View Full Version : TH-700-R4 T.V. Cable adjustment trouble
I have noticed an interesting situation with my Suburban... the transmission "coasts" like it's in neutral when you lift off the throttle at highway speeds. I had read that this is a condition that exists when the TV cable is too loose. So I re-adjusted my cable in the usual way: pressed the button on the cable and snapped the throttle open, the cable snapped into position. I held the throttle wide open and checked the cable, and it was guitar string tight. So then I test drove it. It shifted fine, just like before. Shifts were right on time, firm but not too hard, and it felt good, until I lifted off the throttle and the transmission coasted like I was in neutral again; the engine returned to idle at 60 MPH. I manually re-adjusted the cable tighter one click at a time until it stopped. This took 4 clicks. Once I did that, the transmission stopped coasting when I lifted off the throttle, but the transmission was holding the gears too long, the shifts were harsh, and you can't so much as breathe on the throttle pedal and it drops out of overdrive. Also, If I floor the throttle, the cable snaps back to it's "properly" adjusted position, and then the "neutral" coast at highway speeds returns. The transmission will re-engage with slight throttle pressure. What can be causing this?
When it doesn't coast does it still go into overdrive? I don't know much about the 700, but the 4L80 coasts when it's in OD and you let off the throttle.
When it doesn't coast does it still go into overdrive? I don't know much about the 700, but the 4L80 coasts when it's in OD and you let off the throttle.
Yes, it does, but because the cable is tighter than it is supposed to be, the transmission thinks that the engine is under more load than it actually is, and so it down-shifts almost immediately. The thing that bugs me about the coasting is that the engine returns to idle speed, and when you apply throttle to cruise or accelerate, the transmission engages in a somewhat rough manner. All the other driving dynamics are fine, and the fluid is at the proper level and is not burned at all. It looks like fruit punch.
Try placing the tranny in the D position and not the OD and see what happens.
With the 700 in OD the thing will freewheel unless the lockup is engaged.
Depending on how this has been wired up it normally drops out when the throttle is released.
I am assuming that this condition is a new one ???
The way you adjusted the TV cable (slide back then mash the throttle) is the correct way to do it.
Missy
In Drive it does not do it, only in overdrive. It is a new/old condition, in that it did it on the first test drive, but I adjusted the TV cable slightly tighter (it only took one additional click) and the problem went away. To be fair, my wife uses it all the time, but I noticed it last week when I drove it to the shop for maintenance. So I progressively tightened the cable until it stopped. I do not like that at all. I wonder about adjusting the cable with the snap throttle method again and then using a cable clamp to keep very slight tension on the cable at idle (I.E. clamping the cable with the fast idle solenoid engaged) because that literally is the difference between the coasting feeling and the transmission staying in gear. For the record, my trans has the aux valvebody, and the only electronic TCC control I have is a brake switch interrupt. The TCC may be disengaging because of the aux valvebody at 0% throttle, and therefore causing the coasting feeling. I hate the abrupt re-engagement when you so much as brush the throttle with your foot. Thanks for your input!
DmaxMaverick
05-30-2011, 11:53
For many model years, and depending on emission standard, it should "coast" with 0 (zero) throttle input while in OD/4. This is/was an EPA requirement for several applications, weight ratings and model years, local and Fed emissions.
If it "coasts" with the TV cable properly adjusted, then doesn't with the cable adjusted "one click" away from properly adjusted, then the cable is NOT adjusted correctly. This is a SURE way to fry the tranny prematurely (one click is all it takes). What you've done is taken away the TV's ability to sense Zero Throttle input. Stinky black fluid to follow..... You can do 4 things to help the 700 live a long life: Frequent service; properly adjusted TV cable; keep temps under control; keep the TCC locked as early/often as possible.
From your description, it is entering "coast" mode with the TCC locked with zero throttle input, then slamming the sprag upon throttle-up. Normally, it should also unlock the TC, which should engage shortly after throttle up, softening the engagement. Yours sounded normal, before "mis-adjusting" the TV cable.
The "coast" effect is the 4th gear clutch/band riding the sprag, with no reverse planetary lock. The torque converter may also unlock during this event, depending on model year, chassis and emission standard.
The Transgo HD shift kit and a TCC override can eliminate this condition correctly, with no adverse effects to the tranny.
For many model years, and depending on emission standard, it should "coast" with 0 (zero) throttle input while in OD/4. This is/was an EPA requirement for several applications, weight ratings and model years, local and Fed emissions.
If it "coasts" with the TV cable properly adjusted, then doesn't with the cable adjusted "one click" away from properly adjusted, then the cable is NOT adjusted correctly. This is a SURE way to fry the tranny prematurely (one click is all it takes). What you've done is taken away the TV's ability to sense Zero Throttle input. Stinky black fluid to follow..... You can do 4 things to help the 700 live a long life: Frequent service; properly adjusted TV cable; keep temps under control; keep the TCC locked as early/often as possible.
From your description, it is entering "coast" mode with the TCC locked with zero throttle input, then slamming the sprag upon throttle-up. Normally, it should also unlock the TC, which should engage shortly after throttle up, softening the engagement. Yours sounded normal, before "mis-adjusting" the TV cable.
The "coast" effect is the 4th gear clutch/band riding the sprag, with no reverse planetary lock. The torque converter may also unlock during this event, depending on model year, chassis and emission standard.
The Transgo HD shift kit and a TCC override can eliminate this condition correctly, with no adverse effects to the tranny.
While I understand that a misadjusted TV cable can cause problems, I have always heard that it was because of running too loose. I tightened mine an extra click as opposed to loosening. I am not disagreeing with you, but I have almost 20,000 miles on it running that way and the fluid is like fruit punch and there was no muck in the bottom of the pan when I changed my filter last week. I will look into the trans-go kit however, because I want it to run right when adjusted right.
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