Transmission problems

[O_Knut]

So when I bought the car 1000 miles ago back in 2021, it was fine. Now in 2024 it has no power going over lips. If it’s a part on the external end like on those Gm th400s I would like to know what could be causing this problem. Don’t wanna replace it.

 

[O_Knut]

Vacuum or fluid line?

 

[O_Knut]

Vacuum or fluid line?

Grasping at straws here

 

[O_Knut]

I hope it’s something simple like this olds had

 

[O_Knut]

@ayilar know anything about this?

 

[CBODY67]

"No power going over 'lips'"? As in from a stopped position to drive over a speed bump or similar? Sounds when trying to do so?

Does the car drive normally, otherwise? Fluid level checked correctly when hot?

Why is this relating to a GM THM400?

Just curious,
CBODY67

 

[MONC440]

We need more info in order to help you. No power going over lips is hard to understand. You have this titled transmission problems but help us understand your symptoms better, like does the engine rev but doesn't move the car like it should or does it lack engine power? The 727 doesn't use engine vacuum.

 

[O_Knut]

Sorry at work
The reason I posted the gmt400 was because in the video it’s an external part issue. Because I’ve had so many people say it’s time to replace the transmission. So I was hoping it may be an external part like on the olds. Now what it will do is drive and shift slowly, however, from a stop it definetely is hard to tell if you shift it into gear as it does seem a little weak. Fluids were good. But yeah going into a garage from a slow speed it seems to struggle over the entrance lip, and sometimes when cold can struggle to get going into gear. It’s at the shop right now and they haven’t had much time to look at it or work on it, but they informed me of the issue and aren’t the first to. I’m asking what problems could this be on the external side so I don’t have to pay for either dismantling or purchasing a new transmission. I know my explanation sucks I’ll give more feedback as it’s available

 

[ayilar]

@O_Knut — I am out of my depth here, but just know folks who know. Happily, two of them have already started answering. Provide as much info as you can and they’ll help you.

@david hill @71Polara383 @Big_John (among others) may also have thoughts for your 1971 383-2 / 727 Newport

 

[O_Knut]

C

Sorry at work
The reason I posted the gmt400 was because in the video it’s an external part issue. Because I’ve had so many people say it’s time to replace the transmission. So I was hoping it may be an external part like on the olds. Now what it will do is drive and shift slowly, however, from a stop it definetely is hard to tell if you shift it into gear as it does seem a little weak. Fluids were good. But yeah going into a garage from a slow speed it seems to struggle over the entrance lip, and sometimes when cold can struggle to get going into gear. It’s at the shop right now and they haven’t had much time to look at it or work on it, but they informed me of the issue and aren’t the first to. I’m asking what problems could this be on the external side so I don’t have to pay for either dismantling or purchasing a new transmission. I know my explanation sucks I’ll give more feedback as it’s available

car Had power to move over flat terrain but seems to be weak when going into drive reverse and park, and seems week when attempting to go slowly over speed bumps or lips that require some oomph, seems week under stress

 

[O_Knut]

@O_Knut — I am out of my depth here, but just know folks who know. Happily, two of them have already started answering. Provide as much info as you can and they’ll help you.

@david hill @71Polara383 @Big_John (among others) may also have thoughts for your 1971 383-2 / 727 Newport

Thank you, however, it is a 360 small block which I only mention not to be a pain but because I acknowledge that the small and big block 727 were different

 

[Boydsdodge]

Was and is your kick down linkage installed and adjusted correctly? Trans fluid is up to correct level when checked in neutral and at operating temp? 727 is a 727, just a few bands and springs from a heavy duty to regular and the bell housing bolt pattern for small and big block. What colour is fluid? How many miles on the trans?

 

[O_Knut]

Was and is your kick down linkage installed and adjusted correctly? Trans fluid is up to correct level when checked in neutral and at operating temp? 727 is a 727, just a few bands and springs from a heavy duty to regular and the bell housing bolt pattern for small and big block. What colour is fluid? How many miles on the trans?

Car was restored. Been told either 40 or 60k on trannt, body is 110k

 

[O_Knut]

Car was restored. Been told either 40 or 60k on trannt, body is 110k

sorry I know my lack of info is annoying but essentially besides a rebuild what could the tranny need? Has all gears btw and goes into gear when warmer. Could it just be the nuetral start?

 

[Big_John]

So when I bought the car 1000 miles ago back in 2021, it was fine. Now in 2024 it has no power going over lips. If it’s a part on the external end like on those Gm th400s I would like to know what could be causing this problem. Don’t wanna replace it.

Vacuum or fluid line?

No vacuum lines to a 727 (or a 904 for that matter)

Thank you, however, it is a 360 small block which I only mention not to be a pain but because I acknowledge that the small and big block 727 were different

No real differences for this discussion. Basically the bell housing is the big difference.

It sounds like the trans is slipping badly. First thing is check the level. Engine on, idling in neutral. Should be at the "Add" or a touch above when cold. Is the fluid brown or smells burnt?

Next is checking the throttle linkage (also called "kick down"). First, is the linkage there? Is it adjusted correctly? If it's missing, the damage is already done.

sorry I know my lack of info is annoying but essentially besides a rebuild what could the tranny need? Has all gears btw and goes into gear when warmer. Could it just be the nuetral start?

Quite frankly, the damage is probably already done. There's a lot of internal parts that can go bad, bands and clutches for example. Once they start slipping, they don't last long. This sounds like it's been going on for a while.

 

[MONC440]

When it is "struggling" to move over bumps is the engine reving up and the car isn't moving like it should or is the engine struggling?

 

[myskin]

So when I bought the car 1000 miles ago back in 2021, it was fine. Now in 2024 it has no power going over lips. If it’s a part on the external end like on those Gm th400s I would like to know what could be causing this problem. Don’t wanna replace

Sounds bad. But! There is an exterior adjustment bolt with a locknut for the low-reverse band. It’s on the passenger side. Hopefully it’s just loosened. It requires a very specific torque (in inch-pounds if I recall) before the locknut is set.

 

[david hill]

I do agree w/ @Big_John that burned clutches are very likely the case given your aliments description. A pressure test would confirm this. To adjust the bands would be a wasted effort at this time. A though rebuild w/ new seals, bushings, front pump and torque convertor will cover all the bases to restore proper operation. Don't forget to flush out the oil cooler in the radiator, a known place for debris to hide.

 

[O_Knut]

Well the verdicts in guys, my Chrysler has a 727 toastflight, so it’s back to the drawing board. Thanks anyways, I was hopeful it would be an easy fix ‍

 

[O_Knut]

Well the verdicts in guys, my Chrysler has a 727 toastflight, so it’s back to the drawing board. Thanks anyways, I was hopeful it would be an easy fix ‍

That was supposed to be a shrug emoji