Transmission Help

[rockman20]

Okay, I need help here. I just bought a used 1982 Chevy Scottsdale from a private owner. The truck use to house a 6.2L diesel which the owner before the guy I purchased the truck from swapped out for a SBC 350.

Here is the problem. The truck is fitted with a TH700R4 and I am experiencing what I thought at first was early shifting. After having a few transmission shops look at it, they all agreed that it is the torque converter locking up too early. It locks up at about 30MPH. I was told to replace the TV cable on there. What do I replace it with? Do I get one for a diesel or a gas?

Does this sound right to anyone on this board? I would think that something would need to change internally since the transmission should be setup to shift differently if it is now setup behind a gas rather then a diesel.

I will have many, many, many, more stupid questions in the future here, but let me start with this one first.

I'm a newbie on this form so take it easy on me!

[apstguy]

Maybe it locks up early because is was set up for a diesel??? If the TV cable is not adjusted correctly, it can cause just about any tranny problems. Adjust is first and if it doesn't help, replace it. I don't know how hard it is to replace. Get one for a gas.

BTW - Welcome

[apstguy]

Forgot this - Swerve's site has a walk-through on how to adjust it: http://www.73-87.com/garage/tvcable.htm

[CRRoy71]

Rockman, my tranny was doing about the same thing. It would shift to third way to early, then it would kinda bog down, then downshift back to second, and then run second out all the way.
I adjusted the tv cable just like swervin illustrates on his site, and problem was solved for a while. It is starting to do it again, so I am going to replace it.

Oh yeah, welcome to the board.

[swervin ervin]

What gets me about what you are saying, is you say it's locking at 30 mph. Are you saying the converter is actually locking, or just going into 4th. I find it hard to understand it would lock at 30, but I guess stranger things have happened.

Adjust it and we can go from there.

[gchemist]

I have my 700R4 shifting like this.
1-2 ~15 MPH
2-3 ~30 MPH
3-4 ~45+ MPH depending on throttle amount.

May want to consider changing the governor too.

Don't the diesel torque converters lock at a lower RPM? I like mine ~1800 or up to ~2800 at WOT.

Some additional info:
There are three versions of the vacuum switch. www.lmctruck.com has just started to offer them in their catalogue.
Part: Trans Control Solenoid
32-7635 TH700R4 Blue modulator 82-87 $34.95
32-7636 TH700$4 85-86 $32.95
32-7637 4SPD Auto 82-86 $39.95
From the first and last, one might be for diesels. Not sure on the second. The major difference between the first two is color. The first two and the third have different connections. The first two only have two connections. The third has has three with one spliced off one.

[rockman20]

Thanks for the welcome.

swervin, what is happening is this. If I put the gear selector into 3rd so it can not shift into fourth I get this outcome with normal acceleration

1st to second is about 10MPH
2nd to third is about 25MPH
Right after the 2nd to third shift, the engine is doing alright and then you can feel the converter lock at about 30MPH and then the engine bucks BAD. If you back off, very lightly press on the accelerator, you can usually get it going. But if the engine is cold, dream on. It will buck worse then little yellow jacket did for Chris's million dollar ride.

The TV cable that is on there now is very interesting. Basically looks like a bike brake cable. They clamped it to the bracket by the carb and there is a lot of excess cable hanging out. Then they took a brass stop, slid that on the cable, it hits the throttle arm on the carb, and then they tightened the set screw down and that is how the arm pulls the cable.

So I should get one for a gas engine. Perfect. I'll see what the local dealer here in town can find me. Looking at swervin's site, looks like I may need to get the bracket as well.