Auto Transmission shifting too quick.

[Pepe Le Pew]

Hi, I need some Help.
How does an automatic transmission know when to shift? My 1980 seems to shift real quick when I pull out. It goes right through the gears with only a couple of seconds in between. Seems like I'm not getting the most out of my gears. The downshift cable attached to the carb is working perfect. What should I check? Thanks for any help!:confused

Kenny

 

[22229stingray81]

Pepe,

For what its worth I had sort of the same problem, lockup was coming on too soon and shifting was alllll messed up.. seemed like a tranny problem.. turned out to be my tps sensor.. it was giving the wrong readings, therefore shifting incorrectly.. also what about the detent switch? Just trying to help, sorry if I steer you wrong.

-Tatortot

 

[ChuckG]

Not sure what auto trans is in your car. Turbo 350 or Turbo 400. If it's a 350, check the adjustment of the cable. Also check the vacuum modulator.

If it's a 400, there is no cable. Lo speed shifts are controlled by the vacuum modulator. WOT /passing gear is controlled electrically. The shift points are conrolled internally by the governor. Chuck

 

[1BAD80]

Try unpluging the electric converter lock-up on the front of dash. Maybe the converter is locking up before it should.

 

[Pepe Le Pew]

Thanks for the Idea's. It might be more than I can handle. The engine was replaced by the previous owner. I am not sure if the transmition is the original or not. The only numbers I can see without jacking it up are Y7S 03D stamped on the right side of the fluid pan. I found what I think is the electric converter lock up that you discribed. It has two cables, one going to the trans and one going into the firewall. I'm not sure what it does, but there are no wires connected to the terminals on it. I guess that's not too good. I don't have a clue where the wires are. Any further ;help would be welcome.

:confused
Kenny

 

[1BAD80]

Sorry the lockup was on the Calif. cars in 1980 and all in 1981.
I happened to buy a used one owned by a dealer here in Mich. that's why I thought about the lock-up converter.
How does it shift manually, and how does the trans fliud look, and does it smell like a clutch?
According to the manual , stock is a TH350. The pan has one corner cut off on the 350, thats the only way I can describe it. You can look on a Summit or Jegs parts site and see the differance between the 2 trans.
There are 2 thing's that I can think of, the vacuum module or the governor can cause it to shift fast like your describing.
Hopefully other's will respond to the post.
Heres a site full of links for trans trouble shooting and how-to fix them. Hope this helps you.
http://hotrodders.com/kb/search.pl?Terms=automatic+transmission+shifting&match=1

 

[rpounds]

The shift points are regulated by the 'TV' cable connected to the carburetor at the throttle lever. Some people would call this the 'kick down' cable, which actually in this case, is a misnomer. At any rate, the proper method for adjusting it would be this:

Look for the bracket that mounts the cable to the intake manifold. You will notice that there is a plastic piece that fits into a square hole on this bracket and the cable runs through this plastic housing.

On this plastic housing, usually located at the top, is a cad plated (silver color) metal tab or tang. This tab is spring loaded, but by pushing in on the tab, the spring can be overcome. Anyway, push in on the tab and pull the cable toward the firewall (away from the carburetor).

While still holding in on the tab, move the throttle lever to the full throttle position. This will in turn pull the TV cable back through the plastic mount. Holding the throttle lever in the full open position, release the spring loaded tab. This will return the cable to the 'normal' setting.

Road test the car and observe the shift points. If you want it to shift sooner, push in on the metal tab and slide the cable (a small amount, like maybe 1/8") toward the carburetor. If you want the tranny to shift later, slide the cable toward the firewall. Be aware that if you move the cable toward the firewall beyond the 'normal' setting for a later shift, you will not be able to achieve full throttle on the carb. Also, you will run the risk of shifting too late during WOT operation.

This is applicable on late 70's and early 80's Chevys with either the 700R4 (yours) or on the 200Rs.

Hope this helps.

Ron

 

[Pepe Le Pew]

Thanks for the help. I know a lot more now than I did a couple of days ago. I am going to check and adjust the things that were mentioned. Thanks again everyone!

PS, 1BAD80, The links were great!

Kenny

 

[Pepe Le Pew]

WOW Thanks Ron, ;worship
I adjusted the cable just as you said. What a difference, Its shifting perfect now. I can't believe it!
I feel like I have a new transmission. Thanks a million.
The is the best.
Kenny

 

[rpounds]

Good job Kenny!! Don't ya love it when a plan comes together?

Ron

 

[1BAD80]

DITTO! Good info Ron.