700R4 Transmission Questions/Issues

[NickTransmissions]

As odd as it is… the rig did sit for 15 years and it could be kinda stuck/dry/goopy in the transmission. I’m gonna keep driving it and if it doesn’t get better I think it’s the valve in the transmission. But im seeing minor improvements with each drive.

PS: it does manually downshift just fine and kicks down occasionally now

Perform a line pressure test - see my 700R4 Information Thread on how to do this. You're flying blind without knowing where your baseline transmission pressures are at the current TV set up and adjustment. If your line pressures are within spec, drop the pan and see what's at the bottom...If there's quite a lot of burnt clutch material, put the pan back on w/a few bolts and yank the unit out for overhaul.

 

[Burbinator86]

Haven't read the whole thread, but have you dropped the pan and changed the filter and filled with new fluid?

I haven’t. That’s my next step

 

[David King]

Welcome from the FL Panhandle!

 

[BadBowtie]

I'd drop the pan for inspection. Replace the filter, add the big bottle of Lucas Transmission Conditioner, and top it off with regular Mercon/Dextron IV. This will be a 50% fluid change. Then drive her a bit, let Lucas go to work....

 

[Nardulli]

I have just gone thru this with my '86 GMC build. There are a LOT of 'opinions' regarding how to adjust the TV cable. Here is what I learned as the surest method .

1. Remove the transmission pan.
2. Cuss and bitch about the trans fluid mess you just made. Resolve to get a pan with a drain plug.
3. With the throttle at the idle position, check the lash between the cable end and the plunger . It should be as close to zero lash as you can make it. The result is that ANY movement of the throttle moves the plunger . The plunger should not be depressed at all at idle. Nor should there be any free play between the cable and the plunger.

I'm anticipating many of the knowledgeable folks on here to disagree with this. This is not the only way, but in my experience, it is a sure way. I've done at least half a dozen in this manner and never had an issue and experienced good shifts at the right time.

 

[Burbinator86]

Thank you all for your help. I was finally able to drop the oil pan and there is definitely black sludge in it but no metal shavings. Keep in mind this probably hasn’t been changed in 10 years.

And yes…. It was a disgusting mess i made getting it off… and also smells awful (burnt/old smell)

 

[Burbinator86]

Filter too

 

[NickTransmissions]

Filter too

Yank it for overhaul. Install 97+ 4L60E bonded pistons and corresponding ret spring assy in the forward drum. Ensure the pump is vacuum tested, particularly the pressure regulator valve.

Let us know what you find once it's torn down.