Packard Forum Index » Post-War (1946-54)

When I start off in High (H) in my car when it gets to the point where the torque convertor should lockup there is a rattling noise. When I let off on the gas, it will stop rattling and lock up. Also, this appears to be worse when the trans is warm.

Any thoughts and inputs would be greatly appreciated.

That could be the classic "mooing" sound that many put up with when the direct drive clutch friction material is hard and glazed and slips until the clutch finally grabs. The more noticeable effect when hot could be some worn bushings and a slight loss of apply pressure due to the thinner fluid when it is hot.

In addition, the 51 has the first generation DD assembly with the large diameter clutch plate and large splined piston. The piston could cock slightly and spines were then known to catch and sometimes slow down application which resulted in the 52 introduction of the second generation assembly. That change resulted in a smaller plate and a piston that was supported by 4 sort of flexible straps. It could be that rather than a loss of pressure, the 51 piston assembly might be hindering a quick application and the chatter if the torque converter is the original.

Until the DD clutch starts to slip all the time and the owner decide it needs a rebuild most put up with the noise and control it by letting off the gas and reducing power until the clutch fully applies.

For anyone with the "mooing" there have been reports that changing to a fluid made by B&M called Trick Shift helps the noise and application problem because of additives that soften and change the friction characteristics of the clutch plate. It may also have some additives that can keep the viscosity of the fluid more consistent when hot. I have not tried it so those that have can say whether the higher cost of the fluid is worth the change.

The rattling noise is the pump selector valve shuttling. This was supposed to be reduced by the small pressure sphere mounted on the bell housing. These are often missing nowadays. Later transmissions used small sheet metal check valves in the valve body to eliminate the issue.

You can makes sure you have your pressure sphere, change over to the later check valves, or just live with it. There was a service counselor on the subject, probably in 1951.

I have never heard the valve rattle noise because all my cars have had the second type valve. Ross has probably nailed it if your unit is all original.

The article on the check valve is in this SC and there is a followup in another SC about adding a small hole in one of the new type valves because it could introduce a buzzing noise when the car is in reverse. I believe there is another followup article about clearance. Some of the valves were a bit oversize so some of the valve bodies could be a bit tight causing the new valves to bind.packardinfo.com/xoops/html/downloads/SC/SC-VOL26NO4.pdf

Thanks for the help. It looks like it should be a probably remain in the car. This looks like it is a relatively easy fix since the trans can remain in the car.

Offhand, any ideas where the newer valve can be purchased?

If I think what is being talked.about is that U spring steel valve I think I have some marty.

Rikki,

Please look at the SM which is linked above. If the configuration looks the same, please PM what you want for $$ including shipping.

Thanks

Marty.

The ones I have are slightly different. But. Ross will know if they will work.

The 56 uses a flat and hh56 said that the ones with a dimple might be stude. Made. Later production.

I'll search them out. And take a picture .. No cost. If I had my 400 alignment was right I would drive up and deliver..

Also. Gerry.. Psw.. Would have used ones... In sure...

Several questions I have about what is in the SM.

1) When I remove the valve body are there any springs or parts between it and where it is bolted that might fall or pop loose.

2) When I separate the valve bodies what precautions do I need to take as far as things flying loose.

Thanks in advance for your help.

55.56 plate drops off.

51 that's a Ross question

Here is what they look like. Some have a small hole. Others a dimple.

This is either a 55 or 56..

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