Transmission question
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
Transmission question
My car does not downshift and open up the secondaries when I punch it down from from a roll. I figured I'd check the adjustment on my detent cable but no-go it is adjusted properly so I decided that maybe I'll just replace it along with the vacuum modulator. My car has a turbo 350 trans in it so I go to Napa and they ask me Turbo 350 RPO-M38 or turbo 350 CBC RPO M-33? I don't know, so I go home and look at my window sticker that I obtained from GM and it say's RPO-M40. Hmm, looks like my car originally came with a Turbo 400 not a Turbo 350 like I thought. Okay, no big deal the T-350 has a better 1st gear ratio anyway and that's how I would have probably ordered it had I bought it new. My question is this- Am I on the right track assuming it's either the cable or the modulator? And does anyone know the difference between a Turbo 350 and a Turbo 350 CBC? Is there any visual differences that will tell me?
Thanks
Thanks
Drifting
Joined: Sep 2006
Posts: 1,259
Likes: 2
From: MS
You have the Turbo 350, RPO M38 (L82 in 77 got the T400).
The M33 was the Turbo 350C with the lock-up converter and not used in Vettes til 1980 on the LG4.
The kickdown cable positively identifies your tranny as the T350, the Turbo 400 has an electric kickdown and no cable.
The M33 was the Turbo 350C with the lock-up converter and not used in Vettes til 1980 on the LG4.
The kickdown cable positively identifies your tranny as the T350, the Turbo 400 has an electric kickdown and no cable.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
I think so, but not positive, I'll have to check it. If I'm going say like 30 MPH or so and manually pull it into second and floor it the 4 barrel opens up and she really takes off. If I jump into it just leaving it in drive at that speed or any other speed, nothing.
Last edited by Glassbowtie77; Oct 16, 2007 at 10:38 AM.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
You have the Turbo 350, RPO M38 (L82 in 77 got the T400).
The M33 was the Turbo 350C with the lock-up converter and not used in Vettes til 1980 on the LG4.
The kickdown cable positively identifies your tranny as the T350, the Turbo 400 has an electric kickdown and no cable.
The M33 was the Turbo 350C with the lock-up converter and not used in Vettes til 1980 on the LG4.
The kickdown cable positively identifies your tranny as the T350, the Turbo 400 has an electric kickdown and no cable.
Instructor
Joined: Oct 2006
Posts: 124
Likes: 0
From: Madison WI
The modulator controls the shift points it has nothing to do with kick down. So if you like where the shift points are leave it alone. The Cable that runs to the carb is the one you need to look at first. There is a d shaped button that you press. While holding the button push the center of the cable back alll the way. Then mash the gas pedal to the foor and it should click and pull the center back out some if it doesn't you will need to pull the cable out and check it.
