HI guys, My 67 RS has a 700r4 in it now. I love the highwya overdrive, and am pleased with the tranny in general. My question is, Is there any way to adjust the transmission to hold its 1st gear longer? When I get on the gas, it, IMO, shifts out of 1st too soon.
thanks,
James

Is the TV cable hooked up and adjusted right?

and if the TV cable is correct, then it could be your governor needs to have different gearing.

If the TV cable is correct and it's only 1st gear that doesn't shift properly, you'll probably have to change the 1-2 shift valve spring to a light or heaver guage depending on if it shifts too soon or not soon enough. The govenor will raise or lower all shift points proportionally. However there are two tweaks you can do to the govenor. One is to replace the springs between the primary and secondary weights. The other is to change the weights themselves - usually by removing portions of them. Someone described how the springs vs the weights have different affects at various speeds. But I'm afraid I don't recall the details.

Be VERY careful in your adjustment of that TV cable... you can pretty much ruin that tranny in a short period if you do it wrong.

The throttle valve cable controls transmission pressure. Adjusting this cable is the most important step when installing a 700R4, 4L60 or 200-4R transmission.

The final step is to adjust the throttle valve cable. The cable must be adjusted so it is pulled fully out at wide-open throttle. To make sure disconnect the cable, hold the throttle wide open with your left hand, pull the cable fully out with your right hand and see if the cable end lines up with the button on the throttle lever.

Do not attempt to adjust the shift timing with the throttle valve cable. The shift timing is controlled by the governor springs. For higher shift points at wide-open throttle, install lighter springs. For lower shift points at wide-open throttle, install stronger springs.

I think all this is way over my head...I have no idea what or where a TV cable is, (till now i thought that was what was hooked to the big screen!) let alone how to adjust it. I think i should take it to a tranny shop for this type of adjustment. Or, doe anyone recomend a site or book showing how to do all this?
James

Here is a good article:

http://www.tvmadeez.com/article/index.php

You can do this yourself, I'm sure of it. Also, I don't like to offer unasked for advice, but I suggest you have in your possesion a Chilton's, an Assembly Manual, a small book of wiring schematics, and study both the forum here, and the Internet in general in regards to your car every day. I also subscribe to Hot Rod, Chevy High Performance, and Car Craft. I say this, because these cars will EAT YOU ALIVE with labor charges from your local mechanic if you can't work on them... LOL. If you just go to Google, type in, "TH700-R4 TV adjustment" you will have more info than a human being could want or process.

That is a GREAT tranny to have in there, btw. You are going to have some terrific times cruising with it. You should think about putting in the TRANS-GO shift kit in it someday... make sure you spend the extra money for the kit--about $100 total, I believe--and get the Corvette servo for increase line pressure.

thanks for the encouragement Jethro...Its appreciated.
James

and Al, thanks for the link...Im printing out the article, and doing some homework before trying this. (and yes, Im going to try it myself)
James

Is the TV cable the same as a kickdown cable?

Kickdown cables are different. The best example is the THM350 transmission. The kickdown cable is what causes the transmission to drop down a gear or two at heavy throttle. The THM350 also had a vacuum line attached to what was called a 'vacuum modulator'. In short, the vacuum modulator adjusts line pressure and shift spacing for various throttle openings. At light throttle, the line pressure is low and the shifts are closely spaced. At heavy throttle, the line pressure is increased by about 60 lbs/in^2 and the shifts are spaced farther apart.

What the throttle valve cable (TV cable) on a THM700R4 does is take the place of both the kickdown and vacuum modulator found on the THM350. The throttle pressure needs to be correct to prevent damage. If the throttle cable isn't pulled out far enough at WOT, the line pressure will be too low and slipping is likely to result. That is the main reason why it is so important to set it correctly on the THM700R4.

Jethro, your advice is greatly appreciated. I ran into the same issues with my 700r4. I ran into the problem of playing "telephone" with my tranny guys. I would tell the front desk mechanic the way I wanted it to shift, and he would then tell the tranny builder what I wanted, and I ended up with something completely different.

I had to start working directly with the builder to get things closer. They had a 4mph (4lb) spring in the valve body for my 1-2 shift. It would be out of 1st before I even finished crossing the crosswalk!

We finally went to an 8lb spring. A little better, but I think I'd like a 12lb. It also doesn't want to shift at WOT. I have to back out of it to get it to grab the next gear. He was trying to adjust that characteristic with the TV cable. I agree with you that the governor is probably where that should be addressed.

Just shift it manually. Easy fix, ;) .