700R4 Information Thread

[NickTransmissions]

Hey Nick,
In your vids you make reference to the TV exhaust check ball and recommend not leaving it out in case the cable snaps. Makes good sense to me! While I was servicing the tranny and replacing the TV cable I noticed the TV lever has pin on it that pushes against that check ball as the throttle valve is being pushed in. When should that pin start to push that ball up? My TV cable is adjusted per the factory service manual.
The reason I'm curious about this is late harsh 1-2 shift when just easing off from a stop. If I mash the throttle say 40% then the 1-2 shift is normal and has me wondering if someone ground that pin down some. How much is the line pressure boosted when that ball is on its seat?

The ball wont seat unless pressure drops below certain thresholds; however, over the years, many builders have found it will seat when it isnt supposed to as a result of variability in line pressure characteristics across individual 700R4s so many will decide not to mess with keeping it in.

All that said, the TV check ball is prob not your issue, more than likely you have too aggressive a 1-2 shift calibration that's producing the late/harsh 1-2 upshift only at part throttle. You could always drop the valve body and remove that check ball if you dont want it in there...

 

[Scooterwrench]

The ball wont seat unless pressure drops below certain thresholds; however, over the years, many builders have found it will seat when it isnt supposed to as a result of variability in line pressure characteristics across individual 700R4s so many will decide not to mess with keeping it in.

All that said, the TV check ball is prob not your issue, more than likely you have too aggressive a 1-2 shift calibration that's producing the late/harsh 1-2 upshift only at part throttle. You could always drop the valve body and remove that check ball if you dont want it in there...

I mentioned once before that this tranny was rebuilt so there's no telling what they did to it. I'll run it as is for now and deal with it. I forgot to mention that it's more pronounced when the tranny is cold. If I lift it pops right into second then I can roll on it again. I wish they had done more with the 2-3 and 3-4 shifts,those are a little softer than I like. I haven't made up my mind yet if I'm going NV3500 or 4L60-E and have been gathering up parts for both.

 

[NickTransmissions]

I mentioned once before that this tranny was rebuilt so there's no telling what they did to it. I'll run it as is for now and deal with it. I forgot to mention that it's more pronounced when the tranny is cold. If I lift it pops right into second then I can roll on it again. I wish they had done more with the 2-3 and 3-4 shifts,those are a little softer than I like. I haven't made up my mind yet if I'm going NV3500 or 4L60-E and have been gathering up parts for both.

Yea, my guard is always up a bit when I tear into a unit that I know has already been gone through before, especially if it was done recently...Sounds like the 2-3 feed, BR and 3-4 feed were not drilled large enough while the 1-2 feed was prob over-drilled. Common to see this when folks not familiar with those transmissions try to build them for performance...

 

[Scooterwrench]

Yea, my guard is always up a bit when I tear into a unit that I know has already been gone through before, especially if it was done recently...Sounds like the 2-3 feed, BR and 3-4 feed were not drilled large enough while the 1-2 feed was prob over-drilled. Common to see this when folks not familiar with those transmissions try to build them for performance...

Would lengthening that pin on the TV lever so that it's always holding the ball up unless the cable broke do anything for the 1-2 shift? What other side effect?

 

[NickTransmissions]

Would lengthening that pin on the TV lever so that it's always holding the ball up unless the cable broke do anything for the 1-2 shift? What other side effect?

Prob not, especially considering the rest of your upshifts are soft, which wouldnt likely be the case if the ball is playing a role here. Everything mentioned this far tells me the 1-2 shift was prob not set up correctly. Ball plays no role in that. You need to drop the vb/1-2 acc housing and look at the:
1. 1-2 acc piston and spring set up
2. 1-2 feed hole size in the plate
3. Valve body for mods, particularly to the line bias and 1-2 acc reg valve

You can also do a presssure test before any of the above to see what lp is at idle (min and full TV). If your pressures are normal, the ball is not the cause...

 

[tayto]

if the tv system has been modified (transgo) the factory adjustment doesn't really work anymore in my experience. even with a new GM cable they won't self ratchet. best to make sure the TV cable is tight at WOT

 

[Scooterwrench]

My TV cable is adjusted per the factory service manual.

if the tv system has been modified (transgo) the factory adjustment doesn't really work anymore in my experience. even with a new GM cable they won't self ratchet. best to make sure the TV cable is tight at WOT

Using the factory method does pull the cable tight at WOT at the TB,not the gas pedal.
I have thought of backing it off a click or two to delay kick downs a little. Right now it's downshifting at about 50-60% throttle.

 

[Erik the Awful]

Please get that TV cable right! It matters far more than you know, and there's an utter crapload of misinformation out there on "easy" ways to set it. Pull the pan if you want it right.

Not to demean Nick's expertise, but this video from Performabuilt is the best I've seen on the subject.

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[NickTransmissions]

Please get that TV cable right! It matters far more than you know, and there's an utter crapload of misinformation out there on "easy" ways to set it. Pull the pan if you want it right.

Not to demean Nick's expertise, but this video from Performabuilt is the best I've seen on the subject.

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Not demeaning to me as I haven't done a video yet on 700R4 or 2004R TV cable adjustments but when I do, i'll look to either produce an equivalently informative video to the Performabuilt's or exceed it in all respects.

There's no ETA on such a video as I almost never see the vehicles where my transmissions are installed.

To summarize, TV geometry and adjustment must be spot on and verified via a pressure test that takes readings at min and full TV. If that's not done completely and correctly, you're largely working in the dark (this is for anyone reading this especially if there' new to these units or TV adjustment, not necessarily Scooterwrench).

 

[Scooterwrench]

Not demeaning to me as I haven't done a video yet on 700R4 or 2004R TV cable adjustments but when I do, i'll look to either produce an equivalently informative video to the Performabuilt's or exceed it in all respects.

There's no ETA on such a video as I almost never see the vehicles where my transmissions are installed.

To summarize, TV geometry and adjustment must be spot on and verified via a pressure test that takes readings at min and full TV. If that's not done completely and correctly, you're largely working in the dark (this is for anyone reading this especially if there' new to these units or TV adjustment, not necessarily Scooterwrench).

I still haven't gotten the opportunity to make up a pressure gauge setup. I feel the pressures are OK as it shifts pretty good. It may have a Corvette servo in it. The 2nd and 4th shifts are pretty crisp and 3rd feels like factory. Only ill effects are the late 1-2 shift,TCC locking up as it's going into 3rd and the relock delay in the TCC when you roll back on the throttle and those are probably in the ECM program.