Hi. I am looking for any and all feedback I can get pertaining to the following problems I am
encountering within the transmission in my project. It's a '67 concourse project with a 390 and C6 auto, completely, professionally rebuilt by someone working with Ford transmissions for over 30yrs.
Engine and trans are installed in car and "functioning"... i.e. it starts and runs, yard drives
and sounds good. Car has not been driven on highway or at a speed greater than 10mph.
The following problems have been encountered:
1) Shifting into ANY gear (drive, 1st, 2nd, reverse) will ALWAYS (a) "chirp" both
rear tires and then (b) stall the engine, unless you signficantly increase rpm prior to shifting
into gear.
I have double and triple checked that the rpm at idle is normal and that the C6 has good
vaccum. I have no idea why the thing is SO aggressive when shifting into any gear....just
chirps the tires and then immediately stalls. The only way you can get the car to stay running
in gear is to lay on the throttle before you shift into a gear. This yields a drag-racing start and
is obviously dangerous and undesirable. The professional who performed the rebuild said to drive the
car at highway speeds and it will fix itself. That doesn't sound like a reasonable fix to me.
What could be going on? Help!?
2) The car sat for approximately 3 months without being started. NO leaks of any kind were
noted during this time. Then, without being touched or started or moved in anyway, the transmission
dumped about 1qt of trans fluid onto the shop floor. I have verified it is leaking out of the
pan at the junction between the filler tube and pan. Again, no leaks for months and then 1qt
of fluid onto the floor. I suspected the fluid must have leaked back out of the torque converter
in order to all of a sudden force the fluid level in the pan to be above the filler tube level at
the case. To verify this theory, I simply started the engine and let it run for a few minutes
(to pump fluid back into the converter). No leaks detected in the two weeks since then. What gives!?
I spoke with the professional who performed the rebuild and all he said was to drive the car at
highway speeds and it will fix itself. That doesn't sound like a reasonable fix to me. Help!?
The leak is common though fixable.
The converter slowly bleeds fluid back into the pan - in about three to 12 weeks it will fill the pan to the o-ring seal on the dipstick tube or the pan gasket and leak out. (the o-ring is rarely replaced and the tube can become deformed and the pan gasket ages fast and the seal surface becomes distorted by over-tightening)
The repair is either simple or a bit more complicated but not difficult in either process.
The simplest fix is:
If the dipstick tube goes into the case; drain the transmission and remove the dipstick tube. Replace the o-ring and coat it with a thin layer of Loc-Tite 518. Install the tube and forget it.
If the dipstick goes into the pan:
Drain the transmission and remove the pan. Clean and straighten the pan lip with a hammer and a piece of round bar 3/4" in diameter. Flatten the holes and level the pan rail. (use a straight edge to check it) Coat your new pan gasket on both sides with a thin (.010") film of Loc-tite 518. Place the gasket on the pan, two to four locating studs on the transmission and install the pan finger tight with all the bolts coated with (you guessed it) Loc-tite 518. Tighten the pan bolts to 10 inch pounds and then to recommended torque or until the gasket begins to deform. Fill the transmission to halfway between the ADD and FULL marks with the engine running in PARK. Run through all the gears a few times and check the fluid level again - topping it off to half way between the ADD and FULL marks.
That will solve your leak problem. You can also just start and run the engine once a week to keep the oil in the converter.
As to the hard shifting; without knowing exactly what was done to the transmission, valve body and governor it is difficult to know what to address. However, if you check some pressures it would be helpful. You can check the state of tune - make sure the idle is correct and if there is a dashpot that it is adjusted properly. Tell me, what speed does the C6 shift at? 1-2 and 2-3 You could measure the modulator pin (while you have the transmission drained)if the shifts are hard and late.
