Hello.

My problem started 2 months ago, when suddenly after 5min parking the gearbox was not shift over 2nd gear in "D". Starts with 2nds gear, few seconds moving and then shift to 1st gear. It shifts to 3rd from 1st, when speed up to max rpm. 4th gear wasn't absolutely. Same case is with "OD" too. In "3" its starts with 2nd and shifts to 3rd without problems. Also it wont downshift to 1st. Those shifts (2-3, 2-1 and 1-3) were decent - no slide or any other anomaly.

Last week i finally found time and uninstalled transmission. I was disassembled oil pan, valve body and 1-2 accumulator housing. Found that 1-2 accumulator spring(yellow) was into halves. Becouse of that, the piston was scratched the inner side of housing. Gasket was okay.
Is this possible, that it caused the problems?

There was no metal dust in oil pan and VB. Only little sedimented black **** in the bottom of pan. Other oil was red, not black and there wasn't any burn smell.
I also broke that big black gasket between valve body and separator plate, because it was so fragile. Have to buy new one from ebay, if possible.

I have read many manuals, but still i dont understand all. There was 3 check ***** in VB. Didn't understand, where exactly they're go. I found several different pictures for these. My gearbox number is 8YMM123C


Excuse me for my bad english.


Waiting for any kind of help,
Henri

 

I recommend putting in a shift kit. I used Probuilt's and like it very much: https://www.700r4l60e.com/store/product.php?productid=533&cat=65&page=1

 

This isn't fit to my gearbox, i think. They say this is for 1982-1987 models, but i have 1988. (8YMM123C)

 

https://www.700r4l60e.com/store/prod...&cat=65&page=1

Posted the wrong one, sorry. Very complete kit, comes with modified instructions, corvette servo (must have) and a brand new separator plate (w/ gaskets). If you provide enough information Dana (Probuilt) usually predrills the separator plate. He also recommends a better torque converter (https://www.700r4l60e.com/store/prod...&cat=59&page=1), but I understand if that is out of your budget.

 

Okey, that's better
But what you think, will this kit removes my problem? Sure thing is that the 1-2 accumulator spring was broken. Is this possible that this spring causes that kind of problem?
Do I understand right, in this kit is also this 1-2 accumulator piston, gasket and housing? I need housing and piston too, because mine are a little bit scratched.

Anyway I sent them email to ask, will they ship it to Estonia and how much is cost.

 

some pics

 

I ordered and istalled this kit. Still the same problem. Any thoughts?

 

That's because you didn't fix the real shift problem if you only did the shift kit and replaced the accumulator spring (with the upgraded parts or eliminated it). The 2nd gear starts, random downshift to 1st then upshift to 2/3, etc. is either a problem with the governor not working properly, a mis-adjusted TV cable, stuck TV Valve, or a stuck valve in the valvebody.

Since (I'm going to assume here) you probably pulled and cleaned the valve body thoroughly when you installed the shift kit and made sure all of the valves operated smoothly and there were no burrs or binding in it, then I would start at the governor and make sure that the valve operates smoothly and the gears (drive and driven) are in good shape, etc.

 

Describe what is happening here exactly. Do you have 3rd gear? 4th gear? If you are having a hard time getting 3rd gear, and or it won't hold, then the black stuff in the bottom of the pan was most likely the 3-4 clutch material.

 

On "D", it start with 2nd gear, then it shift to 1st and that's all. Driving with that 1st and shift manually to "3"(number 2 on the display. I have "2" and "1", because originally there was TH350(?) with 3 gears.), then it shift up, but I dont understand anymore, is it 2nd or 3rd. I think, it's 2nd, because @50km/h, the rpm is too high, listening with ear.

Today I disassembled the governor and it was like this:




oops


So anyway I need to get new governor gear. Have to do little research, is this available in Estonia. (if anyone have for sale and can send it to Estonia, let me know)

Can it cause the problem I have?

 

Replaced the governor gear, still the same.

 

Shift cable bad? Cable to trans bracket broken? Bad shifter adjustment? If your indicator is not reading correctly this could be the problem. I had similar issues. Improper shifter adjustment can cause internal damage.