700R4 TV Cable

Ernest

Master Mechanic
Thread starter
Apr 28, 2016
286
63
Texas
Ok.... this past weekend i succesfully installed the new B&M TV cable, somewhat.

After things taking longer than it should have, i finally got the cable hooked up to the TV lever while keeping tension on it to keep it in place, then i slowly lowered the case over the cable and then onto the transmission and wouldnt you know it, the seal that came with it wouldnt go in, like it was slightly larger than the hole in the trans case, kept going in circles trying to press fit it with my hand.

At first, i left the seal attached to the TV cable case, figured it would be lined up perfectly and go into the TV cable hole with minimal force, no dice, then i detached the cable from the TV lever, i then removed the seal from the cable case, then i tried to put into the TV cable hole in the trans itself, no dice there either, going around in circles, again like it was slightly larger or perhaps a tad too thick, i dont know what else to do.

Then i tried using the seal(on the B&M cable) that came with the original TV cable that came with the car, of course not knowing the brand, but the seal resembles the one GM sells from pictures seen online(but differs in looks from aftermarket TV seal), its in great condition, the TV cable area on the trans was dry as a bone, no leaks whatsoever and no tears in the actually seal itself, the TV cable slid out with minimal force and the seal stayed attached to the cabe case, but same exact issue as previously stated, i couldnt get the cable to slide in with the seal attached and i couldnt even insert the seal into the TV cable hole in the trans.

Am i missing something or is this a typical PITA job when it comes to replacing a TV cable while the trans is still in the car and is there possibly a TV cable seal thats perhaps slightly smaller that will go in with minimal force while still providing a factory tight seal?

Btw... i had the car jacked up higher on the passenger side so little to no fluid would spill out, but of course theres that tiny bit that gets on the seal while trying to press fit with my fingers, or does the area need to be 1000% dry so the seal just "pops" right in.

Thanks
 

ELCAM

G-Body Guru
Jun 19, 2021
564
93
The seal needs to be completely lubricated with transmission fluid before installing.
 

CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
2,084
113
Canada
Huh. Did a 700R4 swap this past winter, so a couple of things to consider here. You seem to have acquired the correct application cable as they can come in differing lengths depending on the vehicle. To get the correct one for my swap I had to remove the old one from its location on the case and physically measure it. The first one that came in was the right length but had the wrong sleeve end on it at the transmission. This meant that the cable would hook up but the sleeve was too wide internally to keep the cable end attached to the hook on the actuator link. The replacement solved that. Both these items were post factory replacements but made to the OEM spec. Neither came from a Speed Shop.

For the actual insertion, it was pretty much a case of gently twisting and wiggling, combined with a little bit of push. Once the cable body had hit bottom, then the retaining screw got gently put back in. That screw is both soft metal and metric; be easy with it.

Ahead of the cable, for that long bodied rubber grommet that seals up the dipstick tube, I went with a new OEM part from the dealer. Worked fine. Trick was to get it nice and slippery and then stuff it in until the shoulder grounded out against the lip of the hole. Then wiggle the tube into it. For what I was doing, I had to use a tube and stick assembly from an 85 Van. Cars are shorter and fall closer to the firewall .

For the TV cable adjustment, I first sorted through a few of the various types of OEM cable brackets that I had accumulated and picked one that physically brought the cable both correctly and precisely to the pivot point for the cable end and the matching pin on the throttle body. This is important because the cable has to be in line with the pivot to pull cleanly and easily in response to the throttle. The stock cables come with the D shaped button. Before the cable is installed, make sure that the cable tensioner sleeve is completely pushed back into the body portion. it is toothed so the D button has to be depressed to get it to move back. It has to totally bottom out in the retracted position before the cable is attached to that pin.

As for the actual adjustment of the cable tension, I would suggest reviewing the instructions either on line or in a service manual. This is because the cable tension has to be exactly right or the transmission will NOT shift correctly. Instead it can shift either early or late or very hard or mushy. Summarily, the instructions for the adjustment state that once the cable is attached and the throttle lever is siting in the closed or idle position, with the motor off, the throttle lever is to be twisted/rotated to the full open position by hand. This action will pull the cable forward and should cause the adjusting sleeve to slide forward out of the cable housing and lock into the correct position. If you did it right then a test drive should result in nice up and down shifts without any problem. If you didn't, well you have two options. Reset the sleeve back to the fully retracted position and try again. OR......................... Use the "adjusted" position of the sleeve as a starting point and manually move it from there. This means depressing the D button and using either your fingers or a small screwdriver to gently advance or slide back the sleeve a tooth or two at a time to sneak up on the correct adjustment. This is a "Know it when you feel it" Adjustment, as you will have to tweak it multiple times before you get a feel for which way, in or out, on the sleeve to go and then how much. Too little sleeve showing and your shifts will be late and mushy; too much sleeve and you get hard and quick shifts. You need to be somewhere in the middle. It is the getting there that is a monumental PITA!! Personally it took me several days and multiple tweaks to get it right. Right?? That is when you pull away from a light or make a turn and you don't feel the shift but the change in engine rpm tells you it has happened.

The last item to consider is the converter lockup actuating system. The lock up is electrical and occurs in all gears and initiates as soon as you shift into gear and accelerate. During braking, what happens is that the actuator inside the transmission is deliberately shorted out temporarily by a second circuit wired to it. Once stopped, keeping your foot on the brake keeps the lockup disengaged. Foot off the brake and moving again resets it and the lockup is back in business. On my personal 700, the lockup is actuated by a VOES switch that gets its vacuum from the manifold and power from a fuse or breaker. The "short" is created by the brake light switch; which actually has provisions for two plug ins, one for the brake lights and the other to feed power from the fuse block to the transmission to create the short and turn off the lockup temporarily. If you are sitting at idle and in park with your foot off the brake, the lock up is armed but sort of in standby mode.

You can live without the lockup being wired in but the negative to that is that transmission has to tolerated more heat generated during operation and that means the ATF has to be changed more frequently. If you wander through my posts on the install, you will find a wiring diagram that one of the other residents of this board posted for me to help in the wiring process.



Nick
 
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Ernest

Master Mechanic
Thread starter
Apr 28, 2016
286
63
Texas
Thanks for all that NICK.

Before the change over, the TV cable that came with the car seemed to be set correctly, from what i currently know, that trans has been in the car for about 5yrs, i drove the car 30 highway miles from the sellers home to mine, no issues.

Other than that, i have no history on the trans, like what stall the converter has, if it has a shiftkit or not, if the TV body spring is the original long one that typically came with TB cars or the longer one made for carb installed engines or if its running with a stock spring/weight govenor or a modified one.

I figure if i made it home just fine with the trans working in OD(1900rpm/60mph), that should be the end of it, but i didnt like the mounting setup of original cable, the brackets used for the throttle and TV cable was an OEM piece that attached to the rear two bolts on the intake manifold, that set the cables too far back to my liking and perhaps the geometry could be off, my 1-2 shift point was happening @ 10mph, then 2-3 @ 20mph during testing up the street to the next block, then turned around for home, but the shifts are firm, not soft, and btw way, i recently found out the rear houses 3.73 gears and a posi.

From what i've researched online(other forums/YT videos), the 1-2 shift should happend right around 20mph and so forth, but if its been doing this since it was setup years ago, apparently the trans seems to be ok, but i tried adjusting the cable backward towards the firewall at least 2 clicks, nothing changed, so i put the cable setting back to where i marked them with whiteout before i moved anything, and apon further reading, im seeing the govenor plays a roll in the shift points, certain springs with heavier weights will cause quicker shifts, and certain springs with lighter weights will cause later shifts, so who knows what i've got atm.

But first thing is to replace the original TV cable that came with the car with the B&M one and using the holley throttle/tv cable bracket so i can at least get the geometry more correct and hopefully get the results im after, as in the later more correct shifts, if even after all that, it still produces the same results as the original TV cable, then i'll tap into the govenor and go from there.


Thanks
 

CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
2,084
113
Canada
Couple of things here. First, that mounting bracket for your throttle and TV cables, if stock and original to the motor, was likely to be thecorrect match to the cables and carb in that it positioned them properly in relation to the carb. By this I mean that, with the throttle lever at rest or closed up, each cable, Throttle and TV, when secured in that bracket, should just reach the throttle lever where they ought to attach and snap onto their pivot points. You shouldn't have to pull on them or add extensions to them to get them to where they belong.

Second, those brackets can and do vary in shape and in how they accept and position those cables. During my own project I found that the bracket that I had used with the original T350 did not bring the cables far enough forward when it was pulled and the 700 subbed in. To obtain other possible candidates, a trip to the salvage yard may need to occur and as you move from car to car, if you are allowed to pick your own parts, you'll begin to notice that those brackets can differ from model to model and year to year, as well as from T-mission to t-mission.

You've probably seen the universal ones listed in the various catalogues and on line. They are just that "universal" and not for a specific application which means you have to be able to modify/adapt them as necessary. if you have the patience for that type of tweaking, have at 'er.

On the subject of stock and default shift points, when a transmission like the 700 shifts is entirely dependent on the how fast you accelerate. You describe the default 1-2 shift point as being around 20 mph and that is about right. Under normal acceleration that is about exactly when you ought to feel the t-mission upshift. At around 30, 3rd ought to happen and you may never feel it if the TV Cable is set correctly. For the 700R4 it is ALL about the TV cable and internal pressure in the transmission itself. I am not going to go tech weenie here, there are several excellent and specific texts available that can do a far better job of explaining the how and why of the TV Cable / shift point relationship than I can. The thing to appreciate here is that, if you are not at the point where the tv cable has exerted the correct amount of pull and the internal pressure has reached the correct range of values for the shift, then the box won't shift. As an example, when you are driving slowly, the t-mission is not going to upshift. It will stay in what gear it is in, 1st, or 2nd, because it has not received the internal signal that it needs to make the shift. If it short shifts or shifts early, it is not about how fast you are moving, it is about the t-mission getting that internal signal to shift. Adjusted correctly, the TV cable will not allow a shift to occur until all the parameters that the box needs to "know" that it is time to shift are met.

Going back to my first post, too little tension on the cable gets you mushy or shot shifts, too much tension and it won't shift until a higher rpm point and then the shift will be hard and very noticeable; think shifting at full throttle in a race.

Finally, if the t-mission shifted okay when you drove it home, then tinkering with it is unnecessary and a waste of time. You didn't tear it down or start swapping springs or ?? did you? The gears in the rear end are a nice ratio for the street that won't force you to pass everything except a gas station. From what you describe it is all about the bracket to carb relationship and the proper adjustment of the TV cable. Get the correct bracket and set the cable correctly and you should be good to go.


Nick
 

Ernest

Master Mechanic
Thread starter
Apr 28, 2016
286
63
Texas
If you look at the steel cable between the carb and TV bracket, theres a slight bend when it should be totally straight, also becoming somewhat unravled, and the length should be shorter, i just dont like what i see .

To give you some insight, when giving the carb full throttle slowly by hand, the cable doesnt start moving until the first 1/8 of an inch untill that slack is taken out because of the foremention cable condition, and due to the fact its connect to a kickdown bracket thats meant for the TH350 trans that sets the TV cable too far back, even though theres an extender attached between the cable end and carb linkage.

All this work being done may seem to be a waste of time to some if the trans seems to be working like it should, i just want to start over and properly setup the TV cable like it should have been in the first place IMO, especially from what i've seen/read online in other forums and YT videos, with the proper carb throttle/TV cable bracket, the gometry should be just where it needs to be and any adjustments made afterwards should provide better results.

Thanks
 

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ELCAM

G-Body Guru
Jun 19, 2021
564
93
TV cable adjustment is very important if the TV valve does not open fast enough the line pressure is low and the clutches will slip and wipe out the transmission especially under heavy load and high RPM. You are correct to be concerned about this.
 
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64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,846
113
Upstate NY
If you look at the steel cable between the carb and TV bracket, theres a slight bend when it should be totally straight, also becoming somewhat unravled, and the length should be shorter, i just dont like what i see .

To give you some insight, when giving the carb full throttle slowly by hand, the cable doesnt start moving until the first 1/8 of an inch untill that slack is taken out because of the foremention cable condition, and due to the fact its connect to a kickdown bracket thats meant for the TH350 trans that sets the TV cable too far back, even though theres an extender attached between the cable end and carb linkage.

All this work being done may seem to be a waste of time to some if the trans seems to be working like it should, i just want to start over and properly setup the TV cable like it should have been in the first place IMO, especially from what i've seen/read online in other forums and YT videos, with the proper carb throttle/TV cable bracket, the gometry should be just where it needs to be and any adjustments made afterwards should provide better results.

Thanks
Ultra important, the TV cable adjustments are to adjust line pressure, not to adjust shift feel or points. If your shift feel or points don't seem correct after correct TV cable adjustment, then you have something else wrong and correcting them with the TV cable will only damage the transmission prematurely.
 

Ernest

Master Mechanic
Thread starter
Apr 28, 2016
286
63
Texas
Line pressure only, not for shift points.... i understand that completely, after finding that out not too long ago, thats why i started to delv into the govenor side of things, that will come much later to adjust, but in the begining of my research over the 700r4 trans, the YT videos i've seen and other articles i've read, "1-2 shift should occur at around 20mph, 2-3 around 30mph and so forth", and thats what i was going by.

Like i've mentioned prior, i have no history on my trans, does it have a shift kit, does it use the longer TV body spring for carburated engines, what stall the converter has or what govenor is being use, stock or modified, all iknow for now is the early shifts(heavy weights) and later shifts(lighter weights)... so who knows how long my 1-2 shift has been happening @ 10mph, then the 2-3 shift @ 20mph, but with firm shifts, not soft, so its been running good for me guessing along, but i have no prior knowlege of 700r4 and after doing the reading around, im gaining some valuable insight and just trying to figure out on how to do the correct thing for the trans.

Thanks
 

CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
2,084
113
Canada
DSCN2998 (2).JPG



Shown above are three examples of how the bracket that carries and secures both the throttle cable and the TV cable can appear. From left to right, the middle and right bracket are totally stock; the black one came from a mid 80's 305 Vortec., the blue one, not really sure.

The blue one on the left is an example of how one of these brackets had to be modified to function properly in a unique situation. Essentially it is a pair of the same bracket, each of which was shaved and cut down, to that they could be stacked one on top of the other. The purpose/reason was to raise the height of the pockets for the cables so that they could line up correctly with the carb when it had a spacer set under it. When that Holley was removed along with the spacer, this bracket was removed also, and a bracket that matched the incoming FI Unit was identified and subbed in.



Nick
 

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