700R4 Information Thread

[Broken85]

Nick,
I recently got the 700R4 from my 85 K10 rebuilt. Transmission is installed and before I moved it, I pressure tested the trans per your guide and dialed in the TV cable. Here are the results;

1. Park/Neutral/Drive/3rd - 85lbs @ 1,000 RPMs
2. Reverse- 140lbs @ 1,000 RPMS
3. 2nd and 1st gear low - 110 @ 1,000 RPMs and at full TV extension

#1 and #2 above are near perfect according to your guide. #3 should be between 160-295 lbs, but I don't think I am going to get there.

I decided to take it for a drive, and it is running perfect from what I can tell. I can barely tell when it shifts it is so smooth, no slipping at all. Is 110 a deal breaker? Is it only a matter of time before it burns up? What would early symptoms look like? I took it back to the guy who rebuilt it (who will not remove or reinstall it that **** job is on me so trying to avoid it) he is going to put it on a lift next week and pressure test it himself, but if #1 and #2 are in spec, and I don't think there is anything else I can do to improve the 2nd and 1st gear pressures with just TV adjustments.

 

[NickTransmissions]

Nick,
I recently got the 700R4 from my 85 K10 rebuilt. Transmission is installed and before I moved it, I pressure tested the trans per your guide and dialed in the TV cable. Here are the results;

1. Park/Neutral/Drive/3rd - 85lbs @ 1,000 RPMs
2. Reverse- 140lbs @ 1,000 RPMS
3. 2nd and 1st gear low - 110 @ 1,000 RPMs and at full TV extension

#1 and #2 above are near perfect according to your guide. #3 should be between 160-295 lbs, but I don't think I am going to get there.

I decided to take it for a drive, and it is running perfect from what I can tell. I can barely tell when it shifts it is so smooth, no slipping at all. Is 110 a deal breaker? Is it only a matter of time before it burns up? What would early symptoms look like? I took it back to the guy who rebuilt it (who will not remove or reinstall it that **** job is on me so trying to avoid it) he is going to put it on a lift next week and pressure test it himself, but if #1 and #2 are in spec, and I don't think there is anything else I can do to improve the 2nd and 1st gear pressures with just TV adjustments.

There seems to be a leak in the manual low circuit as 110 PSI is too low if that reading is at full TV, per my guide. Ask the trans builder if he installed a Sonnax o-ringed reverse boost valve (I think the ratio is .283) - the o-rings seal off an otherwise worn bore where manual low pressure can leak. Could also be worn manual valve bore in that location in the valve body but these are just guesses. Lastly, the TV cable may just need some fine-tuning (you may or may not have tried to adjust it).

 

[Broken85]

Thanks for these suggestions Nick. I have tried to adjust the TV cable to bring this up. Park/Neutral/Drive/3rd and Reverse pressures increase, but low and 2nd stay the same. This is allegedly a new valve body, so it should not be a worn bore, but anything is possible. I will follow up after he looks at it.