84Elky

With a new 700R4 that was not shifting properly, thought I’d weigh in on the TV Cable issue and share what solved my problems.

Have a TPI, so fortunately the proper throttle/TV Cable geometry required for the 700R4 was not an issue. The geometry issue is another subject. With a newly rebuilt trans and new Lokar TV cable, which was properly adjusted, my trans shifting was horrible, whether lightly or rapidly accelerating:
- way too quick & mushy 1-2 shift
- bad RPM flare, almost slipping, on the 2-3 shift

In no way am I trans expert; far from it. But invested $35 in a 300# pressure gauge from Bowtie Overdrives. Wasn’t looking forward to installing, and then uninstalling it, but glad I did it.

The pressure gauge showed that my properly adjusted TV cable was not even close. It needed to be pulled out approx 1/8” more before there was any pressure increase on the gauge (which is absolutely IMO what is required to have a properly set TV cable). I believe the reason a pressure gauge is required is because every trans is different primarily as to TV Spring tension, which is the main thing that sets the position of the TV Feed Valve relative to the TV Feed Orifice. The Valve and Orifice must be properly aligned so the slightest throttle movement off idle causes a pressure increase.

While everything on my car seemed tight and properly adjusted according to Lokar and all the TV cable adjustment procedures on this and other forums, my throttle could be opened rather considerably before getting a pressure rise – and this was on a car with everything virtually new with no wear.

So adjusted the TV Cable so there was an immediate pressure rise as soon as the throttle was opened ever so slightly from idle. Now, the 1-2 shift is as it should be and the 2-3 shift flare is totally gone.

Best $35 ever spent! Took 1 hr. start to finish. Probably saved me from trashing a trans.

formula_novice

iTrader: (1)

Thanks for posting this! I've been having issues with my 700r4 shifting also. Where do you hookup the gauge on the transmission? Do you test the pressure driving the car or while in park?

leeperryracing

thereis a 1/4 npt port on the side of the tranny above the shift linkage for the gauge. Do NOT drive the car while making initial adjustments.

http://www.tciauto.com/Products/Tech...e.asp#TH200700

After you get it in the "ballpark" which will be somewhere between min/max pressure, you can now take it for a drive and see how it shifts and adjust from there if needed. I burnt up a nicely built 700r4 once(borg warner HD clutches, beast sunshell, transgo shift kit, 13 vane pump etc.) because i didn't use a pressure guage....believe me i almost cried, i didn't get 50 miles out of the damn thing before 2nd gear let go and 3rd was flaring!

84Elky

You’re welcome. It’s where leeperryracing said. The Bowtie gauge comes with a 90 deg 1/8” male NPT to 1/8” female NPT bushing. Just remove the existing 1/8” plug and install the supplied 90 deg bushing. It’s not easy as there is not much room up there, but it does not have to be overly tight [use some Teflon tape to make screwing it in easy]. Once the 90 deg bushing is in place, screw the end of the pressure gauge hose into the bushing. Look at this:
http://www.tvmadeez.com/press_gauge/pressgauge.html

If you can, jack the car up on the right rear side. In this way, you will only loose a couple of drops of fluid when you removed the plug.

The gauge [http://www.bowtieoverdrives.com/catalog/catalog.php?Action=GETSUBCAT&CATID=SA2] comes with a 7’ hose, so you run it out from under the car (tie it up underneath with a couple of cable ties if there is any chance it will touch exhaust, headers, etc.). Now you can use it under the hood as you play with the TV cable and throttle.

You fix the TV cable issue while it is idling in Park. Set it so that there is immediate pressure rise when moving the throttle off idle. Note if you have a carb and not TPI, you must have proper geometry between the throttle arm and the TV cable attachment. Look here: http://www.bowtieoverdrives.com/Instructions/Holley%20Spread%20Bore.PDF

After the TV cable is fixed, you can pull the gauge inside the car through the window while you are driving to test pressures in each gear as indicated in the link leeperryracing posted. Note however, there are many versions of the 700R4 and each has different pressure charts (see attached from GM manual). Frankly, you just need to be close on pressures. If you are not in a position to disassemble your trans to fix a pressure problem, any pressures you see while driving or testing at certain RPMs are merely informative as to identify a major problem or how you compare to specs. Not much you can do about it.

When done, unscrew the gauge and put your plug back in the 90 Deg bushing to close things up.

Also read these. Very informative.
http://www.tvmadeez.com/tvcable_instructions/braidedadjust.html
http://www.tvmadeez.com/article/