Hey guys, I have a 74 Challenger with a small block 727 Torqueflite.
It was rebuilt back in 92 and has been sitting in my garage in my house since then. In 92 she was working fine.
Now when i start it up, wait a few minutes then put it into reverse or drive it acts like its locked, she wont move. On a lift the wheels won't move. I checked to make sure i had enuf tranny fluid and it doesn't smell burnt and looks clean.
I checked/adjusted the front and reverse bands as per specs but same thing happens.
This happens every time i start the car and move her when the tranny is cold. After it seems to work fine. I can't bring her on the road as my resto is not complete.
Any ideas?

Parking brake not releasing? With the driveshaft disconnected from the rear end are the wheels still immobile?

Wheels don't move at first then they do.
Don't have the parking brake cable installed

When you say it takes a bit for the wheels to move about how long? The 727 doesn't pump fluid in park, just in neutral and in gear, so you may just be experiencing normal delay caused by converter drain back. If you let it idle in neutral it may not hesitate.

I'll repeat the question...do the wheels turn freely by hand with the motor off, trans in Neutral?

yes

Are you saying the trans doesn't work cold and does warm? If so this classic symptoms of old hard rubber seals, it needs to be rebuilt.

Sorry John misread the question.
Yes in the air in neutral, motor off, the wheels turn fine and freely by hand. One thing that i just thought of is trying to move the car on the ground in drive with the motor off.

What i am saying is you get in and turn it on, wait one minute or two to warm, then put it in gear either reverse or forward and start to give it gas. It goes no where like the brakes are on. Then after about 30-45 seconds at 2500k or 3500k RPM it slowly starts to move. It feels like it's not in gear. After that initial hiccup it's fine forward and back. It's very gradual when it does catch and it's not like a hard jam into gear and no banging or clunking into gear. It's like it's slipping but works fine after initially going in to gear
The autobody shop it is at has a dyno for when it was needed for inspection stickers in NY. They put it on the dyno and no slipping, perfect shifts or any problems after that initial hiccup.
After a little while the same thing will happen.
They thought let it run on the dyno for a while since it sat for a long time but still the same the next day.

HemiRick - Even though it was rebuilt back in 92 and worked fine then put away in a climate controlled garage in my house?

Sounds like converter drain back. Fire it up in neutral let it idle for a minute or so and then put it in gear. If it drives just fine it's the converter draining back. Very common.

Ok thx cuda so how do you fix it?

I'd say it sounds more like a seals issue, but it would have to be both clutch drums to make both forward and reverse act up. Usually if it's converter drain-back it just takes a couple seconds in neutral to fill the converter, not 30-45.

It seems that now you are starting it, letting it run for a minute, and then when you put it in D or R there is a delay to engage - correct? Try starting it, putting it in N for that 1st minute, then trying D or N. If it moves right when you put it in gear, it's converter drain-back. If it takes time to engage - it's seals.

Some shift kits address converter drain-back. If it's seals, it's rebuild time. There are snake oils that may soften the seals, but are a temporary fix at best.

That is the next thing to try, always make the initial start of the day in Neutral not Park.

Ok i tried it in neutral for 60 seconds and when i put it into reverse same thing.
Do i have to actually start the car in neutral or after i start it in park put it in neutral?

It doesn't really matter if you start in P or N - main issue is to get the trans in N reasonably soon to get the converter charge circuit flowing. But for arguments sake - start it in N.

Since it really should not take more than a few seconds to fill converter - running it 60 seconds in N should have been more than plenty. So IMO if you already tried running it in N for 60 seconds and it didn't move when you put it into R within 1-2 seconds you have already ruled out a converter fill issue.

When you adjusted the bands did you change the filter?

Ditto. My 50,000 mile RR does this exact thing. I always start the car and put into N. Rev motor to 1,500 or so for 20-30 seconds and then it's fine.

Are there specific seals that get hard and break or is it all of them?

It's usually the lip seals on the pistons in the clutch drums that cause this.

Since everything else has been covered it's most likely hardened/shrunk piston lip seals. 20+ years of sitting doesn't help the life expectancy of rubber components.

You could try some "miracle in a bottle" like Lucas or Trans-X, they will soften hardened seals.

No i did not open the pan up yet.
I am waiting for a new aluminum pan with a drian plug to come in then i will have a peek and change the oil and filter.