Technical Gm th350 transmission trouble.

Hello everyone, my ok 50 Ford has a sbc and a th 350 transmission which has developed an issue. It drives and shifts perfectly when the car is in drive, but if you pull the shifter all the way down in low it is like it has a trans brake. It loads the motor but will not move but when you move the shifter to 2nd and the car takes off. And it’s making a loud growling noise I think is coming from the tail shaft. Never had one do that before.

 

I bet a nickel you're gonna have to take it apart to fix it...

 

Before the next smart A can I’ll say leave it in drive!

 

Sounds like Reverse clutch pack is engaging along with 1st forward when you put the lever into Low. I'm not familiar with the valve body and how that can occur as Reverse position is all the way up on the other side of Neutral, but I would start with checking the shift linkage. Maybe somebody more familiar with the valve body will chime in and explain if this is possible.

 

I'm looking at hydraulic diagrams and I don't really see anything hydraulic that would cause this. Since you have to go through manual second to get to manual low, is it possible that the linkage isn't moving the shift lever all the way to manual low? This isn't likely, but it might be possible to still be in manual second and partially in manual low at the same time, that will lock the gear train. What happens if you put it in manual low when the vehicle is stopped? Does it still lock up? The growling noise, is it only in manual low or in all gears?

In manual second the transmission starts in automatic low and shifts to second. The difference between manual second and automatic second is that you apply the intermediate band along with the second gear clutch. This it to give you engine braking in manual second. When you shift to manual low you apply the low/reverse clutch. Again this isn't applied in automatic low as a one way clutch takes car of holding the rear planet carrier stationary. The low/reverse gives you engine braking in manual low. In manual low you should have the rear clutch and the low/reverse clutch applied. Applying any other clutch or band will lock up the gearset.

 

Did you put a shift kit in it recently? Or just started doing it out of the blue? Reverse works normal? If nobody has recently messed with it, try pouring a bottle of fuel injection cleaner in the trans fluid and run it in drive. See what happens. The injection cleaner won't hurt anything

 

Are you sure the shifters adjusted properly and it’s not in between gears?

 

Sorry jaracer. Didn’t see you already asked about that.