Technical 700r4 problems, TV cable?

Hi all, I've been combating an issue with a used 700r4 I have recently installed in my c10. I used the correct brackets on the Holley carb and I think I have the cable adjusted correctly. It is tight at wot. The problem is, it will not go into third gear. It shifts from first to second nice and firm at about 15 mph then that's it. Around 30 mph, the trans seems to slip. I have tried manually shifting through the gears and get the same result, just first and second. As far as the condition of the trans prior to my installing, I really can't say except that it has (I am told) 140k miles on it but supposedly was good. The fluid I drained out of it was very dark but not burnt smelling. I am just trying to get my ducks in a row before I go to the trouble of pulling it back out.

 

I’m probably wrong,,,,but I always thought the cable was supposed to be adjusted where it had almost no slack at idle.
Being tight at wot didn’t matter .

I’m not familiar with a 700R4 though.

Tommy

 

I haven't messed with them enough to know, but I have heard that using a pressure gauge on the transmission is pretty helpful in setting up the cable. And then diagnosing problems when you discover it's not the cable adjustment that's the issue.

 

My experience with alleged "good" used transmissions is that they are in fact not good. Also the cable is self adjusting, you push the adjuster button and push the cable jacket all of the way in and then actuate the the throttle to wide open with the engine off. Then it will pull the cable jacket out to where it needs to be. You'll hear a bunch of clicks as it adjusts.

 

Sounds like burned 3/4 clutch plates. As described above the cable adjustment should be taut at WOT.

 

I just went through this nightmare with a 700R4. I too thought I had my TV cable adjusted correctly, but I didn't, and I absolutely cooked the trans within the first mile of driving the car. You live and you learn. A few things I learned;

-It's good that you've got the correct 700R4 bracket so there is the proper amount of pull off of the carb. The further from the throttle blade center line that you are, the longer the pull, so using the correct bracket is critical here.
-If you're using a universal TV cable, make sure the compression sleeve that locks the cable is tight. This is part of where I went wrong. The universal cables telescope so they can be lengthened and shortened for different applications. But one you get yours set, the sleeve needs to be locked, because if the cable collapses, it's going to throw your adjustment out the window.
-The TV cable has to be adjusted off of WOT, NOT off of idle. This is why you really can't go off of the idea of "no slack". When adjusted properly, it always feels tight, even at idle. Either have someone hold, or lock the throttle blade at WOT. All the way back, 100% open. Then take your TV cable and pull that bastard as far as it will go. Lock that all in place. That should be damn close to where you need to be, and you can adjust either up or down from there with the fine adjustment on the cable. When the cable is adjusted this way, it will appear to be tight even at idle, but obviously it will be able to come out further because you had it pulled to WOT. This is one of those situations where if you're going to err, err to too tight rather than too loose. You can always loosen the cable if the trans shifts too hard or shifts too late, like it's holding the gear for too long. If you leave it too loose, well, there are immediate consequences.

Unfortunately, if you're having the symptoms you're having, in all likelihood, it's already too late. The trans is likely cooked. As correctly stated by @milwscruffy the 3/4 clutch pack is what gets toasted by the lack of fluid pressure. There's no shame in this mistake, it's a learning experience. I documented the same mistake I made in my post here, https://www.jalopyjournal.com/forum/threads/the-consolation-prize-61-olds-super-88.1267254/page-3 right at the top of the page on post #61. Good luck.

 

57Joe is correct on all counts...

In addition since the actual condition when you bought it is unknown, and in the long term, it would probably behoove you to bite the bullet and have it rebuilt or rebuild it yourself..

But on the other hand if it's just old and not burned up on the clutches the first thing to do is to do a pressure test you can research that by googling.. and if your pressures are low perhaps installing a Sonnax .500 pressure control valve and then rechecking your pressures might help but more than likely not..

 

I would also add this analogy if it helps to illustrate the point.

Think of your TV cable pull and throttle throw in terms of being on a scale from 0 to 100, 100 being totally WOT. When adjusting the cable, 100 on the throttle is 100 on the TV cable. Neither will go any further. However, at idle you will have 0 on the throttle, but there still may be 25 on the cable. It's not entirely linear in that regard. Even at idle, where the throttle is bottomed out, there is still tension on the TV cable.

This is the main mistake I made because I didn't understand this conceptually. I was trying to make the cable and throttle match at a one to one ratio, 100/100, and 0/0. In reality, what happened was that 0 on the TV cable roasted the trans with the lack of fluid pressure.

I hope that makes sense

 

Thanks for all the quick replies. It is a little loose at idle. Trying to learn on your own often finds yourself learning lots of misinformation on the internet. This is the first time I have heard of it needing to be tight at idle as well as wot. I am going to adjust it again later when I get home, but if my problems were due to adjusting the cable wrong, I am afraid I may have caused myself irreversible damage already. Worst case, I may be on the hunt for a long tail th350..

 

These are not hard to rebuild.

 

That is what I have heard. I guess my big fear is doing the rebuild then shooting myself in the foot by making the same mistakes again with the tv cable. Unfortunately I don't have many people around me with experience or advice on things such as this and those that do are usually too busy ( understandably with kids, ect.) to physically offer a set of eyes or hands to help.

 

Question. If it’s tight at WOT but loose at idle, wouldn’t this indicate the wrong mounting bracket, bracket on Holley or ? As in too much travel?

 

When I say loose, I should elaborate. It is not floppy or anything like that. There is tension, but not much where as at wot it is tight with just a little bit of give in the cable.

 

It should be spring loaded at idle, and tight (as in you can't pull it any more) at WOT. I guess the real trick is getting the bracket geometry correct so that it is pulling just the right amount at each part throttle point. Because that's all the valve body has to go on as to how much pressure to apply to the clutches, so they won't shift harshly, or slip. If the geometry is wrong and it thinks it's at idle when it's really at 1/4 throttle, that will cause it to burn up also, eh?

 

Geometry should be correct. That part I am sure of. I used the carb throttle lever adapter and cable bracket recommended by Holley. The throttle lever packaging recommends you use the cable bracket I bought and vice versa. If I still had the packaging I would post the part numbers. I'm sure I could dig through my summit purchase history and find them though. It sounds like I have the cable too loose. I will re adjust the cable when I get home to ight so that there is no give at all at wot. The plus side is that after testing, I could not smell any burn in the transmission fluid so I am hoping I didn't destroy it.

 

Never assume the geometry is correct.
I have never seen a bolt on "geometry corrector lever that was correct, on older Holley non removable throttle levers.

It has to start at a certain degree and end at a certain degree in the throttle travel.

There are many diagrams on the net with the correct setup. Set it up as close as possible.

Most Holley carbs I do, I take off the car, and modify the existing throttle lever for the proper geometry and not use the so called bolt on corrector.

I use my grade school, probably 55 year old plastic protractor to measure the degrees.

The symptom you are describing though is a classic 3-4 clutch failure.

Bill

 

i always get the BowTie Overdrive bracket so O know the geometry is correct. Not only need it fully deployed at WOT, needs to be properly positioned at part throttle too. BowTie provides phone consultation during tuning of the cable, checking fluid pressure at several shift points.

https://orders.bowtieoverdrives.com/SecureCustomerArea/docs/checktv/tvcheck.html

http://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=217

 

The Bowtie kit is nice and correct.
I do think it's over engineered though.

Bill

 

So I just went out and re-adjusted the cable to make it tight at idle and really tight at wot. Take off is quicker with a hard, firm shift into second, but then the same rev into slippage. I am going to go with burnt up 3-4 clutch.

 

Again, it isn't a matter of 'really tight' at either end of the stroke. It is a matter of proper stroke profile over the full throttle stroke for proper fluid pressure at all speeds/loads. These OD trannys are very sensitive to that profile. I am happy to spend the premium $300 for a proper linkage to protect a $2000+ slush box!!

 

Does a 700 have a governor? I don't remember. I pulled the one out of my car and gladly helped the guy load it. Got $200 and dance back into the house. So long sucker!! I have never bought a used transmission that was good. They're all cores from here on out.

 

I'm going to assume that you're running a SBC mated to that 700R4. In my build my throttle linkage was FUBAR'ed prior to the engine swap, so I just converted over to a cable and used the Edelbrock bracket that bolts onto the intake. I liked it in particular because it was chrome and worked with my dual quad application. I also used the 700R4 geometry correction bracket on my Edelbrock carbs.

 

Yes, it has a governor.

 

Then could that be the issue?

 

Usually when the governor is a problem it's because the gear broke, and the transmission just won't shift at all, or shifts very late.

 

The last one i had break, turbo 350, wouldn't shift 2-3. But I'm not up to speed on the 700R4, know enough to know that I don't want anymore lol. The whole lockup converter is another issue.

 

If it were a governor thing. it would shift early or late, but still shift.

 

I was wrong, had to go back and look it up. It wouldn't shift 1-2

 

Many years ago when I did my first 700R I thought I adjusted it the way the tranny shop told me. Obviously not as it barely made it out of the shop and into the trailer, lesson learned. After an expensive rebuild on my dime we pushed it out of the shop and hauled it to the tranny shop for adjustments. Had a simular experience with an AOD, cooked that dam thing in a couple minutes in the shop, never moved. I still really like a turbo 350.

 

The symptoms he's getting are typical of the burned 3/4 clutch pack. Like he mentioned, he's getting a nice, snappy 1-2 shift now that there is sufficient fluid pressure, but that is a separate assembly from the 3/4 clutch. Once the trans goes into third, it's over. Or as it was in my case, it would go into 3rd and had enough clutch material left to drive, but would feel like it was searching for the right gear, sliding in and out of 4th and back into 3rd.

Now having put some miles on my car with the 700R4 functioning properly, and having had any number of vehicles with TH350s that had TCI internals, performance valve bodies, etc., I would agree that I like the way the TH350 works better. It also goes without saying that I like the simplicity of the setup better, since I only ran mine with the vacuum modulator and no kick down, electing for manual control instead. That said, having OD is really magnificent, especially for someone like myself that really drives a lot of miles. Less wear and tear on the engine, better fuel economy, quieter in the car, much higher cruising speed... it's really nice. So in that regard, it's a trade off. Maybe running a TH350 with a GV is the best of both worlds?