What happened to my 700R4: Freezing cold Sat. Edition

[the_experience3006]

I need to replace the transmission (or rather whole truck) so the fix really isn't important. I'm just looking for some bench racing advice as to what actually happened to the thing.

Last night it was BALLS ass cold out. It made slower shifts, but nothing out of the ordinary considering what dino based transmission fluid is like at -20. Then, on my way back in the driveway it wouldn't downshift to 1st...until it did...hard. Whatever...I went back inside.

Now today I went to drive the truck. I have no 3rd or 4th. I can accept that it has a burnt 3-4 clutch. Whatever. But why the FAWK will it only make the 1-2 shift at full throttle and wound up tight or at nearly no throttle on an icy parking lot? There is no in-the-middle 1-2 shifting to be done.

So...let's hear the theories.

[MrWillys]

Check the TVS???? It's worth a l@@K

[the_experience3006]

I could check it, but it's not really worth it. The fresh fluid that was in it is now brown, aerated, and fully of glitter. I'm not worried about it as the truck was just a beater and I'm done with it. I'm just curious as to what the series of events was that led to its demise. It did feel like the 2-3 shift "held up" a little last night. Now I know the 700R4 isn't a synchronous transmission, but I believe it is still possible for it to try and engage 2nd and 3rd at the same time. That would have cooked that clutch pack in a hurry and the debris in the fluid could be what's now causing my shifting woes in the gears I have left.

[ryan_thompson87]

That does sound odd. I think you are partially correct, I have heard if the TV cable is out of adjustment it can try to apply 2nd and 3rd together. Odd that your 1-2 is fucked up to, I have cooked 3 700R4s and drove them around for months with just 1st and second with the burnt ass fluid in them with no troubles what so ever.

[the_experience3006]

But TV cables don't just jump out of adjustment and it had been fine, perhaps even just a click on the tight side. I'm trained as a mechanic, but an auto tranny guy I am not. I've had nothing be problems with them over all the vehicles I've owned. Of course, I've also always had the ones that are noteworthy for their unreliability...TH200-R4, TH700R4, A4LD, 41TE....

[Big Red 88]

with 700r4's tv makes all the difference. they rely on that tv cable. if it breaks it will cook the trans quickly. thats what happened to mine, driving back from wheeling all the sudden i lost fourth (it had been about 7 yrs since it was gone through so i figured it was just its time) but by the time i got to the shop (about 25 miles) i had no third or fourth. when i pulled it to rebuild it i went to unhook the tv cable and realized it was busted, i work at a trans shop and i have seen that story a lot (except the wheeling part). as far as the 1-2 being wierd you're prolly right about all that material because that went through your valvebody and now your valves are prolly sticking

[the_experience3006]

Post mortem shows a burr on the 2-3 shift valve. It moves freely now, but I suspect that with the cold it did not. There was nothing left of the steels or the clutches in the 3-4 pack. I plan to throw a $275 junkyard tranny in it this weekend to get the beater back on the road and hopefully it will be all good for a few months anyway.