700R4 shifting odd.

[Blue90]

I just installed a used 700R4 into my 88 K5 and wanted to get some opinions on what it doing.

When accelerating at a moderate speed from first to second it seems to be shifting at a higher RPM and more aggressively. If I accelerate in a spirited manner it seems to shift smoothly.
-This only happens from first to second gear.
- I have toyed with the TV cable mostly had it all the way out) but don't seem to be getting any noticeable changes. Wouldn't it shift smoother the further out it is adjusted?

 

[MajMike]

Yep . . .

Mine is similar except it pretty much always shifts hard from 1-2, but fairly smoothly between the others. I checked my tv cable and nothing changed, now wondering if a previous owner (po) maybe put in a shift kit.

 

[Blue85]

The 1-2 shift is normally the hard one in a 700, and also highest RPM. So if it's not extreme, you could maybe just live with it.

You should be able to tell some difference by adjusting the cable (but be careful with this!). It's possible the valve is stuck inside the valve body, but that's hard to know for sure without dropping the valve body. You should be able to disconnect the cable from the throttle (engine off) and flick it open a few times, which could (maybe, possibly) free the valve.

It's also possible somebody went overboard with a shift kit - like the did a higher pressure pump mod AND a bigger servo AND shimmed the 1-2 accumulator like crazy. This can make you think the ring and pinion will shatter.

 

[Blue85]

Try different throttle positions (like 10%, 25%, 50%, etc) and record MPH and/or RPM of the shift if you can.

 

[Greg Ducato]

My dead stock 60K mile 700R4 in my 1989 Burb does the same thing, if I back off a little on the tv cable it isn't as bad but then my shift timing in the rest of the gears is off and the line pressure is reduced. I pulled the pan, changed accumulator springs, checked band clearance, and made a few mods. I brought the 2-3 shift more in line but the 1-2 still is a little late and a little extra firm at light throttle. My next step is to have a look at the governor to see if the inner valve bore is worn, bleeding off governor pressure at low throttle and low speed. This is a head scratcher but I'll get tracked down