700r 1-2 shift. Flare? Slip?

[weq92f]

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Under light to medium acceleration, the tranny shifts good, at the proper speeds and works well. However under WOT, the 1-2 shift doesn't happen unless I lift...and I lift because it just feels wrong!

When the tranny goes to shift 1-2 at WOT, I can feel the acceleration wane then when it should shift the RPM stays where it is ( maybe rising just a bit ) and it very slowly engages 2nd. So slow that it isn't really a shift but more of a slip-into that feels to me like it's gonna break the thing unless I lift.

I took the pan off this weekend. The fluid was good, no off color or smell. The pan was clean aside from a decent amount of material on the magnet. I'd say the tranny has 8k miles since rebuild. TV has been adjusted as directed/researched/felt good to the point where 1-2 shift is pretty solid up until WOT or close to WOT. Running a BTO ratchet and cam.

Any guesses? Would a shift kit install be a waste of effort here? Should I just punt and take it to a shop?

-klb

[AussieinNC]

Way too many variables here, especially with a 700R4....

If you have done all the TV set procedures, fluid is correct level and and this only happens under WOT....take it to a shop.....

Dont be surprised if the 2nd band is toast....

[IIGW]

did this just start? if so, probably have bad news for you

[weq92f]

Originally Posted by IIGW

did this just start? if so, probably have bad news for you

Yes I figure this is bad news! Fortunately the thing is performing properly aside from the WOT shift. Although the shifts from 1-2 get more sloppy as the power increases toward WOT.

This behaviour has been the norm since I've owned the truck. I'm looking to correct it either by some easy fix or a complete rebuild!

-klb

[Bigdav160]

Throttle valve cable/linkage geometry is off or the valve is sticking in the valve body

[weq92f]

Originally Posted by Bigdav160

Throttle valve cable/linkage geometry is off or the valve is sticking in the valve body

I can adjust the cable to the point where my light throttle shifts occur at too high an rpm and are harsh. At that adjustment, 1-2 shift is still bad under heavy or wide open throttle.

Would that indicate the valve is sticking or some other mechanical issue?

Any easy check/fix for a sticking valve?

Pardon my tranny ignorance!

-klb

[cadillac_al]

FWIW my Dad bought a brand new 85 C10 with 305/700r4 and it never shifted right from day 1. WOT would totally confuse it. The dealer couldn't figure it out or fix it. I pretty much avoided those trannys since then and lived without OD all my life. I now have a Jeep WJ that works fine in normal driving but WOT totally confuses the trans. I don't fully understand automatic transmissions either. I hope somebody can point the OP in the right direction.

This may be one trans that does benefit greatly from a shift kit.

[AussieinNC]

700R4 transmissions can be reworked to make them drivable under just about all throttle conditions...

However......

Your statement about "decent amount of material" on the magnet in the pan is a RED flag warning....it doesnt take much to burn up the band , have it go metal to metal....and failure is just around the corner....

There are shift kits available.....most likely wont work to help your case...

There are several threads on here that deal with 700R4 issues....this one in particular is really detailed

https://67-72chevytrucks.com/vboard/...d.php?t=634121

Enjoy the read, but seriously...its shop time in my mind...

[truckdude239]

my best recomendation is let a shop that is very reputable set up the trans and tv cable together when they build the unit cause they can set it using pressure gaguges that way if it burns up again they cant say it was installer error