700R 1-2 shift, need help

[davet85]

I rebuilt my 700R about 3 years ago. Now I'm getting what
appears to be slipping on the 1-2 upshift. I've checked the
1-2 shift valve in the valve body, the 2nd servo, and the 1-2
accumulator piston. When I pulled the pan it was as clean as
the day I put it back together, the oil doesn't smell burnt.
What should I be looking for.

Also, since I had the vehicle I place the trans in park and
can turn the output shaft about 1/4 turn, I get a loud clunk
when going from park to reverse and from neutral to drive,
and thoughts.

 

[jwaller]

Re: 700R 1-2 shift, need help

check your line pressure and line rise to see if you have a TV related issue.

the clunk is totally normal, the parking pawl drops into a notch in the output ring gear and thats the clunk.

 

[George Blake]

Re: 700R 1-2 shift, need help

Pressures tell everything. Since it started all of the sudden, I'd think it would be TV related as well. Stretched line, worn out TV adjuster are the two main things that happen. Others have done work to the throttle body and not set everything back up appropriately. Try adjusting the TV cable. Push it in all the way and then rotate the throttle to WOT, if it clicks once or twice and then pops all the way out, the adjuster is shot and the cable needs replaced. When you pull the pan next time, make sure the forward feed tube is still connected and that the aux valvebody looks ok. I've seen issues with both of these components.

 

[davet85]

Re: 700R 1-2 shift, need help

I justed check the line pressures
park, neutral, od, 3rd read 75psi
reverse reads 125psi
2nd, lo reads 125psi

 

[George Blake]

Re: 700R 1-2 shift, need help

What do the pressures do as you increase throttle?
Did you drive it around and watch to make sure pressure rose as throttle was applied?

 

[davet85]

Re: 700R 1-2 shift, need help

When I adjusted the TV cable it just stayed all the way toward the
fitting, that is, when I manually open the carb to WOT it didn't move
at all, is that OK. I'll have to check the pressures while driving,
later today.

 

[George Blake]

Re: 700R 1-2 shift, need help

Your TV cable is shot.
Replace it very soon or the trans will burn up. As the TV cable pulls on the plunger in the valvebody, the response is increased pressure to hold the clutches due to increased engine load. With no increase in pressure, the clutches will slip and will very quickly burn up.

 

[Loeryder]

Re: 700R 1-2 shift, need help

When I adjusted the TV cable it just stayed all the way toward the
fitting, that is, when I manually open the carb to WOT it didn't move
at all, is that OK. I'll have to check the pressures while driving,
later today.

To adjsut your TV You should be pushing the metal button in and pull the cable towards the driver side of the truck.
Effectively pulling it away from the Throttle linkage.
Then opening the TB blades to WOT by hand you should hear it click or ratchet into place.

If it is not clicking at all the adjuster is worn out adn needs to be replaced.

 

[davet85]

Re: 700R 1-2 shift, need help

I'll install a new cable and see what happens, thanks for your help,
I'll let you know if that was the fix.