Packard Forum Index » V-8 (1955-56)

I wonder if any of you wizards out there can give me a hint or two as to the most probable cause(s)to what`s happening in the transmission:
The selector is in H or D, and as long as there is a load on the trans everything works fine. When the load is very little and I press the gas pedal just a bit down the direct drive clutch? slips? with a little rumble, and I have to press the gas pedal further down to get some load avoiding the slip.
Otherwise everything seems to be ok, except a minor fluid leak from what I can see occurring from the bell housing after driving minimum 20 miles.

Thanks
Tom

It's not the load that is the issue, but some internal hydraulic pressures in the trans that respond to how far the throttle is pushed. From what you describe, yours are set too low.

You will need to adjust the throttle linkage to the trans as per the shop manual (page 53, Ultra section)--I believe Howard posted all the latest and best information on that subject.

Further, I find that as the transmissions wear and age, the throttle pressures need to be set higher, that is the little sliding link described in the literature needs to be set slightly further rearward than what is described. You might want to mark your existing location with a bit of tape before you start making adjustments.

Note that on a 56, the rod should be in the middle hole of the three on the lever.

Ross
Thanks for the prompte answer.

Perhaps my nose is too big, but could you please tell me where the "little sliding link" is situated?

Tom

I'll give Ross a hand answering the slider question. The slider is that little piece connected to the angled rod near carburetor shown in the middle of threaded section of linkage.

The measurement given is a preliminary starting adjustment so if yours is really way off from that, other things will affect it and would need to be looked at. Means starting from scratch so for your purpose now, as Ross mentioned, just loosen the nut on rear side of slider only and move it a little bit rearward. Re-tighten both nuts in new position.

Also check out the bulletin they mention and the other article I posted earlier with the last adjustment procedure S-P published.

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Thanks for advice.

Tom

This note is for Ross:

I did a little research. Type A (the original trans oil) is essentially AW32/46 hydraulic dyed red. Type F is a little heavier on average.

If the problem with these old transmissions is worn parts (especially gear to body and gear to cover clearances) then why not try mixing Dexron (AW32 plus modifiers) with AW68 hydraulic to increase line pressures?

The specs for these transmission oils are all over the map and I suspect things like Lucas are just heavy hydraulic oils that increase line pressure.

For what it's worth, your symptoms don't sound too different than my carb problem produced. Just without the rumble. So, if the excellent advice from Howard & Ross doesn't solve the problem, you might look at the carb.

Thanks for info Tim. As these things wear, thicker is better up to a point.

As you know, the most common (first)complaint with with these things is a weak direct clutch. In my experience this is most often due to excess clearance between the input shaft and the front pump bushing. A little thicker oil by means of chemistry or by just keeping it cooler will make a dodgy trans good for quite a while.

I agree, the Lucas is just a thick oil with perhaps a dose of friction modifiers; that being said, it has granted a reprieve to several transmissions I've tried it on. It will however not raise the dead!

When you are in D, it starts out on the low range band. Does your slippage occur after the trans shifts to the high range clutch. The difference between H and D is that H starts off with the high range clutch. Worn bushes on the front pump or wear on the high range clutch input shaft will directly affect the pressure available to the high range clutch piston and direct drive clutch piston (The direct drive clutch and high range clutch pistons, upon Governor operation, are fed from the rear pump but use the same front pump bushings to enter the shaft to pressurise the High range and Direct drive clutches). It doesn't take much wear either, around 10 thou is very noticeable.
Using a higher viscosity trans fluid should improve the high range and direct drive clutch pressure, but will almost certainly alter the operation and characteristics of various shuttle and differential pressure valves in the valve bodies. In other words ......It may not be all good news, but probably worth a try. PT.

Thanks for all your info.

Peter Packard.
As far as I can understand my slippage always occur with the direct drive clutch.

Tom