727 transmission without forward or reverse

[Theslo1]

I've been working on a 69 coronet basket case 440/727/8.75. Finally got it so I can move it under it's own power, or so I thought. I tried to back it out of the shop last night and I have nothing. I put it in reverse and heard a slight change in engine noise and felt a little motion in the car. But when I let off the brakes nothing happened. I gave it a little gas still nothing. Tried drive, nothing, pulled it down in 1, nothing. Each time I felt a little motion in the car, and gave it a little gas. Everything in this car has been sitting a while but the fluid and level look ok. Im open to ideas. Thanks

 

[Greg Ducato]

First check and see if the driveshaft is spinning when you put it in gear to be sure it isn't the rear diff or an axle. If the fluid is full and it has no motion it will most likely be a pump, converter spline or input shaft failure. Since you don't know anything about the driveline I would try and overfill it by a quart before you call it quits, it may have the wrong dipstick or even a loose or missing filter. Be sure and check fluid level running, in neutral.

 

[69a100]

I don't know tranny's, sounds like a boat anchor to me. Good Luck

 

[Theslo1]

Thanks, I hadn't even though of a broken axle, or incorrect dipstick. I'll try the fluid, and I'll get my dad to operate the car while I look at the drive shaft. This car is such a mixture of other cars, the 440 and tc are from a motor home(I kept them together because of the engine balance) the trans came from a 69 RR I think, the rear and drive shaft are 67 coronet, and it has volare disks with an aluminium master cylinder.

 

[Garys1969RR]

If your low/reverse band isn't adjusted properly, it won't move back, but I think it would move forward because the over running clutch would hold. You can adjust/tighten the kickdown band from the outside of the trans. The low/reverse band has to be done after pulling the pan. Read the shop manual on how to adj the bands. Look online, or check threads on how to do it.

 

[Garys1969RR]

Also the low or high clutch could be slipping. Pull the pan and look for signs of clutch plate failure, or debris in there.. Does the fluid have a burnt smell to it?

 

[Theslo1]

Thanks for the replies, the dipstick wasn't marked very well, so I added another qt and it moves! But it feels sluggish. I was reading these posts and it reminded me that I have a book on this thing. I'm so stoked about it now, I'm going to go through all the adjustments. This was the first time driving this car, even if it was less than 1/4 mile at about 5mph. Awesome.

 

[plymouth67]

Sounds like the over running clutch...although usually they will move a little if you trump on it....especially if you put it in low...

 

[Theslo1]

Will the car still move if the over running clutch is damaged?

 

[plymouth67]

Sometimes in low gear they will try to move...

 

[dvw]

No one clutch or band will prevent vehicle movement. One component can eliminate a forward gear, multiple forward gears, or reverse and one forward gear.
A tutorial for aspiring automatic technicians.
For components applied see below.
1st gear in D, rear clutch and overrunning clutch
1st gear in manual low, rear clutch and low/reverse band
2nd gear in either D or manual 2, forward clutch and K/D band
3rd gear in D, rear clutch and forward clutch
Reverse, forward clutch and low reverse band.
Each gear needs the two selections listed above to function. as you can see adjusting a band will only effect a few gears. K/D; second only, Low/reverse; reverse only. A failed low reverse band will also prevent low from pulling the engine down on decel but 1st will function normally on accel due to the over running clutch holding the rear drum. Also the over running clutch can fail and 1st will still function in manual low. A quick check to see if the pump works is to check fluid level before starting the engine. Then start and run in neutral (not park). If the level goes down from the previous reading while running the pump is moving fluid. Questions?
Doug

 

[Garys1969RR]

Thanks Doug! I love talking about transmissions. I do know that in drive, when you start out, the trans is in 1st gear, and the over running clutch holds. Then to go into second, the kickdown band suddenly applies, and the overrunning clutch free wheels or over runs. That's why the 1-2 upshift is so instant. Also as stated above, the rear clutch is applied. And the low reverse band isn't, except when you're in manual low. Then on the 2-3 upshift, the kickdown band releases as the forward clutch applies. So the release/apply happens at the same time, or slight overlap. If it over runs or slips at this shift point, suspect the high clutch. Not sure if the high clutch is the front or rear one? I think it's the rear one.

 

[Theslo1]

This is really interesting. Automatic transmissions are the last thing that I don't understand in cars. Turns out my problem was a bad dipstick, the fluid was low, and the linkage from the carb to the trans was not adjusted properly and missing a spring. I'm going to fix the exhaust, an oil leak and a few other things then drive it again and see how it acts.

 

[dvw]

Thanks Doug! I love talking about transmissions. I do know that in drive, when you start out, the trans is in 1st gear, and the over running clutch holds. Then to go into second, the kickdown band suddenly applies, and the overrunning clutch free wheels or over runs. That's why the 1-2 upshift is so instant. Also as stated above, the rear clutch is applied. And the low reverse band isn't, except when you're in manual low. Then on the 2-3 upshift, the kickdown band releases as the forward clutch applies. So the release/apply happens at the same time, or slight overlap. If it over runs or slips at this shift point, suspect the high clutch. Not sure if the high clutch is the front or rear one? I think it's the rear one.

 

[dvw]

High/rev clutch is the one located in the forward position.
Doug