delayed reverse in 700

[redhotrod]

Hey all,
I need some help with a problem, just rebuilt my 700 in my pickup truck. I added a .500 boost valve, corvette servo, kevlar band, and a transgo 700 jr shift kit.
All gears work fine but my reverse seems like it is low on pressure. I dropped the pan and checked the reverse boost valve and pressure regulator to be sure they weren't sticking. Also checked the converter valve to see it that was sticking. And I also checked the accumulator overrun valve too. Nothing seemed sticky.
When I assembled everything, I pressure checked everything according to the atsg manual. Only thing that really leaked air was when air checking the overrun port on the input shaft it blew air out of the checkball near where the reverse input drum meets the input drum.
Something else I'm thinking is if I'm using a .500 boost valve, do I need to upsize the reverse boost valve?
I was going to go get some hydraulic hose to rig up a 300psi gauge to check pressure but everyone is closed today do to memorial day. I'll try and check pressures tomorrow.

 

[Otto J]

What year 700? In the model years 87 to 92 there was a problem with the piston in the reverse drum. THey made a fix for it, But being that it is back together, not much you can do. But in the piston they have a small capsule you put in teh bleed hole to make it smaller and gives a better an a reverse apply with no delay, It seemed that it only happened after a rebuild. Unless also you did stack the drum right?
Otto

 

[redhotrod]

The transmission I rebuilt was a 1991 (model CNM)
I was given this one to replace the original one in the truck. I tore the replacement down to upgrade and only thing noticably worn was the 3-4 clutches in the reverse input drum.
All the clutches were stacked right upon rebuild per atsg instructions.
If the piston in the reverse drum is this culprit, will it hurt to leave it be?

 

[Otto J]

How bad is the dealy? If its like 1 second leave it be. If its like 4-10 seconds something is probably wrong, Double check the pressure in reverse

 

[redhotrod]

you can feel the shift into reverse immediately but to get it to move takes some throttle, more than the forward gears.
I'll check the pressure tomorrow if I can get a hydraulic hose.

 

[Otto J]

Ok well that doesnt sound like the problem then, Either the seals in the drum, THe sealing rings on the back of hte pump or The reverse boost valve is installed upside down. If you feel the shift right away, its not the piston.