Transmission trouble - still

[bigdaddykarl]

This weekend I crafted a new wiring harness for the transmission circuit, but I'm still having the same trouble: slipping out of high gear, and the occasional missed shift. What's my next plan of attack?

I'm thinking of a fluid change and perhaps a kerosene bath for the Fluid Drive unit.

Question: is the fluid drive separate from the transmission? If so, how does one add fluid to it, I can't seem to find an access panel that would accomodate this...

[Guest imported_BaronvonR]

The access panel for the fluid unit is located on the transmission hump on the passenger side of the car, under the front floormat. There are two panels there, you want the one that is higher up on the hump. It is also the smaller of the two. Once opened you will have to rotate the drum until the fill plug is at the top. Remove the plug being VERY careful not to drop it and rotate the drum to the 6 o'clock position to drain it. It is very messy so be sure you have a large pan to collect the oil. If the unit was full there should be about 8 quarts there. Once drained you can rotate back to top and fill the unit to the top with transmission fluid....run that through a short run and redrain it......this will help to clean the drum out of all of the sludge. If it comes out very black, you may want to do this twice. Then refill the unit. Here is where the differences come...I use 10W non detergent oil, others say use hydraulic oil or tractor fluid....its your choice. Like I said I use 10W non-detergent and do just fine.

IF the unit was not completely full it may have lead to your slipping problem. Either way, it is a good idea to have fresh oil in the unit. Oh and to answer your other question, on my 50 and 51 the transmission oil is seperate from the fluid drive unit, the transmission takes 10W non-detergent as well...only a few pints there instead of 8 quarts.

BvR

[bigdaddykarl]

Thank you, Baron, this is great info.

I checked the fluid in the FD unit several weeks ago, and it was full, to my surprise. This is what redirected me into thinking that my problem was electrical rather than due to low fluid level. However, this fluid is almost certainly the original fluid in the car, as I know my father has never done anything with it in the 35 years he owned it, and my great-grandfather most likely never changed it while he owned it, not with only 40,000 miles. Might this fluid be not doing it's job properly causing my slip?

Where might I find the fill plug on the transmission? Will that be apparent when I crawl under the car?

[55PackardGuy]

Karl,

Some thoughts:

A fluid coupling that's not working properly may feel like it's "slipping" as engine RPM will be high for a given speed. If the coupling is full of whatever kind of fluid, it is not likely to give a sensation of slipping. Changing the fluid is a great way to make sure the coupling is giving you all the power it can, and also helps maintain the seal. You're lucky it isn't leaking as the seal can give problems. Even thought the coupling is full now, it's very likely it has been "topped up" once or twice, with who-know-what oily substance. Once you've flushed it and filled it, you've pretty much eliminated the coupling as a problem. The clutch plate itself can also wear out and slip, but they usually last a long time in these cars because the coupling takes up the clutch "slip" when starting out from a stop.

If your trans is jumping out of high gear as you describe, that would not be a coupling issue but a transmission or solenoid problem. Is the "slipping out of high" problem perhaps the trans "kicking down" or is it completely out of gear? The lack of upshifts with this type of transmission CAN be a problem with engine RPM. If it's too high, the trans won't shift right when you let off the gas. Familiarizing yourself with exactly how the semi-automatic transmission is supposed to behave could help you localize the problem.

I have a feeling that once you change out the fluid in the coupling and the trans, you will notice a big difference. I wonder if someone put heavy gear oil in the trans? That would be a real performance-killer. While you're at it, be sure to service the differential too if you haven't already.

[bigdaddykarl]

Guy,

The car is definitely falling out of gear, and though now it may sound like I've been barking up the wrong tree, I feel it's a good idea anyway to flush and refill the FD unit.

But onto what sounds to be more likely the gremlin, the gearbox. 10W ND oil, drain and refill. Then onto the solenoid, what can I do to check that to make sure it is operating correctly? How is is affixed to the gearbox? Does it just screw into the side of the tranny?

Thanks so much. I'm learning a tremendous amount.

-Karl

[55PackardGuy]

Definitely flush and fill that fluid drive! I didn't mean to imply otherwise, just that it's not likely to be the culprit in your shifting and jumping out of gear problems. The solenoid system is a mystery to me. Sorry I can't help you there. (They didn't have the semi-auto trans in '47.) You're onto some good information about it both here and on P15-D24, so just keep asking around. I take it you have the shop manual with repair information and wiring schematics? Between that and some practical know-how from others familiar with the system, you'll get it.

[bigdaddykarl]

I have good news: the problem is solved. Somewhere along the line, I was distracted into thinking that my problem was in the Fluid Coupling, perhaps because everything I read in my service manual and the resources I downloaded from the Imperial Club pointed me in that direction. Then I thought about electrical problems, since everything began when I jumped the car via 12-volt.

The REAL culprit? Low on transmission fluid.

That's it. Real simple. Runs like a champ now.

And not only does she run and shift smooth, she's got a brand new wiring harness for the tranny. Despite that not being the present problem, it would have been in the near future.

I had an idea, and perhaps y'all could point me in the right direction, I was considering donating my old wiring harness to one of the harness companies so that they could dissect it and replicate one for their product line. Who would you suggest? Does one company cater more to their customers than the other? I like to reward those who go out of their way to help others...

[Guest imported_BaronvonR]

I sent my transmission wiring harness to Rhode Island Wiring , Att. Mark

They have been great to do business with and they make exact copies of what you send them, so the color coding is correct as well as the guage of the wire and the proper ends as well.

I told them to toss it once they were finished with it as I had no use for it.

BvR

[55PackardGuy]

It seems that it's usually something simple, but I wouldn't rule out your problem being partly electrical. At least you have that buttoned up good now--and you learned a lot! (So did I.) I'm not sure how you go about changing the transmission oil, but since it was low and is probably old, you might want to still do that. I'll just re-state the obvious: any fluids in an old car, from the gas tank to the radiator, are suspect and need to be flushed and replaced.

[bigdaddykarl]

I did change the transmission oil, and it NEEDED it. Quite sludg-y and burnt. I parked the car on a banked decline, putting the drainplug at the southern-most point of the transmission to get as much of the fluid out as possible, then refilled with 30W ND. Then I parked the car on flat ground and added fluid until it was level with the fill opening. Worked like a charm. Next up is the Fluid Drive unit, followed by the rear end. What fluid is recommended for the rear end? I don't have my manual handy, and even if I did, I'm quite sure it will state some product that is no longer in production.

[55PackardGuy]

Nothing very special about the diff lube. From P15-D24:

"Drain and refill, SAE 90 above average -10 Degrees, SAE 80 for average below -10 degrees."

I would think good old 80/90 from the parts store would be fine.