700R4 help

[86C20crum]

Hi everyone. I've been cruising this forum for a while now. Great knowledge here. I'm having trouble with my 700R4 in my 86 C20. If I drive with the trans in OD it will miss 3rd gear almost every time. It will also miss 3rd on 4-3 downshifts under throttle. I can drive in 3rd and manually shift to 4th and it shifts great. I've adjusted the TV cable as per bowtie overdrive's. Any thoughts?

 

[Cuba]

How long has it been doing that? Have you ever done any maintenance on it? How many miles does it have (approx)?

 

[86C20crum]

I've owned the truck for about 3 months. It has done it the entire time. As far as miles, unknown, it's showing 85k. The truck is in great shape for the year but it has had a goodwrench 350 put in it. I haven't done any maintenance on trans. Fluid smells good not burnt.

 

[Cuba]

Well since it's done this the entire time, you really don't know how it was treated or how it was driven. It's possible internal damage at this point then. It's very possible the 3rd gear clutches are burnt or maybe the accumulator spring(s) is(are) broke.

I'm leaning towards the that clutch pack being burnt cuz that's quite common (4th too), especially without a cooler. Like I said, you don't know how the PO drove.

But the fact you can shift manually perplexes me a little bit. I know quite a few others on here are better versed with the trans than I, & rebuild them more often or tinker on them. They'll chime in soon, I'm sure. Still early.

 

[Ashton84W]

Although I may not be to experienced, I learned a good bit with me having troubles with my tranny. Could it possibly be that the check balls had worn their housings inside the valve body? Could that possibly cause this???? Idk for sure that just why I'm asking...

 

[Cuba]

No...check balls don't wear out in the housings... sometimes they wear out the separator plate itself, but it still functions.

 

[Ashton84W]

No...check balls don't wear out in the housings... sometimes they wear out the separator plate itself, but it still functions.

Alright just curious. Thanks...

 

[Cuba]

BTW, noobie 86C20crum, welcome to the forum!

 

[Cuba]

Alright just curious. Thanks...

No prob.

 

[86C20crum]

BTW, noobie 86C20crum, welcome to the forum!

Thanks

 

[86C20crum]

Well since it's done this the entire time, you really don't know how it was treated or how it was driven. It's possible internal damage at this point then. It's very possible the 3rd gear clutches are burnt or maybe the accumulator spring(s) is(are) broke.



I'm leaning towards the that clutch pack being burnt cuz that's quite common (4th too), especially without a cooler. Like I said, you don't know how the PO drove.

But the fact you can shift manually perplexes me a little bit. I know quite a few others on here are better versed with the trans than I, & rebuild them more often or tinker on them. They'll chime in soon, I'm sure. Still early.

The fact that it manually shifts without any slippage has me stumped also.

 

[MikeB]

Could it be a matter of the T/C locking up during the 2-3 shift, which might feel like the trans shifted from 2nd to 4th? Of course, that doesn't explain missing third on downshifts.

Would be nice to temporarily disable lockup as a test.

 

[Cuba]

Could it be a matter of the T/C locking up during the 2-3 shift, which might feel like the trans shifted from 2nd to 4th? Of course, that doesn't explain missing third on downshifts.

Would be nice to temporarily disable lockup as a test.

Well.. he can just unplug the trans connector to test that theory. At least up until 87, the only connections were the 2 wires for the TCC, I believe.

Easy to verify by counting the wires to tranny.

***CORRECTION***
I went and looked it up. It seems that there were trannys that did have solenoids that only had 2 wires connections before 87, so my prior post is void. The only way to tell is by trans model # & the number of wires to connector.

According to my manual, the (c) trucks with 5.0 & 5.7... 2WD also has 3 solenoids. Solenoids that were used specifically for 3rd. Also, 4-3 downshift and an 4th clutch switch.

Here's a pic that may help?

Looks like I'm having image uploading issues..grrr. I'll try again....

 

[86C20crum]

Well.. he can just unplug the trans connector to test that theory. At least up until 87, the only connections were the 2 wires for the TCC, I believe.

Easy to verify by counting the wires to tranny.

I've tried unplugging the TCC. No luck. I may have missed quoted by saying that it missed 3rd.... It doesn't skip to 4th, but like it hits neutral.

 

[Cuba]

Well.. he can just unplug the trans connector to test that theory. At least up until 87, the only connections were the 2 wires for the TCC, I believe.

Easy to verify by counting the wires to tranny.

I've tried unplugging the TCC. No luck. I may have missed quoted by saying that it missed 3rd.... It doesn't skip to 4th, but like it hits neutral.

Sorry I had to edit that post. I was wrong, I think. Lol
They made at least 15 different type VB setups..which include the wiring as well (from 82-86). I have at least 12 of those diagrams..but hard to say what you have inside without knowing the model # at least or removing the pan, even better.

Here's my 8th attempt at loading the image I wanted to in the last post

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