trannmission prob.
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 18
Likes: 0
trannmission prob.
i have a 1981 corvette and i put a new 1980 carb.and a new 1980 dist.on i also did away with the emissions components along with the computer now when i drive the car the transmission will drop in 1st. at about 15mph and drop in 2nd at 25 mph but it will not drop into 3rd at all is there a add an to the transmission when you change the carb. and dist. or did i disconnect something
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Hmm, the only thing that ties the CCC and Tranny together is the TCC system. If you didn't do anything to connect the Lockup Converter I can see that not working, but it should still shift into 3rd. You sure its not going to 3rd? How fast were you going? What RPM?
Just thought of something else, is the Vacume Modulator still connected to the manifold?
Just thought of something else, is the Vacume Modulator still connected to the manifold?
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 18
Likes: 0
i can go from 0 to 85 mph and it only drops in to 1st and 2nd at 15mph and from 25 to 35mph and nothing at 45mph and i no nothing about a vacume modulator or weather it is discinnected or not do you have a photo of what it looks like and where it goes to go to and from . i am verry new at doing my own work
Drifting
Joined: Jun 2005
Posts: 1,523
Likes: 1
From: grand prairie texas
I am not really familiar with the 81 corvette transmission but a lot of the gm automatics that have the computer lock-up system also have a cable that replaces the old kickdown cable that is adjustable that controls the shifting of transmissions If I remember correctly it is called something like the TCC cable. If it dont have that and has the vacumn modulator it is a round small a little bigger than a shot glass that attaches to the rear of the passengers side of the transmission with a vacumn line that runs up to a tee at the rear of your intake manifold
Race Director
Joined: Jul 2004
Posts: 12,706
Likes: 329
From: Scottsdale Arizona
Sounds to me like you messed up the kick down cable. It's on the driver's side and connects to the carb. Properly adjusted, it lowers the gear when you stomp on it. If misadjusted, it'll keep it from upshifting.
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Race Director
Joined: Jul 2004
Posts: 12,706
Likes: 329
From: Scottsdale Arizona
Pretty simple if all the parts are correct and stock. There is a button on the side of the cable where it connects to the bracket at the carb. With the engine off and the throttle fully off, press the button. This SHOULD release some cable if it is adjusted incorrectly. To adjust the cable, push the gas pedal to the floor. That's all there is to it. The cable is self adjusting.
If the cable, bracket or linkage is after market, the adjustment is a little harder.
If the cable, bracket or linkage is after market, the adjustment is a little harder.
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 18
Likes: 0
i adjusted the cable but it is still not dropping into 3rd gear thank you for the help. also my tempiture is running hot almost to the red line on my temp. guege when i put the a/c on could that be part of the prob.i live in baltimore md i do alot of city driveing and it gets about 90/95 here remomber i am verry new at posteing on this board i am also a first time corvette owner so who ever reades my post for help please be patent i will catch on i have a feeling i will need everybody's help i am a corvette rookie. thanks . [i already no bad spelling]
Last edited by charles.stencil; Jul 11, 2007 at 03:38 PM. Reason: for got to add something
Drifting
Joined: May 2007
Posts: 1,491
Likes: 2
From: North Royaton Ohio
I read your post about your tranny problem today, as I usually do with all of the posts, and this one stumped me. I decided to go for a drive and didn't give the post a second thought until I was going down the road in my Vette, which is also a 1981 with disconnected computer and a 1980 carb and distributor, and watched my speedometer. If I"m correct, you claim that it drops into first at around 15 mph, second at 25, and third not at all.
If I'm correct, I don't believe you even have a problem with your transmission. From a standing stop, you are in first gear, whether you are moving or not. At normal acceleration, that 1st gear takes you through 15mph, when you transmission then shifts into 2nd gear, not first. That second gear then accelerates up to 25mph, when you then reach your final drive/3rd gear.
Just a misunderstanding, really, because what gear would you be in before 15mph? 1/2 gear?
If I'm correct, I don't believe you even have a problem with your transmission. From a standing stop, you are in first gear, whether you are moving or not. At normal acceleration, that 1st gear takes you through 15mph, when you transmission then shifts into 2nd gear, not first. That second gear then accelerates up to 25mph, when you then reach your final drive/3rd gear.
Just a misunderstanding, really, because what gear would you be in before 15mph? 1/2 gear?
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
How do you know its not working? Once your in 3rd gear and cruising along the torq converter (TCC) will "Lockup" you can tell by watching the tach, it will drop a couple hundred rpm. keep your foot on the gas, no changes and tap the brake, the tach will jump up a couple hundred rpm.
For the cruise, same test, set the cruise and then tap the brake to disengage it
For the cruise, same test, set the cruise and then tap the brake to disengage it
