904 bang into 2nd only

[LittleSlantSwinger]

Good day or night everyone, so my 72' dart swinger slant six is my daily and first car had it for around 3 years now. About a year ago the transmission started to bang into second gear no other gear does it. and is sometimes followed by a scrape sound right after. i have kinda neglected finding the sounds origin cause i simply cant find any info online and it still drives too this day but im getting more worried about it as time goes on. I have adjusted bands, checked fluid and filter had to pull the valve body at one point for the shift shaft seal that was leaky. Checked linkage to carb its a little worn out But i dont think thats the issue. The thing is it seems to be related to throttle maybe??? Because if youre real light on the gas going into 2nd its a lot more tame but im pretty bad at the whole transmission thing still learning. I have dropped the pan a few times and there is always a little band material in the pan never any chunks and it does leak a little from center of the slip yoke as well. but if anyone has info and things i could check it would be greatly appreciated. And sorry if i rambled on a bit just trying to cover most info of my problem that i can.

 

[Desoto291hemi]

It sounds mechanical
But if you had the pan and valve body off you would have seen evidence of something failing

Are you certain you don’t just have a bad u joint ?

Tommy

 

[LittleSlantSwinger]

It sounds mechanical
But if you had the pan and valve body off you would have seen evidence of something failing

Are you certain you don’t just have a bad u joint ?

Tommy

U joints fine has hardly any movement if any at all. I know its gotta be something mechanical im just surprised it hasn't killed itself yet lol.

 

[Desoto291hemi]

Was there anything in the pan when you pulled the valve body off?

 

[Desoto291hemi]

I have seen the Sunshells have a lot of wear around the perimeter
If there is enough clearance that might bang when it applies 2nd gear ?

Tommy

 

[Desoto291hemi]

Here are a few pics of wear on the sun shell I was speaking of .
I have several shells like this .

Two of the pics show a bad wear pattern,,,probably an 1/8 ,,maybe 3/16 or more deep .
The good pic is what the other side of the register looks like on the no load side .
That wear will add a lot of slop into the system.
It might be what you are hearing,,I’m not sure ?

Tommy

 

[LittleSlantSwinger]

I have seen the Sunshells have a lot of wear around the perimeter
If there is enough clearance that might bang when it applies 2nd gear ?

Tommy

Here are a few pics of wear on the sun shell I was speaking of .
I have several shells like this .

Two of the pics show a bad wear pattern,,,probably an 1/8 ,,maybe 3/16 or more deep .
The good pic is what the other side of the register looks like on the no load side .
That wear will add a lot of slop into the system.
It might be what you are hearing,,I’m not sure ?

interesting, but what exactly is a sunshell on a transmission? Sorry if its a pretty common knowledge thing, I've just never heard that term. Either way though ill probably drop the valve body again soon, cause its been a fairly long time since I've dropped it. Also to answer your question of there being anything in the pan. There was just some super fine metal band material i think??? And one other time i dropped it to change a leaky gasket same band material and maybe 2-3 slightly bigger chunks of metal. Damage might be in the valve body i just have to look again soon when i get a chance.

 

[Desoto291hemi]

The sun shell is a large shell,,,that the planetary,,,and the sun gear fit inside of .
The sun gear is splined to the sun shell .
Also ,,,,the front clutch is located inside and drives the planetary .
The planetary rides around in a circle inside and drives the output shaft when engaged .
Just like back in school with the explanation of the solar system .
All the planets,,,,(planetary ),,,,revolve around the sun,,( sun gear ) .
The sun shell simply keep them all housed in place .
And the direct drum drives off of the lugs ,,the pics showed .
That’s why there can be ,,sometimes,, a lot of wear on them ,,especially in a 904 .

This is an over simplification of the workings,,,,but a basic explanation of how it works .

Tommy

 

[LittleSlantSwinger]

The sun shell is a large shell,,,that the planetary,,,and the sun gear fit inside of .
The sun gear is splined to the sun shell .
Also ,,,,the front clutch is located inside and drives the planetary .
The planetary rides around in a circle inside and drives the output shaft when engaged .
Just like back in school with the explanation of the solar system .
All the planets,,,,(planetary ),,,,revolve around the sun,,( sun gear ) .
The sun shell simply keep them all housed in place .
And the direct drum drives off of the lugs ,,the pics showed .
That’s why there can be ,,sometimes,, a lot of wear on them ,,especially in a 904 .

This is an over simplification of the workings,,,,but a basic explanation of how it works .

Tommy

I like your explanation of it! Thanks tommy, you've given me another thing to check when i open it up either this weekend or the next when im free. When i do ill take some photos and post them here if i find something. But still, any other info from you or anyone else is greatly appreciated.

 

[RedFish]

I didn't read all the comments but I did agree with one. Have you looked at mounts? Trans mount and left motor mount. Good luck.

 

[Desoto291hemi]

I like your explanation of it! Thanks tommy, you've given me another thing to check when i open it up either this weekend or the next when im free. When i do ill take some photos and post them here if i find something. But still, any other info from you or anyone else is greatly appreciated.

Thank you,,,I’m really just a novice at this .
There are some very good transmission guys around that could explain it much better than myself .
I just tried to break it down so it seemed more manageable to understand .
Thank you for the kind words .

Tommy

 

[Bewy]

How many threads on the kick down [ 2nd gear ] band are visible above the locking nut? This adjustment was made external because it wears the most. If only a few threads visible, band has worn & maybe down to the metal [ klang, klang]..

 

[71Demon540]

Being an automatic shift valve body, I would suspect the kickdown linkage needs adjusted. At least that is where I would start. Put car on jack stands, have someone sit in car with the vehicle OFF. Another person crawl under the car and look at the throttle valve linkage on the valve body. Have the person in the car slowly open the throttle until it is fully open. With the throttle fully open, the TV should be all the way to the rear of the car. If the TV is fully open before wide open throttle, the kickdown linkage needs adjusted. The TV controls governor pressure. So if at mid throttle, if the TV is too far to the rear of the car, it will increase the pressure the transmission is seeing. This can cause harsh shifts at low RPM. Automatic shift valve bodies are very sensitive to proper kickdown linkage adjustment as well as ensuring the throttle valve in the valve body is not opening too fast, even if the kickdown linkage is adjusted properly. That is another story, but for now I’d triple check the kickdown adjustment and start there.

As far as kickdown band adjustment goes, knowing the kickdown lever ratio is critical to proper band adjustment. Also, is the clunk coming when you manually shift the valve body from 1st to 2nd, or when you have it in drive and it is automatically shifting? That can lead to another story. If you are going from manual low to 2nd, the low/reverse band is applied in manual low. When you shift manually into second gear, the low/reverse band releases and the kickdown band is applied. Improper band adjustment will cause more band overlap. Also resulting in a “clunk”. This is because the low/reverse drum is held stationary in 1st gear via the overrunning clutch (sprag) and if in manual low, the low reverse band is also applied. When car is shifted into second manually, the low reverse drum begins to spin clockwise letting the sprag freewheel (overrun, hence the term overrunning clutch). So if the low/reverse band is not released enough before the kickdown band is applied, the overlap will cause a clunk.

Sorry this is long winded but I hope it helps in some way.

 

[LittleSlantSwinger]

Being an automatic shift valve body, I would suspect the kickdown linkage needs adjusted. At least that is where I would start. Put car on jack stands, have someone sit in car with the vehicle OFF. Another person crawl under the car and look at the throttle valve linkage on the valve body. Have the person in the car slowly open the throttle until it is fully open. With the throttle fully open, the TV should be all the way to the rear of the car. If the TV is fully open before wide open throttle, the kickdown linkage needs adjusted. The TV controls governor pressure. So if at mid throttle, if the TV is too far to the rear of the car, it will increase the pressure the transmission is seeing. This can cause harsh shifts at low RPM. Automatic shift valve bodies are very sensitive to proper kickdown linkage adjustment as well as ensuring the throttle valve in the valve body is not opening too fast, even if the kickdown linkage is adjusted properly. That is another story, but for now I’d triple check the kickdown adjustment and start there.

As far as kickdown band adjustment goes, knowing the kickdown lever ratio is critical to proper band adjustment. Also, is the clunk coming when you manually shift the valve body from 1st to 2nd, or when you have it in drive and it is automatically shifting? That can lead to another story. If you are going from manual low to 2nd, the low/reverse band is applied in manual low. When you shift manually into second gear, the low/reverse band releases and the kickdown band is applied. Improper band adjustment will cause more band overlap. Also resulting in a “clunk”. This is because the low/reverse drum is held stationary in 1st gear via the overrunning clutch (sprag) and if in manual low, the low reverse band is also applied. When car is shifted into second manually, the low reverse drum begins to spin clockwise letting the sprag freewheel (overrun, hence the term overrunning clutch). So if the low/reverse band is not released enough before the kickdown band is applied, the overlap will cause a clunk.

Sorry this is long winded but I hope it helps in some way.

That's another thing i guess i could check the TV. I have checked or at least tried too by myself. But maybe that wasnt good enough. And checking 1st to 2nd manually ill do cause i swear ive tried that but might as well do it again. Like i said cars been like this awhile but ive kinda been at a loss and busy so ive kinda said use it till it blows. Not that i want that too happen. But im picking back up on it. Also your post isnt long winded i love when people take time too write long possible causes