Setting the Passing Gear Cable, TH350

[fxrsrider]

1975 C10 Shortbox
385 sbc, QFT 680cfm carb (basically a Holley)
TH350

How do I properly set the passing gear cable that is coming from my TH350 so that the passing gear engages automatically when I'm in third gear and step on it (say, to pass someone)?

This is what I'm thinking:
1. With the engine off, have someone push the accelerator pedal all the way down.
2. With acc pedal all the way down (throttle "fully open"), pull the cable that is coming from the TH350 until full tension is reached.
3. Tighten set screw on cable linkage such that the corresponding carb linkage is engaged at this full rate of tension.

Am I missing anything?

[enaberif]

Open this lock and open the throttle all the way then lock it down when at its max travel.

[fxrsrider]

Open this lock and open the throttle all the way then lock it down when at its max travel.
http://i80.photobucket.com/albums/j199/64elcamino/transmission%20stuff/tvcable1.jpg

perfect.  Thank you!

[LTZ C20]

I should probably point out that if it is a TH350 as you stated you have, they DO NOT use a Throttle Valve (TV) cable. The TV cable is used on the 200 and 700R4's. A TH350 uses a SHIFT cable.

[enaberif]

I should probably point out that if it is a TH350 as you stated you have, they DO NOT use a Throttle Valve (TV) cable. The TV cable is used on the 200 and 700R4's. A TH350 uses a SHIFT cable.

The premise applies for the Th350

[LTZ C20]

The actual purpose and use is different tho. A TH350 also uses a vacuum modulator. A 700R does not the TV cable is constantly changing based on throttle input, this changes fluid pressure. A TH350 uses a cable to command a down shift on hard accell.

The 2 do not function similarly.

[enaberif]

The actual purpose and use is different tho. A TH350 also uses a vacuum modulator. A 700R does not the TV cable is constantly changing based on throttle input, this changes fluid pressure. A TH350 uses a cable to command a down shift on hard accell.

The 2 do not function similarly.

Yes I know but you still have to adjust the cable on a TH350.

[fxrsrider]

It's a TH350 (not a 400).....and it definitely only has 3 gears and no overdrive (80mph @ approx 3500rpm)

I appreciate the dialogue so much!  But now I'm a bit confused. 
My linkage/cable seems to match the picture that enaberif shared in his initial response.  Apart from the "Unlock, then Lock" directions that he mentioned, I figured that the sequence from my original post was correct.

I've attached a .pdf and .jpg of my linkage and throttle & trans cables for your reference.  Hopefully it will help the discussion....and ultimately my question.

Thanks again!!!!

[LTZ C20]

Enaberif, I gave the explanation more for fxrsrider.

Fxrsrider, I understand it's a TH350, there is also a TH400 model transmission that is Biggers than a 350. A TH400 and a 700R4 are not the same transmission either. Just so you understand, there is a TH300, TH350 and a TH400, that are all in the same family. They use a shift cable.

There is a 2004R and a 700R4 that are in the same family. They use a throttle valve cable.

I want to make sure that Fxrsrider understands the difference and that there are different setup procedures for each.

[fxrsrider]

Enaberif, I gave the explanation more for fxrsrider.

Fxrsrider, I understand it's a TH350, there is also a TH400 model transmission that is Biggers than a 350. A TH400 and a 700R4 are not the same transmission either. Just so you understand, there is a TH300, TH350 and a TH400, that are all in the same family. They use a shift cable.

There is a 2004R and a 700R4 that are in the same family. They use a throttle valve cable.

I want to make sure that Fxrsrider understands the difference and that there are different setup procedures for each.

Thank you!!!!  Yes, I understand that the TH...family and the R4 families are different....(primarily that the R4 family has an overdrive gear and vacuums).

Thank you for the response and clearing things up. [correction] I am STILL NOT perfectly clear as to what I need to do to set the passing gear on my TH350 now.

If I'm on any of the LA freeways....flowing with traffic....say at about 75-80mph......and want to pass the tool in front of me who keeps braking for no apparent reason other than the fact that he/she is texting their Ph.d. dissertation, then I change lanes and floor the acc pedal.  But my tranny does not, currently, drop into 2nd....so my acceleration is gradual as opposed to potentially wheel skidding immediacy.....with a 385sbc (with an extremely aggressive cam) and my carb....I should be able to accelerate quickly....(and impressively).

If I downshift using my B&M, I get the performance I'm looking for.......But...particularly here in LA where there are plenty of "tools" to pass on the freeway every moment of everyday....I'm simply looking to properly set up my TH350 cable....in the photo above.....properly, so that my tranny takes care of the business for me.

[enaberif]

Look at the backside of the cable behind the bracket. You should see a clip part that can be lifted up with a screwdriver.

[LTZ C20]

Enaberif, I gave the explanation more for fxrsrider.

Fxrsrider, I understand it's a TH350, there is also a TH400 model transmission that is Biggers than a 350. A TH400 and a 700R4 are not the same transmission either. Just so you understand, there is a TH300, TH350 and a TH400, that are all in the same family. They use a shift cable.

There is a 2004R and a 700R4 that are in the same family. They use a throttle valve cable.

I want to make sure that Fxrsrider understands the difference and that there are different setup procedures for each.

Thank you!!!!  Yes, I understand that the TH...family and the R4 families are different....(primarily that the R4 family has an overdrive gear and vacuums).

Your welcome, The full name of a 200 and 700 is a TH2004R and a TH700R4. So they are the same family but are normally considered seperate. You could say that they have the same mom but different dads or are related by marriage haha.

 The R4 group originally do NOT use vacuum, only when a kit is used to control the TCC originally controlled by an ECM. The TH350 originally does use a vacuum source, as it uses a vacuum modulator during operation.


The rest of your response that I didn't quote made me laugh out loud. Thanks for that.

[rich weyand]

The "downshift cable" on the TH350 moves a valve that bypasses the vacuum modulator and provides full pressure ATF to the governor.  The governor then runs all the shifts without the vacuum modulator in circuit.  The shifts are then strictly rpm-based.  When a certain rpm is reached, based on the springs and weights in the governor, the weights swing out and depress the governor piston valve, which is being held in place by the pressure.  The springs and weights can be adjusted to change shift points.

When the modulator is not bypassed, it adjusts the pressure sent on to the governor based on the vacuum.  The more vacuum, the less pressure to the governor, the less pressure holding the governor piston valve out, the less rpms of the governor it takes to swing out the weights and depress the piston valve, and the sooner the shifts will occur.  The latest shifts (in rpm) will always be with the modulator bypassed and full pressure on the governor piston valve.

The recommended adjustment procedure is to pull out that clip-lock doo-dad on the cable end housing, hold the throttle pedal all the way to the floor, and then push the doo-dad back in.

If you want to cut the modulator out earlier in the throttle travel, you can push the throttle all the way down, then let up just a touch, and hold the pedal there while someone pushes the doo-dad in.

If the cable is adjusted improperly, you may cut the modulator out at half-throttle, say, or it may not get cut out even at full throttle.  Sounds like yours is doing this last.  This can happen if someone adjusts the cable while holding the throttle bell crank in full-throttle position when pushing the doo-dad back in, so as to be able to do it all under the hood.  The problem with that method is that full depression of the throttle pedal may not get the bell crank all the way to that position.  You really need someone inside the truck to set it properly.