700R4 Shifting too Soon when Pulling a Load

[85K10SB]

Good morning,
    Truck info; 85' K10, 350, 4:11 gears, 33" tires.
Recently I found my converter lockup switch on the brake pedal out of adjustment, it wasn't being depressed at all.  I reset the switch and now my converter locks up perfectly and my rpm at 60mph was reduced by 250r pm and fluid temps are much cooler while running in OD.  The transmission has never performed this well since I bought the truck in 07'. 
   Now onto my problem.  I pulled my boat to the lake yesterday (3800lbs roughly) and the transmission is shifting from 1 to 2 waaaaaayyy too early.  From a stop, it makes the shift before I complete a turn through an intersection causing the engine to lug terribly.  It will also shift into 3rd too soon if I let it.  I bypassed the problem by shifting it manually and the shifts were firm with no issues.  I have red that trying lighter governor weights could help cure this problem, but, why would the transmission only do this while pulling a load?  One peculiar thing I should mention is my truck has a diesel TV cable installed on it.  I'm not sure why as it was on there when I got the truck.  If I adjust it the way you adjust the button type cable pressure is way too low and the transmission slips horribly at every shift.  Through trial and error I have it set to where it felt "right".  Is it possible that my cable is set too tight causing higher pressure and thereby giving me early shifts while towing but good performance while bobtailing?  I think I'm on the right track to fixing this anomaly but I would appreciate your experienced opinions on this problem.  Thanks for your time.

Josh

[VileZambonie]

You have your logic reversed. Try tightening the cable as tight as you can get it without impeding on the throttle from fully opening and use that as your baseline setting. If it shifts too late loosen it one click at a time and see if you can get it dialed in right.

[85K10SB]

Thanks for the response.  I'll give it a try and report the results tomorrow evening after work.

[jg1977c20]

dont do any guessing when adjusting the T V cable you really need to do this with a pressure guage on the transmission as that cable controls line pressure , a good number of these trans have been destroyed this way ,and its never a good idea to use O/D when pulling a heavy load .

[VileZambonie]

dont do any guessing when adjusting the T V cable you really need to do this with a pressure guage on the transmission as that cable controls line pressure , a good number of these trans have been destroyed this way ,and its never a good idea to use O/D when pulling a heavy load .

Although a weak 700R4/4L60 may burn up with a loose TV cable, it is a misconception that you cannot adjust the TV cable using the baseline setting method nor should you be fearful of using this method. In fact this is the method GM stuck with throughout it's production years. You do not need to set and test your adjustments with a pressure gauge. In fact you will not be able to accurately differentiate the TV pressure since it's derived from mainline pressure which is variable so essentially you would be wasting your time unless you are doing an overall health check or pinpoint test. There is no linear spec that will satisfy your specific driveline needs as the adjustment is intended to allow the trans to respond appropriately to driver demand. Thank the internet for tons of repeated misinformation around this unit and websites dedicated to masking underlying problems with over analyzing the TV cable adjustment. You can tow with overdrive however it is recommended that you manually shift into overdrive appropriately and add an auxiliary cooler.

[LTZ C20]

dont do any guessing when adjusting the T V cable you really need to do this with a pressure guage on the transmission as that cable controls line pressure , a good number of these trans have been destroyed this way ,and its never a good idea to use O/D when pulling a heavy load .

Although a weak 700R4/4L60 may burn up with a loose TV cable, it is a misconception that you cannot adjust the TV cable using the baseline setting method nor should you be fearful of using this method. In fact this is the method GM stuck with throughout it's production years. You do not need to set and test your adjustments with a pressure gauge. In fact you will not be able to accurately differentiate the TV pressure since it's derived from mainline pressure which is variable so essentially you would be wasting your time unless you are doing an overall health check or pinpoint test. There is no linear spec that will satisfy your specific driveline needs as the adjustment is intended to allow the trans to respond appropriately to driver demand. Thank the internet for tons of repeated misinformation around this unit and websites dedicated to masking underlying problems with over analyzing the TV cable adjustment. You can tow with overdrive however it is recommended that you manually shift into overdrive appropriately and add an auxiliary cooler.

This is the most accurate information I've seen here yet.

[85K10SB]

dont do any guessing when adjusting the T V cable you really need to do this with a pressure guage on the transmission as that cable controls line pressure , a good number of these trans have been destroyed this way ,and its never a good idea to use O/D when pulling a heavy load .

I don't tow in OD and never stated that I did.  I did however adjust my cable and the transmission responded favorably.  I think I need a new cable or a trans rebuild because the cable is preventing the carb from achieving WOT.  It's not far off but still restricting it none the less. If I adjust the cable to allow WOT, pressure is way too low and the shifts are slipping badly. I'm thinking the diesel style cable may be the problem...I'll post findings when I get to it.

[85K10SB]

Now it's doing something different.  While NOT towing, the shifts are firm but it it feels like the converter is locking up in 2nd gear.  Kinda feels like a two stage shift, it shifts normal then engine rpm drops again once it's in 2nd.  I've had a few 700r4s and don't recall any of them feeling like this.  Any thoughts?  Doesn't seem right to me but I don't low what would cause this.

[VileZambonie]

Are you sure it's not in 3rd gear when the converter locks? Are you manually shifting to verify? Have you checked the governor yet?

[85K10SB]

It's definitely not locking in third.  Yes I manually shifted it and it did the same thing.  If I stuff my foot in it it feels OK but under normal acceleration it will lock and lug in 2nd.  I have not checked the governor.  Never had one apart before.  What should I be looking for once the cover is off?

[VileZambonie]

Remove it, make sure the the valve is moving, check the springs and weights.

Unplug the TCC solenoid connector and see if it still happens.

[85K10SB]

Thanks for the directions...I'll get into it tomorrow and report back.

[85K10SB]

I think I should clear the bad info I have provided in this problem.  My problem was not shift points as I originally thought, it was the converter locking up too soon.  I just unplugged the TCC solenoid connector and all my problems went away.  It shifts perfect whether I am accelerating hard or slowly.  So now that I finally completed that simple trouble shooting step; Where do I go from here?  I would like to get converter lock up working properly because it keeps the temp way down compared to running unlocked in OD.  My truck DOES have the firewall mounted vacuum lock up switch.

[VileZambonie]

check the wiring and check the pressure switch. If all else fails put a standalone wiring kit in.

As far as the trans fluid temp goes, an auxiliary cooler is cheap.

[85K10SB]

I have an aux cooler.  With the lock up functioning it never runs above 135° in OD.  Without the lock up it fluctuates between 160 and 180°.  My guage is getting temps from fluid that is on its way to the radiator and aux cooler via the line.  There have been occasions (not frequent) where the fluid temp has hot the 220° mark while in OD on a longer trip.  Are these temps normal for where I'm getting them from?  Thanks