700R4 1-2 shift issue, please help!

[AlexK10]

Hi, I'm having issues with the 700R4 on my 84' K10.

Ok let me provide details of what I've done and where I'm at.

Initial issue:

Not shifting from 1st to 2nd until 30mph. Engine screams at those rpms (don’t know the rpms, don’t have a tachometer installed), but based on the engine noise it seems very excessive at 30mph for a 1-2 shift. I've read its supposed to be near 15-20mph.

TV Cable

New TV cable adjusted properly at WOT, no change in 1-2 shift.

Disconnected the TV cable completely from the carb linkage. Some say this should give a stacked shift 1-2-3-4. Still the 1-2 shift is at 30mph and 2-3-4 is as always, not stacked.

Tried the pull and release method of the TV cable while on reverse gear and on drive gear. Several about 20 times each (reverse and drive) to free up the tv valve if its sticking, which I don’t know.

Still the same 1-2 shift at 30mph.

Governor

Checked the governor function and its free/no binding or rough action of the valve.

Original governor set up is both C weights, one white and one purple spring.

Bought a Shift Technology Products K018 governor weights and springs kit.

Read and confirmed with the instructions that heavier weights and springs give an earlier shift.

Installed the heaviest weights, A and B with the same white and purple springs - Now it doesn’t even shift 1-2, took it up to 35mph on 1st gear and it never shifted.

Installed the lightest weights, E and F with the same white and purple springs - Still doesn't shift 1-2, took it up to 35mph on 1st gear and it never shifted.

Next step:
Go back to the original C weights the governor had and see if it shifts at 30mph like it did originally.

Will use a gram scale to weigh and classify all K018 kit weights in relation to the original C weights.


Any ideas after that?

 

[AlexK10]

Update:
I weighed the weights I have out of the governor, and the original C weights are heavier than the A and B weights in the K018 kit.

So the first weight change I did to the heavier kit weights (A, B) actually were lighter than the original setup.

Original C weights - 15.1 grams
Kit A weight - 14.4 grams
Kit B weight - 12.5 grams
Kit C weight - 10.6 grams
Kit D weight - 8.3 grams

Pending E and F weights currently installed. Will weigh those in a few minutes.

Update: on E and F weights from K018 kit
Kit E weight - 7.0 grams
Kit F weight - 6.2 grams

I also tested the springs by hand and they are as follows:
Heaviest (Early shift)
Kit Black
Kit Blue
Original Purple
Kit Orange
Kit Green
Kit Red
Original White
Kit Purple
Lightest (Later shift)

Will reassemble with original C weights 15.1 grams and Black and Blue springs (heaviest from the bunch).

 

[AlexK10]

Ok this is the next update:
Ran the truck just now with the original C weights 15.1 grams and Black and Blue springs (heaviest from the bunch).

Result: Now its shifting 1-2 consistently at 25mph. Didn't get up to speed to check the 2-3-4 shift.

However I would like to get the 1-2 shift down to 20mph.

Let me add this, last time I had the trans out/when I was redoing the 305 top end, I installed a corvette servo. Before that change, I do not recall at what speed it was shifting at 1-2 but I wanted a firmer shift hence the corvette servo to apply more pressure to the band. I did get the firmer shift.

Another reason why I may not have noticed a late shift at 30mph before could be because the k10 had silent mufflers and now it has straight cherry bombs which are loud.

*Any idea how to get a lower 1-2 shift? Even stiffer springs? (Would need to source these at the hardware store since I'm already using the stiffest from the K018 kit. (Black/Blue)

 

[Matt69olds]

Is the TV PLUNGER free in the valvebody?drop the pan, make sure the tv valve comes all the way out. Is the 2-3 and 3-4 shifts also delayed? If so, that also suggests a tv valve problem.

 

[AlexK10]

Thanks Matt.

I have no idea if the TV plunger is stuck. I do know the TV cable with the associated hook and return spring inside the transmission case is ok (returning with spring action etc). But I guess that doesn't say much about the plunger itself.

I know there's a tv plunger upgrade available to prevent it from sticking. Does that upgrade require dropping the valve body itself or the whole transmission?

Will test Friday the 2-3-4 shifts and report back.

 

[yevgenievich]

If only 1-2 that is delayed, that rules out governor or tv valve. If all shifts only happen at high rpm/throttle position then stuck tv plunger likely

 

[Matt69olds]

I don’t think valve body removal is needed for the tv valve upgrade. Hopefully that’s your problem?

 

[AlexK10]

I am hoping dropping the valve body is not required, that would force me to drop the transmission and transfer case.

Does anyone have experience with doing the tv valve/plunger upgrade?

Any recommended part/kit numbers to purchase?

 

[Matt69olds]

Why would you need to remove the transmission to remove the valve body?



Here are the instructions for the Sonnax tv valve kit. Doesn’t say anything about removing the valve body, just the retaining pin

 

[AlexK10]

Hi Matt, I don't see your posted instructions but found them in the Sonnax site.

Are you referring to the 77966-94K kit?

Based on the instructions you are right, its only a retaining pin.

However, is there enough room between the case and the valve/plunger area to slide it out?

See attached image showing a "virtual" valve body out of the case.

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[HotRodPC]

OK, forgive me, I'm not reading all the other posts, so if it's been said already..... I'd highly suspect a stuck TV Valve in the valve body. Governor would have been my first guess, since it's easy to check. You've done that and satisfied that it's good, then #2, Check TV Cable adjustment which you've done and same result with it disconnected, so yeah, I'm going with hung up TV valve in the valvebody.

 

[yevgenievich]

If I remember correctly, valve body does need to come off to get the pin out. Install the 700r4 Jr kit at the same time. It comes with the anti stick piece for the TV plunger as well

 

[AlexK10]

Why would you need to remove the transmission to remove the valve body?

I've never removed the actual valve body. Is this something I can do under the truck upside down and not loose any check balls or springs that may be in it after taking out all its bolts?

Also, I found this on another forum that may be helpful to someone trying to diagnose a stuck TV valve/plunger: See attached image for credit to original post author.
"The easiest way to know if the TV valve is stuck is with a pressure gauge, Unhook TV cable, If pressure is over 100 psi....You have a stuck TV valve or Plunger.

If you had experience with this...You can tell by feel of the cable, Explaining feel on the internet can be tricky

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.

Pull the Governor out, Check for the gear being stripped Check for a stuck valve (Hold the weights closed & shake the valve) You will hear the valve if it is free. If the valve is stuck, Clean the governor good with brake clean 'till free. Reinstall governor & test drive.

If NO problems found with Governor, Remove Governor springs, Cut 2 1/4" long pieces of 5/16" fuel hose, Insert the fuel hose pieces where the springs were.
This will block the Governor open, If the trans now shifts....The TV Valve or Plunger IS stuck.
Depending on how far down the TV is stuck, The trans may take off in Second gear then do a real quick 2-3 & 3-4 shift.
This test is to ensure the trans itself is sound."

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[HotRodPC]

If I remember correctly, valve body does need to come off to get the pin out. Install the 700r4 Jr kit at the same time. It comes with the anti stick piece for the TV plunger as well

That's exactly what I'd do. It will fix other things too. Don't pay to much for that kit. Let me find the guy I bought one from on eBay not long ago.

Yes, to pull the pins to release valves, the body has to be dropped.

 

[HotRodPC]

Trans Go Shift Kit Jr 700r4. $24 Free Shipping.

https://www.ebay.com/itm/TransGo-GM...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649