Trans will not upshift under WOT

[Knute]

Hi, my trans will not shift under WOT. 1987 Buick Grand National 200r4 I changed the filter and fluid and tried to adjust the tv cable. I do not believe the cable will adjust correctly. I push in the tab and pull the sheath all the way back towards the firewall. Then I do three WOT with the accelerator pedal and only about (maybe) 1/8th in. comes out. I can't even see the teeth. With this setting, the trans would not shift up unless I was almost completely off the throttle. So I played around with the cable. I pulled it off the throttle blade and pulled on the cable by hand. It moves but seems tight. I am not sure how it should feel because I don't work on older transmissions. Anyway, I was able to push in the tab and force the sheath back forward towards the cooling fans and it looks to be out about where it was originally. Now it shifts better under moderate acceleration(even 3/4 throttle) but still not WOT. I am thinking I am compensating for something else by adjusting the cable. I understand the governor valve and tv valve are fighting against each other to allow shifting. TV for kickdown, governor for upshift. My understanding is the when the governor valve exhausts it allows an upshift. It exhausts when the valve overcomes the spring pressure. Thus if the spring was worn, it should shift too soon but it does the opposite. I guess I have to pull the pan off once again but I don't know what I am looking at(aside from the normal, valve body, ports etc. I am just not sure which one is the governor valve or tv valve). I can't find any good diagrams online (so far) of how everything should look. I figure since the TV cable seems tight ( I can still move it) that maybe something is jammed but maybe that is how it should be? Even so, I thought a binding TV cable causes an upshift only under WOT. So to recap, the trans does not shift under WOT unless I left off and back in it. I can't get the TV cable to adjust properly either (at least I think so). The very first time I adjusted the TV cable, there was slack in the cable. Now there is no slack but it does not seem to come out far enough and it causes the trans not to shift unless I am almost completely off the throttle. Thanks for the help.

 

[INEEDAGN]

hold the throttle blade wide open and manually adjust the cable so that it hits its max extension at the exact point of wide open throttle. no more, no less. It needs to allow wide open throttle without trying to rip the cable apart but also must not allow any more cable movement beyond wide open throttle. Sometimes the ratchet method simply doesn't work.

 

[Knute]

ok, i did what you said but now there is some slack in the cable..is this considered normmal? i am on my phone now so sorry for the grammatical errors.

 

[INEEDAGN]

Looks way too loose. Either it's not set right or the tv plunger is stuck in the valve body. When you set it I want you to pull the cable hard to make sure that the cable is indeed Bottoming out in the trans. There's a point in its motion where it will get stiffer spring pressure against it but will continue to move Needs to be completely maxed out at wide open throttle. If in doubt, tighten it one click at a time and try to go wot until you can see the throttle blade trying to tweak the cable/bracket forward. Then you'll know it's maxing out the cable. That pic looks really loose

 

[fastblackracing]

excellent description on adjusting the cable ^^^^^^^^^^^^^^^^^^^^^^^ This should have you within 1 click of perfect.

 

[Knute]

Ok thanks, I will try that today. Maybe the plunger is stuck becuase I remember that cable feels tight to move by hand. If the plunger is stuck, should I just try to free it up (possibly file it if it has burrs) or get a new one (or new valve body). Do you think this will cause the no upshift at WOT or just the incorrect cable adjustment? To replace the cable would I have to drop the pan anyway? Just was wondering if there is anything else I should check while I am in there. I figure I will change the filter and fluid again.

 

[INEEDAGN]

Ok retyping this reply from my goddamn phone thanks to the endless forum errors on windows based devices....

IF it's a stuck plunger, the plunger can be removed without removing the valve body. It's held in place by a roll pin. The large tv plunger spring will be behind it. It's probably salvageable with some fine grit sandpaper, think 400 grit or finer wet paper soaked in oil. 600-800 would be better, you just want to deburr it, not change its dimensions. If it's not salvageable, sonnax makes new plunger assemblies, available from any trans vendor here.

After rereading this thread, it actually sounds like a bad cable that's frayed internally and doesn't move freely. Yes it can be removed without dropping the pan, gonna be messy though.

 

[Knute]

ok, I adjusted the cable a tooth at a time..at wot the cable pulls on the bracket..there is no slack anymore..I am trying to find someone I know who has a tv cable on their car to see what they are suppose to feel like but so far no luck..the first pic is how far the adjuster comes out doing the procedure by the book(recommended setting) but causes no upshift unless i am completely off the throttle. the second is where the cable is now but no road test yet

 

[Knute]

ok, the big picture is where the cable is adjusted now

 

[INEEDAGN]

If it seems to be moving freely and retracting smoothly. Road test that sumbitch.

 

[Knute]

It seems to retract smoothly but I would say pulling it out seems tight still. Anyway, I road tested it and it still will not shift at WOT. I guess I will order a filter kit and see what I find when I drop the pan.

 

[INEEDAGN]

Probably find the governor spring...

Pull the governor cover and see if there's a spring behind the small weight.

 

[Matone213]

Probably find the governor spring...

Pull the governor cover and see if there's a spring behind the small weight.

Any update? Having the same issue.

 

[Ttype6]

My first guess is that you have a TV plunger spring that is longer than stock. This is a common upgrade at Extreme Automatics. Usually it is done in conjunction with the original TV valve (ink pen spring) being replaced with a conical spring. The other thing that can cause this is installing a spacer with the original TV plunger spring.

 

[Matone213]

My first guess is that you have a TV plunger spring that is longer than stock. This is a common upgrade at Extreme Automatics. Usually it is done in conjunction with the original TV valve (ink pen spring) being replaced with a conical spring. The other thing that can cause this is installing a spacer with the original TV plunger spring.

Yes car does have 1" spacer how does that effect trans shifts