4r70w no reverse

[stretch]

Ok, fresh rebuild. I have forward gears, but no reverse. US Shift trans controller. Fluid level is approx lower third of stick when cold. I haven’t checked line pressure yet, probably this weekend. Looking for ideas that will keep me from dropping the tranny again.

 

[Broncobowsher]

Pull it into manual 1st gear. Get up to speed and lift off the throttle.
Do you have engine braking in 1st gear?

If not I would be looking at the low/reverse band.

And the controller should have no influence on reverse (except maybe lowering the line pressure). You can completely unplug the transmission and still have reverse and 2nd gear (with no engine braking)

 

[stretch]

Just ran it down the road. I do have first gear engine braking. I’m looking at the dip stick (Lokar, which I don’t care for) and the it barely registers when Its cold. I currently have 12.5 quarts in the tranny. Is it possible I’m still low?

 

[Broncobowsher]

I'm out of easy fixes. You said forward gear, all of them?
Leaning toward a stuck valve in the valve body.

 

[ratbilt]

I have an extra valve body (call me if needed 916-337-4557 Rich)

 

[stretch]

I appreciate it Ratbit. I'm going to check my pressures first. If these look good, I'm heading to the VB. I'll let you know.

 

[stretch]

Alright, tested it this morning. Started out at 65psi neutral across all gears at idle. Shifted back to neutral and reved the engine went up to 100psi or so. This is when it gets confusing. Trans shuttered gauge pressure dropped out then it went and held at 125 and stayed there. Put it in gear and it dropped to 120. Still no reverse and pressure held e same as neutral 125.

thoughts?

 

[stretch]

Scratch what I wrote earlier. Seems that the spike in pressure may have damaged my gauge. Using the 100 psi gauge, I’m still holding at a steady 65 psi across all gears. Pressure will rise with increase rpm, then it will spike and the pressure line and gauge will cavitate like it has air under pressure. I do have pink froth coming through the pressure line. I’m going to remove a little fluid from the system as I’m sitting on the high end of the stick.

 

[Broncobowsher]

Were you just checking main pressure, or checking all the clutch pressure ports? Sounds like you have line pressure. Now to see if it is getting to the clutches. I have my books packed away and can't look it up at the moment at what clutches should be pressurized in what gears.

 

[stretch]

Update time. Pull the valve body and initially didn’t find anything wrong. I checked the movement of all the valve, no problems found. Torquing the final VB bolts down and readjusted my grip, and notice a empty hole where the head of the boost valve was suppose to be. Looked everywhere for the head and couldn’t located it. Gave the filter a good shake d there it was Had to take the filer apart o find the accelerator valve that goes inside the head. All back toether now and I have reverse.