Transmission takes to long to shift

STROKERBU

Weekend Racer
Jan 20, 2009
79
0
0
Savannah, GA
What would cause a TH350 to take to long to shift to a higher gear and want to downshift to a lower gear to quick? It does not have a manual regulator. It seemed to have a vacum one but right now it is plugged. When it finally goes to 3rd it jerks back and forth between 3rd and 2nd. Help please!
 

STROKERBU

Weekend Racer
Jan 20, 2009
79
0
0
Savannah, GA
So basically I need to drain the fluids, change the filter and blow the valve body with air before I put it back together? Someone said that if my B & M shifter linkage is not adjusted right it could cause this? Also I think I have a TH400 instead of a TH 350. The research I have done does not show a vacum regulator on the TH350, hELP PLEASE.
 

Doober

Moderator
Jun 2, 2003
14,704
1
38
Catalina, AZ
www.cardomain.com
TH350 will look like a square pan with a notch taken out, TH400 will have an irregular (i.e. not square) shape to it.

Checked your fluids? How's your kickdown cable operating?
 

STROKERBU

Weekend Racer
Jan 20, 2009
79
0
0
Savannah, GA
That is the whole thing, It does not have a kick down cable. It has a vacum kick down, I guess cause that is where the manual kick down goes on a TH350, that is plugged in. I looked at the pan and it looks like TH350 pan but the TH200 has a similar pan. Maybe it's a 200? It also has another vacum cannister on the rear right side of the transmission as you are sitting in the driver seat that is not hooked up. I am confused as to what transmission is in it :-k
HELP!!!
 
A

Anonymous

Guest
I may be wrong, but the 200 is all one piece, no bolt on tail. The 350T has a bolt on tail. The 350T is considerably bigger than the 200 best I can remember.

Having said that, it sounds to me, based on your descriptions, that you are missing the kickdown cable, and instead the hole where the cable goes in and connects to the valve body is plugged. In addition, the vacuum modulator is plugged off, rather than hooked up. It'll never shift right this way.

You need a kickdown cable, you'll have to take the pan off to hook it up. I would also run a vacuum line to the vacuum modulator.

And the description does sound like a 350T to me.
 

STROKERBU

Weekend Racer
Jan 20, 2009
79
0
0
Savannah, GA
Yep, It's a TH350. There is no band adjustment screw behind the oil lines which is the only difference between a TH350 and a TH250. Question, If I remember right the manual modulator is a bulky round piece with the cable sticking out of it and it connects to the carburator linkage. My transmission seems to only have a brass tube sticking out of the transmission with a screw and silicone at the end to clogge it. Does the cable just goes through that tube, hooked up inside the valvebody? And where do I hook up the vacum modulator from the right rear of transmission? To a vacum line off the carb or intake? I am getting closer to solving this. Thanks guys for your help.
 

Z-man

Dragway Regular
Aug 12, 2006
1,058
0
0
Barnesville MN/ Fargo ND
First we need to determine what transmission you have. A th200 will have METRIC stamped into the pan , has no vac hookup and has a one piece case.

TH350 has pan shaped as stated above, a vac modulator on right rear that's hooked to manifold vac and a cable for kick down.

Th400 has a odd shaped pan, vac hookup on right front and electric prong for kick down.

that being said I think you governor is not up to snuff (sticking broken etc) at what RPM does it shift ?
 
A

Anonymous

Guest
The detent cable will all be one piece. If you have a piece of plastic bolted to the detent hole now it is likely someone just cut the end of a detent cable off, filled it with RTV, and plugged it. The new cable will replace all of that.

Assuming they left the linkage from the valve body, you may not have to remove the pan. Remove the hold down bolt and the piece they've plugged the hole with and see if this linkage is sticking out:
gm_tv_fig1.gif


If it is, then you just need a new cable and the detent bracket at the carb to hook the cable to the throttle.

The vacuum to the vacuum modulator goes to the carb. Anything above the base of the carb is throttle controlled vacuum, anything below the base is vacuum all the time (manifold vacuum).

For the modulator, I may be wrong (as it has been a long time), but I believe you hook it to manifold vacuum. <<Corrected

Looking for help here, it's been a long time since I worked with the TH350. Rebuilt a bunch when I was racing, but that's been years ago.

If you are missing the linkage from the valve body to the cable, I can probably drop some in the mail. I have two or three large containers of TH350 parts.
 

MalibuRacing.com Gear

Stickers & Shirts!!