Turbo 350 Transmission Kickdown Adjustment

[81GMCSierra1500]

Hi Again guys,

I'm having a wee issue with my transmission, I'll punch the gas, and my transmission just won't kick from 3rd to 2nd... or "passing gear." I am curious how to go about adjusting it, I really don't want to blow my transmission.

Cheers,

[geezer#99]

Simple process!
On the backside of the bracket that the kick down clips too there is a small tab on the cable.You push the tab up from the bottom, open your throttle wide open, hold it open and push the tab back down.
Then go out and test.
Speaking of test. Where on this little Island do you live?

[81GMCSierra1500]

I will try that! Can I just turn the throttle valve by manually from the carb? And I'm up in the Comox Valley, it's awesome to see somebody else on the forum this close! Thanks for the help!

[81GMCSierra1500]

Just went out to try, there are two cables, one smaller one at the top of the bracket, that gets pushed into the housing at WOT, and a much larger on at the bottom that gets pulled from it's housing at WOT, there is no "tab" on either cable... I'll take it to a shop tomorrow...

[rich weyand]

The cable that goes into the housing is the throttle cable from the pedal. The one that gets pulled out is the trans kickdown cable. Here is what the cable termination looks like. The "tab" is a slider through the termination behind the bracket, shown in pic 1 in the "open" position. Open it, have someone push the pedal to the floor, then slide it "closed" (pic 2).

[81GMCSierra1500]

Originally Posted by rich weyand

The cable that goes into the housing is the throttle cable from the pedal. The one that gets pulled out is the trans kickdown cable. Here is what the cable termination looks like. The "tab" is a slider through the termination behind the bracket, shown in pic 1 in the "open" position. Open it, have someone push the pedal to the floor, then slide it "closed" (pic 2).

Hi, That doesn't even remotely look like the one I have, and if it does, I hope I'm not missing that tab, because I couldn't feel it in there... Like I said, I'll take one more look at it in the morning, and if I can't get it then, I'll take it to a shop... I heard that you can destroy a transmission by not having it set correctly, so I'll have to do it soon...

[geezer#99]

Excellent pics Rich!!
Maybe you don't have a turbo 350. Could be a 700R4 for a turbo 400.

[81GMCSierra1500]

Originally Posted by geezer#99

Excellent pics Rich!!
Maybe you don't have a turbo 350. Could be a 700R4 for a turbo 400.

I'll try to get a photo now of what my setup looks like. How to I attach a photo?

[81GMCSierra1500]

Hi geezer,

Here are a couple photos of my throttle cable/kickdown bracket, in the photo where the kickdown cable is visible, the cable itself appears to be very slack, as it bends in between the housing and valve assy. The upper one and spring are not the worry (they're the throttle cable & return spring), but the problem is, I couldn't really get my fingers in the space where the button could be, and when I did, I couldn't feel any sort of "adjustment button." I've attached a photo of the trans too, so you guys can judge what kind of trans it is, I know the photo isn't great, I never got a "full view," but my original had a cruise control option, and the replacement was identical, minus the CC. (I was told it was a Turbo 350.

[81GMCSierra1500]

This just in... Did some research, I have a 700R4 Transmission, not a 350. If that is judge-able just be looking at the kickdown cable. At least that's sorted! Now, same adjustment procedure?

[geezer#99]

Perhaps not!!
That last pic is a turbo 350 or 700r4.
Easy to tell by the position of the modulator.
Turbo 400 has it on the passenger side closer to the front.
And the cable by your carb is the tv cable.
I got a pic of it in my Haynes manual.
You better get a pro to check it out. Trannies aren't cheap. Wrongly adjusted could toast it quickly.

[81GMCSierra1500]

Originally Posted by geezer#99

Perhaps not!!
That last pic is a turbo 350 or 700r4.
Easy to tell by the position of the modulator.
Turbo 400 has it on the passenger side closer to the front.
And the cable by your carb is the tv cable.
I got a pic of it in my Haynes manual.
You better get a pro to check it out. Trannies aren't cheap. Wrongly adjusted could toast it quickly.

Yeah, that's what I thought. I was really worried, and am kind of freaked out that it was able to get from Victoria to here... I'll take it to my local shop tomorrow, but still do let me know when you're in town!

[rich weyand]

Originally Posted by geezer#99

You better get a pro to check it out. Trannies aren't cheap. Wrongly adjusted could toast it quickly.

As in, on the way to the shop. How far away is your shop?

Of course, you haven't toasted it yet apparently. But I wouldn't recommend you adjust it yourself. Take it to the shop.

[81GMCSierra1500]

Originally Posted by rich weyand

As in, on the way to the shop. How far away is your shop?

Of course, you haven't toasted it yet apparently. But I wouldn't recommend you adjust it yourself. Take it to the shop.

The shop I am a regular at, is less than three kilometers away.

[81GMCSierra1500]

Slowly, I'm feeling more and more stupid, as I've been driving it like it is (just around town) for a couple weeks... So I'm really pissed at myself... but I'll get 'er done the right way and my shop tomorrow.

[geezer#99]

Send me a pm with your contact info and where the local shop is. We'll buzz you when we're close and maybe meet you there. Boss wants to stop in Bowser.

[Tx Firefighter]

First, you have a turbo 350. I can see the vacuum modulator on the right side of the picture you posted of your trans.

Second, you have an aftermarket kickdown cable not an original GM one. It adjust slightly differently than was described above. Rather than lift the tab like he showed, yours requires you to push the button. In the top picture you can see a silver button on top of the cable. Push it down, turn throttle to wide open throttle and release the button. They are sometime pretty stiff to push down.

[MountainGoat1966]

I must have a weird 350 then.
I tried adjusting my cable but to no avail, it was constantly kicking down at higher engine and road speeds and passing gear was not needed at the time.
I disconnected the cable one day and left the vacuum hose hooked up to the modulator. It drives and shifts perfectly normal, kicks down exactly as needed at the right time and speeds.
And I did verify it's a 350 by the shape of the oil pan.

[Rich72C10]

Sorry to dig up this thread but I seem to be having a smilier issue... I get a kick how up to about 40mph - don't know what hear it is going in but I feel it and I see my RPMs popup. Then past 40 and most definitely at/past 50 no kick down. Which when I am at 50mph I am right about 2k RPMs. Manual downshifting works a-okay.

So this button at the bottom (darn hot back there btw trying to push it up) I can feel it push in but am I suppose to see it push up from the top? So I can push it down once I am in WOT? Should I spray some lube in there?

Three photos attached of my TH350 Kickdown for my SBC350. 1st is where it is connected to my throttle, then what the front of it connected to the bracket and then the flip side of it (using a mirror - kind of a crap photo).

[Rich72C10]

Well, never mind I did spray a little liquid wrench and let it soak. After a bit of time I put my rock on the gas pedal and give it a go again. Still did not want to popup but I could now feel the top coming up. So I helped it ever so slightly with a small screw driver. The thingy came up and the back spring when "BOING". Then I made double sure I was WOT and push the top down.

Oh My Gosh, I now have some great shifting with WOT in all speed ranges! It is a whole new truck from taking off to punching it at 50mph!! Hot Damm, I running good now!

Called my brother (he did the rebuild) and confessed "ahhh, I forgot to do that after I put it back together". That dork, I knew I was right and it wasn't given me all it could LOL!!


Edit: Opps. I just realized I was in the wrong sub-section!! Sorry guys But here are some links of me at 50mph and from me making a right turn, then punching it

https://drive.google.com/file/d/1Fzz...w?usp=drivesdk

https://drive.google.com/file/d/1taq...w?usp=drivesdk