ragtopblue

So new trans cooler lines went in fine, ( aside from some adjustments to the bends ). But New issues have shown up after driving it with the new trans lines. No downshift passing gear won't go to 2nd and 3rd gears and can't shift into S and L gears at the console. Figured out the shifter issue, by detaching the shifter cable, Shifter has clear range, so I have a bound shifter cable. While under the car there is a suspect Trans Governor issue. I have a lead on an OEM unit. Need your input. AUG, 71 built but 72 model. Is this the correct part # for the TH350 and also TH400 ? UNITED DELCO #1 - 6261706 Unit is similar to this.

droldsmorland

First, verify sufficient fluid level.
Verify the vacuum modulator is hooked up, the line isn't obstructed and it's hooked up to the intake manifold.

matt69olds

If the fluid is full, and it absolutely won’t shift, most likely the govonor gear is stripped. Even if the modulator line is unhooked, it will still shift at the normal wot speed. Zero vacuum=wot.

pull the govonor, if the gear is stripped, make sure the govenor bore isn’t chewed up. The plastic gear is designed to be the weak point, if something prevents the govenor from spinning, the gear is designed to fail first.

if the governor isn’t spinning, as far as the valve body is concerned the car isn’t moving.

The gear can be changed if that’s all that’s wrong. If the case is chewed up, there are repair bushings available to fix it it will require complete trans disassembly, some machine work, and then reassembly.

ragtopblue

Thanks Matt69olds,
We did find a cracked rubber hose to the Vac Modulator and replaced it. The Module was working properly, I am suspect of the Governor and plan to install a new one, thus why I am asking if the Governor Part No ( # 6261706 ) is the correct one for my TH350.
And have the new shifter cable to install since floor shifter wouldn't shift into S-L, hard bind, When disconnected ( shifter cable ), the shifter has full range from park to L. I plan on seeing either a concave or broken gear, or gummed up valve body. or should say hoping to see, that way the problem isn't going internal to the trans.

Thanks T.

ragtopblue

Also, I have seen pictures of a few bad gears broken or concave, Question I had was especially when the plastic gear is broken, where are the broken parts? If mine is broken where do I need to clean out the debris? Or do i need to do that.

matt69olds

Th350 governors are a dime a dozen. If the only problem you find is a stripped gear, just replace the gear. That way you are sure to keep the same shift points.

Any governor will interchange, the calibration might be different. They make govenor calibration kits in the aftermarket. It just takes a lot of trial and error to get the shift points where you want them.

Most likely the stripped parts from the gear will end up in the bottom of the pan, or remain inside the govenor housing in the case.

I have no way of confirming the number you provided. I’d bet any part number will be a “service replacement” number, meaning it will work in any application regardless of engine or driveline. All that means is it will “work”, just won’t be ideal for every application. I bet if you install a service replacement governor in a W-31 car, the shift points will be much lower than the W-31 specified part. Which is why I suggest just getting a replacement gear.

If you just need a governor to get it going, I bet your local transmission shop has a bucket full of governors, or could order one for you. Just take you old governor with you, try to find one with similar shaped weights.

geardoc66

No downshift or upshift can also be caused by a stuck detent cable or valve. Have you checked the TV cable travel and adjustment?

matt69olds

even if the valve or cable is stuck in it’s maxed out position, it will eventually shift. Once vehicle speed reaches the normal WOT upshift speed, the trans should shift. The valve body can’t tell the difference between the cable being stuck fully open, or being held open by the throttle.

ragtopblue

Matt69olds, I found an NOS one that says / claims it is correct for 69-73 TH350 3 speed floor shift. But I'm going to check my assembly manual also for confirmation. But will give me something to do over the winter. Had engine rebuilt last year and is bored 0.60 over with stepped cam and 70 flat dish pistons, split exhaust manifolds and 2.5 dual exhaust X pipe, So it might be worth looking into changing the weights for a more compatible shift / engine ratio. First will be the shifter cable, cause I know that is an issue since I can't move the shifter to S and L on the console. But one thing I have also noticed is the engine idle is a bit high, trans shifts are hard when shifting between park, reverse, neutral and drive.

matt69olds

If the engine is idling fast, you might get a hard clunk shifting into gear. It will be even more violent if the high idle is caused b a split vacuum hose to the modulator.

Technically, 350 and 400 governors will interchange. The difference is the direction the gear teeth taper. I don’t remember which is which, but one of the trans has the govenor above the output shaft, the other is below. Because of that difference, the governors need to turn opposite directions. Th350 and 700 governors will also physically interchange, but they differ in calibration. Some people like to use the governors from S style 4 cylinder trucks with low gear ratios in in a 350 to get shift points far beyond what Hydromatic designed. Probably far more info than you wanted!!

I don’t know if the assembly manual will outline what gov came in what trans since I assume the transmission was delivered to the assembly plant fully assembled and ready to install. I’m sure someone has a parts list specifying each individual component that went into each specific calibration trans, but I have never seen one. There is occasionally a black stencil label on the governor, I assume that is a way to identify the governor part numbers. The stencil holds up in transmission fluid, it disappears in any type of cleaning fluid.