TH350 Automatic Hard/Jerk Shifting in First, Second Gear almost non Existent.

[MalibuDavyou5]

Got a problem that just propped up recently. I am experiencing a very Hard Jerk/Shift into First Gear, Second Gear almost non-existent. Recently I had just changed out the Transmission Filter using a gasket set, I over filled the Transmission when all this started and since I was under there I went ahead and replaced every thing in there and gave it 4 Quarts of Dextron III Transmission fluid. Maybe a Rebuild will have to be done? Hard Shifting seems to be only in First and Second if Second will shift.

 

[SoFloG]

Is the vacuum modulator hooked up and funtioning properly? I had one fail after overfilling transmission and ended up sucking atf in to the intake while driving and not shifting correctly.

 

[MalibuDavyou5]

Is the vacuum modulator hooked up and funtioning properly? I had one fail after overfilling transmission and ended up sucking atf in to the intake while driving and not shifting correctly.

I'll check it out tomorrow, unfortunately dealing with a nasty flu at the same time. . . I've seen similar responses with the Modulator on google, that may be the problem. . Thanks

 

[SoFloG]

I'll check it out tomorrow, unfortunately dealing with a nasty flu at the same time. . . I've seen similar responses with the Modulator on google, that may be the problem. . Thanks

Good luck. Vitamin C!

 

[olds307 and 403]

I had the same issue, thought it had a shift kit in it. I actually modified the governor to raise the shift points. Hard shifts went away and the shift points did increase.

 

[MalibuDavyou5]

Good luck. Vitamin C!

Is the vacuum modulator hooked up and funtioning properly? I had one fail after overfilling transmission and ended up sucking atf in to the intake while driving and not shifting correctly.

Thanks, Struggled with the Flu but replaced the Modulator, Shifts alot smoother now. Yep Sure enough it was loose alright. The Rubber Hose connected to the End of the Modulator was not just loose but also looks too big to fit on the End of the old one (pictured) . . . Just wow! Anyway I now know how to replace that part if needed. Many Thanks and enjoy the pictures. You'll see what I am talking about.


Old Modulator with Large Sized Hose.


Replaced Modulator.

 

[SoFloG]

Most of them are adjustable. There is a small torx or flathead screw inside the vacuum port and you can adjust the shift points by 100-200 rpm or so.

 

[MalibuDavyou5]

Most of them are adjustable. There is a small torx or flathead screw inside the vacuum port and you can adjust the shift points by 100-200 rpm or so.

Yep this one I bought is an adjustable, I saw a Youtube video one the installation of one of these, it was recommended 2 full turns, so I did just that. Gear Shifts are on point where they once where.

 

[SoFloG]

Yep this one I bought is an adjustable, I saw a Youtube video one the installation of one of these, it was recommended 2 full turns, so I did just that. Gear Shifts are on point where they once where.

That's great. It's a very gratifying repair.

 

[78Delta88]

Older post... Just seen this.

Good you got the adjustable modulator.

Future reference on the two to get..

One Red stripe is basic street car or still emission controlled. It will handle a little big bigger cam, but too big. It is an adjustable unit.

One Red with One Black stripe is for bigger cams, that have base idle vacuum around 16 in/hg or less. These are the "Low Vacuum" units and they are adjustable.

When you change to a Lumpity, Lumpity cam, make sure to change to the Red&Black stripe unit, or it will not shift right.