Packard Forum Index » V-8 (1955-56)

Lately I have experienced that my direct drive clutch fails to engage, but only after having driven the car for some time(15 minutes/5 miles). Could hotter ATF causing this? The ATF has been used approx 7-8.000 miles.
Any suggestions to remedy this?

Tom

Fluid level full? Heat exchanger working?

I doubt the viscosity of the fluid would degrade over those miles unless it has been "cooked". Does it smell burned? If so I'd change the fluid and clean the filter screen. And in either case I'd run the pressure tests.

Thanks for your answer.
The fluid does not smell burned and level OK. I cannot understand why the clutch is working when the engine and transmission are "cold", ie untill the car has been driven 5-10 miles. WRT pressure tests, there's at least one problem. When you say "Twin Ultramatic" in an Norwegian workshop, they look as they have fallen from the moon.
Tom

As the fluid warms up of course the viscosity and consequently the pressure drops. As far as transmission shops in Norway, I'm knowing nothing but all automatics, Ultramatic included, run on hydraulic pressure so the principle should be familiar to them. As to the specifics, the shop manual has very detailed instructions on how to read the pressures and what they should be.

Good luck, keep us posted on your progress.

Don't know how handy you are in the shop but measuring the DD pressure is one of the easier to do. The port is right on the bottom in full view. You would need to pick up a brass fitting for the US NPT port size which might not be readily available in Norway but everything else should be easy to come by. You might even be able to supply the needed items and a trans shop would do the work.

The DD port and most of the others are threaded standard 1/8" NPT so buying that hose adapter would take care of most readings. There are a couple of odd ones though. The one that might be harder to adapt is the pump pressure which they suggest reading in conjunction with DD. That port thread is 3/4-16 so you would need an adapter from that to the 1/8 hose fitting.

You could pick up some adapters, hose and a couple of gauges in different ranges to measure expected pressures plus a bit of safety margin and cobble your own set together.

This isn't a recommendation and maybe someone here has heard a similar fix.

One old timer I knew said to accelerate at full throttle in High range as fast as the car would go then release the throttle. I think this is safer with the straight 8 than the V-8, but apparently one of the valves is hanging up. Not at all uncommon and equally common is for the problem to go away by itself.

Thank you all.
As I was afraid of, it seems most probable I can't avoid doing a pressure test. I will have serious trouble getting hold of inch threads in Norway (everything is in metric) for making my own test set. Does anyone perhaps know where I can purhcase a complete test set, or the items necessary to make my own.
Anyway it will not be an urgent matter, as the Clipper has soon to be tucked away for the winter.

Tom

I have only rebuilt one UltraMatic, and that was for a 56J, in the late 1980s, under John Bryan's tutelage. (For those who remember him, in So-Cal.) Rebuild & overhaul, to me, are not synonymous. To me, rebuild means, "make new again" and I tried hard to do so. Anything not well within spec was tossed, modern clutch materials were used, and every upgrade John suggested was installed, i.e. steel backed, perforated bushings, steel parking lever, etc.. I even incorporated a couple of my own, i.e. a BMW motorcycle seal for the shift-shaft.

When I re-installed the transmission, all was well, and leaks were minimal. Only problem was (as yours), it would not stay in DD, and the more it warmed up, the worse the problem. Long story short, it turned out to be the rear pump, if I recall correctly. Even though the pump was well within spec, with the feeler gauge, per the Shop Manual.

So, of course try all the simple stuff first, but you might wind up coming back to the pump.

Once fixed, I chickened out at 120 MPH, in doing a top speed test on a 2-lane desert road in So-Cal. My point being, the DD holds up well, when operating properly.

Last I heard, the car is still on the road with the guy I sold it to, up in Maryland. But he is getting older, and drives it very little now days, so his wife says.

En route to its hibernaculum my Clipper decided to let the direct drive clutch engage. The clutch now seems to work ok, after having sped? the car with 70 MPH on the clock. I also added approx 1 litre ATF.
However I still want to do a pressure test, so I now know what to write on top of my list to Santa.
Thank you for your help.
Tom

Maybe a piece of debris lodged in the valve body or governor? I've also read that similar problems can result from incorrect/uneven torque on the valve body retaining bolts so perhaps in the spring you'll want to pull the pan, clean it and the filter screen, and check the torque on the valve body bolts.