67 Charger, 727 trans question

[Potshot]

This is a car I've been reviving in my free time. I've been making steady progress but recently got stuck. Literally. After changing the radiator, the transmission cooling lines bled out a good bit of fluid, so replaced the resulting low transmission fluid with Dextron IV to the correct level with with the car at operating temp and in neutral.

I attempted to drive the car out of the driveway, but this is where I'm having problems. I can shift into both drive and reverse and feel the car engage in both directions, but when giving it the gas it acts like I've got my foot on the brakes.

With the car off the ground, the front wheels roll easy. In neutral, the rear wheels roll a little heavy, but both roll in the same direction. With a sure grip I look at this as expected behavior.

Again the wheels roll freely when up in the air, but on the ground the car refuses to budge when in gear and under power.

Any idea where I should start looking?

 

[Big Bad Dad]

Band adjustment?

 

[Fran Blacker]

Did hook the lines up to the radiator?

 

[Potshot]

I know nothing about automatic transmissions, but I did start it up while it was off the ground and in neutral the wheels want to spin forward. I can stop them with some effort, but that may be normal. Or not.

 

[Potshot]

Did hook the lines up to the radiator?

Yep, threaded in nicely with no leaks.

 

[Potshot]

Also, I can roll the car when it's on the ground.

 

[Big Bad Dad]

I ask again about the band adjustment.. Did the car move BEFORE you replaced the radiator?? Have you changed the trans fluid? What did the old fluid and filter look like, if you did? And, one of the band adjustments needs to be made with the pan off.

 

[Potshot]

I ask again about the band adjustment.. Did the car move BEFORE you replaced the radiator?? Have you changed the trans fluid? What did the old fluid and filter look like, if you did? And, one of the band adjustments needs to be made with the pan off.

Sorry, no. Nothing other than a fluid level top off has been done by me. This is the first attempt to move the car under its own power since 1994. I did look at the fluid when I first inspected what I was getting, and it looked clean and a healthy reddish. All of my other efforts have been to refresh/rebuild the fuel, cooling and brake systems. This is my intro to crossing my fingers and slipping the car into gear.

 

[qkcuda]

Convertor drain back? Did you run it in neutral for a minute before trying to back it up?

 

[Potshot]

Convertor drain back? Did you run it in neutral for a minute before trying to back it up?

I don't know how that figures in, how does that work?
The level is good and things had to come up to temp before I added fluid... I can try again tomorrow and will start by letting it warm up, and re-checking the level. How long should I wait?

 

[qkcuda]

If you start the car in park and then try and put it in gear, it feels like it doesn't want to move. Slip it into neutral for 30 seconds and then put it in gear. If it is convertor drain back it will now move normally

 

[Dave6T4]

After sitting for even 2-3 days, the fluid in the torque converter will drain back into the transmission. You need to start your car in neutral, and let it run for a minute or so to refill the torque converter. It will not refill as fast in park. Back when these cars were new and used daily, this never became a problem.

 

[Potshot]

If you start the car in park and then try and put it in gear, it feels like it doesn't want to move. Slip it into neutral for 30 seconds and then put it in gear. If it is convertor drain back it will now move normally

Interesting, I'll give that a shot and update this tomorrow.

 

[Big Bad Dad]

Interesting, I'll give that a shot and up this tomorrow.

He said he has started the car and let it run in neutral until up to operating temp. I'm still thinking the bands are out of adjustment or stuck. It's been sitting since 1994..... Why was it parked in the first place? Was there a transmission issue then? Or is this unknown??

 

[Dave6T4]

Could also be a plugged filter. Dropping the pan could reveal this. Look for $hit in the pan.

 

[Potshot]

He said he has started the car and let it run in neutral until up to operating temp. I'm still thinking the bands are out of adjustment or stuck. It's been sitting since 1994..... Why was it parked in the first place? Was there a transmission issue then? Or is this unknown??

I don't think so. He mentioned that it had a shift kit and that it shifted a little hard for the street and I might want to do something about that, but unfortunately he passed late last year and that's all I have. He had put it away because of recurring axle leak and then life got in the way. I've fixed the leak.

 

[Lefty71]

One of my early Torqueflites has that feel like an internal brake is on when the car is in gear at low idle.... but the car moves normally when you rev it up.
I would check the fluid level carefully in neutral as directed by the manual. Make the thing is thoroughly warmed up and try moving the car again, since it has sat for so long. There's a possibility that seals could be bad from sitting so long....but don't worry about that yet.

 

[dvw]

Bands have absolutely nothing to do with this issue. It does actually go into gear and the fluid level with the engine running in neutral is good, correct? When changing the trans lines did you disconnect the linkage? if so is it correctly installed and adjusted? Are the trans lines interfering with the linkage? No reason for any internal trans issue if it was fine prior to the line swap. If it's actually in gear and you rev the engine it should feel like its doing a brake torque. Now if it doesn't really go into gear, that's a different story. Check the fluid level after setting. Then start it a check. It should be over full with the engine off. Then drop to the correct level running in Neutral. If this doesn't happen it most likely has broken the inner pump gear tangs. Let me know what the answers are to these questions.
Doug

 

[Potshot]

Bands have absolutely nothing to do with this issue. It does actually go into gear and the fluid level with the engine running in neutral is good, correct? When changing the trans lines did you disconnect the linkage? if so is it correctly installed and adjusted? Are the trans lines interfering with the linkage? No reason for any internal trans issue if it was fine prior to the line swap. If it's actually in gear and you rev the engine it should feel like its doing a brake torque. Now if it doesn't really go into gear, that's a different story. Check the fluid level after setting. Then start it a check. It should be over full with the engine off. Then drop to the correct level running in Neutral. If this doesn't happen it most likely has broken the inner pump gear tangs. Let me know what the answers are to these questions.
Doug

Neutral seems good if tires moving forward while the car is in the air is ok (see my previous post.) I didn't change the trans lines, I just disconnected and reconnected during a radiator swap and the linkage was never touched. Interesting point on the overfull at rest, then good level while up to temp in neutral. I'll check that before trying again after work.

 

[Potshot]

Check fluid, it should be high. It is.
Put the car in park. Done.
Start the car and let it come to temp Done.
Check fluid, it should be lower. It is.
Try moving forward. Nope.
No go? Slip into neutral for 30 secs. Done.
Try again. Nope.
Repeat.
Try again in reverse. Nope.
I get the same results.

Here's some video, ignore the phone chattering on the wheel.


One other detail that I may not have been clear on is that with the car off the ground and in drive (or reverse) the wheels spin like they mean it.

it's a mystery.