those are applying with air pressure and holding pressure. That is what this guy is doing.


There are pistons that when the hydraulic pressure is applied to them they clamp the bands. There are seals that when hydraulic pressure is applied compresses the clutch packs. First you need to find out if the pump is creating enough to clamp down those clutch packs or bands. Most transmissions have external test ports that you can take pressure readings from.

Your shifter's position changes where the fluid pressure is routed to though a maze of passages in the throttle body. So you need to make sure the shifter linkage is adjusted so that when the transmission is in the drive detent that the shifter indicator is lined up with the drive symbol. We want to make sure we are directing that pressure where we want it to go. That way you know the correct command is being made to direct the pressure to the correct clutch packs and bands. That would be the first thing you would check.

The automatic shifting is controlled by a battle between the governor and the vacuum modulator. Think of it as a pipe with a valve with pressure on each side in that can move sideways in the pipe. Which way the valve moves depends on which end is bleeding off the pressure. The governor closes it off one end with high vacuum but as the vacuum drops off the it bleeds off the pressure. On the opposite side is the governor controlled by speed. At slow speeds it is bleeding off the pressure by creating a leak. As the tailshaft speed increases the leak is shut off causing the pressure to rise and push the piston towards the modulator end and the trans shifts into third When you hold the throttle down you are bypassing the modulator and keeping the pressure higher on that end until the governor speed finally closes off the leak and the pressure builds higher and it shifts into third. Some governors can be checked by removing them from the outside of the trans and the modulators can be checked with a vacuum pump to see if they hold vacuum. But you also need to make sure the vacuum controlling the modulator is connected to a Intake manifold vacuum port not a Ported vacuum port.

Its hard to say what is wrong with your trans. The rebuilder could have cut a seal assembling it. That should have been caught on the pressure test during reassembly. Any shifting problem would have been caught on a road test. That's why they don't like people walking in and handing them a transmission. Now they don't know if they screwed up or you did? They could have lost a ball in the valve body. No way to know with out running some tests. I understand wanting to pull the trans yourself and save some money. There are so many videos that you could rebuild one yourself buy but you need to understand how they work They are not that complicated
 

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Discussion Starter #10
Here is my limited background with automatic trans. We had hundreds of them in the fleet. We serviced them and replace parts like governors that could be accessed from the outside of the transmission, like on the Allsisons. I replaced shift solenoids like the Ford AOD trans have inside. We did not rebuild them in-house because of the time it took. We pulled them and swapped them out with factory rebuilds. In order to get my ASE Masters Certification I had to pass a test on automatic transmission operation and repair. I can read a book and pass a test but I wanted to rebuild a couple before taking the test. We had two guys in another yard that were drag racers and were both real good at rebuilding them. I went to their yard one night and we rebuilt one 727 Dodge trans together. Then I came back and rebuilt two more on my own after I bought the tool to compress the clutch discs. They both worked and ran for year's until they went off to auction. I'm not an expert but I know how they work.

If your were looking for transmission problems the first thing yo do is look in the pan. There is usually a little grey film on the bottom of the pan and tiny bit of metal on the magnet if it has magnet. Its always a good idea to stick one in there. That is normal. If the pan is full of material from the clutch disc or the bands or if there is a mountain of metal filings on the magnet. No amount of fluid and filter flushing is going to fix that trans. Its rebuild time.

If the pan is clean the friction material is probably good. Then you could have a shift linkage adjustment problem. on some transmissions a kick down linkage adjustment problem, a fluid pressure problem or a broken hard part like a planetary gear. If your linkage is adjusted properly and there not a pile of gear teeth or clutch material in the pan then you need to check fluid pressure. Most transmissions have test ports and there will be specificaitons to what pressure should by at each pot what in what gear.

In your case you need to know which clutch packs and which bands are being applied or not applied to create third gear. Your looking to see if those are applying with air pressure and holding pressure. That is what this guy is doing.


There are pistons that when the hydraulic pressure is applied to them they clamp the bands. There are seals that when hydraulic pressure is applied compresses the clutch packs. First you need to find out if the pump is creating enough to clamp down those clutch packs or bands. Most transmissions have external test ports that you can take pressure readings from.

Your shifter's position changes where the fluid pressure is routed to though a maze of passages in the throttle body. So you need to make sure the shifter linkage is adjusted so that when the transmission is in the drive detent that the shifter indicator is lined up with the drive symbol. We want to make sure we are directing that pressure where we want it to go. That way you know the correct command is being made to direct the pressure to the correct clutch packs and bands. That would be the first thing you would check.

The automatic shifting is controlled by a battle between the governor and the vacuum modulator. Think of it as a pipe with a valve with pressure on each side in that can move sideways in the pipe. Which way the valve moves depends on which end is bleeding off the pressure. The governor closes it off one end with high vacuum but as the vacuum drops off the it bleeds off the pressure. On the opposite side is the governor controlled by speed. At slow speeds it is bleeding off the pressure by creating a leak. As the tailshaft speed increases the leak is shut off causing the pressure to rise and push the piston towards the modulator end and the trans shifts into third When you hold the throttle down you are bypassing the modulator and keeping the pressure higher on that end until the governor speed finally closes off the leak and the pressure builds higher and it shifts into third. Some governors can be checked by removing them from the outside of the trans and the modulators can be checked with a vacuum pump to see if they hold vacuum. But you also need to make sure the vacuum controlling the modulator is connected to a Intake manifold vacuum port not a Ported vacuum port.

Its hard to say what is wrong with your trans. The rebuilder could have cut a seal assembling it. That should have been caught on the pressure test during reassembly. Any shifting problem would have been caught on a road test. That's why they don't like people walking in and handing them a transmission. Now they don't know if they screwed up or you did? They could have lost a ball in the valve body. No way to know with out running some tests. I understand wanting to pull the trans yourself and save some money. There are so many videos that you could rebuild one yourself buy but you need to understand how they work They are not that complicated
good information my friend. Thanks I appreciate your input.
Tim
 
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