Slipping in 3rd; no downshift from 4

[turbojimmy]

I recently put my transmission back in after resolving a torque converter lock-up problem. The converter was not locking (Vigilante 5-disk). I had the trans and converter looked at; both checked out fine.

This time we installed Precision's pump kit and removed the checkball per their instructions. The converter locks up HARD now. That's the good news.

Bad news is that the trans slips bad.

I thought it might be the TV cable but I've adjusted it from one extreme to the other. If I let the throttle set the TV cable it will shift 1-2 fine but the 2-3 and 3-4 happen instantly at light throttle. At mid-full throttle it just slips when it tries to shift above 2nd gear. It won't come down from to 3rd from 4th unless I manually shift it, but 3rd slips anyway.

Tightening the cable (pushing the adjustment toward the firewall) fixes it to an extent, but 2-3 and 3-4 upshifts are sloppy and it will slip as it tries to downshift from 4-3 and 3-2. It will then not want to downshift as I cruise to a stop, I assume because the pressure is too high in lower gears.

I think tightening the cable is forcing a higher pressure that the transmission can't attain normally.

While the transmission was out the only changes, other than the pump tube kit, were:
- new Gbody radiator (possible defective internal trans cooler)?
- new lines spliced in (via flaring and unions, not compression fittings) at the trans (possible kinked line? one of the bends was tight....)

Any ideas would be appreciated. The car hasn't run right in almost 2 years now and I'm really at the end of my rope with this thing.

TIA,
Jim

 

[mikestertwo]

Sounds like you have low pump pressure. Put a pressure gauge on it and post the pressures.

 

[Lee Thompson]

If I remember right

The instructions with the lockup tube kit mentions nothing about sealing the tube in the pump body. May be sucking air BIG TIME !!!! I agree sounds like low pump pressure and maybe other things.

 

[turbojimmy]

The instructions with the lockup tube kit mentions nothing about sealing the tube in the pump body. May be sucking air BIG TIME !!!! I agree sounds like low pump pressure and maybe other things.

I think it is a problem with the lockup tube kit. Nothing else was changed. The pump was new and the other mods I made have little to do with the problem.

I'm going to yank the trans out again tomorrow.

Jim

 

[turbojimmy]

Well it works now, but only after CK swapped the entire transmission out. His concern over having everything just right is amazing. The trans is 2 years old but he gave me an 'off-the-shelf' unit to make sure there were no more problems.

I used the same Vigilante converter but did not do the pump mod, check ball mod nor install the restrictor in the cooler line.

I had the pump out of the old trans and while there was no sealant applied to the tube where it goes into the pump body, I don't see how it could be leaking. It's a very tight fit. There was a lot of sludge in the oil for something that only had 50 or so miles on it.

Jim

 

[Blazer406]

FWIW.... right, wrong, or indifferent.... I didn't do any of the mods either... they all make the converter lock much harder.... I figured out it would be harder on tranny parts if it locked any harder....

 

[turbojimmy]

FWIW.... right, wrong, or indifferent.... I didn't do any of the mods either... they all make the converter lock much harder.... I figured out it would be harder on tranny parts if it locked any harder....

The trans has lots of hard parts in it anyway but it locks up hard as-is (and did when I first put the trans in back in 2005). Something happened to it and the converter started slipping when locked under a load. That's when I had Chris put the pump tube in and remove the checkball. That's what led to this thread. It slipped in 3rd and 4th and just felt sloppy overall. The converter locked fast and hard though.

Now, with a 'stock' pump arrangement the converter still locks hard though slower (by maybe 1/2-3/4 of a second) than with the pump mods. I also have all my gears back and it drops into gear more solidly. I suspect something was awry with the pump kit installation on the prior version of this arrangement. I'm just glad I have the car back on the road.....just in time for the crappy Northeast weather.

Jim